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Cochlear Implant Outcomes in Cochlea Nerve Aplasia and Hypoplasia
Abstract
Objective:
To assess cochlear implant (CI) outcomes, and factors affecting outcomes, for children with aplasia/ hypoplasia of the cochlea nerve. We also developed a new grading system for the nerves of the internal auditory meatus (IAM) and cochlea nerve classification.
Study design:
Retrospective patient review.
Setting:
Tertiary referral hospital and cochlear implant program.
Patients:
Children 0 to 16 years inclusive with a CI who had absent/hypoplastic cochlea nerve on magnetic resonance imaging (MRI).
Intervention:
Cochlear implant.
Main outcome measures:
MRI, trans-tympanic electrical auditory brainstem response, intraoperative electrical auditory brainstem response, Neural Response Telemetry, Categories of Auditory Perception score, Main mode of communication.
Results:
Fifty CI recipients (26 males and 24 females) were identified, 21 had bilateral CIs, 27 had developmental delay. MRI showed cochlea nerve aplasia in 64 ears, hypoplasia in 25 ears, and a normal nerve in 11 ears. Main mode of communication was analyzed for 41 children: 21 (51%) used verbal language (15 speech alone, 5 speech plus some sign, 1 bilingual in speech and sign), and 20 (49%) used sign language (10 sign alone, 9 sign plus some speech, 1 tactile sign). Seventy-three percent of children used some verbal language. Cochlea nerve aplasia/ hypoplasia and developmental delay were both significant factors affecting main mode of communication. Categories of Auditory Performance scores were available for 59 CI ears; 47% with CN Aplasia (IAM nerve grades 0-III) and 89% with CN hypoplasia (IAM nerve grade IV) achieved Categories of Auditory Performance scores of 5 to 7 (some verbal understanding) (p = 0.003).
Conclusion:
Our results are encouraging and useful when counselling families regarding the likelihood of language outcomes and auditory understanding.
... Specifically, patients with cochlear nerve deficiency (CND; ie, aplasia or hypoplasia) typically achieve poorer outcomes following cochlear implantation as they are less likely to respond to electrical stimulation. 1,11 Traditionally, computerized tomography (CT) of the temporal bone was the imaging modality of choice for the evaluation of CI candidates because of the ease and short duration of the study allowing for reduced anesthesia exposure as well as the ability to visualize the cochlea and round window. Patients with a narrow internal auditory canal (IAC) or stenotic cochlear aperture visualized on CT are suspected of having CND. 12 However, since the cochlear nerve cannot be directly visualized on CT, abnormalities may be missed, and previous studies suggest that accurate evaluation of cochlear nerve status can only be obtained via magnetic resonance imaging (MRI). ...
... Confirming cochlear nerve status in the affected ear is of paramount importance because it influences intervention options and informs counseling regarding postimplant outcomes in children with SSD. 11,19 Additionally, there is a significant unmet need in terms of timely and effective intervention for children with SSD who have CND. ...
... Prior studies have shown that children with CND who receive a CI are more likely to rely on sign language than listening and spoken language and that those with a hypoplastic nerve have better speech understanding than those with an aplastic nerve. 1,11 Based on these results, we argue that the presence of a cochlear nerve in children with SSD must be confirmed via MRI as part of the workup for determining cochlear implant candidacy. Less than one-third of children in this cohort underwent imaging before 18 months of age. ...
Objective:
This study aimed to assess the prevalence of cochlear nerve deficiency (CND) in a cohort of pediatric patients with single-sided deafness (SSD). A secondary objective was to investigate trends in intervention and hearing device use in these children.
Study design:
Case series with chart review.
Setting:
Pediatric tertiary care center.
Methods:
Children ages 0 to 21 years with SSD (N = 190) who underwent computerized tomography (CT) and/or magnetic resonance imaging (MRI) were included. Diagnostic criteria for SSD included unilateral severe-to-profound sensorineural hearing loss with normal hearing sensitivity in the contralateral ear. Diagnostic criteria for CND included neuroradiologist report of an "aplastic or hypoplastic nerve" on MRI or a "stenotic cochlear aperture" on CT.
Results:
The prevalence of CND was 42% for children with CT only, 76% for children with MRI only, and 63% for children with both MRI and CT. Of the children with MRI and CT, there was a 90% concordance across imaging modalities. About 36% of children with SSD had hearing devices that routed sound to the normal hearing ear (ie, bone conduction hearing device/contralateral routing of signal), while only 3% received a cochlear implant. Approximately 40% did not have a hearing device. Hearing device wear time averaged 2.9 hours per day and did not differ based on cochlear nerve status.
Conclusion:
There is a high prevalence of CND in children with SSD. Cochlear nerve status should be confirmed via MRI in children with SSD. The limited implementation and use of hearing devices observed for children with SSD reinforce the need for increased support for early and continuous intervention.
... Researchers have proposed a new IAM nerve grading system and a CN classification system based on MRI findings of nerves within the IAM and the size of the CN, which is as follows: grades 0-III indicated zero, one, two, and three nerve bundles observed in the IAM, respectively (aplasia); grade IV, four nerve bundles in the IAM with a hypoplastic CN (hypoplasia); and grade V, four nerve bundles in the IAM with a normalsized CN and normal position of the nerves (normal). The results of a study showed that patients with IAM grade IV had higher auditory performance than those with grades 0-III (11). Although recent studies have evaluated the validity of this CN classification system to predict outcomes of CI in patients with CND, the results have been varied, and few studies have reported longitudinal results on auditory and speech performance after CI (12,13); this is important because children with CND might have delayed auditory and speech development. ...
... MRI images, particularly parasagittal IAM views, provided precise information regarding the CN. Children with CND were divided into four groups according to the IAM nerve grading system (11). All imaging findings were assessed by a senior experienced radiologist. ...
... This means that the absence of the CN according to MRI did not always represent the absence of the anatomical CN and that some CN fibers may be present within the vestibular or facial nerve. In our study, the performance of children with CND was not related to the IAM nerve grade, which was based on the MRI findings of nerves within the IAM and the size of the CN; this finding is not in line with those of some reports (11,12,22), which concluded that better performance was related to more nerve bundles. The reason for this difference might be the small sample size of these studies, as many were case reports wherein statistical analysis was not conducted. ...
Objectives
This study aimed to examine the audiological characteristics and validity of predicting outcomes of cochlear implants (CIs) in children with cochlear nerve deficiency (CND) based on the internal auditory meatus (IAM) nerve grading system.
Methods
The audiological characteristics of 188 ears in 105 children diagnosed with CND were analyzed based on the IAM nerve grading system. In addition, 42 children with CND who underwent CI were also divided into four groups based on the system, and their auditory and speech performance at baseline (preoperative) and 6, 12, and 24 months after CI were analyzed and compared with those of the control group (n = 24) with a normal cochlear nerve (CN) and CI.
Results
The audiological test results showed no significant differences among the four CND groups in terms of elicited rates of distortion product otoacoustic emission (DPOAE) (p = 1.000), auditory brainstem response (ABR) (p = 0.611), and cochlear microphonic (CM) (p = 0.167). Hearing in the CND IV group was significantly better than that in the CND I group (p < 0.05). In children with CI, the auditory and speech performance of the control group was significantly higher than all CND groups from 6 to 24 months (p < 0.05) and 12 to 24 months (p < 0.05), respectively. Meanwhile, there were no significant differences between each pair group in the four CND groups (p > 0.05).
Conclusion
Children with CND, including those in whom the CN was not visualized by MRI, can benefit from CI. Additionally, the IAM nerve grading system could not predict the outcomes of CI in children with CND.
... This might be due to the limited amount of CN and auditory stimulation. The results were consistent with those of previous studies (Birman et al., 2016;Han et al., 2019). ...
... Clinically, the IAC diameter, BCNC diameter, area of the VCN, area ratio of the VCN to the FN, and IAC grade can indirectly determine the condition of the CN. These parameters have been reported to predict the effect of CI after surgery (Shelton et al., 1989;Minami et al., 2015;Birman et al., 2016;Wei et al., 2017;Chung et al., 2018;Han et al., 2019). The maximum diameters of the IAC and the BCNC can indirectly reflect the number of CN fibers and are generally considered to be related to CND (Shelton et al., 1989;Chung et al., 2018). ...
... Oblique plane sagittal IAC views can show four nerve bundles on MRI: CN, FN, inferior vestibular nerve, and superior vestibular nerve (Govaerts et al., 2003). Since it is difficult to distinguish the CN from other nerves on MRI, Birman et al. (2016) suggested classifying CND according to the number of nerves within the IAC. From oblique plane sagittal IAC views on MRI, IAC nerve grades 0, I, II, and III represent no nerves, one, two, and three nerve bundles, respectively, inside the IAC. ...
Cochlear nerve deficiency (CND) is often associated with variable outcomes of cochlear implantation (CI). We assessed previous investigations aiming to identify the main factors that determine CI outcomes, which would enable us to develop predictive models. Seventy patients with CND and normal cochlea who underwent CI surgery were retrospectively examined. First, using a data-driven approach, we collected demographic information, radiographic measurements, audiological findings, and audition and speech assessments. Next, CI outcomes were evaluated based on the scores obtained after 2 years of CI from the Categories of Auditory Performance index, Speech Intelligibility Rating, Infant/Toddler Meaningful Auditory Integration Scale or Meaningful Auditory Integration Scale, and Meaningful Use of Speech Scale. Then, we measured and averaged the audiological and radiographic characteristics of the patients to form feature vectors, adopting a multivariate feature selection method, called stability selection, to select the features that were consistent within a certain range of model parameters. Stability selection analysis identified two out of six characteristics, namely the vestibulocochlear nerve (VCN) area and the number of nerve bundles, which played an important role in predicting the hearing and speech rehabilitation results of CND patients. Finally, we used a parameter-optimized support vector machine (SVM) as a classifier to study the postoperative hearing and speech rehabilitation of the patients. For hearing rehabilitation, the accuracy rate was 71% for both the SVM classification and the area under the curve (AUC), whereas for speech rehabilitation, the accuracy rate for SVM classification and AUC was 93% and 94%, respectively. Our results identified that a greater number of nerve bundles and a larger VCN area were associated with better CI outcomes. The number of nerve bundles and VCN area can predict CI outcomes in patients with CND. These findings can help surgeons in selecting the side for CI and provide reasonable expectations for the outcomes of CI surgery.
... Furthermore, children with CND required a significantly longer time to obtain appropriate programming stimulation parameters than those with normal-sized cochlear nerves, which also impaired their perception ability in the post-implantation period. Furthermore, a previous study showed that approximately half of the children with CND have concurrent neurological deficits, which would also affect their cognitive function and learning ability (Birman et al. 2016). ...
... In an analysis of 22 participants with CND treated with CIs, only one child used oral communication (Buchman et al. 2011). In the study by Birman et al.,15 out of 51 children with CND used speech language alone, and half of them used sign language (Birman et al. 2016). In addition, approximately half of the children with cochlear nerve aplasia had SIR scores of 3 or less after more than 5 years of CI use, indicating that it was difficult for them to express intelligible connected speech even after an extended CI use. ...
Objectives:
In this study, we aimed to (1) review the long-term outcomes of cochlear implantation in children with cochlear nerve aplasia and (2) compare the development of their auditory and speech abilities to children with normal-sized cochlear nerves.
Design:
This is a retrospective case-control study. Patients who underwent unilateral cochlear implant (CI) surgery in a tertiary referral center from September 2012 to December 2018 were reviewed. The study group included 55 children with cochlear nerve aplasia diagnosed using preoperative images. The control group included 35 children with normal-sized cochlear nerves. The control group did not differ from the study group in terms of age at implantation, pre-implantation auditory and speech abilities, or the electrode array type. Cochlear implantation outcomes were assessed using a test battery, including the Categories of Auditory Performance (CAP) score, the Speech Intelligibility Rating (SIR) score, behavioral audiometry, and closed- or open-set speech recognition tests. The development of auditory and speech abilities was compared between the two groups using Generalized Linear Mixed-effect Models.
Results:
The mean duration of CI usage was 4.5 years (SD = 1.5, range = 2.0 to 9.5) in the study group. The CAP scores, SIR scores, and aided hearing thresholds improved significantly post-implantation in the study group, but were significantly poorer than those in the control group. Generalized Linear Mixed-effect Models showed that the development of CAP and SIR scores was significantly slower in the study group than in the control group. Overall, 27 (49%) children with cochlear nerve aplasia had some degree of open-set speech perception skills, but the monosyllabic and bisyllabic word recognition rates were significantly lower than those in the control group.
Conclusion:
For children with cochlear nerve aplasia, auditory perception and speech intelligibility continued to improve in the long-term follow-up, but this progress was significantly slower than in children with normal-sized cochlear nerves. Most children with cochlear nerve aplasia could obtain the ability of common phrase perception and understanding simple spoken language with consistent CI usage and auditory rehabilitation.
... [16] These patients usually do not benefit from cochlear transplants due to the absence of the cochlear nerve. [28] Vestibular anomalies were seen in 11 ears (4.6%) out of the total population and this corresponds to 68.8% of inner ears anomalies. These anomalies include cystic dilatation, hypoplasia, and aplasia. ...
... [12,23,27] Likewise, groups of patients with isolated semicircular anomalies in theory are well suited for cochlear implants as the nerve is usually present. [28] The internal auditory canal (IAC) anomalies were seen in 3 ears (1.3%) out of 240 ears and correspond to 18.8% of the inner ear anomalies. These anomalies include ectasia and atresia. ...
... Previous studies have demonstrated that CN deficiency, one of the major inner ear anomalies, is seen in approximately 1-5.3% of children with bilateral sensorineural hearing loss (SNHL) [3,4]. CN deficiency, especially CN aplasia, has traditionally been considered a contraindication for cochlear implantation (CI) because the outcomes of CI are largely associated with CN status [5][6][7], even in the severely malformed cochlea [8]. In most patients, the presence of the CN and modiolus can be confirmed using magnetic resonance imaging (MRI) [8]. ...
... In particular, the retrospective nature of this study may limit the generalizability of our results. Although all cochlear implant recipients underwent comprehensive preoperative evalua-tion, including check-ups for significant global or neurodevelopmental delays, potential confounding factors that may affect language outcomes after CI, such as delayed developmental delay and comorbidities (e.g., medical syndromes) [5,29], were not completely evaluated in our cohort, which might have biased the results of this study. Our main findings depended on CAP score for the assessment of auditory development in subjects. ...
Background and Objectives: Many otologists face a dilemma in the decision-making process of surgical management of patients with cochlear nerve (CN) aplasia. The goal of this study is to provide fresh evidence on cochlear implantation (CI) results in patients with CN aplasia. Materials and Methods: We scrutinized functional outcomes in 37 ears of 21 children with bilateral CN aplasia who underwent unilateral or bilateral CI based on cross-sectional and longitudinal assessments. Results: The Categories of Auditory Performance (CAP) scores gradually improved throughout the 3-year follow-up; however, variable outcomes existed between individuals. Specifically, 90% of recipients with a 1-year postoperative CAP score ≤1 could not achieve a CAP score over 1 even at 3-year postoperative evaluation, while the recipients with a 1-year postoperative CAP score >1 had improved auditory performance, and 72.7% of them were able to achieve a CAP score of 4 or higher. Meanwhile, intraoperative electrically evoked compound action potential was not correlated with postoperative CAP score. Conclusions: Our results further refine previous studies on the clinical feasibility of CI as the first treatment modality to elicit favorable auditory performance in children with CN aplasia. However, special attention should be paid to pediatric patients with an early postoperative CAP score ≤1 for identification of unsuccessful cochlear implants and switching to auditory brainstem implants.
