Figure 1 - uploaded by Frank Garcea
Content may be subject to copyright.
Preoperative and postoperative behavioral and MRI findings. (A) MLU in the Cookie Theft test of spontaneous speech. Patient AF completed the test multiple times postoperatively (see Table 1), with the average MLU shown plotted in A. (B) Mean RT of each patient, preoperatively and postoperatively, averaged over 80 trials of picture naming. (C) Mean functional connectivity between the posterior inferior frontal gyrus (IFG) and the pre-SMA over all BOLD scans (excluding scans used to functionally define language areas) for each patient, preoperatively and postoperatively. (D) Mean functional connectivity between the posterior IFG and the middle temporal gyrus over all BOLD scans for each patient, preoperatively and postoperatively. (E) Mean FA of the left FAT for each patient, preoperatively and postoperatively. Averages plotted here were calculated at the 15% threshold (see Table 2 for other thresholds). Error bars show the standard error of the mean, over voxels. (F) Mean FA of the left ILF for each patient, preoperatively and postoperatively. Averages were calculated at the 15% threshold. Error bars show the standard error of the mean, over voxels.
Source publication
Frontal and temporal white matter pathways play key roles in language processing, but the specific computations supported by different tracts remain a matter of study. A role in speech planning has been proposed for a recently described pathway, the frontal aslant tract (FAT), which connects the posterior inferior frontal gyrus to the pre-SMA. Here...
Contexts in source publication
Context 1
... tractography successfully reconstructed the FAT in both the left and right hemispheres, preopera- tively and postoperatively, as well as the left ILF (see Figure 2). The waytotal for the preoperative left hemi- sphere FAT was 623,757. Postoperatively, the left- hemisphere FAT waytotal decreased to 40,957 (a 93% decrease). The number of voxels contained within the tract decreased by an average of 148 voxels (range = 96-253 voxels) across all thresholds, an average decrease of 32.3%. Despite contiguous bundles of the FAT success- fully reconstructed both before and after surgery, clear changes in the diffusivity measures were observed after surgery. Of note, FA decreased after surgery (see Fig- ure 3). This effect was robust across thresholds (see Tables 2 and 3). MD, RD, and AD significantly increased across all thresholds. By comparison, there was no change in FA postoperatively in the ILF in Patient AF (see Figure 1). Additional analyses (not reported herein) in which we adjusted the sizes of the spheres used as seeds for the DTI analysis (decreased and increased by 2 and 4 mm) did not change any of these core findings. Those control analyses indicated that the decision to use 1-cm sphere for fiber tracking did not affect the overall pattern of the ...
Context 2
... observed a double dissociation across the two pa- tients: Functional connectivity between the pre-SMA and the posterior inferior frontal gyrus decreased for Patient AF as a function of surgery but was unchanged Table 2 for other thresholds). Error bars show the standard error of the mean, over voxels. (F) Mean FA of the left ILF for each patient, preoperatively and postoperatively. Averages were calculated at the 15% threshold. Error bars show the standard error of the mean, over voxels. for Patient AG. In contrast, functional connectivity be- tween the middle temporal gyrus and inferior frontal gy- rus decreased for Patient AG but was unchanged for Patient AF (see Figure 1). The three-way ANOVA with fac- tors Patient (two levels: patient AF, patient AG), ROI pairs (two levels: the posterior inferior frontal gyrus and the middle temporal gyrus, the posterior inferior frontal gyrus and the pre-SMA), and Test session (two levels: preoperative, postoperative) was significant (F(1, 81) = 15.66, p < .001, η p 2 = 0.20). The two-way interactions were not significant between Patient and ROI (F < 1), Patient and Test session (F < 1), or ROI and Test session (F < 1). How- ever, within each patient, there were significant two-way in- teractions between ROI and Test session (AF: F(1, 47) = 9.44, p < .005, η p 2 = 0.18; AG: F(1, 23) = 6.47, p < .02, η p 2 = 0.24). The only significant main effect was that of Pa- tient (F(1,81) = 36.4, p < .001, η p 2 = 0.40). Hypothesis- driven tests for each pair of ROIs for each patient indicated that the reduction between test sessions in functional con- nectivity supported by the Frontal Aslant Tract was signifi- cant for AF (t(23) = 2.60, p < .02, d = 1.06) but not for AG (t(11) = −1.43, p = .178, d = 0.67); in contrast, the re- duction in functional connectivity supported (in part) by the inferior longitudinal fasciculus was significant for AG (t(11) = 2.54, p = < .03, d = 1.20) but not for AF (t(23) = −2.02, p = .06, d = ...
