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Magnetic resonance and CT images obtained in a patient in this study demonstrating the characteristic features of medial acoustic neuroma. A: Axial 3D-SPACE MR image depicting a large medial acoustic tumor; note the CSF formation juxtaposed against the tumor, with expansion of the cisterns anteriorly and posteriorly, the presence of CSF filling the IAC and the absence of any CSF rim against the brainstem. B and C: Axial (B) and coronal (C) T1-weighted Gd-enhanced MR images of tumor prior to resection, demonstrating the large size of the tumor, absence of tumor in the meatus, and presence of brainstem compression. D: Preoperative coronal CT scan demonstrating symmetric bilateral IACs, without significant expansion of the meatus region. E and F: Postoperative brain-window (E) and bone-window (F) CT scans demonstrating that removal of a medial acoustic neuroma through the transmastoid approach does not require opening of the IAC.
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Object:
Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that th...
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Symptomatic cavernous malformations involving the brainstem are frequently difficult to access via traditional methods. Conventional skull-base approaches require significant brain retraction or bone removal to provide an adequate operative corridor. While there has been a trend toward limited employment of the most invasive surgical approaches, re...
Citations
... Kim et al. (2016) reported that sudden or progressive hearing loss is the key symptom in individuals with acoustic neuroma. Dunn et al. (2014) reported that progressive hearing loss (88%) was the most common initial symptom in patients with medial acoustic neuroma. By analyzing the 825 cases with vestibular schwannoma throughout the 25 years, Bento et al. (2012) found that progressive hearing loss was the chief complaint in 656 patients (79.5%). ...
... Speech discrimination scores were mostly affected in the ear with acoustic neuroma, which decreased with an increase in tumor size (Johnson, 1977;Selesnick, et al., 1993). The results of the studies included in this review also supported the previous statement (Ahsan et al., 2015;Bento et al., 2012;Dunn et al., 2014;Lee et al., 2015;Patel et al., 2015;Tutar et al., 2013). Recent studies like Koors et al. (2013) reported that ABR has a sensitivity of 93.4% in detecting VS of any size, with a relatively higher sensitivity of 95.6% for larger tumors and a slightly lower sensitivity of 85.8% for smaller tumors, which was also supported by various other authors (Barrs et al., 1985;Glasscock et al., 1979;Guyot et al., 1992;Pensak et al., 1985;Pfaltz et al., 1991;Telian et al., 1989). ...
... All the studies included in this review have reported the findings of the MRI, and two studies have evaluated CT along with the MRI (Dunn et al., 2014;Salem et al., 2019). Jeong et al. (2016) found that 13 out of 291 patients with SNHL showed MRI abnormality. ...
... With 9 of the 368 patients (2.4%) demonstrating preoperative facial nerve palsy, they pointed out that this group contained patients with relatively large lesions and the possibility of improvement of facial nerve function after surgery. 1 In our present study, which to the best of our knowledge is the first investigation of a relatively large number of patients with preoperative tumoral facial nerve palsy, the incidence was 2.8%, similar to previous reports (approximately 2%-6%). [1][2][3][4][5] Both in our series and in previous reports, the degree of preoperative facial nerve palsy was variable, being between grades II to VI. [1][2][3]19 In this study, we found that facial nerve palsy was more common in older patients. This may be owing to a decrease in tissue regeneration ability, which was suggested in a previous study of postoperative facial nerve function in older patients with vestibular schwannomas. ...
... Intratumoral hemorrhage, as shown in Figure 1 and in our previous report, 15 may also cause rapid growth of the tumor and a stretching effect, resulting in preoperative facial nerve palsy. A tendency of patients with preoperative facial nerve palsy to have medial or cisternal tumors was reported previously, 19 but more significant meatal extension was seen in the patients in our present series. Further clinical studies are required to clarify the association between meatal extension and preoperative facial nerve palsy. ...
... The improvement of facial nerve function after surgical decompression of the facial nerve was found in a few previous studies. 1,19,24 In our present study, 25 of the 33 patients (75.8%) experienced postoperative improvement of facial nerve function within 2 yr. Our study demonstrated a substantial contribution of surgical intervention toward the recovery of facial nerve function in patients with preoperative tumoral facial nerve palsy, but postoperative course varied with each patient. ...
Background:
Facial nerve palsy is a rare presenting symptom of vestibular schwannomas and has not been investigated in detail.
Objective:
To investigate the incidence, clinical features, and postoperative long-term outcomes of facial nerve function in patients with vestibular schwannomas causing preoperative facial nerve palsy.
Methods:
After excluding patients with neurofibromatosis type 2 and those with prior treatment, 1228 consecutive patients who underwent vestibular schwannoma surgery were retrospectively investigated. Patients with and without preoperative facial nerve palsy were compared statistically to clarify their clinical features.