... These results suggest, similarly with the BCNC, that the CN has an effect on the eCAP thresholds only when it is abnormally small or absent [12]. This study population included no patients with aplastic or hypoplastic CN, but in future it would be valuable to investigate eCAP thresholds in different kind of anomaly ears because earlier studies show that the hearing rehabilitation results are highly variable and generally worse in ears with CN hypoplasia when compared to normal [29,30]. In CI recipients with CN aplasia the hearing outcomes are even worse, 65% of the patients use sign language as their main mode of communication [30]. ...
... This study population included no patients with aplastic or hypoplastic CN, but in future it would be valuable to investigate eCAP thresholds in different kind of anomaly ears because earlier studies show that the hearing rehabilitation results are highly variable and generally worse in ears with CN hypoplasia when compared to normal [29,30]. In CI recipients with CN aplasia the hearing outcomes are even worse, 65% of the patients use sign language as their main mode of communication [30]. ...
Objectives
A narrow bony cochlear nerve canal (BCNC), as well as a hypoplastic and aplastic cochlear nerve (CN) have been associated with increased electrically-evoked compound action potential (eCAP) thresholds in some studies, suggesting poorer neural excitability in cochlear implantation. Also, in large cochleae the extent of activated spiral ganglion neurons with electrical stimulation is less than in smaller ones. However, a detailed description of the relationship between eCAP thresholds for a lateral-wall electrode array and dimensions of the inner-ear structures and internal auditory canal (IAC) is missing.
Design
The study subjects were 52 pediatric patients with congenital severe-to-profound hearing loss (27 females and 25 males; ages 0.7–2.0 years; 1.0 ± 0.3 years, mean ± SD) implanted bilaterally with Cochlear Nucleus CI422, CI522, or CI622 implants with full insertion of the Slim Straight electrode array. Diameters of the cochlea and the BCNC as well as the widths and heights of the IAC and the CN were evaluated from preoperative computed tomography and magnetic resonance images. These anatomical dimensions were compared with each other and with the patients’ intraoperative eCAP thresholds.
Results
The eCAP thresholds increased from the apical to basal direction (r = 0.89, p < 0.001). After sorting the cochleae into four size categories, higher eCAP thresholds were found in larger than in smaller cochleae (p < 0.001). With similar categorization, the eCAP thresholds were higher in cochleae with a larger BCNC than in cochleae with a smaller BCNC (p < 0.001). Neither IAC nor CN cross-sectional areas affected the eCAP thresholds. Correlations were found between cochlea and BCNC diameters and between IAC and CN cross-sectional areas (r = 0.39 and r = 0.48, respectively, p < 0.001 for both).
Conclusions
In the basal part of the electrode array, higher stimulation levels to elicit measurable neural responses (eCAP thresholds) were required than in the apical part. Increased eCAP thresholds associated with a larger cochlear diameter, but contrary to the earlier studies, not with a small size of the BCNC or the CN. Instead, the BCNC diameter correlated significantly with the cochlea diameter.
... If the results of any test suggest the cochlear nerve is present, CI can still be offered. In a recent investigation, it was observed that following CI, approximately 50% of individuals with cochlear nerve aplasia and 90% of those with CN hypoplasia achieved some degree of speech understanding [63]. ...
Cochlear implantation has emerged as a transformative intervention in addressing profound hearing loss, offering a paradigm shift in auditory rehabilitation for individuals with restricted auditory function. Throughout its history, the understanding of contraindications for cochlear implant (CI) surgery has evolved significantly. This review comprehensively analyzes the chronological advancements in the understanding of CI contraindications, examining studies conducted from historical timelines to the present. Recent research has revealed significant developments in the field, prompting a reevaluation of established criteria and resulting in expanded indications for CI. The chronological evolution of contraindications underscores the transformative nature of the field, offering potential improvements in outcomes and enhancing the quality of life for individuals with profound hearing loss. In conclusion, this narrative review emphasizes the dynamic nature of the field, where the reevaluation of contraindications has created new opportunities and broader indications for CI. The emerging prospects, including improved outcomes and enhanced quality of life, hold promise for individuals with profound hearing loss.
... Unilateral CND was diagnosed based on internal auditory meatus (IAM) magnetic resonance imaging (MRI). All of our SSD subjects due to CND had IAM nerve grades of I (only one nerve visible in the IAM), II (two nerves visible in the IAM), or III (three nerves visible in the IAM), according to the previously proposed IAM grading system [9]. We only included children who had never used hearing aids or other hearing assistance technology. ...
This study aimed to compare the development of pronunciation in South Korean preschoolers with unilateral cochlear nerve deficiency (CND) to that of age-matched preschoolers with normal hearing, a topic that has not been explored previously. In a retrospective analysis, 25 preschoolers with unilateral CND who had undergone a speech evaluation battery, including a pronunciation and vocabulary test, were enrolled. Utilizing the Urimal Test of Articulation and Phonation and customized language ability tests, pronunciation and vocabulary were assessed. The subjects’ speech evaluation scores were converted into age-adjusted z-scores using normal controls’ data. While vocabulary performance was within normal limits, their average pronunciation z-score was -2.90, significantly lower than both the zero reference point and their vocabulary z-scores. None of the subjects scored above average in pronunciation. Thirteen patients were recommended for articulation therapy, seven were considered as potential candidates for this therapy, and the remaining five were within normal limits. There was no observed correlation between the development of pronunciation and vocabulary. Notably, some subjects’ pronunciation scores did not improve, even after serial follow-up during their preschool years. Despite typical vocabulary development, preschoolers with unilateral CND exhibit significant delays in pronunciation. These findings emphasize the necessity for vigilant monitoring of their language development.
... The outcomes of cochlear implantation (CI) are closely related to the integrity of the cochlea and cochlear nerve (CN) [82,83]; therefore, CI is traditionally contraindicated in cases of cochlear nerve deficiency (CND), such as CN aplasia and hypoplasia. CND could be detected by computed tomography (CT) measurement of the inner auditory canal (IAC) and cochlear nerve bone canal (BCNC) diameters [84]. ...
Single sided deafness (SSD) is characterized by significant sensorineural hearing loss, severe or profound, in only one ear. SSD adversely affects various aspects of auditory perception, including causing impairment in sound localization, difficulties with speech comprehension in noisy environments, and decreased spatial awareness, resulting in a significant decline in overall quality of life (QoL). Several treatment options are available for SSD, including cochlear implants (CI), contralateral routing of signal (CROS), and bone conduction devices (BCD). The lack of consensus on outcome domains and measurement tools complicates treatment comparisons and decision-making. This narrative overview aims to summarize the treatment options available for SSD in adult and pediatric populations, discussing their respective advantages and disadvantages. Rerouting devices (CROS and BCD) attenuate the effects of head shadow and improve sound awareness and signal-to-noise ratio in the affected ear; however, they cannot restore binaural hearing. CROS devices, being non-implantable, are the least invasive option. Cochlear implantation is the only strategy that can restore binaural hearing, delivering significant improvements in speech perception, spatial localization, tinnitus control, and overall QoL. Comprehensive preoperative counseling, including a discussion of alternative technologies, implications of no treatment, expectations, and auditory training, is critical to optimizing therapeutic outcomes.
... Implantable hearing technology has become a life-transforming prosthesis for children born with severe-to-profound sensorineural hearing loss. An auditory brainstem implant (ABI) has been developed for individuals with hearing loss who cannot benefit from a cochlear implant (CI) due to neurofibromatosis type 2 (NF2), cochlear nerve deficiency or aplasia, temporal bone fracture, and severe inner ear malformation or ossified cochlea [1][2][3]. ABI bypasses the cochlea and auditory nerve and offers users the opportunity to perceive and recognize auditory information through electrical stimulation of the cochlear nucleus [4,5]. A highly experienced multidisciplinary team is required for ABI surgery, device programming, and auditory rehabilitation of children who will use ABI. ...
Background:
Previous studies observed that children with cochlear implants (CIs) have poor language, working memory, and attention skills. The ability to perform cognitive tasks, such as attention and memory, plays a crucial role in the academic achievement and everyday life of children with hearing impairment.
Purpose:
This study aimed to evaluate and compare the effects of age at the time of implantation and bilateral hearing on cognitive skills, such as language development, working memory, and selective attention, among children with CIs.
Research design:
Language skills were assessed using the Test of Language Development-Primary: Fourth Edition (TOLD-P:4), working memory using the Visual-Aural Digit Span Test-Revised Form (VADS-R), and selective attention skills using the Stroop Test TBAG Form.
Study sample:
A total of 58 participants, comprised of 21 children with early unilateral CIs (before 2 years), 18 children with late unilateral CIs (after 2 years), and 19 children with bilateral CIs, between the ages of 6 and 9 years, were included in the study.
Data collection and analysis:
According to the age at the time of implantation and whether or not the participant was unilaterally or bilaterally implanted, the mean scores, percentage values, and resultant scores of the participants were calculated using the Mann-Whitney U test. The number of repeated backward digit spans for the VADS-R test, completion times, number of errors and corrections for the Stroop test, raw scores, scaled scores corresponding to raw scores at the relevant age, descriptive terms for the TOLD-P:4 test, and within-group comparisons for all tests were examined.
Results:
There were significant differences in language, working memory, and attention skills between individuals with early and late unilateral cochlear implantation, whereas there were no significant differences in many subtests between individuals with early unilateral and bilateral cochlear implantation.
Conclusion:
These findings demonstrate the importance of early cochlear implantation and bilateral hearing on the development of cognitive processes, such as language development, selective attention, and memory skills, which are important factors that may contribute to children's academic performance and overall success.
... diameter and number of nerve fibers) are significant predictors of hearing and speech outcomes in cochlear implant candidate patients with cochlear nerve deficiency. 14 On the other hand, a study by Birman et al. 15 proved otherwise, a considerable number of children (73.2%, 30/41 children) with cochlear nerve deficiency were able to use some spoken language. In their study, 89% and 47% of the children with hypoplastic and aplastic cochlear nerve had a fair CAP index (score of 5-7), respectively. ...
Background: Data on hearing and speech outcomes following cochlear implantation in prelingual sensorineural hearing loss (SNHL) children with cochlear nerve hypoplasia, especially in Indonesia, is still limited. Purpose: To evaluate the hearing and speech function of prelingual SNHL children who had undergone cochlear implantation. Method: A retrospective cross-sectional study was conducted on 28 children who had undergone cochlear implantation procedures at the Department of Otorhinolaryngology and Head and Neck Surgery, Dr. Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia, for more than 12 months. The hearing and speech function of the subjects were assessed using the modified Categories of Auditory Performance (CAP-II) and the speech intelligibility rating (SIR) scores. Result: Children with cochlear nerve hypoplasia showed an increase in CAP-II and SIR scores after using cochlear implants for more than 12 months (versus pre-surgery, high CAP score [≥5]: 89.3% [25/28 children] vs 3.6% [1/28 children] and high SIR score [≥3]: 82.1% [23/28 children] vs 7.1% [2/28 children]; both p<0.001). Post-operative CAP-II and post-operative SIR scores were highly positively correlated (r=0.705, p<0.001). Type of cochlear nerve hypoplasia (unilateral vs bilateral) were not significantly associated with post-operative CAP-II and SIR scores (p=0.382 and p=0.459, respectively). Conclusion: Prelingual SNHL children with cochlear nerve hypoplasia may still get the benefit from cochlear implantation, as shown by a remarkable improvement in hearing and speech function as assessed with the CAP-II and SIR scores. Keywords: auditory perception, cochlear implants, cochlear nerve hypoplasia, prelingual sensorineural hearing loss, speech intelligibility
... Cochlear implantation has been performed in these patients with varying outcomes in speech perception and auditory stimulation [21••]. This is an area of ongoing re-evaluation, as several studies have demonstrated meaningful improvement in sound perception following CI in carefully selected patients [26][27][28]. Auditory brainstem implantation is ultimately considered when CI cannot be performed [24,29]. ...
Purpose of the Review
Cochlear implantation is an effective treatment for severe to profound hearing loss in children and adults. Computed tomography, radiography, and magnetic resonance imaging are essential throughout the cochlear implantation process. The purpose of this article is to provide a comprehensive review of the uses of imaging at each stage of cochlear implantation, highlighting clinically relevant points for the radiologist as well as areas of ongoing exploration.
Recent Findings
The newer, evolving nature of the field presents many rising opportunities for collective imaging-based research. For example, standardization and improvement in imaging indications and protocols, as well as methods of cochlear duct length measurement and reporting have potential to significantly contribute to refinements in cochlear implant placement and detection of complications.
Summary
In collaboration with audiologist and otolaryngologists, radiologists serve an important role in the initial work up of cochlear implant candidates, pre-operative surgical planning, and post-operative monitoring.
... Presence of a cochlear nerve, even if hypoplastic, has been shown to provide meaningful benefit after CI in some bilateral HL patients. 64,65 Moreover, expectations for patients with comorbidities like developmental delay should be established from the beginning. Family dynamics need to be probed adequately in the preoperative visits to minimize limited device usage. ...
Objective:
Cochlear implants (CIs) for single-sided deafness (SSD) have only been approved for patients 5 years and older despite data supporting that younger children can also benefit from implantation. This study describes our institution's experience with CI for SSD in children 5 years and younger.
Study design:
Case series with chart review.
Setting:
Tertiary referral center.
Methods:
A case series with chart review identified 19 patients up to age 5 years who underwent CI for SSD between 2014 and 2022. Baseline characteristics, perioperative complications, device usage, and speech outcomes were collected.
Results:
The median age at CI was 2.8 (range, 1.0-5.4) years, with 15 (79%) patients being below age 5 at implantation. Etiologies of hearing loss were idiopathic (n = 8), cytomegalovirus (n = 4), enlarged vestibular aqueduct (n = 3), hypoplastic cochlear nerve (n = 3), and meningitis (n = 1). The median preoperative pure-tone average was 90 (range, 75-120) and 20 (range, 5-35) dB eHL in the poor and better hearing ears, respectively. No patients had postoperative complications. Twelve patients achieved consistent device use (average, 9 h/d). Three of the seven who were not consistent users had hypoplastic cochlear nerves and/or developmental delays. The three patients with available preoperative and postoperative speech testing showed significant benefits, and five patients with available postoperative testing demonstrated speech recognition in the implanted ear when isolated from the better ear.
Conclusion:
CI can safely be performed in younger children with SSD. Patients and families accept early implantation, as evidenced by consistent device use, and derive notable benefits in speech recognition. Candidacy can be broadened to include SSD patients under age five years, particularly individuals without hypoplastic cochlear nerves or developmental delay.