Context 3
... opposite dissociation across the two patients was observed when looking at picture naming performance: Patient AF's accuracy was slightly better postoperatively, with no change in RT (see Figure 1B). By comparison, Patient AG's accuracy decreased from 95% preoperatively to 74% postoperatively (t(158) = 4.36, p < .001, d = 0.49), and her correct trials were slower postoperatively than preoperatively (t(158) = 5.40, p < .001, d = ...
Context 4
... quantified the difficulties that Patient AF exhibited with verbal fluency by measuring the MLU; postopera- tively, there was a reduction in MLU in Patient AF, but not in Patient AG ( Figure 1A). We also analyzed where pauses occurred in spontaneous speech (Cookie Theft picture description test); Patient AF paused more fre- quently before verbs and verb phrases. Of 11 pauses be- tween utterances, nine came before the subject of a verb phrase (n = 5) or the verb itself (n = 4; two additional pauses before an adjective and an adverb). The mean duration of pauses was 12.16 sec before the subject of a verb phrase (SD = 5.76 sec), 3.21 sec before the verb itself (SD = 1.44 sec), and 3.05 sec for the other two pauses (SD = 1.43 sec). By comparison, Patient AG produced more speech with more frequent but much shorter pauses. Fifteen of 29 pauses came before a noun (n = 11) or noun phrase (n = 4). Only five pauses came before a verb (n = 2) or verb phrase (n = 3). An addi- tional five pauses came before a preposition; two, before a conjunction; and two, before an adjective. The mean duration of pauses was 1.09 sec before a noun (SD = 1.7 sec), 0.47 sec before the head of a noun phrase (SD = 0.26 sec), 0.33 sec before a verb (SD = 0.01 sec), and 0.57 sec before the subject of a verb phrase (SD = 0.56 sec). The mean duration for the pauses was 0.21 sec before a preposition (SD = 0.05 sec), 0.48 sec before a conjunction (SD = 0.35 sec), and 0.55 sec before an adjective (SD = 0.33 ...
Citations
... The left frontal aslant tract (FAT) connects the SMA complex to LIFG (including pars triangularis and pars opercularis) and has been shown to play an important role in speech production and verbal fluency (Catani et al., 2013;Ford et al., 2010). Studies using interoperative direct electrical stimulation and/or postoperative tractography based on DTI demonstrated interruption of the left FAT has been associated with reduced verbal fluency (Chernoff et al., 2018(Chernoff et al., , 2019Fujii et al., 2015;Kinoshita et al., 2015;Sierpowska et al., 2015;Vassal et al., 2014), motivating pre-operative planning to avoid lesions in FAT to minimize such deficits (Briggs et al., 2021). Interruption of the left FAT using direct electric stimulation was shown to reduce voluntary speech fluency or sentence completion but did not affect sentence repetition or picture naming (Chernoff et al., 2018;Dragoy et al., 2020). ...
... Studies using interoperative direct electrical stimulation and/or postoperative tractography based on DTI demonstrated interruption of the left FAT has been associated with reduced verbal fluency (Chernoff et al., 2018(Chernoff et al., , 2019Fujii et al., 2015;Kinoshita et al., 2015;Sierpowska et al., 2015;Vassal et al., 2014), motivating pre-operative planning to avoid lesions in FAT to minimize such deficits (Briggs et al., 2021). Interruption of the left FAT using direct electric stimulation was shown to reduce voluntary speech fluency or sentence completion but did not affect sentence repetition or picture naming (Chernoff et al., 2018;Dragoy et al., 2020). Damage to or abnormal development of the FAT (most often left lateralized) is associated with verbal dysfluency, reduced speech initiation and stuttering, non-fluent/agrammatic variant primary progressive aphasia (nfvPPA), and developmental stuttering (Catani et al., 2013;Cipolotti et al., 2020;Costentin et al., 2019;Kemerdere et al., 2016;Keser et al., 2020;Kronfeld-Duenias et al., 2016;Mandelli et al., 2014Mandelli et al., , 2016. ...