Results:
Preoperative tumoral facial nerve palsy was seen in 34 patients (2.8%). Their clinical features included older age, having large cystic tumors with significant meatal extension, and showing abnormal electrogustometric responses, compared with patients without preoperative facial nerve palsy. Owing to the frequent insufficient intraoperative responses on facial nerve electromyography, the tumor resection rate was lower in the group with preoperative facial nerve palsy (mean: 95.2%). Among the 33 patients with sufficient follow-up data (mean: 63.9 mo), additional treatment was required only in 1 patient and facial nerve function improved in 25 patients (75.8%) within 2 yr postoperatively.
Conclusion:
Facial nerve palsy is a rare preoperative symptom that occurs in less than 3% of patients with vestibular schwannoma. Tumor resection in such patients tends to be challenging owing to their advanced age, having large cystic tumors with significant meatal extension, and difficulties in intraoperative facial nerve monitoring, but surgical decompression of the facial nerve can assist in the improvement of their long-term functions.
... This was most consistent with a giant cystic medial vestibular schwannoma. [1][2][3] There was significant compression of the brainstem with effacement of the fourth ventricle resulting in obstructive hydrocephalus. The preoperative audiogram showed a left pure tone average of 15 dB and word discrimination score of 88%, consistent with class A hearing. ...
In this illustrative video, the authors demonstrate retrosigmoid resection of a giant cystic vestibular schwannoma using the subperineural dissection technique to preserve facial nerve function. This thin layer of perineurium arising from the vestibular nerves is used as a protective buffer to shield the facial and cochlear nerves from direct microdissection trauma. A near-total resection was achieved, and the patient had an immediate postoperative House-Brackmann grade I facial nerve function. The operative nuances and pearls of technique for safe cranial nerve and brainstem dissection, as well as the intraoperative decision and technique to leave the least amount of residual adherent tumor, are demonstrated.
The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21128
... Studies have advocated that observation should be the firstline treatment of asymptomatic patients (wait and scan approach) due to the slow growth rate of AN [38,39]. When observing tumors with a wait and scan approach, if a tumor demonstrates interval growth, hearing declines more in growing tumors than those which stay stable in size [40,41]. Besides, with the mass effect and long-term compression of the cochlear and facial nerve by the tumor, patients are at a higher risk of sudden deafness during the wait and scan period and decreased rates of postoperative hearing preservation after a long observation period. ...
PurposeThe aim of this study was to investigate an imaging biomarker based on contrast enhanced T1-weighted and T2-weighted magnetic resonance imaging (MRI) to determine the hearing loss related to acoustic neuromas (AN).Methods
In this retrospective study, 441 acoustic neuromas treated with microsurgery were included. The diagnostic and follow-up MRI and audiometry of these patients were compared.ResultsWe discovered a new MRI grading biomarker based on the percentage of tumor filling the inner auditory canal (TFIAC classification). The area under the receiver operating characteristics (AUROC) curve was highest for TFIAC (0.675), followed by period of observation (0.615) and tumor size (0.6) (P < 0.001). The percentage of patients in TFIAC grade III (90.1%) experiencing hypoacusis prior to microsurgery was significantly higher than that in TFIAC grade I (72.7%, P = 0.037) and TFIAC grade IV patients had a higher rate of non-serviceable hearing compared to TFIAC grade III patients (P < 0.001). During the follow-up, TFIAC grade IV patients experienced a significantly higher rate of non-serviceable hearing than TFIAC grade III patients in all ANs (P < 0.001) and in serviceable hearing acoustic neuroma cases prior to surgery (TFIAC grade IV 55.4%, TFIAC grade III 69.0%, P = 0.045). The TFIAC grade IV patients experienced a significantly higher rate of facial nerve dysfunction than TFIAC grade III patients after surgery (grade IV 48.0%, grade III 26.1%, P < 0.001).Conclusion
The TFIAC classification serves as a potential imaging biomarker for preoperative and postoperative hearing prediction in ANs, which may aid neurosurgeons in predicting hearing loss and selecting optimal surgical strategies.
... 1,2 Surgical resection of theses schwannoma is particularly challenging not only due to their size and hypervascularity, but also given their particular arachnoidal rearrangement inducing marked adherence to the brainstem and facial nerve. 2 The treatment is surgical resection, despite, however, their giant size hearing preservation should be sought and is attainable. [1][2][3][4][5] Transmastoid approach with squeletonization and reflection of the transverse sigmoid sinus provides lateral exposure avoiding cerebellar retraction. ...