... www.nature.com/scientificreports/ have concurrent neurological deficits 10 . In the clinic, cochlear implant programming for children with CND remains a stiff issue. ...
It is challenging to program children with cochlear nerve deficiency (CND) due to limited auditory and speech abilities or concurrent neurological deficits. Electrically evoked compound action potential (ECAP) thresholds have been widely used by many audiologists to help cochlear implant programming for children who cannot cooperate with behavioral testing. However, the relationship between ECAP thresholds and behavioral levels of cochlear nerve in children with CND remains unclear. This study aimed to investigate how well ECAP thresholds are related to behavioral thresholds in the MAP for children with CND. This study included 29 children with CND who underwent cochlear implantation. For each participant, ECAP thresholds and behavioral T-levels were measured at three electrode locations across the electrode array post-activation. The relationship between ECAP thresholds and behavioral T-levels was analyzed using Pearson’s correlation coefficient. The results showed that ECAP thresholds were significantly correlated with behavioral T-levels at the basal, middle, and apical electrodes. ECAP thresholds were equal to or higher than the behavioral T-levels for all tested electrodes, and fell within MAP’s dynamic range for approximately 90% of the tested electrodes. Moreover, the contour of the ECAP thresholds was similar to the contour of T-levels across electrodes for most participants. ECAP thresholds can help audiologists select stimulation levels more efficiently for children with CND who cannot provide sufficient behavioral response.
... There is also a wide range of speech perception skills among pediatric CI users. Performance ranges from no awareness of environmental sounds to conversation without lipreading (Galvin et al., 2007;Birman et al., 2016;Han et al., 2019). A comprehensive understanding of how electrical stimulation is encoded and processed in the auditory nerve (AN) may help explain a portion of the variability in CI outcomes and provide insight for improving speech perception for CI patients. ...
Cochlear implants (CIs) provide acoustic information to implanted patients by electrically stimulating nearby auditory nerve fibers (ANFs) which then transmit the information to higher-level neural structures for further processing and interpretation. Computational models that simulate ANF responses to CI stimuli enable the exploration of the mechanisms underlying CI performance beyond the capacity of in vivo experimentation alone. However, all ANF models developed to date utilize to some extent anatomical/morphometric data, biophysical properties and/or physiological data measured in non-human animal models. This review compares response properties of the electrically stimulated auditory nerve (AN) in human listeners and different mammalian models. Properties of AN responses to single pulse stimulation, paired-pulse stimulation, and pulse-train stimulation are presented. While some AN response properties are similar between human listeners and animal models (e.g., increased AN sensitivity to single pulse stimuli with long interphase gaps), there are some significant differences. For example, the AN of most animal models is typically more sensitive to cathodic stimulation while the AN of human listeners is generally more sensitive to anodic stimulation. Additionally, there are substantial differences in the speed of recovery from neural adaptation between animal models and human listeners. Therefore, results from animal models cannot be simply translated to human listeners. Recognizing the differences in responses of the AN to electrical stimulation between humans and other mammals is an important step for creating ANF models that are more applicable to various human CI patient populations.
... In participants with measurable ECAP responses, the percentage of electrodes with ECAP, ECAP thresholds, maximum amplitude, and slopes of the ECAP I/O function varied greatly among individual children, highlighting the variability of cochlear nerve function in individuals with cochlear nerve aplasia. Such variability may contribute to the various outcomes of cochlear implantation observed in children with cochlear nerve aplasia (Birman et al., 2016;Ehrmann-Muller et al., 2018;Yousef et al., 2021). Furthermore, in our patients, the slope of the ECAP I/O function and the maximum ECAP amplitude tended to gradually decrease, while the ECAP threshold tended to gradually increase, from basal to apical electrodes. ...
This study aimed to assess the function of the cochlear nerve using electrically evoked compound action potentials (ECAPs) for children with cochlear implants who were diagnosed with cochlear nerve aplasia and to analyze the correlation between preimplantation imaging results and ECAP responses. Thirty-five children diagnosed with cochlear nerve aplasia based on magnetic resonance imaging (MRI) were included. Preimplantation MRI and high-resolution computed tomography (HRCT) images were reconstructed, and the width of the bone cochlear nerve canal (BCNC), the diameter of the vestibulocochlear nerve (VCN), and the diameter of the facial nerve (FN) were measured. ECAP input/output (I/O) functions were measured at three electrode locations along the electrode array for each participant. The relationship between ECAP responses (including ECAP threshold, ECAP maximum amplitude, and slope of ECAP I/O function) and sizes of the BCNC and VCN was analyzed using Pearson's correlation coefficients. Our analysis revealed that ECAP responses varied greatly among individual participants. Overall, ECAP thresholds gradually increased, while maximum amplitudes and ECAP I/O function slopes gradually decreased, as the electrode location moved from the basal to the apical direction in the cochlea. ECAP responses exhibited no significant correlations with BCNC width or VCN diameter. The ratio of the VCN to FN diameters was significantly correlated with the slope of the ECAP I/O function and the maximum amplitude. BCNC width could not predict the function of the cochlear nerve. Compared with the absolute size of the VCN, the size of the VCN relative to the FN may represent an indicator for predicting the functional status of the cochlear nerve in children diagnosed with cochlear nerve aplasia based on imaging results.
... Based on radiologic evidence, all included patients were confirmed with cochlear nerve aplasia or hypoplasia according to the IAC nerve grading system described by Birman et al. 11 The evaluation of nerves within the IAC was performed with the reconstructed parasagittal MR images. Figure 1 shows MRI findings of patient number 6 with cochlear nerve aplasia (a) and patient number 2 with cochlear nerve hypoplasia (b). ...
Template provided by: "posters4research.com" TABLE 2. Comparison of preoperative and aided postoperative (using CI processors) audiologic measures. NR indicates no response; SAT, speech awareness threshold; CI, cochlear implantation. • Audiological benefit has been found in subjects 1, 2 (hypoplasia group). They showed comparable results as regarding aided hearing threshold and SRT. • Subject 3 showed relative improvement in comparison to the other 4 subjects in the aplasia group. • There was a significant improvement in threshold levels for speech perception as a result of cochlear implantation and there was no significant effect of group on the results (p> 0.05). FIG. 3. Average stimulation levels for THR (left panel) and MCL (right panel) are shown for three groups of patients. Individual stimulation levels are also shown for THR and MCL in lower panels. THR indicates thresholds; MCL, maximum comfortable level; SD,standard deviation. • Results revealed a significantly higher stimulation levels for the aplasia in comparison to the control group (P<.01). • On the other hand, stimulation levels for the hypoplasia group were not significantly different than those obtained in either group (P>.05). • The group with nerve deficiency exhibited a large variability in stimulation levels in comparison to that in the control group. The relations between IAC diameter and THR (A) and MCL (B) • There was a significant negative association between THR and the diameter of the IAC such that larger IAC diameter resulted in lower thresholds (r =-.75, n=7, p = .05). • This relationship was not found significant for MCL (r =-.72, n=7, p = .06) but a similar trend can be seen. Cochlear nerve deficiency is one of the known causes of congenital sensorineural deafness. 1,2 The prevalence of cochlear nerve deficiency has been reported to be as high as 18% in pediatric patients diagnosed with congenital sensorineural hearing loss .3 It is generally agreed that a cochlear nerve is considered hypoplastic if it is smaller in diameter than that of the facial nerve in the midportion of the internal auditory canal or aplastic if it is absent as confirmed by imaging findings. 2,4
... Implantable hearing technology has become a life-transforming prosthesis for children born with severe-to-profound sensorineural hearing loss. An auditory brainstem implant (ABI) has been developed for individuals with hearing loss who cannot benefit from a cochlear implant (CI) due to neurofibromatosis type 2 (NF2), cochlear nerve deficiency or aplasia, temporal bone fracture, and severe inner ear malformation or ossified cochlea [1][2][3]. ABI bypasses the cochlea and auditory nerve and offers users the opportunity to perceive and recognize auditory information through electrical stimulation of the cochlear nucleus [4,5]. A highly experienced multidisciplinary team is required for ABI surgery, device programming, and auditory rehabilitation of children who will use ABI. ...
Purpose
This study aimed to assess the written language skills of children with auditory brainstem implants (ABI).
Methods
In this study, 15 children (from second to eighth grades) with ABI were evaluated for their written language abilities using a written expression skill assessment form. Five different features of written expression points were scored and analyzed, yielding a composite score for written expression skills.
Results
This study showed that all children with ABI needed more verbal cues than spontaneously written samples. Moreover, these children used short and simple sentences with limited vocabulary and repeated words and sentences. Furthermore, these children were deficient in writing an introduction, the body, and the conclusion paragraphs and could not write events in a logical sequence.
Conclusions
The written language skills of children with ABI depend on age at implantation, duration of implant use, and additional handicaps. Written expression skills in children with ABI are highly complex skills. The findings highlight the importance of ABI during the critical language development period and the enhancement of training programs for written language skills in children who underwent ABI.
... In particular, the retrospective nature of this study may limit the generalizability of our results. Potential confounding factors that may affect language outcomes after CI, such as developmental delay and comorbidities such as medical syndromes, 5,25 were not completely evaluated in our cohort, which might have biased the results of this study. Furthermore, the lack of a control group, comprising patients with CN aplasia without CI, may weaken our ndings. ...
Many otologists face a dilemma in the decision-making process of surgical management of patients with cochlear nerve (CN) aplasia. Currently, evidence on cochlear implantation (CI) outcomes in patients with CN aplasia is limited. We scrutinized functional outcomes in 37 ears of 21 children with bilateral CN aplasia who underwent unilateral or bilateral CI based on cross-sectional and longitudinal assessments. The Categories of Auditory Performance (CAP) scores gradually improved throughout the 3-year follow-up; however, variable outcomes existed between individuals. Specifically, the majority of recipients with a 1-year postoperative CAP score ≤1 remained steady or achieved awareness of environmental sounds, while recipients with early stage hearing benefit had markedly improved auditory performance and could possibly discriminate some speech without lipreading. Meanwhile, intraoperative electrically evoked compound action potential was not correlated with postoperative CAP score. The dynamic range between T and C levels remained unchanged. Our results further refine those of previous studies on the clinical feasibility of CI as the first treatment modality to elicit favorable auditory performance in children with CN aplasia. However, special attention should be paid to pediatric patients with an early postoperative CAP score ≤1 for identification of unsuccessful cochlear implants and switching to auditory brainstem implants.
... Furthermore, magnetic resonance imaging (MRI) of the temporal bone revealed a bilateral CA with a dilated vestibule and a malformed semicircular canal located posteroinferiorly to the IAC, both of which contain two nerves that may represent both the facial and cochleovestibular nerves with larger sizes in the left ear ( Figures 1-2 show the axial and the parasagittal view of both sides, respectively). According to the IAC grading system, grade II represents the presence of nerves in the parasagittal plane on both sides [10]. ...
Inner ear malformation is a congenital anomaly associated with prelingual sensory neural hearing loss in the pediatric population. This is a case report of bilateral radiologically diagnosed cochlear aplasia in a child who underwent unilateral left cochlear implantation with audiological results at one-year follow-up after surgery. Sixteen months after the cochlear implantation surgery, the child could produce 200 words and say a sentence with two words. In certain cases of inner ear malformation, the subgrouping of cystic cavity can be difficult and should not delay the trial of cochlear implant provided an acceptable anatomical appearance of the inner ear with cochleovestibular nerve existence and a proper electrode used for implantation.
... In situations in which the cochlear or vestibulocochlear nerve is missing or cut, cochlear implantation is contraindicated since no auditory sensations can be transmitted (71). However, in cases of congenital auditory nerve hypoplasia or aplasia, there is still a possibility of auditory stimulation with cochlear implants (72). The resolution of magnetic resonance imaging, even with 3 Tesla devices, may be too low to detect the presence of the nerve fiber entering the modiolus. ...
Cochlear implantation is currently the only routinely used treatment to restore the function of a sense organ. Cochlear implantation was first introduced in 1961 but it was only with the advent of multichannel devices in the early 1990s, that it has gained an established place for the treatment of severe to profound hearing loss.
There are multiple positive and negative factors predicting the hearing outcomes after implantation. One of the most significant negative predictive factors is possible inner ear trauma induced by the surgery. There are mainly two mechanical factors which determine the occurrence of inner ear trauma: electrode design and the insertion technique.
The cone-beam computed-tomography (CB-CT) has recently become a more popular modality in the postoperative evaluation of the results of electrode insertion. The insertion depth, extracochlear electrode contacts, electrode tip fold overs and gross trauma can be easily detected with CB-CT. Even though CB-CT can also quite reliably recognize scala dislocation up to the second turn of the cochlea, a more detailed evaluation of trauma such as elevations or ruptures of the basilar membrane is not possible. Fusion imaging has emerged as a promising modality for achieving a more precise evaluation of electrode positioning and trauma assessment after cochlear implantation.
In the first two studies of this thesis, the insertion results of two newly introduced electrodes were evaluated in freshly frozen temporal bones. The first study was a radiological and histological study that evaluated the Slim Modiolar electrode TM (Cochlear corporation, Sydney, Australia) (SME) which represents a completely new design of a modiolar (precurved) electrode. It was designed to have a more reliable structure and to achieve better hearing preservation than its predecessor, a stylet- type modiolar electrode. In this evaluation study, we detected one scala dislocation in 20 temporal bones inserted with SME. The image fusion with pre- and
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postoperative CB-CT was performed in all of the 20 TBs. The image fusion proved to be an accurate method in the evaluation of electrode placement inside cochlea.
The second study investigated the insertion characteristics of a new lateral wall electrode, the SlimJ –electrode (Advanced Bionics, Valencia, USA) in 11 freshly frozen temporal bones. In this study, we found one scala dislocation in postoperative fusion imaging. These results are comparable to other temporal bone studies with modern straight electrodes. SlimJ is reasonably predictable with respect to the insertion results, however the final evaluation of insertion properties will require clinical verification.
In the third study, we retrospectively analyzed hearing preservation results with SME in 17 clinical patients (18 ears) with low frequency residual hearing. The preliminary results (mean follow-up 582 days) showed a good hearing preservation rate. There were no total hearing losses and seven patients could use electric-acoustic stimulation (EAS). This study revealed significantly more favorable hearing preservation rates than reported for other stylet-type modiolar electrodes.
Fusion imaging was validated with histological samples in the first temporal bone study made with SME. The fusion imaging provided a fast and accurate method for the evaluation of the electrode placement. We observed no significant difference between histologic or fusion imaging measurements.
The fourth study investigated a new fusion imaging technique which may enable better visualization of the basilar membrane. Visualization was conducted in twelwe temporal bones. The perilymph was evacuated from the scalae prior to pre-operative CB-CT. The frozen temporal bone (TB) was initially immersed in Ringer solution to rehydrate both scalae. Insertion was made after rehydration followed by post- operative CB-CT imaging. With the application of this technique, it was easier to detect the individual anatomy of the basilar membrane and a reliable trauma assessment was possible beyond the second turn of the cochlear partition.