Word finding difficulty is a frequent complaint in older age and disease states, but treatment options are lacking for such verbal retrieval deficits. Better understanding of the neurophysiological and neuroanatomical basis of verbal retrieval function may inform effective interventions. In this article, we review the current evidence of a neural retrieval circuit central to verbal production, including words and semantic memory, that involves the pre‐supplementary motor area (pre‐SMA), striatum (particularly caudate nucleus), and thalamus. We aim to offer a modified neural circuit framework expanded upon a memory retrieval model proposed in 2013 by Hart et al., as evidence from electrophysiological, functional brain imaging, and noninvasive electrical brain stimulation studies have provided additional pieces of information that converge on a shared neural circuit for retrieval of memory and words. We propose that both the left inferior frontal gyrus and fronto‐polar regions should be included in the expanded circuit. All these regions have their respective functional roles during verbal retrieval, such as selection and inhibition during search, initiation and termination of search, maintenance of co‐activation across cortical regions, as well as final activation of the retrieved information. We will also highlight the structural connectivity from and to the pre‐SMA (e.g., frontal aslant tract and fronto‐striatal tract) that facilitates communication between the regions within this circuit. Finally, we will discuss how this circuit and its correlated activity may be affected by disease states and how this circuit may serve as a novel target engagement for neuromodulatory treatment of verbal retrieval deficits.
... The SMA is thought to facilitate speech initiation due to the direct connection to the PO of the IFG provided by the FAT (Vergani et al., 2014). Functionally, the left FAT serves as a key communicative link between sentence planning and lexical access (Chernoff et al., 2018;Kinoshita et al., 2015;Kronfeld-Duenias et al., 2016), whereas, the right FAT has been associated with executive functions (Dick et al., 2019;Landers et al., 2022). Moreover, a pattern of non-homologous connections through the anterior corpus callosum connecting the SMA to the contralateral medial and lateral superior frontal gyrus was identified (Baker et al., 2018). ...
Previous research has documented the impact of bilingualism on the functional connectivity (FC) of brain networks responsible for processing of two languages during a resting-state brain activity. However, the BOLD signal modulation during task-evoked neural activity remains unclear. To address this question we focused on language-related differences of fMRI-based FC of bilingual brains during morphosyntactic processing in L1 and L2 among balanced L1-Turkish-L2-Persian bilinguals who had learnt L2 at age 7. The task required grammaticality judgements to alternating L1-L2 sentences. In our previous study on the present dataset, we had demonstrated changes in BOLD activation in the Pars opercularis (PO), posterior Superior Temporal Gyrus (pSTG), Planum Temporale (PT), and Supplementary Motor Area (SMA), associated with auditory morphosyntactic processing. In the present reanalysis of these data we focused on FC within and between the language network and the control network. Regions of interest were based on the syntax-and control-specific regions activated by the task. Our findings confirm the FC between the syntax-specific regions PO and pSTG within the language network. The FC between these areas in the processing of morphosyntax turned to be quite similar for L1 and L2, reflecting the high competences of our balanced bilinguals in both languages. In the control network, direct FCs were found in two key areas of the PT and SMA (i.e. left PT to right PT and left PT to left SMA), supporting the view that these areas subserve control operations when bilinguals perceive and process spoken language. Remarkably, inter-and intra-hemispheric connectivities in the control network were indistinguishable for L1 and L2. Regarding intra-network results, although increased FCs were observed in L1 for the left PO-PT neurocircuit and in L2 for the pSTG-PT neurocircuit, none of them significantly interacted with grammaticality. Overall, these results suggest that being balanced bilingual with age of acquisition at 7 years appears to be associated with similarities of FC between syntax processing-related and input-and output-related brain networks. Considering that previous resting state studies had not found evidence for the above-mentioned connections in bilinguals, the present results indicate the importance of task-driven reconfigurations on functional connections between brain networks.
... Second, AVHh+, but not AVHh− , differed from HC in a decreased utterance length in a picture-based story which represents the deficient syntactic programming (Akhutina, 2015;Angelopoulou et al., 2018; Chernoff et al., 2018). Along with poor programming of an utterance, AVHh+, but not AVHh− , demonstrated more general deficits of planning as indicated by decreased productivity in Picture Arrangement test and increased number of moves in Tower of London test (Harsa et al., 2022;Patrikelis et al., 2016). ...