... 1,2 Surgical resection of theses schwannoma is particularly challenging not only due to their size and hypervascularity, but also given their particular arachnoidal rearrangement inducing marked adherence to the brainstem and facial nerve. 2 The treatment is surgical resection, despite, however, their giant size hearing preservation should be sought and is attainable. [1][2][3][4][5] Transmastoid approach with squeletonization and reflection of the transverse sigmoid sinus provides lateral exposure avoiding cerebellar retraction. 6 In this report, we demonstrate the specific surgical considerations applied to the resection of a giant medial acoustic tumor in a 40-yr-old patient presenting with ataxia, vertigo, facial paresthesia, and intact hearing. ...
Medial acoustic tumors are a rare distinct type of vestibular schwannoma having distinguished clinical and radiological features.1 Originating medially in the cerebellopontine angle without extending into the lateral internal auditory meatus, they are frequently giant in size at presentation in younger patients with a relatively preserved hearing, while they have other neurological deficits from cerebellar or brainstem compression and associated hydrocephalus. Imaging typically shows a cystic tumor with local mass effect and an internal auditory canal filled with cerebrospinal fluid.1,2 Surgical resection of theses schwannoma is particularly challenging not only due to their size and hypervascularity, but also given their particular arachnoidal rearrangement inducing marked adherence to the brainstem and facial nerve.2
The treatment is surgical resection, despite, however, their giant size hearing preservation should be sought and is attainable.1–5 Transmastoid approach with squeletonization and reflection of the transverse sigmoid sinus provides lateral exposure avoiding cerebellar retraction.6 In this report, we demonstrate the specific surgical considerations applied to the resection of a giant medial acoustic tumor in a 40-yr-old patient presenting with ataxia, vertigo, facial paresthesia, and intact hearing. The patient agreed to the surgery and photography.
Image at 1:44 © Ossama Al-Mefty, used with permission; Image at 8:21 from Dunn et al,2 used with permission from JNSPG.
... MR spectroscopy (MRS) is considered a non-invasive means for characterization of the tissues according to the phenomenon known as chemical shift, where the MR frequency spectrum is received by nuclei resonating at different frequencies [26][27][28][29][30]. Spectroscopy is largely used in neurological imaging evaluation for both local and diffuse disease. ...
Background
CPA masses are uncommon lesions and usually have quite distinctive imaging features. Still, diagnosis can be challenging in some cases, carrying a significant impact on the choice of treatment and surgical approach. The purpose of this study was to validate the usefulness of MRI spectroscopy, diffusion, and susceptibility in the characterization of CPA masses with the emphasis on the two commonest lesions: schwannomas and meningiomas.
Results
The study included a total of 27 cases: schwannomas ( n = 12), meningiomas ( n = 7), epidermoid cysts ( n = 2), two chondrosarcomas ( n = 2), arachnoid cyst ( n = 1), glomus tumor ( n = 1), a meningeal metastasis ( n = 1), and an endolymphatic sac tumor ( n = 1). DWI revealed: eight lesions showed low ADC (<1 × 10 ⁻³ mm ² /s), 15 lesions with intermediate ADC values (1–1.8 × 10 ⁻³ mm ² /s), and 4 lesions had high ADC (>1.8 × 10 ⁻³ mm ² /s.) Meningiomas showed low to intermediate ADC values while schwannomas showed intermediate to high ADC values. A cut-off ADC value of (1 × 10 ⁻³ mm ² /s) is statistically significant in the differentiation of meningioma from schwannoma. A myoinositol peak was in all 12 schwannomas and single meningioma while 6 meningiomas displayed alanine peak, with a very good statistical significance. Remaining lesions revealed non-specific spectra. SWI made in 18 lesions revealed signal voids in three schwannomas and glomus.
Conclusions
Though MRI features of CPA masses are distinctive in most clinical settings; MRI spectroscopy, diffusion, and susceptibility can provide highly informative additional data in problematic cases. An intermediate to high ADC value plus myoinositol peak and signal voids of micro-bleeds are highly suggestive of schwannomas. This is in contrary to meningiomas displaying low to intermediate ADC and an alanine peak with no micro-bleeds. The less common lesions revealed non-specific data.
... It may be noted that results from these series are confounded as they are not adjusted for size and preoperative functional status. In the absence of preoperative serviceable hearing, both the RS and the TL approaches have been used with the intent of a GTR [33,36,39,104,108,109,187]. Results from retrospective or nonrandomized prospective series are discordant regarding functional preservation and significant variability related to tumor size and surgeon's preferences do not allow for definite conclusions. ...
Background and objective: The optimal management of large vestibular schwannomas continues to be debated. We constituted a task force comprising the members of the EANS skull base committee along with international experts to derive recommendations for the management of this problem from a European perspective.
Material and methods: A systematic review of MEDLINE database, in compliance with the PRISMA guidelines, was performed. A subgroup analysis screening all surgical series published within the last 20 years (January 2000 to March 2020) was performed. Weighted summary rates for tumor resection, oncological control, and facial nerve preservation were determined using meta-analysis models. This data along with contemporary practice patterns were discussed within the task force to generate consensual recommendations regarding preoperative evaluations, optimal surgical strategy, and follow-up management.