The new studied electrode designs provide not only more atraumatic but also more predictable insertion results. The fusion imaging is an accurate method making possible a more detailed electrode placement evaluation as compared to postoperative CB-CT alone. It also represents a fast and cost-effective method for evaluating insertion results in temporal bone studies
OBJECTIVE: To identify associations between cochleovestibular anatomy findings and hearing outcomes found in children with imaging evidence of an absent or hypoplastic cochlear nerve treated with cochlear implantation (CI).
STUDY DESIGN: retrospective review.
SETTING: Cochlear implant program at tertiary care center.
METHODS: A retrospective review was performed to identify children with imaging evidence of cochlear nerve absence or deficiency who underwent CI evaluation. High-resolution 3-dimensional T2-weighted magnetic resonance imaging in the oblique sagittal and axial planes were reviewed by a neuroradiologist to identify cochleovestibular anatomy. Hearing was assessed pre and postoperatively with Speech Perception Category scores.
RESULTS: Seven CI recipients were identified (n = 10 ears) who had bilateral severe to profound sensorineural hearing loss with lack of auditory development with binaural hearing aid trial and imaging evidence of cochlear nerve aplasia/hypoplasia. All ears had 2 nerves in the cerebellopontine angle (100%, n = 10), half of the ears had evidence of 2 or less nerves in the internal auditory canal (IAC). All children showed large improvement in speech perception after CI.
CONCLUSION: Our experience with CIs for children with absent or hypoplastic cochlear nerves demonstrates that CI can be a viable option in select patients who satisfy preoperative audiological criteria. Radiological identification of a hypoplastic or aplastic cochlear nerve does not preclude auditory innervation of the cochlea. CI recipients in this subgroup must be counseled on difficulty in predicting postimplantation language and speech outcomes, and cautioned about facial nerve stimulation.
Objective
To examine the clinical characteristics and auditory performance of patients with CHARGE syndrome following cochlear implantation (CI), as well as the prognostic factors affecting auditory outcomes.
Study Design
Retrospective cohort.
Setting
Tertiary academic center.
Methods
A retrospective chart review was performed in patients with CHARGE syndrome who underwent CI from 2007 to 2022. The category of auditory performance (CAP) score was used to assess the CI outcomes, and factors that may affect the speech outcomes were also evaluated.
Results
In 14 children with CHARGE syndrome, 22 CIs were performed, 6 unilaterally and 8 bilaterally. The mean age at CI was 25.9 months (range: 10‐62). All patients had ear abnormalities and developmental delays, and cochlear nerve deficiency (CND) was present in all ears. At the last follow‐up (mean: 49.6 months), the mean CAP score improved significantly compared to the preoperative measure (from 0.36 ± 0.81 to 3.21 ± 1.70, P = .001), with 6 patients (42.9%) achieving a CAP score of 4 points or higher. However, between the unilateral and bilateral CI groups, the final CAP score or change in CAP score was similar. Factors including age, coloboma, and CND did not significantly affect speech outcomes (all P > .05).
Conclusion
Even though CHARGE syndrome features challenging anomalies, CI can be conducted safely and can offer effective contribution to significant speech improvement. Patients with CHARGE syndrome should be given the opportunity to undergo CI to maximize their audiological progress.
Objective:
To determine the utility of computed tomography (CT) and magnetic resonance imaging (MRI) in cochlear implant candidates.
Study design:
Retrospective case review.
Setting:
Tertiary referral hospital.
Patients:
A total of 207 cochlear implanted patients with CT and/or MRI.
Interventions:
N/A.
Main outcome measures:
Age versus abnormal radiologic findings, imaging abnormality versus postoperative outcomes, postoperative outcomes versus electrode design, Cambridge Cochlear Implant Protocol (CCIP) status for imaging abnormalities, sensitivity and specificity of CT and MRI for round-window/cochlear occlusion, and MRI for incomplete partitions.
Results:
A total of 207 patients with CT, MRI, or both were reviewed retrospectively. Less than half (15.5%) of CT scans had findings that might affect surgical intervention compared with 5.9% of MRI. No significant difference was found between children and adults for relevant imaging abnormalities (grade 4 or higher) with either CT (p = 0.931) or MRI (p = 0.606). CCIP status correlated with cochlear abnormalities (p = 0.040); however, only 46.2% of radiographic abnormalities on CT would be identified by these criteria. For detecting cochlear occlusion requiring surgical intervention, the sensitivity and specificity for CT were 40% (4 of 10; 95% confidence interval [CI], 12.16-73.76) and 95.73% (95% CI, 91.40-98.27), respectively. For MRI, the sensitivity and specificity were 33.33% (1 of 3; 95% CI, 0.84-90.57) and 96.97% (63 of 65; 95% CI, 89.32-99.63), respectively. There was no difference for postoperative AzBio scores for higher-grade imaging abnormalities (p = 0.6012) or for electrode designs (p = 0.3699).
Conclusions:
Significant radiographic abnormalities were relatively uncommon in cochlear implant patients on either CT or MRI at our single-center institution. If present, abnormal imaging findings rarely translated to management changes. CCIP status does not reliably predict which patients are likely to have abnormalities. Both MRI and CT have low sensitivity for round-window or cochlear occlusion, but detection likely leads to changes in surgical management.
Objectives:
Children with cochlear nerve deficiency (CND) have wide variability in outcomes with cochlear implant (CI) use. The current study aims to report a large cohort of pediatric CI recipients with CND and to evaluate for factors that may predict improved performance.
Methods:
The current study is a retrospective review of pediatric CI recipients with CND at a tertiary academic hospital. Variables including cochlear nerve status (hypoplasia vs aplasia), age at implantation, cochleovestibular malformation, bony cochlear nerve aperture, internal auditory canal aperture, and cognitive delay were evaluated for predictors of postoperative performance. A stepwise multinomial regression analysis was performed.
Results:
Forty-seven CI recipients (54 ears) were included in the analysis. A majority (59%) showed auditory capabilities with their CI. Twenty percent of recipients achieved some level of open-set speech perception with their CI. The regression analysis identified cochlear nerve status and cognitive delay as predictors of performance. CI recipients with cochlear nerve hypoplasia had significantly improved performance compared to those with aplasia (p = 0.003). Recipients with cognitive delay had more limited benefit than those without cognitive delay (p = 0.033).
Conclusions:
Children with CND can benefit from CI use, with outcomes spanning from non-use to development of spoken language. Predictive factors for improved performance include a lack of cognitive delay and cochlear hypoplasia rather than aplasia. These can be important considerations for parent counseling and decision making.
Background:
Infants and young children with vestibulocochlear nerve (VCN) hypoplasia/aplasia present with severe hearing loss and are candidates for cochlear implantation (CI). It is unknown whether vestibular function is related to CI outcome and if vestibular tests can guide the operation decision.
Aims/objectives:
Our aim was to describe the vestibular function in patients with VCN hypoplasia/aplasia before a possible CI.
Materials and methods:
Forty-two ears in 23 patients were tested between 2019 and 2022 with bone-conducted cervical vestibular evoked myogenic potentials (BCcVEMP), video head impulse test (vHIT) and miniice-water caloric test (mIWC).
Results:
All ears could be tested with at least one vestibular test and 83% could be tested with more than one method. Twenty-nine ears (61%) showed normal function with at least one method. The presence of a normal response to any test doubled the likelihood of a measured hearing threshold after CI, the best predictors being the BCcVEMP and vHIT (p < 0.05).
Conclusion:
Canal function may represent a predictor of auditive pathway integrity with a possible favourable audiological outcome after CI operation.
Significance:
Our results demonstrate high vestibular response rates suggesting a functioning pathway despite the radiological diagnosis.
Cochlear nerve deficiency in cochlear aplasia is a contraindication for cochlear implantation (CI) anticipating poor auditory response. Few authors have reported auditory outcomes even without nerves following CI. This study outlines the audiological outcomes of a patient in early childhood with cochlear aplasia and cochlear nerve deficiency who underwent CI. Auditory and speech-language development were assessed using the Categories of Auditory Performance (CAP) scale, Speech Intelligibility Rating (SIR) scale and Ling-6 sound test; at the time of switch-on, after 6 and 12 months of auditory verbal therapy. Significant differences across CAP, SIR and Ling-6 sound detection scores were noted, with the highest mean scores at the 12th-month postimplantation, indicating substantial improvement in auditory and speech-language skills. In cochlear aplasia cases, residual cochlear elements and nerve fibres cannot be ruled out. Our report emphasises the need for research, as this has the potential to impact the existing guidelines for CI candidacy.
Objective:
We examined how sociodemographic and audiologic factors affect receptive and expressive language outcomes in children with cochlear implantation.
Study design:
Retrospective cohort study.
Setting:
A hearing loss (HL) clinic at a tertiary center.
Methods:
Sociodemographic variables, HL characteristics, age at implantation, and receptive language scores (Preschool Language Scale and the Clinical Evaluation of Language Fundamentals) were collected from patients with congenital HL who received their first implant by 4 years old after January 1, 2007. t Tests, linear regression, Mann-Whitney, Cohen's d, and mediation analysis were used for descriptive statistics and hypothesis testing.
Results:
Among 79 patients, 42 (53%) were females, 44 (56%) under-represented minorities, and 56 (71%) had public insurance. At least 1 year after implantation, the median receptive language score was 69 (range 50-117). Females (p = .005), having private insurance (p = .00001), having a Cochlear Implant Profile score below 4 (p = .0001), and receiving their implant at or before 12 months of age (p = .0009) were significantly associated with improved receptive language outcomes. Insurance type had a significant effect on receptive language outcomes, independent from age at first implantation (total effect: coef = -13.00, p = .02; direct effect: coef = -12.26, p = .03; indirect effect: coef = -0.75, p = .47). Sociodemographic variables had large effect sizes, with the Cochlear Implant Profile score having the largest effect size (d = 1.3).
Conclusion:
Sociodemographic factors have a large impact on receptive language outcomes. Public insurance is associated with worse receptive language, not mediated by later age at implantation, suggesting that other factors primarily impact language outcomes in publicly insured children with cochlear implants.
Introduction:
Congenital unilateral sensorineural hearing loss (cuSNHL) carries potentially significant social, educational, and developmental consequences. Early diagnosis enables investigation, and consideration of options for management and early intervention, helping to mitigate the effects of hearing loss. Cochlear nerve dysplasia (CND) is a prominent cause of cuSNHL and may affect candidacy for cochlear implantation. Socioeconomic disadvantage may impact on a patient's family's capacity to participate in necessary intervention and follow-up.
Methods:
Infants with severe-profound cuSNHL referred to a large Australian quaternary pediatric center between October 2004 and December 2020 were retrospectively included. Audiometric and clinical data, and the presence of hearing loss risk factors were obtained from a prospectively collated database. In Australia MRI scans are provided free-of-charge to citizens and residents. MRI scans were reviewed to determine the status of the nerves within the internal acoustic meatus (IAM grade) along with attendance rates. Travel distance to the hospital was also calculated. Reasons for non-attendance at MRI were obtained from patient medical records and correspondence. Socioeconomic, educational, and occupational indices, and travel distances were obtained using patient residential postcodes with reference to Australian Bureau of Statistics data.
Results:
A total of 98 patients were reviewed, 64.3% (n = 63) of whom underwent MRI. The median age at diagnosis was 40 days (IQR 27). The prevalence of CND was 75% (n = 47). Importantly, there was no significant difference in the degree of hearing loss between IAM grades (F(4,57) = 1.029, p = 0.405). Socioeconomic indices were significantly lower in patients not attending MRI investigations compared with patients who did attend. Travel distance was not significantly different between the two groups.
Conclusion:
CND is a prominent cause of cuSNHL in Australian infants. MRI at a young age allows parent education regarding management options and timely intervention where indicated. Socioeconomic disadvantage significantly impacts on participation in further routine assessment of cuSNHL, potentially limiting management options for these children long term.
Preoperative auditory and electrophysiological evaluations of cochlear nerve deficiency (CND) before cochlear implantation (CI) are important for indication and side selection. However, the elicited rate of these tests for CND is limited. This chapter will review and share the results and experience of our center for audiological assessment and electrophysiology tests, such as the electrically evoked auditory brainstem response and electrically evoked auditory nerve compound action potential before and during surgery.
Cochlear implantation (CI) is the primary intervention for patients with severe to profound sensorineural hearing loss. The mechanism of CI is to convert acoustic signals into electrical signals, directly stimulate the spiral ganglion (SGN), and transmit the signal to the auditory brainstem through the cochlear nerve (CN) fibers within the vestibulocochlear nerve (VCN). In patients with cochlear nerve deficiency (CND), the auditory brainstem can receive limited stimulation due to the reduced absolute number of CN fibers and the insufficient number of SGN. CND was once considered a contraindication to CI. In recent years, numerous studies have shown that patients with CND could benefit from CI. With advances in CI techniques, more patients with CND combined with inner ear malformation (IEM) are also included as indications for CI. This chapter describes CI outcomes in patients with CND with or without IEM and describes the role of radiological and electrophysiological factors in predicting hearing and speech outcomes after CI.
Cochlear nerve deficiency (CND) may exist alone or be accompanied by other inner ear malformations (IEMs), especially cochlear malformation, which may pose a challenge for cochlear implantation (CI) surgery. The implant side and sequence selection need to be considered based on the different IEMs, CND classifications, and residual hearing. This chapter mainly introduces the CI surgical approaches, side selection, and electrode choice strategies for CND patients based on the clinical requirements and the experience at our center.
Objective:
Cochlear nerve deficiency (CND) is often combined with modiolar deficiency-type inner ear malformations, which cause variable cochlear implantation (CI) outcomes. We aimed to assess the postoperative development of auditory and speech perception in CND patients with modiolar deficiency-type malformations after 3 years of follow-up to determine the factors correlated with CI outcomes.
Methods:
Sixty-seven CND patients with modiolar deficiency-type malformations who underwent CI surgery were retrospectively reviewed. Modiolar deficiency-type malformations included common cavity (CC), cochlear hypoplasia (CH) (including CH-I and CH-II) and incomplete partition-I (IP-I). Categorical auditory performance (CAP) and the infant-toddler meaningful auditory integration scale (MAIS) were used to assess auditory ability. The speech intelligibility rating (SIR) and meaningful use of speech scale (MUSS) were used to assess the speech intelligibility of these CI patients. The CI outcomes were evaluated at 0, 12, 24 and 36 months after implant activation.
Results:
All patients demonstrated improvements in auditory ability and speech intelligibility after CI. There were no significant differences in CI outcomes at any time point according to the malformation type. The number of nerve bundles within the internal auditory canal (IAC) showed significant differences at 12, 24 and 36 months after CI (p < 0.05). Patients with one nerve bundle had relatively poor CI outcomes.
Conclusions:
CND patients with modiolar deficiency-type malformations showed continuous improvement in auditory and speech abilities after CI. Compared with malformations, the number of nerve bundles should be given more attention when selecting the side for CI.