Background: As demonstrated by a plethora of studies, compromised executive functions (EF) and language are implicated in mechanisms of auditory verbal hallucinations (AVH), but the contribution of their interaction to AVH remains unclear. We hypothesized that schizophrenia patients with history of AVH (AVHh+) vs. without history of AVH (AVHh-) have a specific deficit of executive control of language and alterations in functional connectivity (FC) between the brain regions involved in EF and language, and these neuropsychological and neurophysiological traits are associated with each other.
Methods: To explore the executive control of language and its contribution to AVH, we used an integrative approach involving analysis of neuropsychological and resting-state fMRI data of 34 AVHh+, 16 AVHh-, and 40 healthy controls. We identified the neuropsychological and FC measures that differentiated between AVHh+, AVHh-, and HC, and tested the associations between them.
Results: AVHh+ were characterized by decreased category and phonological verbal fluency, utterance length, productivity in the planning tasks, and poorer retelling. AVHh+ had decreased FC between the left inferior frontal gyrus and the anterior cingulate cortex. Productivity in category verbal fluency was associated with the FC between these regions.
Conclusions: Poor executive control of word retrieval and deficient programming of sentence and narrative related to more general deficits of planning may be the neuropsychological traits specific for AVHh+. A neurophysiological trait specific for AVHh+ may be a decreased FC between regions involved in language production and differentiation between alien- vs. self-generated speech and between language production vs. comprehension.
... Firstly, it is essential to conduct longitudinal studies involving a larger sample size to establish whether the degeneration of the IFOF is robust across a wider population and holds predictive value for future cognitive impairment. Secondly, it is advisable to extend the scope of pointwise analysis to encompass other WM tracts of cognitive significance, such as the fornix and frontal aslant tract [10,11]. Thirdly, the application of free water correction to DTI data has demonstrated the potential to improve the accuracy of DTI metrics [12,13]. ...
... A substantial amount of literature has been dedicated to refining techniques for reducing damage to traditional eloquent areas for mitigating post-surgical deficit risk. Recent efforts have focused on functional preservation techniques in less well-known anatomy, including preservation of the inferior frontal-occipital fasciculus (IFOF) [31] and FAT [32,33]. Such outcomes provide Fig. 2 MRI images and the networks showed by the Quicktome in patient no. 2, who had the glioma resection in the right frontal, temporal, insula lobe. ...
Background:
Patients with insulo-Sylvian gliomas continue to present with severe morbidity in cognitive functions primarily due to neurosurgeons' lack of familiarity with non-traditional brain networks. We sought to identify the frequency of invasion and proximity of gliomas to portions of these networks.
Methods:
We retrospectively analyzed data from 45 patients undergoing glioma surgery centered in the insular lobe. Tumors were categorized based on their proximity and invasiveness of non-traditional cognitive networks and traditionally eloquent structures. Diffusion tensor imaging tractography was completed by creating a personalized brain atlas using Quicktome to determine eloquent and non-eloquent networks in each patient. Additionally, we prospectively collected neuropsychological data on 7 patients to compare tumor-network involvement with change in cognition. Lastly, 2 prospective patients had their surgical plan influenced by network mapping determined by Quicktome.
Results:
Forty-four of 45 patients demonstrated tumor involvement (< 1 cm proximity or invasion) with components of non-traditional brain networks involved in cognition such as the salience network (SN, 60%) and the central executive network (CEN, 56%). Of the seven prospective patients, all had tumors involved with the SN, CEN (5/7, 71%), and language network (5/7, 71%). The mean scores of MMSE and MOCA before surgery were 18.71 ± 6.94 and 17.29 ± 6.26, respectively. The two cases who received preoperative planning with Quicktome had a postoperative performance that was anticipated.
Conclusions:
Non-traditional brain networks involved in cognition are encountered during surgical resection of insulo-Sylvian gliomas. Quicktome can improve the understanding of the presence of these networks and allow for more informed surgical decisions based on patient functional goals.
... In line with this hypothesis are two other reports of intraoperative stimulations, by Chernoff et al. (2018) and Dragoy et al. (2020). In the former study, the authors reported a patient with surgical damage to the connectivity of the left FAT, who showed a selective post-surgical impairment of fluency in the form of difficulty with voluntary speech and more complex sequences, while remaining unimpaired in production tasks such as picture naming and auditory repetition. ...