Results: Tumor classification grades should be systematically used in the perioperative management of patients, with large vestibular schwannomas (VS) defined as > 30 mm in the largest extrameatal diameter. Grading scales for pre- and postoperative hearing (AAO-HNS or GR) and facial nerve function (HB) are to be used for reporting functional outcome. There is a lack of consensus to support the superiority of any surgical strategy with respect to extent of resection and use of adjuvant radiosurgery. Intraoperative neuromonitoring needs to be routinely used to preserve neural function. Recommendations for postoperative clinico-radiological evaluations have been elucidated based on the surgical strategy employed.
Conclusion: The main goal of management of large vestibular schwannomas should focus on maintaining/improving quality of life (QoL), making every attempt at facial/cochlear nerve functional preservation while ensuring optimal oncological control, thereby allowing to meet patient expectations. Despite the fact that this analysis yielded only a few Class B evidences and mostly expert opinions, it will guide practitioners to manage these patients and form the basis for future clinical trials.
... Magnetic resonance imaging (MRI) showed a medial intrameatal expansive lesion on the left side, slightly debording into the cerebello-pontine cistern, with a maximum diameter of 1.5 cm, isointense to the cerebral parenchyma on T1 and T2 weighted images, with contrast enhancement (Fig. 1). According to Dunn et al. [44], preoperative clinical MRI diagnosis was medial acoustic neuroma. ...
Cavernous angiomas originating in the internal auditory canal are very rare. In the available literature, only 65 cases of cavernomas in this location have been previously reported. We describe the case of a 22-year-old woman surgically treated for a cavernous hemangioma in the left internal auditory canal, mimicking on preoperative magnetic resonance imaging MRI an acoustic neuroma. Neurological symptoms were hypoacusia and dizziness. The cavernous angioma encased the seventh and, partially, the eighth cranial nerve complex. A "nearly total" removal was performed, leaving a thin residual of malformation adherent to the facial nerve. Postoperative period was uneventful; hearing was unchanged, but the patient had a moderate inferior left facial palsy (House-Brackmann grade II) slightly improved during the following weeks. On the basis of the observation of this uncommon case, we propose a revision of the literature and discuss clinical features, differential diagnosis, and treatment.
Background
The progression of vestibular schwannoma (VS) is intricately linked with interactions between schwannoma cells and the extracellular matrix. Surgical resection of VS is associated with substantial risks as tumors are adherent to the brainstem and cranial nerves. We evaluate the role of matrix metalloproteinase 9 (MMP9) in VS and explore its potential as a biomarker to classify adherent VS.
Methods
Transcriptomic analysis of a murine schwannoma allograft model and immunohistochemical analysis of 17 human VS were performed. MMP9 abundance was assessed in mouse and human schwannoma cell lines. Transwell studies were performed to evaluate the effect of MMP9 on schwannoma invasion in vitro. Plasma biomarkers were identified from a multiplexed proteomic analysis in 45 prospective VS patients and validated in primary culture. The therapeutic efficacy of MMP9 inhibition was evaluated in a mouse schwannoma model.
Results
MMP9 was the most highly upregulated protease in mouse schwannomas and was significantly enriched in adherent VS, particularly around tumor vasculature. High levels of MMP9 were found in plasma of patients with adherent VS. MMP9 outperformed clinical and radiographic variables to classify adherent VS with outstanding discriminatory ability. Human schwannoma cells secreted MMP9 in response to TNF-α which promoted cellular invasion and adhesion protein expression in vitro. Lastly, MMP9 inhibition decreased mouse schwannoma growth in vivo.
Conclusions
We identify MMP9 as a pre-operative biomarker to classify adherent VS. MMP9 may represent a new therapeutic target in adherent VS associated with poor surgical outcomes that lack other viable treatment options.
Objective:
This article provides an overview of imaging modalities and findings associated with common skull base tumors including meningiomas and how to use imaging features to guide surveillance and treatment decision making.
Latest developments:
Ease of access to cranial imaging has led to a higher number of incidentally diagnosed skull base tumors, which merit careful consideration for management with observation or treatment. The point of origin of the tumor dictates the pattern of anatomic displacement and involvement by the tumor as it grows. Careful study of vascular encroachment on CT angiography, as well as the pattern and extent of bony invasion on CT, abets treatment planning. Quantitative analyses of imaging, such as with radiomics, may further elucidate phenotype-genotype associations in the future.
Essential points:
Combinatorial application of CT and MRI analyses improves the diagnosis of skull base tumors, clarifies their point of origin, and dictates the extent of treatment needed.