In the early days of cochlear implantation (CI) surgery when the types of electrodes were limited and the etiology of sensorineural hearing loss (SNHL) was not well understood, the one-size-fits-all approach to CI held true like all other fields. However, in the era of personalized medicine, there have been attempts to associate CI performance with etiology of SNHL and to establish customized surgical techniques that can maximize performance according to individual cochlear dimensions. Personalized genomic-driven assessment of CI candidates and better understanding of genotype-phenotype correlations could provide clinically applicable diagnostic and prognostic information about questions such as who, how, and when to implant. Rigorous and strategic imaging assessments also provide a better insight into anatomic etiology of SNHL and cochlear dimensions, leading to individualized surgical techniques to augment CI outcome. Further, precision medicine approach to CI is not necessarily limited to preoperative planning but can be extended to either intraoperative electrode positioning or even decision of a timing of initial switch-on. In this review, we will discuss the implications of personalized diagnosis (both genetic and nongenetic) on planning and performance of CI in prelingual and postlingual SNHL.
Each child who is considered for, receiving and benefitting from a cochlear implant involves a team effort. The team includes the surgeon, paediatrician, audiologist, speech therapist, teacher of the deaf, social worker amongst others. This chapter deals specifically with the role of the surgeon. The aetiology, medical concerns and possible surgical problems are discussed.
Although the technical challenge has increased, along with the complexity of accessing the cochlea and electrode array insertion following the introduction of cochlear implant surgery in individuals with inner ear malformations and potentially useable residual natural hearing, CI surgery remains an operation that is generally safe and associated with very few lasting complications. Initial concerns about a negative effect upon balance function, especially in bilaterally implanted young children, have not materialized. In fact, there is increasing interest in the potential beneficial effect upon overall balance function. Likewise, the effect of cochlear implantation is more likely to be positive than to exacerbate intrusive tinnitus. Salvaging extruding receiver-stimulator packages continues to be a rare but significant challenge, which can often result in explantation (leaving the electrode array in the cochlea as a ‘spacer’) and reimplantation several months later when the inflammation has settled. It remains the responsibility of the operating surgeon to provide the patient and/or family with a detailed explanation of the potential risks of cochlear implantation, wherever possible illustrating the level of risk with their own surgical data.
Cochlear Implant (CI) has reached its maturity after 35 years of extensive research and developmental activities by the CI manufacturers in collaboration with clinicians from across the world. The impact resistance of the implant stimulator case plays a critical role in the reliability of the device, and over time, the ceramic-based stimulator case has transformed into a titanium-based stimulator case offering the highest impact resistance. Diametrically designed MRI-compatible implant magnet would enable trouble-free MRI procedures without the need for the surgical removal of the magnet. The intracochlear electrode arrays have seen a tremendous evolution more toward flexible and slimmer design enabling them to preserve the intracochlear structures. The audio processor is the one that has undergone continuous changes as it started from the body-worn type to a single unit processor recently. Signal processing strategies as well have seen changes over time which started with simultaneous multichannel analog stimulation to channel-specific sequential stimulation that resulted in power consumption and better hearing experience by the CI users.KeywordsAudio processorElectrode arrayImplant magnetImplant stimulator caseSignal processing strategy
For years, the term “Mondini dysplasia” was used to describe virtually every type of congenital inner ear malformation detected in imaging tests. More recently, histopathologic and imaging studies led to the description of several novel morphologic features, which were categorized into new groups according to morphologic patterns of the inner ear abnormalities. In addition, those new findings made possible to hypothesize potential pathophysiologic and embryogenic mechanisms involved in the genesis of each specific type of malformation. However, there are still obscure areas that still need to be better understood, such as quantitative and qualitative pathologic changes in the cellular, sensorial, and neural elements in the inner ear of patients with inner ear abnormalities. Therefore, histologic analysis of human temporal bones from patients who had inner ear malformations constitutes a tool of invaluable value. The clinical impact of past studies involving inner ear malformations is clear: today, cochlear implants or auditory brainstem implants are well indicated to treat hearing loss in patients with inner ear malformations, who were previously excluded from candidacy criteria. In the future, a broader understanding of yet obscure aspects of those malformations may increase even further the candidacy for those implants and create strategies for improved functional results. Thus, the objective of this chapter is to report, based on a review of the literature, otopathologic findings in human temporal bones from donors with inner ear malformations and to correlate the findings with embryogenic factors and their clinical implications.KeywordsHistopathologyEarInner earHumanCochleaVestibuleCochlear implant
Cochlear nerve (CN) hypoplasia presents a dilemma to the implanting teams in choosing the most appropriate habilitation method. In patients with CN hypoplasia (CN deficiency), cochlear nerve has a smaller diameter than normal and usually the results of cochlear implantation (CI) are not as good as in children with normal cochlea and CN. For better outcomes, they may need a contralateral auditory brainstem implantation (ABI) during follow-up. Therefore, it is important to diagnose this condition preoperatively and counsel the family accordingly. In this chapter cochlear nerve deficiency is defined and a classification of cochlear nerve abnormalities is presented. Indications for CI and ABI are provided. Certain cases that need CI and contralateral ABI (simultaneously or consecutively) are highlighted. Finally indications for bilateral ABI are provided.KeywordsInner ear malformationsCochleovestibular malformationsClassificationCochlear nerve hypoplasiaCochlear nerve deficiencyCochlear implantationAuditory brainstem implantation
Objectives/Hypothesis
To identify the imaging characteristics associated with better hearing outcomes found in cochleovestibular nerve (CVN) abnormalities treated with hearing aids and/or cochlear implantation (CI).
Study Design
Retrospective review.
Methods
A retrospective review was undertaken of 69 ears with CVN abnormalities seen on magnetic resonance imaging (MRI) treated at a tertiary referral academic center analyzing the clinical features, imaging characteristics, and hearing data. We searched for associations among the hearing and imaging data, hypothesizing that the imaging data was not a good indicator of hearing function.
Results
In univariable analysis of all those who underwent aided testing (hearing aid and CI), health status (P = .016), internal auditory canal (IAC) midpoint diameter (P < .001), and number of nerves in the IAC (P < .001) were predictors of positive hearing outcome. Modiolar abnormalities, cochlear aperture diameter, cochlear malformations, vestibular malformations, and nerves in the cerebellar cistern did not predict hearing outcome (P = .79, .18, .59, .09, .17, respectively). For patients who received CI, health status (P = .018), IAC midpoint (P = .024), and number of nerves in the IAC (P = .038) were significant. When controlling for health status, IAC midpoint diameter (P < .001) and number of nerves in the IAC (P < .001) remained significant. In our cohort, one out of the eight ears (13%) with Birman class 0 or 1 exhibited responses to sound compared to nine out of 13 ears (70%) with Birman class 2–4.
Conclusions
Current imaging modalities cannot accurately depict the status of the cochleovestibular nerve or predict a child's benefit with a CI. Cochlear implantation should be considered in children with abnormal cochleovestibular nerves.
Level of Evidence
3 Laryngoscope, 2022
Objectives:
This study aimed to determine the effect of advanced age on how effectively a cochlear implant (CI) electrode stimulates the targeted cochlear nerve fibers (i.e., the electrode-neuron interface [ENI]) in postlingually deafened adult CI users. The study tested the hypothesis that the quality of the ENI declined with advanced age. It also tested the hypothesis that the effect of advanced age on the quality of the ENI would be greater in basal regions of the cochlea compared to apical regions.
Design:
Study participants included 40 postlingually deafened adult CI users. The participants were separated into two age groups based on age at testing in accordance with age classification terms used by the World Health Organization and the Medical Literature Analysis and Retrieval System Online bibliographic database. The middle-aged group included 16 participants between the ages of 45 and 64 years and the elderly group included 24 participants older than 65 years. Results were included from one ear for each participant. All participants used Cochlear Nucleus CIs in their test ears. For each participant, electrophysiological measures of the electrically evoked compound action potential (eCAP) were used to measure refractory recovery functions and amplitude growth functions (AGFs) at three to seven electrode sites across the electrode array. The eCAP parameters used in this study included the refractory recovery time estimated based on the eCAP refractory recovery function, the eCAP threshold, the slope of the eCAP AGF, and the negative-peak (i.e., N1) latency. The electrode-specific ENI was evaluated using an optimized combination of the eCAP parameters that represented the responsiveness of cochlear nerve fibers to electrical stimulation delivered by individual electrodes along the electrode array. The quality of the electrode-specific ENI was quantified by the local ENI index, a value between 0 and 100 where 0 and 100 represented the lowest- and the highest-quality ENI across all participants and electrodes in the study dataset, respectively.
Results:
There were no significant age group differences in refractory times, eCAP thresholds, N1 latencies or local ENI indices. Slopes of the eCAP AGF were significantly larger in the middle-aged group compared to the elderly group. There was a significant effect of electrode location on each eCAP parameter, except for N1 latency. In addition, the local ENI index was significantly larger (i.e., better ENI) in the apical region than in the basal and middle regions of the cochlea for both age groups.
Conclusions:
The model developed in this study can be used to estimate the quality of the ENI at individual electrode locations in CI users. The quality of the ENI is affected by the location of the electrode along the length of the cochlea. The method for estimating the quality of the ENI developed in this study holds promise for identifying electrodes with poor ENIs that could be deactivated from the clinical programming map. The ENI is not strongly affected by advanced age in middle-aged and elderly CI users.
Objective:
We aimed to investigate the clinical features of cochlear nerve deficiency (CND), and in particular, the long-term course of hearing disability and audiogram shapes.
Study design:
Retrospective observational nonrandomized group study.
Setting:
Academic medical center.
Patients/interventions:
The subjects were 63 children with congenital hearing loss who visited our hospital between 2009 and 2019 and underwent MRI, based on which they were diagnosed with CND. There were 61 cases of unilateral CND and two cases of bilateral CND.
Main outcome measures:
Imaging tests by MRI and CT and audiometric assessments by pure-tone audiometry and distortion product otoacoustic emission were performed.
Results:
Among the cases of CND diagnosed by assessing the cochlear nerve on MRI, approximately 20% of the bony cochlear nerve canals that could be assessed on CT were normal. Of the 61 cases diagnosed with unilateral CND, 55 cases had cochlear nerve aplasia (90.2%), and six had cochlear nerve hypoplasia (9.8%), with a mean hearing ability of 92.2 and 94.6 dB HL, respectively. Thus, the majority of cases had severe-to-profound hearing loss. The overall audiometric patterns were 78.7% flat, 9.8% cookie-bite, and 9.8% high-frequency. Six of 61 cases (9.8%) had a distortion product otoacoustic emission (DPOAE) response based on the affected side, and none of the cases lost the response during follow-up.
Conclusions:
Herein, we report the largest study on CND and performed CND image and audiometric assessments. Accurately in diagnosing CND requires not only CT but also MRI assessment. Hearing loss is often severe to profound; however, various audiometric patterns have been observed. CND includes a small number of cases that respond to DPOAE, indicating that some CND cases are clinically diagnosed with auditory neuropathy spectrum disorder (ANSD). A sustained DPOAE response might help in differentiating CND from other ANSDs. Children with congenital deafness who have passed the newborn hearing screening by DPOAE should be examined by MRI to rule out CND.
This chapter will share information gleaned from our combined experience in a specialist pediatric otologic practice, specifically focusing on middle ear and mastoid surgery, bone conduction devices and cochlear implantation, and highlighting and discussing the key issues. The diagnosis and surgical management of hearing loss and middle ear and mastoid disease in children require specific considerations. Challenges arise from age-specific differences and from the unique etiology and distribution of disease within the pediatric population. Optimization of outcomes requires an approach that not only takes these factors into account but also recognizes the interplay between clinical management and the developmental trajectory of the child.
Objective
To determine the prevalence of cochlear nerve anomalies on magnetic resonance imaging in patients with unilateral or bilateral sensorineural hearing loss.
Methods
A retrospective case series was conducted at a tertiary referral centre. The inclusion criteria were paediatric patients with bilateral or unilateral sensorineural hearing loss, investigated with magnetic resonance imaging. The primary outcome measure was the rate of cochlear nerve hypoplasia or aplasia.
Results
Of the 72 patients with unilateral sensorineural hearing loss, 39 per cent (28 cases) had absent or hypoplastic cochlear nerves on the affected side. Fifteen per cent (11 cases) had other abnormal findings on magnetic resonance imaging. Eighty-four patients had bilateral sensorineural hearing loss, of which cochlear nerve hypoplasia or aplasia was identified only in 5 per cent (four cases). Other abnormal findings were identified in 14 per cent (12 cases).
Conclusion
Paediatric patients with unilateral sensorineural hearing loss are more likely to have cochlear nerve anomalies than those patients with bilateral sensorineural hearing loss. This has important implications regarding cochlear implantation for patients with single-sided deafness.
OBJECTIVE: Describe the long-term benefits of early cochlear implantation. Provide a comprehensive description of outcomes, including: language, speech production, and speech perception. Compare the communication outcomes for the early implanted children to those of normally hearing children and children who received a cochlear implant at a comparatively older age. METHOD: Retrospective review of the communication development of 35 children implanted between 6 and 12 months of age and 85 children implanted between 13 and 24 months of age. Audiologic assessments included unaided and aided audiograms, auditory brainstem response (ABR), auditory steady state response (ASSR), and otoacoustic emissons (OAEs). Formal language, speech production, and speech perception measures were administered, preimplant and at 1, 2, 3, and 5 years postimplant. RESULTS: The children who received their cochlear implant by 12 months of age demonstrated language growth rates equivalent to their normally hearing peers and achieved age appropriate receptive language scores 3 years postimplant. The children who received their cochlear implant between 13 and 24 months demonstrated a significant language delay at 3 years postimplant. Speech production development followed a similar pattern to that of normal-hearing children, although was delayed, for both groups of children. Mean open-set speech perception scores were comparable with previous reports for children and adults who use cochlear implants. CONCLUSION: Children implanted by 12 months of age demonstrate better language development compared with children who receive their cochlear implant between 13 and 24 months. This supports the provision of a cochlear implant within the first year of life to enhance the likelihood that a child with severe-to-profound hearing impairment will commence elementary school with age-appropriate language skills.
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In children with cochlear implant (CI), the recording of the electrically evoked compound action potential (ECAP) of the auditory nerve represents an option to assess changes in auditory nerve responses and the interaction between the electrode bundle and the neural tissue over time.
To study ECAP in children during the first year of CI use.
The ECAP characteristics have been analyzed in 13 children implanted younger than three years of age. Series study.
During the first year of CI use there was a significant statistical raise in the N1 peak amplitude, in basal electrodes, between the second and third return visits. There were not any significant differences obtained for N1 peak, latency, slope, p-NRT or recovery time, in the return visits.
During the first year of CI use, the electrical stimulation provided by the intracochlear electrodes did not cause significant changes to ECAP characteristics, except for an increase in N1 peak amplitude.
The purpose of this study was to characterize the transtympanically evoked, perioperative electrically evoked auditory brainstem response (EABR) and define its relationship with preoperative hearing, age and hearing loss etiology in 59 children (10-60 months of age) who had received cochlear implants. The results indicate that there was no difference between wave V latency obtained from the younger (10-36 months) and the older (37-60 months) children. There was a statistically significant difference in the preoperative pure-tone average between the higher-EABR threshold group (650 microA and above) and the lower-EABR threshold group (600 microA or less). Patients with post-meningitic deafness exhibited the longest EABR wave V latencies. Perioperative, transtympanic, promontory EABR is an effective clinical procedure which can decrease the likelihood of placing a cochlear implant in a non-stimulable ear, and may provide the clinician with a valuable tool for selecting the most appropriate ear for implantation.