Much is known about the role of cortical areas in language processing. The shift towards network approaches in recent years has highlighted the importance of uncovering the role of white matter in connecting these areas. However, despite a large body of research, many of these tracts’ functions are not well-understood. We present a comprehensive review of the empirical evidence on the role of eight major tracts that are hypothesized to be involved in language processing (inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, extreme capsule, middle longitudinal fasciculus, superior longitudinal fasciculus, arcuate fasciculus, and frontal aslant tract). For each tract, we hypothesize its role based on the function of the cortical regions it connects. We then evaluate these hypotheses with data from three sources: studies in neurotypical individuals, neuropsychological data, and intraoperative stimulation studies. Finally, we summarize the conclusions supported by the data and highlight the areas needing further investigation.
... The SMA is thought to facilitate speech initiation due to the direct connection to the PO of the IFG provided by the FAT (Vergani et al., 2014). Functionally, the left FAT serves as a key communicative link between sentence planning and lexical access (Chernoff et al., 2018;Kinoshita et al., 2015;Kronfeld-Duenias et al., 2016), whereas, the right FAT has been associated with executive functions (Dick et al., 2019;Landers et al., 2022). Moreover, a pattern of non-homologous connections through the anterior corpus callosum connecting the SMA to the contralateral medial and lateral superior frontal gyrus was identified (Baker et al., 2018). ...
... В работах по сравнению послеоперационных проявлений повреждения FAT и лобно-полосатого пучка выявлены транзиторные нарушения инициации речи для FAT и аналогичные отклонения касательно движений тела для лобнополосатого пучка [74,75]. Нарушение целостности FAT приводит к таким последствиям, как снижение либо отсутствие спонтанной речи, семантическая и фонетическая девиация, затруднение поиска глаголов [49,74,76]. В исследованиях с поражением дополнительной моторной коры и нижней лобной извилины наблюдались речевые нарушения, подобные тем, которые возникают при повреждении FAT, что подтверждает их анатомо-функциональную связь [77]. ...
Introduction . History of study of speech function of the brain has started in the middle of the 19th century. First studies discovered cortical representations of speech in the brain, proposed different theories of speech function structure. Technological breakthroughs of the 20th century allowed to study not only cortical representations of speech function but also complex connections of the white matter important for practical work of neurosurgeons. Deeper studies of speech led to revisions of the old theories, proposals of new theories. Current study methods showed complexity of speech organization, multifunctionality of speech tracts.
Aim . To analyze and systemize historical and current scientific data on organization of speech function of the brain, as well as methods of preoperative evaluation and intraoperative techniques of identification of speech zones in the cerebral cortex.
Materials and methods . As a results of data search in the PubMed database, 77 articles published between 1954 and 2020 were selected.
Results . Studies of characteristics of speech function are widely represented in current scientific literature, and their number grows every year. Some researchers study individual speech aspects: cortical representation, individual speech tracts. Others deal with general consequences of speech impediments after tumor resection, strokes, traumas. The authors cross-linked and systemized numerous data from different sources of information.
Conclusion . Speech function of the brain is one of the most complexly organized aspects of the higher nervous function, and it is being actively researched worldwide. Implementation of such revolutionary examination techniques as intraoperative mapping of the cerebral cortex, magnetic resonance tractography provided a plethora of new information on morphofunctional characteristics of speech function. Further studies of speech function of the brain and systematization of the obtained data are necessary for deeper understanding of the details of speech organs' functionality. Advances in this direction will help surgeons avoid unwanted neurological deficit in communication ability, one of the most important abilities, and improve patients' quality of life.
... Stimulation to the FAT intraoperatively produced speech arrest in two of these studies (Fujii et al., 2015;Vassal et al., 2014) while stuttering was provoked in the third study (Kemerdere et al., 2016). In another study, the case of a patient who sustained a FAT lesion post-operatively was compared with the case of a patient who sustained an ILF lesion post-operatively (Chernoff et al., 2018). It was found that the patient with the FAT lesion demonstrated dysfluent speech but no word finding difficulty, while the other patient exhibited the reverse pattern. ...