Central auditory responses to electrical stimulation from a cochlear implant were studied in 75 pre-lingually deafened children and 11 adults. Electrically evoked auditory brainstem response (EABR) latencies significantly decreased with duration of cochlear implant use and were not significantly affected by the age at implant activation. Significant decreases in early latency waves and interwaves occurred within the first 1-2 months of implant use, whereas longer term changes (6-12 months) were found for eV and eIII-eV, which measure activity in the more rostral brainstem. Comparisons to acoustically evoked auditory brainstem response (ABR) in children with normal hearing suggested shorter interwave EABR latencies, reflecting either distinct neural generators or increased neural synchrony, but similar rates of change in the later latency eV and eIII-eV with time in sound. In sum, normal-like development of the rostral auditory brainstem is promoted by cochlear implant use in children of a wide range of ages.
The advent of universal neonatal hearing screening in some countries and the availability of screening programs for at-risk infants in other countries has facilitated earlier referral, diagnosis, and intervention for infants with hearing loss. Improvements in device technology, two decades of pediatric clinical experience, a growing recognition of the efficacy of cochlear implants for young children, and the recent change in the U.S. Food and Drug Administration's age criteria to include children as young as 12 mo has led to increasing numbers of young children receiving cochlear implants. Evidence to support provision for infants younger than 12 mo is extrapolated from physiological studies, studies of children using hearing aids, and studies of children older than 12 mo of age with implants. To date, however, there are few published research findings regarding communication development in children between 6 and 12 mo of age who receive implants. The current study hypothesized that earlier implantation would lead to increased rates of language acquisition as the children were still in the critical period for their development.
A retrospective review was completed for 19 infants (mean age at implantation, 0.88 yr; range, 0.61-1.07, SD 0.15) and 87 toddlers (mean age at implantation, 1.60 yr; range, 1.13-2.00, SD 0.24) who received the multichannel implant in Melbourne, Australia. Preimplantation audiological assessments for these children included aided and unaided audiograms, auditory brain stem response, auditory steady state response (ASSR), and otoacoustic emission and indicated profound to total bilateral hearing loss in all cases. Communication assessment included completion of the Rossetti Infant-Toddler Language Scale and educational psychologists' cognitive and motor assessment. Computed tomography scan, magnetic resonance imaging, and surgical records for all cases were reviewed. Postimplantation language assessments were reported in terms of the rate of growth over time on the language comprehension and language expression subscales of the Rossetti Infant-Toddler Language Scale.
Results demonstrated that cochlear implantation may be performed safely in very young children with excellent language outcomes. The mean rates of receptive (1.12) and expressive (1.01) language growth for children receiving implants before the age of 12 mo were significantly greater than the rates achieved by children receiving implants between 12 and 24 mo, and matched growth rates achieved by normally hearing peers. These preliminary results support the provision of cochlear implants for children younger than 12 mo of age within experienced pediatric implantation centers.
Stjernholm C. Aspects of temporal bone anatomy and pathology in conjunction with cochlear implant surgery. Stockholm 2002.
Cochlear implantation is a treatment for patients with severe sensorineural hearing loss/deafness, who get no help from ordinary hearing aids.
The cochlear implant is surgically placed under the skin near the ear and a very thin electrode array is introduced into the cochlea of the inner ear, where it stimulates the remaining nerve fibers ( 1,2). The operation is complicated; it is performed with the aid of a microscope, and involves drilling very close to vital vessels and important nerves.
The method was introduced in Sweden in 1984 by Professor Göran Bredberg, then at Stockholm Söder Hospital.
High resolution computed tomography (CT) of the temporal bone is a part of the preoperative evaluation preceding cochlear implantation. It is a method for visualizing the bony structures of the middle and inner ear – to diagnose pathology and to describe the anatomy.
In Stockholm, these examinations have usually been performed at the Radiology Department of Stockholm Söder Hospital. Examinations of cochlear implant candidates from other parts of Sweden and from abroad are also sent there for special reviewing.
The first work concerns CT of the temporal bone and cochlear implant surgery in children with CHARGE association. This is a rare condition with multiple congenital abnormalities, sometimes lethal. Children with CHARGE have different combinations of disabilities, of which impairments of vision and hearing, as well as balance problems and facial palsy can lead to developmental delay. There have been few reports of radiological temporal bone changes and none of cochlear implant surgery for this group. The work includes a report of the findings on preoperative CT and at surgery, as well as pos-timplant results in two children. A review of the latest diagnostic criteria of CHARGE and the temporal bone changes found in international literature is also included.
The conclusion was that certain combinations of temporal bone changes in CHARGE are, if not specific, at least extremely rare in other materials. CT can visualize these changes and be used as a diagnostic tool. This is important, since some of the associated disabilities are not so obvious from the start. Early treatment is vital for the child's development. This work also shows that cochlear implantation may help some of these often very isolated children to communicate.
The second work is a radioanatomic study of one of the structures of the inner ear – the bony canal for the cochlear nerve. It involves measurements of the dimensions of the canal on 117 silicone rubber casts of the temporal bone (from a unique collection of casts at Uppsala temporal bone laboratory) and on 50 clinical CT-studies (100 ears). The purpose was to show the normal variation, which is of use in the appraisal of congenital temporal bone malformations on CT.
Based on our results we propose that if the canal is less than 1.4 mm, as measured on CT, the possibility of cochlear nerve abnormality should be considered. This is of interest since aplasia of the cochlear nerve is a contraindication to cochlear implantation. If the canal is wider than 3.0 mm, then other anomalies may coexist, with the risk of CSF gusher when a cochleostomy or stape-dectomy is performed.
The auditory brainstem implant (ABI) was initially developed for patients with deafness as a result of neurofibromatosis type 2. ABI indications have recently extended to children with congenital deafness who are not cochlear implant candidates. Few multi-institutional outcome data exist. Herein, we aim to provide a systematic review of outcomes following implantation of the ABI in pediatric patients with nontumor diagnosis, with a focus on audiometric outcomes.
PubMed, Embase, and Cochrane.
A systematic review of literature was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations. Variables assessed included age at implantation, diagnosis, medical history, cochlear implant history, radiographic findings, ABI device implanted, surgical approach, complications, side effects, and auditory outcomes.
The initial search identified 304 articles; 21 met inclusion criteria for a total of 162 children. The majority of these patients had cochlear nerve aplasia (63.6%, 103 of 162). Cerebrospinal fluid leak occurred in up to 8.5% of cases. Audiometric outcomes improved over time. After 5 years, almost 50% of patients reached Categories of Auditory Performance scores >4; however, patients with nonauditory disabilities did not demonstrate a similar increase in scores.
ABI surgery is a reasonable option for the habilitation of deaf children who are not cochlear implant candidates. Although improvement in Categories of Auditory Performance scores was seen across studies, pediatric ABI users with nonauditory disabilities have inferior audiometric outcomes.
© American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.
CHARGE syndrome is a complex cluster of congenital abnormalities, these children may have absent or hypoplastic auditory nerves. Our objective was to assess preoperative factors and outcomes for paediatric cochlear implant recipients with CHARGE syndrome, to enable better surgical preparation and family counselling.
The Sydney Cochlear Implant Centre database was searched for children with CHARGE syndrome who had received a cochlear implant at ages 16 and less. Data were collected regarding clinical history; hearing assessments; MRI and CT scan findings; preoperative transtympanic electrical Auditory Brainstem Response (ABR); intraoperative findings and intraoperative electrical ABR and Neural Response Telemetry; and language outcomes in terms of main language used and Categories of Auditory Performance scores (0-7 ranking).
Ten children were identified. All seven prelingual profoundly deaf children with CHARGE syndrome had hypoplastic or absent auditory nerves bilaterally on MRI scans. Middle ear anatomy was often abnormal, affecting surgical landmarks and making identification of the cochlea very difficult in some cases. Three cases required repeated surgery to obtain successful cochlear implant insertion, one under CT scan image guided technique. All seven children used sign language, or simpler gestures, as their main mode of communication. Two children of of these children, who were implanted early, also attained some spoken language. CAP scores ranged from 0 to 6. The three children with CHARGE syndrome and progressive sensorineural hearing loss had a normal auditory nerve in at least one ear on MRI scans. All had preoperative verbal language, with CAP scores of 6, and continued with CAP scores of 6 following receipt of the cochlear implant.
Children with CHARGE and congenital profound hearing loss all had hypoplasia or absent auditory nerves, affecting their outcomes with cochlear implants. They often had markedly abnormal middle ear anatomy and CT image guided surgery can be helpful. These children should be offered a bilingual early intervention approach, using sign language and verbal language, to ensure best language outcomes. Children with CHARGE syndrome and progressive profound hearing loss did well with cochlear implants and continue to be able to use verbal language.
Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Auditory brainstem implants (ABIs) can provide useful auditory perception and language development in deaf children who are not able to use a cochlear implant (CI). We prospectively followed up a consecutive group of 64 deaf children up to 12 years following ABI surgery. The etiology of deafness in these children was: cochlear nerve aplasia in 49, auditory neuropathy in 1, cochlear malformations in 8, bilateral cochlear postmeningitic ossification in 3, neurofibromatosis type 2 in 2, and bilateral cochlear fractures due to a head injury in 1. Thirty-five children had other congenital nonauditory disabilities. Twenty-two children had previous CIs with no benefit. Fifty-eight children were fitted with the Cochlear 24 ABI device and 6 with the MedEl ABI device, and all children followed the same rehabilitation program. Auditory perceptual abilities were evaluated on the Categories of Auditory Performance (CAP) scale. No child was lost to follow-up, and there were no exclusions from the study. All children showed significant improvement in auditory perception with implant experience. Seven children (11%) were able to achieve the highest score on the CAP test; they were able to converse on the telephone within 3 years of implantation. Twenty children (31.3%) achieved open set speech recognition (CAP score of 5 or greater) and 30 (46.9%) achieved a CAP level of 4 or greater. Of the 29 children without nonauditory disabilities, 18 (62%) achieved a CAP score of 5 or greater with the ABI. All children showed continued improvements in auditory skills over time. The long-term results of ABI surgery reveal significant auditory benefit in most children, and open set auditory recognition in many. © 2014 S. Karger AG, Basel.
Objective
The aim of this study was to report on auditory performance after cochlear implantation in children with cochlear nerve deficiency.
Methods
A retrospective case review was performed. Five patients with pre-lingual profound sensorineural hearing loss implanted in an ear with cochlear nerve deficiency participated in the study. Postoperative auditory and speech performance was assessed using pure tone average threshold with cochlear implant, speech perception categories, and speech intelligibility ratings. All patients underwent high resolution computed tomography and magnetic resonance imaging.
Results
According to Govaerts classification, three children had a type IIb and two a type IIa cochlear nerve deficiency. Preoperatively, four patients were placed into speech perception category 1 and one into category 2. All patients had an improvement in pure tone average threshold with the cochlear implant. Despite this, at the last follow-up (range 18-81months, average 45 months), only one girl benefited from cochlear implantation; she moved from speech perception category 2 to 6 and developed spoken language. Another child developed closed set speech perception and had connected speech that was unintelligible. The other 3 children showed little benefit from the cochlear implant and obtained only an improved access to environmental sounds and improved lipreading skills. None of these 4 children developed a spoken language, but they were all full-time users of their implants.
Conclusions
The outcomes of cochlear implantation in these five children with cochlear nerve deficiency are extremely variable, ranging from sporadic cases in which open set speech perception and acquisition of a spoken language are achieved, to most cases in which only an improved access to environmental sound develops. Regardless of these limited outcomes, all patients in our series use their device on a daily basis and derive benefits in everyday life. In our opinion, cochlear implantation can be a viable option in children with cochlear nerve deficiency, but careful counseling to the family on possible restricted benefit is needed.
The assessment process is critical in deciding whether a profoundly deaf child with cochlear nerve deficiency (CND) will be suitable for a cochlear or auditory brainstem implant (ABI). Magnetic resonance imaging (MRI) using submillimetric T2 weighted gradient echo or turbo spin echo sequences is mandatory for all profoundly deaf children to diagnose CND. Evidence of audition on behavioural or electrophysiological tests following both auditory and electrical stimulation sometimes allows identification of significant auditory tissue not visible on MRI. In particular electric auditory brainstem response (EABR) testing may allow some quantification of auditory tissue and help decide whether a cochlear implant will be beneficial. Age and cognitive development are the most critical factors in determining ABI benefit. Hearing outcomes from both cochlear implants and ABIs are variable and likely to be limited in children with CND. A proportion of children will get no benefit. Usually the implants would be expected to provide recognition of environmental sounds and understanding of simple phonetics. Most children will not develop normal speech and they will often need to learn to communicate with sign language. The ABI involves a major neurosurgical procedure and at present the long term outcomes are unknown. It is therefore essential that parents who are considering this intervention have plenty of time to consider all aspects and the opportunity for in depth discussion.
Objective: The objective of this study was to explore, from the parents' perspectives, decision-making regarding a cochlear implant (CI) for their child when a favourable outcome is less likely because of abnormal neurophysiology. Design: The primary research method of this single case study was qualitative interviewing drawing on a narrative approach to elicit the parents' perspectives about their experiences over time. Each parent was interviewed separately, but thematic analyses were undertaken both within and across interviews in order to identify overlaps and differences. Study sample: Participants included the parents of a five-year old child with severe-profound hearing loss, cochlear nerve deficiency, and bilateral common cavities who had received a CI at the age of 18 months. Results: Four themes were identified across the four narrative stages that emerged from the parents' accounts of their experiences regarding their daughter's CI. Themes included hope and despair, questioning professionals' motivations, does deafness need a cure, and bringing the child into the family. Although these themes emerged from both parents' accounts, each parent expressed different perspectives and insights within them. Conclusions: Findings highlight the central place of parental needs and perspectives in decision-making regarding a CI, particularly in the context of uncertain outcomes.
Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high-resolution T2-weighted sequence with a surface coil in a 3-Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia.
Prospective study.
Seven patients with cochlear nerve hypoplasia or aplasia were prospectively examined using a high-resolution three-dimensional variable flip-angle turbo spin-echo sequence using a surface coil, and the images were compared with the same sequence in standard resolution using a standard head coil. Three neuroradiologists evaluated the magnetic resonance images independently, rating the visibility of the nerves in diagnosing hypoplasia or aplasia.
Eight ears in seven patients with hypoplasia or aplasia of the cochlear nerve were examined. The average age was 2.7 years (range, 9 months-5 years). Seven ears had accompanying malformations. The inter-rater reliability in diagnosing hypoplasia or aplasia was greater using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence (fixed-marginal kappa: 0.64) than with the same sequence in lower resolution (fixed-marginal kappa: 0.06).
Examining cases of suspected cochlear nerve aplasia using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence in combination with a surface coil shows significant improvement over standard methods.
3b Laryngoscope, 2013.
Conclusion:
The width of the bony cochlear nerve canal (BCNC) and the size of the cochlear nerve are reliable predictors of long-term speech perception abilities for children with auditory neuropathy spectrum disorder (ANSD) after cochlear implantation (CI). In addition, electrical stapedial reflex (ESR) and electrical compound action potential (ECAP) also have considerable value in predicting postoperative speech perception abilities in these children.
Objectives:
To assess whether speech perception abilities after CI in children with ANSD can be predicted from the results of radiologic studies and electrophysiologic tests.
Methods:
Fifteen children with ANSD underwent CI. The width of the BCNC and the size of the cochlear nerve were measured using preoperative CT and MRI. The results of early postoperative ESR, ECAP, and implant evoked electrical auditory brainstem response were reviewed. The latest speech perception test scores were also reviewed.
Results:
Radiologic findings of normal BCNC and normal cochlear nerve correlated with excellent speech perception abilities after CI. A narrow or obliterated BCNC and a deficient cochlear nerve correlated with poor speech perception abilities. Children with good speech perception abilities showed robust responses on ESR and ECAP, but there were no responses from any of the children with poor speech perception abilities.
Compare outcomes among children with inner ear malformations and/or cochlear nerve deficiency (CND) who have received a cochlear implant (CI).
Individual retrospective cohort study from 1993 to 2010.
A select cohort of 76 children was identified. Imaging characteristics, operative findings, complications, mapping parameters, and performance were assessed. Comparisons among the different groups were undertaken.
Surgery was mostly uncomplicated. Nearly all children demonstrated behavioral responses to CI stimulation irrespective of inner ear morphology or the presence of CND. Children with CND had higher pure tone averages (PTAs) and required greater charge for stimulation than other malformation types. Open-set speech perception was achieved in 100% of children with incomplete partition-enlarged vestibular aqueduct (IP-EVA), 50% of those with hypoplastic malformations, and 19% of CND cases. Robust responses on eighth nerve compound action potential (ECAP) testing through the implant was associated with higher levels of speech perception. Manually supplemented communication strategies were more common among children with hypoplastic malformations (69%) and CND (95%) than those with IP-EVA (18%).
Children with IP-EVA malformations have an excellent prognosis for developing open-set speech perception and using oral communication modes following CI. On the contrary, children with severe malformations or CND may have elevated charge requirements for attaining sound detection alone. These children's prognosis for obtaining open-set speech understanding, using exclusive oral communication, and participating in mainstream education is more limited. These findings have important implications for considering alternative forms of intervention such as auditory brainstem implantation and/or supplementation with visually based communication strategies.
To evaluate speech perception after cochlear implantation in children with cochlear nerve absence or deficiency.
A retrospective case review was performed to identify children who underwent cochlear implantation with cochlear nerve absence or deficiency. The cochlear nerve was evaluated by high-resolution three-dimensional T2-weighted fast spin echo MR in the oblique sagittal and axial planes. A deficient cochlear nerve was defined as a cochlear nerve that is smaller in diameter when compared with the adjacent facial nerve in the midportion of the internal auditory canal. The cochlear nerve was considered absent if there was no imaging evidence of a cochlear nerve. Speech awareness threshold and the speech perception category score were used to measure speech perception after cochlear implantation.
Seven children who underwent cochlear implantation in an ear without imaging evidence of a cochlear nerve were identified. One child developed early closed-set speech recognition. The other 6 children developed only speech detection or pattern perception. Two children underwent cochlear implantation with a deficient cochlear nerve. One developed consistent closed-set word recognition and the other developed early closed-set word recognition. The mean follow-up time for all patients was 3.8 years (range, 1.1-7.1 yr).
Cochlear nerve deficiency is not an uncommon cause for profound sensorineural hearing loss and presents a challenge in the decision-making process regarding whether to proceed with a cochlear implant. Children with a deficient but visible cochlear nerve on magnetic resonance image can expect to show some speech understanding after cochlear implantation; however, these children do not develop speech understanding to the level of implanted children with normal cochlear nerves. Children with an absent cochlear nerve determined by magnetic resonance imaging can be expected to have limited postimplantation sound and speech awareness.
To demonstrate that parasagittal constructive interference in steady state (CISS) magnetic resonance imaging (MRI) can be used to accurately measure cochlear nerve cross-sectional area and thereby evaluate for statistically significant differences in the cochlear nerve cross-sectional areas of postlingually deafened and normal-hearing adults.
Cross-sectional study.
Tertiary care medical center.
Parasagittal CISS MRIs of postlingually profoundly deafened cochlear implant candidates and normal-hearing patients at a tertiary care academic medical center between 2006 and 2009 were retrospectively identified. Two independent and blinded investigators measured the cochlear nerve height and width and calculated the cross-sectional area [π(H/2)(W/2)] at the fundus of the internal auditory canals. Measurements of both investigators were analyzed for reliability and agreement with an Altman plot, and deafened patient measurements were compared with results of the normal-hearing patients via Wilcoxon rank sum tests.
The cochlear nerve cross-sectional area of postlingually deafened patients (mean ± SD = 0.61 ± 0.16 mm(2)) was less than normal-hearing patients (0.94 ± 0.28 mm(2)). The difference was statistically significant (P = .002). There was good agreement between independent observer measurements.
Parasagittal CISS MRI can be used to measure the cochlear nerve with good interobserver agreement, and there is a significant difference between the cross-sectional area of postlingually deafened and normal-hearing adults. The cross-sectional area may correlate with residual spiral ganglion cells and provide a prognostic indicator for post-cochlear implant performance, which is the focus of our ongoing research.
The results of this study show that the temporal processing ability in children with auditory neuropathy (AN) can be restored to some degree by electrical stimulation through a cochlear implant. In addition, the electrically evoked compound action potential (ECAP) may be a useful index to predict outcomes in implanted children with AN.
The purpose of this study was to evaluate restoration of the temporal processing abilities in implanted children with AN using ECAP recovery function and speech perception.
Ten children who had received cochlear implantations participated in this study, including six with AN and four with sensorineural hearing loss (SNHL). ECAP recovery functions were measured, and the slopes of ECAP recovery functions in implanted children with AN were compared with those of implanted children with SNHL. Open-set speech perception test scores of implanted children with AN were compared with those of 78 implanted children with SNHL.
The slopes of the ECAP recovery function in children with AN did not differ significantly from those in children with SNHL. The group of children with robust ECAPs showed good postoperative performance. However, the group with no ECAPs showed poor performance.
To describe the imaging findings and clinical outcomes of children with apparent cochlear nerve aplasia undergoing cochlear implantation.
Retrospective case review.
Tertiary care center.
Three patients with imaging findings consistent with absent cochlear nerve canal on diagnostic imaging and questionable audiometric responses on testing who underwent promontory stimulation and subsequent cochlear implantation.
Magnetic resonance imaging and computed tomography, audiologic assessment, and cochlear implantation.
Audiologic performance after cochlear implantation.
Three patients were identified to have hearing loss on newborn hearing screening and underwent auditory brainstem response testing revealing absent brainstem responses. ASSR testing was inconclusive when performed. Imaging in all cases identified 1 ear with a small internal auditory canal with 2 nerves present, one of which seems to enter the vestibule in each case and the other is assumed to be the functioning facial nerve. There was a bony plate present over the entrance to the cochlea in 2 of the 3 patients. Over time, 2 of the families reported responses to auditory stimuli with amplification. Promontory stimulation testing showed reproducible responses to electrical stimuli in the ears in question. After cochlear implantation, all 3 patients have shown responses to auditory stimuli.
The absence of a visible cochlear nerve or cochlear nerve canal on radiologic imaging does not preclude auditory innervation of the cochlea. Cochlear implantation can be a viable option for patients with apparent cochlear nerve aplasia who have undergone appropriate testing. Electronically evoked auditory brainstem response is critical in the evaluation of this patient group.
To investigate postoperative outcomes after cochlear implantation in young children with cochlear nerve deficiency and compare the results with those of cochlear implantation in patients with normal cochlear nerve.
Historical cohort study.
Tertiary referral center.
Six children under the age of 36 months with cochlear nerve deficiency, as determined by magnetic resonance imaging (MRI), received cochlear implantation between July 2006 and March 2008. Fifteen children under the age of 36 months with normal cochlear nerve in the implanted ear underwent cochlear implantation during the same period and were selected as the control group. Medical records, imaging studies, and speech evaluations were reviewed.
Our study group scored lower in the Infant-Toddler Meaningful Auditory Integration Scale compared to the control group. Our study group produced categories of auditory performance scores not less than 4 except for one patient. Speech intelligibility rating scores in the control group gradually increased after cochlear implantation, but for the study group, the score remained zero 12 months after the implantation. In open-set one-syllable tests, five patients with cochlear nerve deficiency showed no response at the latest follow-up, whereas patient 6 began to show delayed improvement after 18 months. The results of the open-set two-syllable test were similar to those of the open-set one-syllable test.
Young children with nonvisualized cochlear nerve on MRI showed worse outcomes compared to the children with normal cochlear nerve. Cochlear nerve deficiency on MRI is a marker of very poor outcome with cochlear implantations.
To report on the outcomes of sequential bilateral cochlear implantation (CI) in children with inner ear malformation. The study design is a retrospective case study. The setting is a tertiary reference center. Two children presenting a profound bilateral congenital hearing loss with bilateral hypoplasia of the cochleovestibular nerves and hypoplasic external semicircular canal had a cochlear implant at respectively 16 months and 33 months. A second implant was proposed at respectively 17 and 20 months after the first implant. The main outcome measures are audiometry, perceptive results in closed and open set words (CSW and OSW) and oral production at follow-up. The first cochlear implant gave respectively mean thresholds at 60 dB and 70 dB. Bilateral CI showed mean threshold at respectively 40 dB and 55 dB. In case 1, perceptive assessment was 83% and 70% in respectively CSW and OSW with oral production and comprehension of sentences after 1 year follow-up. In case 2, the perceptive assessment showed no perceptive or linguistic evolution at 6 months follow-up. In cochleovestibular nerve hypoplasia, bilateral implantation could be discussed in cases of limited result after unilateral implant.
Deficient cochlear nerves (CN) have been associated with poor cochlear implant performance. Normative data on CN diameter based on radiographic imaging have not been published. The objectives of this study were to determine if CN diameter could be reproducibly measured on parasagittal constructive interference in steady state (CISS)-sequence magnetic resonance imaging (MRI) and to establish a normative range for CN diameter.
Retrospective review of MRI images by two independent blinded observers.
Thirty patients (45 ears) with a CISS-sequence MRI done for auditory complaints in patients with normal hearing in one ear were included. CN diameters were measured in a parasagittal plane just medial to the internal auditory canal (IAC) fundus by two independent observers. Cross-sectional areas were calculated and interobserver agreement was evaluated.
The CN was identified in 100% of studied ears. In 93%, the diameters were able to be measured by both observers. In 7% of ears, the cochlear nerve was unable to be measured secondary to the proximity of the CN to IAC wall. The CN vertical diameter (1.4 mm +/- 0.21 mm), horizontal diameter (1.0 mm +/- 0.15 mm), and cross-sectional area (1.1 mm +/- 0.26 mm(2)) were normally distributed. There was good interobserver correlation for each measure.
CN diameter can be reliably measured at the IAC fundus. This study establishes normative radiographic data for the CN diameter. These data may be used to evaluate the cause and treatment prognosis in patients with sensorineural hearing loss.
Preoperative CT and MRI assessment of children with severe or profound sensorineural hearing loss (SNHL) is critical for determining implant candidacy.
There are a significant number of children who do not show any auditory development with a cochlear implant (CI), possibly due to cochlear nerve (CN) aplasia/hypoplasia. Regardless of the suspected etiology, if a CI is not providing auditory development the clinician should carefully evaluate the possibility of a CN malformation and re-evaluate the child with detailed neuroimaging studies. If the imaging evaluation shows severe cochlear malformation or CN aplasia there is some developmental urgency to consider auditory brainstem implant (ABI) surgery.
Twenty-eight children affected by congenital SNHL were examined by CT and MRI. Evaluation of the cerebellopontine angle (CPA), internal auditory canal (IAC), cranial nerves, and membranous labyrinth was performed. Six children had been previously fitted elsewhere with a CI with no sound detection.
Suspected congenital anomalies were confirmed by CT and MRI in all 28 children: 16 with associated labyrinthine malformations; 1 with outer, middle, and inner ear malformations; and 2 with associated monolateral facial nerve aplasia.
Categories of Auditory Performance (CAP) is an index consisting of eight performance categories arranged in order of increasing difficulty. It has been used to categorize 53 children who had been deafened below the age of 3. The children were assessed by means of the CAP before implantation, and over the following 3 years. Before implantation, only 2 of the children showed awareness of environmental sounds; immediately after initial tuning, all children showed awareness of environmental sounds, and 50% showed awareness of speech sounds. Their auditory receptive abilities gradually developed over the 3-year period, and by the 3-year assessment interval, 80% were understanding phrases without lipreading, and 40% were understanding conversation. Using these data, we predict that 90% of such children will understand conversation without lipreading 5 years after initial tuning.
To introduce aplasia or hypoplasia of the vestibulocochlear nerve (VCN) as a possible cause of hearing loss and to identify the magnetic resonance (MR) imaging characteristics of this entity.
In seven patients with congenital deafness or unexplained sensorineural hearing loss, MR imaging enabled diagnosis of aplasia or hypoplasia of the VCN. Axial (0.7-mm) three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) images and parasagittal reconstruction images perpendicular on the course of the VCN were obtained. Twenty normal inner ears were also studied; their findings were compared with those of the patients.
The facial nerve and inferior and superior vestibular and cochlear branches of the VCN were identified on the MR images in the 20 normal inner ears. Aplasia of the VCN was detected in two patients with normal labyrinths but with a severe stenosis of the internal auditory canal. A common VCN with absence of the cochlear branch was found bilaterally in two patients with a congenital malformation of the labyrinth. A common VCN with absence or hypoplasia of the cochlear branch was found in three patients with normal internal auditory canals and labyrinths.
Submillimetric gradient-echo images (eg, 3DFT-CISS) should always be used to exclude aplasia or hypoplasia of the cochlear branch of the VCN in all cochlear implant candidates and patients with congenital deafness. This entity, which can occur with or without associated labyrinthine malformation, should be confirmed in two planes.
To summarize the current applications of auditory evoked potential in children with cochlear implants and candidates for implantation.
Perioperative transtympanic EABR is used routinely for ear selection and to establish the electrical stimulability of the ear intended to be implanted. The perioperative transtympanic EABR is supplemented with EABR obtained immediately following the insertion of the electrode array and the seating of the implant's receiver. Postoperatively, EABR and averaged electrode voltages are used effectively to properly adjust the implant stimulus parameters and to determine whether the implant is functioning adequately. Postoperatively, cognitive evoked potentials to speech and tonal stimuli may also be obtained.
EABR results have contributed to effective implant placement and function. There were several significant correlations between speech recognition and cognitive evoked potential.
These measures help assure proper implant function and effective stimulus delivery.