... As predicted, the loss of integrity of the FAT was associated with deficits in motor speech function. With regards to speech function, the FAT has previously been shown to be associated with stuttering (Kemerdere et al., 2016;Kronfeld-Duenias et al., 2016;Misaghi et al., 2018;Neef et al., 2018), speech arrest post-tumor resection (Fujii et al., 2015;Vassal et al., 2014), and speech fluency in individuals with resected glioma, post-stroke aphasia and primary progressive aphasia (Basilakos et al., 2014;Catani et al., 2013;Chernoff et al., 2018;Halai et al., 2017;Mandelli et al., 2014). Here, we found that damage to the FAT was associated with apraxia of speech, which, to our knowledge, is an association that has not previously been observed. ...
The frontal aslant tract (FAT) is a recently-described intralobar tract that connects the superior and inferior frontal gyri. The FAT has been implicated in various speech and language processes and disorders, including motor speech impairments, stuttering disorders, opercular syndrome, and verbal fluency, but the specific function(s) of the FAT have yet to be elucidated. In the current study, we aimed to address this knowledge gap by investigating the underlying role that the FAT plays in motor aspects of speech and language abilities in post-stroke aphasia. Our goals were three-fold: 1) To identify which specific motor speech or language abilities are impacted by FAT damage by utilizing a powerful imaging analysis method, High Angular Resolution Diffusion Imaging (HARDI) tractography; 2) To determine whether damage to the FAT, is associated with functional deficits on a range of motor speech and language tasks even when accounting for cortical damage to adjacent cortical regions; and 3) To explore whether subsections of the FAT (lateral and medial segments) play distinct roles in motor speech performance. We hypothesized that damage to the FAT would be most strongly associated with motor speech performance in comparison to language tasks. We analyzed HARDI data from thirty-three people with aphasia (PWA) with a history of chronic left hemisphere stroke. FAT metrics were related to scores on several speech and language tests: the Motor Speech Evaluation (MSE), the Western Aphasia Battery (WAB) aphasia quotient and subtests, and the Boston Naming Test (BNT). Our results indicated that the integrity of the FAT was strongly associated with the MSE as predicted, and weakly negatively associated with WAB subtest scores including Naming, Comprehension, and Repetition, likely reflecting the fact that performance on these WAB subtests is associated with damage to posterior areas of the brain that are unlikely to be damaged with a frontal lesion. We also performed hierarchical stepwise regressions to predict language function based on FAT properties and lesion load to surrounding cortical areas. After accounting for the contributions of the inferior frontal gyrus, the ventral precentral gyrus, and the superior precentral gyrus of the insula, the FAT still remained a significant predictor of MSE apraxia scores. Our results further showed that the medial and lateral subsections of the FAT did not appear to play distinct roles but rather may indicate normal anatomical variations of the FAT. Overall, current results indicate that the FAT plays a specific and unique role in motor speech. These results further our understanding of the role that white matter tracts play in speech and language.
... Catani et al. were the first to describe a negative relation between dominant FAT integrity and verbal fluency in patients with primary progressive aphasia [6]. Illustrative was a case study published by Chernoff et al. in which a patient with postoperative damage to the left FAT showed marked reduction in verbal fluency but no semantic or phonemic paraphasias [9]. These results were consistent with a larger series of patients published by Kinoshita et al. in which the distance of the postoperative resection cavity correlated with verbal fluency problems. ...
The supplementary motor area (SMA) syndrome is a frequently encountered clinical phenomenon associated with surgery of the dorsomedial prefrontal lobe. The region has a known motor sequencing function and the dominant pre-SMA specifically is associated with more complex language functions; the SMA is furthermore incorporated in the negative motor network. The SMA has a rich interconnectivity with other cortical regions and subcortical structures using the frontal aslant tract (FAT) and the frontostriatal tract (FST). The development of the SMA syndrome is positively correlated with the extent of resection of the SMA region, especially its medial side. This may be due to interruption of the nearby callosal association fibres as the contralateral SMA has a particular important function in brain plasticity after SMA surgery. The syndrome is characterized by a profound decrease in interhemispheric connectivity of the motor network hubs. Clinical improvement is related to increasing connectivity between the contralateral SMA region and the ipsilateral motor hubs. Overall, most patients know a full recovery of the SMA syndrome, however a minority of patients might continue to suffer from mild motor and speech dysfunction. Rarely, no recovery of neurological function after SMA region resection is reported.