We present a case of bilateral absence of the eighth cranial nerve in the internal auditory meatus (IAM). This caused total failure of responses after cochlear implantation in a six-year-old patient with congenital deafness. Pre-operative magnetic resonance (MR) imaging is important to show not only the anatomy of the middle and inner ears but also the structures in the IAM.
The objective of this study was to outline the possible implications and potentially valuable techniques for managing cases in which the neural integrity of the peripheral auditory system is in question.
This study was a retrospective case review.
A 3-year-old child with a profound blilateral sensorineural hearing loss was assessed for suitability of cochlear implantation. Audiologic tests confirmed that the child met the audiologic criteria for cochlear implantation. Computed tomographic scanning and magnetic resonance imaging were undertaken.
Computed tomographic scanning showed bilateral narrow internal auditory canals. Magnetic resonance imaging showed the absence of the acousticofacial bundle on the left side and possible atrophy of the bundle on the right. After detailed discussion, the parents elected to proceed with implantation on the right ear using the Nucleus mini-22 cochlear implant. Tuning of the device resulted in myogenic facial activity with no electrically stimulated auditory sensation. Postoperative electrophysiologic testing confirmed the presence of a compound muscle action potential only.
Seven months after implantation, the child was explanted uneventfully. The electrical auditory nerve action potential and the electrically evoked auditory brainstem response, using intracochlear stimulation, are potentially valuable measurements to assess neural integrity before the decision to proceed with implantation is made.
The objective of this study was to determine the relationship between electrically evoked whole nerve action potential (EAP) and electrical auditory brain stem response (EABR) thresholds and MAP threshold (T-level) and maximum comfort level (C-level) for subjects who use the Nucleus 24 cochlear implant system.
Forty-four adult Nucleus 24 cochlear implant users participated in this study. EAP thresholds were recorded using the Neural Response Telemetry System developed by Cochlear Corporation. EABR thresholds were measured for a subset of 14 subjects using standard evoked potential techniques. These physiologic thresholds were collected on a set of five electrodes spaced across the cochlea, and were then compared with behavioral measures of T-level and C-level used to program the speech processor.
EAP thresholds were correlated with MAP T- and C-levels; however, the correlation was not strong. A technique for improving the correlation by combining measures of T- and C-levels made on one electrode with the EAP thresholds was presented. Correlations between predicted and measured T- and C-levels using this technique were 0.83 and 0.77, respectively. Similar results were obtained using the EABR thresholds for a smaller set of subjects. In general, EABR thresholds were recorded at levels that were approximately 4.7 programming units lower than EAP thresholds.
Either EAP or EABR thresholds can be used in combination with a limited amount of behavioral information to predict MAP T- and C-levels with reasonable accuracy.
Auditory neuropathy (AN) is a hearing disorder that presents with a grossly abnormal or absent neural response as measured by evoked potentials in the presence of normal outer hair cell function evidenced by present otoacoustic emissions or cochlear microphonics. Rehabilitation for patients with AN is challenging due to abnormal temporal encoding at the auditory nerve leading to severely impaired speech perception. Although patients with AN may demonstrate improvement in thresholds with amplification, temporal encoding dysfunction, and consequently speech perception degradation, is not alleviated by amplification. Another issue is the heterogeneity of the AN population in terms of audiologic and neurologic findings, in addition to uncertain etiology and pathophysiology. For children with prelingual onset of AN, development of auditory and oral communication skills is particularly compromised. All children with hearing loss in the severe-to-profound range who do not benefit from conventional amplification can be considered candidates for a cochlear implant (CI). This paper presents a case study of a child with AN who received a CI. Whereas no synchronous neural response auditory brainstem response could be elicited to acoustic stimuli, an electrically evoked auditory nerve action potential was evident following implantation, suggesting restoration to some degree of neural synchrony. Significant improvement in speech perception was found post-CI. Recommendation to implant all patients with AN would be premature, but these findings suggest that electrical stimulation in some cases of auditory neuropathy can be a viable option.
The finding of an abnormally narrow internal auditory meatus during the assessment of a child for cochlear implantation raises the possibility that the meatus may not contain the normal number of nerves. Even with currently available MRI techniques it may be extremely difficult to decide whether or not to offer cochlear implant in such cases. We present a child of 4 1/2 years, assessed for cochlear implantation. MRI and CT imaging suggested aplasia of one vestibulocochlear nerve and hypoplasia of the other. However, audiological tests showed clear responses to sound in both ears and functional use of sound in her daily life. This child was eventually implanted with encouraging postoperative results.
To identify the clinical and radiologic characteristics of aplasia and hypoplasia of the eighth nerve.
Retrospective case-note review.
Cochlear implant program.
All children at the authors' institution in whom the cochlear implant assessment failed because of absence or hypoplasia of the eighth nerve.
Computed tomography of petrous bones and magnetic resonance imaging of the brain.
Presence or absence of eighth nerve and other radiologic factors contraindicating implantation.
Of 143 cochlear implant candidates, 237 were judged ineligible for cochlear implantation. The preimplant assessment failed in 10 candidates of 143 because of bilateral aplasia or hypoplasia of the eighth nerve (7 cases) or unilateral aplasia or hypoplasia of the eighth nerve and a contraindication to operation on the other side (3 cases). The aplasia or hypoplasia of the eighth nerve was confirmed by magnetic resonance imaging in seven cases (5%): six were syndromic (3 CHARGE, 1 VATER-RAPADILLINO, 1 Möbius, 1 Okihiro), and one was nonsyndromic autosomal-recessive. All seven children had delayed motor milestones and absence of auditory brainstem responses.
Aplasia and hypoplasia of the eighth nerve are not uncommon in pediatric cochlear implant candidates, particularly in the presence of a syndrome such as CHARGE. Magnetic resonance imaging of the brain is mandatory before implantation because it can identify the presence or absence of the eighth nerve. Parents of children with profound hearing loss, delayed motor milestones, absence of auditory brainstem responses, and a syndromic diagnosis, should be made aware of this possible abnormality.
The purpose of this work was to study the diagnostic value of CT and MRI in children with sensorineural hearing loss and to analyze anatomic abnormalities of the inner ear and the vestibulocochlear nerve in this patient group.
We evaluated 42 inner ears in 21 children with congenital deafness who had congenital inner ear malformations and who were candidates for cochlear implants. All patients were studied with high resolution MR and helical CT examinations. The MR study included a T2-weighted 3D fast SE sequence. We describe and tabulate the anatomic abnormalities. Special attention was given to abnormalities of the vestibulocochlear nerve. The field of view in the plane according to the length axis of the internal auditory canal (IAC) was 4 cm. Additional continuous parasagittal reformations perpendicular to the length axis of the IAC were studied with a field of view of 3 cm.
CT and MRI allowed accurate identification of malformations of the inner ear in children with congenital deafness. We identified 99 malformations, with a majority of patients demonstrating multiple abnormalities. Common imaging findings were Mondini abnormality and Mondini variants (12/42) and fusion of the lateral or superior semicircular canal with the vestibule (12/42). MRI demonstrated in 9 of 21 patients a rudimentary or absent vestibulocochlear nerve in the auditory canal.
CT and MRI are important modalities to analyze the inner ear in children who are candidates for cochlear implants. MRI with an extremely small field of view should be used to study possible abnormalities of the vestibulocochlear nerves. This may alter clinical care and allow cochlear implant placement in patients whose electrodiagnostic studies suggest that the implant should not be performed. The detailed analysis of abnormalities of the inner ear might establish prognostic factors.
Auditory neuropathy (AN) is a term used to describe an auditory disorder in which there is evidence of normal outer hair cell function (otoacoustic emissions and/or cochlear microphonics) and poor function of the auditory nerve (absent or highly distorted auditory brain stem response starting with wave I). Many of these patients have evidence of generalized peripheral nerve disease, leading to an assumption that the peripheral portion of the auditory nerve is the most likely site of lesion. A small group of these patients has received cochlear implants, and the majority of them achieve average to above-average performance. Although this outcome may seem incongruous with neural disease, average performance by patients with AN may be a result of the reintroduction of neural synchrony by electrical stimulation and/or the fact that most deaf patients have poor nerve survival. Although cochlear implants are promising for deaf patients with AN, more study of the disorder is needed.
The main aim of this study was to validate a new technique, neural response telemetry (NRT), for measuring the electrically evoked compound action potential in adult cochlear implant users via their Nucleus C124M implant. Thirty-eight adults were evaluated with a variety of measurement procedures with the NRT software. Electrically evoked compound action potentials were obtained in 31 of the 38 adults (81.6%) and in 132 of the 160 electrodes (82.5%) tested. In addition to validating this technique, we also established a set of default clinical test parameters.
In this study, differences between electrically evoked whole-nerve action potential (EAP) and electrically evoked auditory brainstem response (EABR) measurements within Nucleus CI24R cochlear implant recipients were evaluated. Precurved modiolus-hugging internal electrode arrays, such as the CI24R, are designed to provide more direct stimulation of neural elements of the modiolus. If the electrode array is closer to the modiolus, electrically evoked and behavioral levels might be lower than were previously recorded for the straight electrode array, the CI24M. EAP and EABR growth functions and behavioral levels were obtained for 10 postlingually deafened adults. Results revealed no significant differences between EAP and EABR threshold levels, and these levels were not significantly lower than those obtained using the CI24M.
The history of cochlear implants is marked by large improvements in performance, especially over the past two decades and especially due to the development of ever-better processing strategies. Although the progress to date has been substantial, present devices still do not restore normal speech reception, even for top performers and particularly for listening to speech in competition with noise or other talkers. In addition, a wide range of outcomes persists, with some patients receiving little benefit using the same devices that support high levels of speech reception for others. The purpose of this review is to describe some likely possibilities for further improvement, including (a) combined electric and acoustic stimulation of the auditory system for patients with significant residual hearing, (b) use of bilateral implants, (c) a closer replication with implants of the processing steps in the normal cochlea, and (d) applications of knowledge about factors that are correlated with outcomes to help patients presently at the low end of the performance scale.
To report on the outcome of four patients with aplasia or hypoplasia of the cochleovestibular nerve who have received a cochlear implant.
Retrospective case review.
Tertiary referral center.
Four patients with: 1) type I aplasia; 2) type IIa aplasia; 3) type IIa hypoplasia; and 4) type IIb aplasia received a cochlear implant. All patients had corner audiograms even with hearing aids.
Three patients received a LAURA multichannel implant, and one patient received a Nucleus 24 implant.
Auditory performance, educational setting.
The patients with type I and type IIb aplasia did not have auditive perception with their implant and became non-users. Both are now in a total communication educational setting. The patients with type IIa aplasia and hypoplasia had moderate audiological results with the implant with audiometrical thresholds of approximately 40-60 dB HL (pure tone average), moderate phoneme discrimination, and poor word discrimination. One child is in a total communication educational setting and the other in an oral educational setting, but the preferred mode of communication remains total communication for both. Both appear to benefit from the implant nonetheless.
Patients with aplasia/hypoplasia of the cochleovestibular nerve should be counseled with caution with respect to cochlear implantation, but particular circumstances may justify the intervention. At present these circumstances seem to be a type IIa aplasia or hypoplasia in which the end organ (cochlea or common cavity) still connects to a neural structure on MRI.
This study aimed to evaluate the relationship between the diameters of the auditory and eighth cranial nerves and improvements in post-implant performance. Twenty prelingually deafened children (aged from 2.0 to 6.0 years) who received the Nucleus 24 cochlear implant participated in this study. All subjects had used their implant for at least 1 year after device connection. The diameters of cochlear and eighth cranial nerves were retrospectively measured on preoperative T2-weighted axial magnetic resonance image (MRI). In 17 of 20 subjects, the cochlear and eighth cranial nerves could be identified on MRI. The mean diameter of the cochlear and eighth cranial nerves were 0.9 +/- 0.2 mm and 1.2 +/- 0.3 mm, respectively. In the remaining three subjects, the cochlear and eighth cranial nerves could not be identified on MRI. These three subjects had significantly lower scores in the Infant-Toddler-Meaningful Auditory Integration Scale (IT-MAIS) than the other 17 subjects at 12 months post-implant. There was no significant correlation among the maximal diameters of the nerves and age, ECAP thresholds and IT-MAIS scores. A sufficient outcome from cochlear implantation can be expected when cochlear and eighth cranial nerves are depicted on MRI, regardless of the nerve diameters.
Cochlear implants (CI) represent the current treatment for patients affected by profound sensorineural hearing loss (SNHL). Initially only deaf adult patients were considered to be candidates for a CI; however, the development of technology and matured experience have expanded the indications for cochlear implantation. Today, CIs are implanted in adults and children and broader indications are followed. There are, however, a number of patients who do not completely fulfill the current indications and who are potential candidates for CI. The duration of deafness and residual hearing represent prognostic indicators for CI performance; however, the candidacy of children with residual hearing and prelingually deafened adults are still under debate. Anatomical variants such as cochlear ossification, cochlear malformation and chronic otitis media represented and still represent for some surgeons a contraindication to CI. The otological experience of CI surgeons and the advent of auditory brainstem implants have changed the approach to these patients, who may still benefit from hearing rehabilitation. This paper briefly analyses and reviews the results obtained in these groups of patients, who were not, at least initially, considered to be candidates for cochlear implantation.
To report on the outcomes of cochlear implantation (CI) in a child with cochleovestibular nerves (CVN) hypoplasia.
Retrospective case review.
Tertiary referral center, University hospital.
An 18-month-old child with profound bilateral congenital hearing loss and bilateral hypoplasia of the CVN at imaging.
Left CI at age 29 months with a Nucleus Contour device (Cochlear Ltd., Lane Cove, New South Wales, Australia) after unsatisfactory results of hearing aid use for 10 months.
Speech perception tests, behavioral observation, electrophysiologic tests, and cognitive evaluation.
Although the child scores poorly in every perceptive category with the CI alone, the device greatly enhances his speech understanding with the hearing aid in the opposite ear. In the bimodal condition, his words and sentences identification, recognition, and comprehension far exceed the monaural figures. The Meaningful Auditory Integration Scale (MAIS) tests reaches a score of 26/40, and the MacArthur's questionnaires confirm the improvement of language production and comprehension. These results became noticeable after 5 to 6 months and continued to improve up to the 10th month. The child's cognitive scores and overall performance competences greatly benefit from the CI, with the mental age overcoming the chronological age.
We can confirm the chance of achieving satisfactory results by CI even when the imaging of CVN is doubtful and the electrophysiological tests are disappointing. In our experience, a CI in Type IIb dysplasia of the CVN is a feasible option, provided that the candidate shows some responses at aided audiogram and at least minimal signs of language development. Adequate counseling is necessary for these children because the expected outcome is somewhat lower than that of their deaf peers with normal appearance of the nerves.
Pediatric cochlear implants: Additional disabilities prevalence, risk factors, and effect on language outcomes
- Birman
Early language outcomes of children with cochlear implants: Interim findings of the NAL study on longitudinal outcomes of children with hearing impairment
- Ching
Variable long-term outcomes from cochlear implantation in children with hypoplastic auditory nerves
- Bradley