A Study of Outcome of Pediatric Cochlear Implantation in Patients with Cochleovestibular Nerve Deficiency.

OBJECTIVES: A cochleovestibular nerve deficiency (CVND) could compromise stimulation of nerve by electrical pulses delivered from a cochlear implant, thereby hindering activity along auditory pathway. The evaluation of children with congenital hearing loss with a high-resolution magnetic resonance imaging is presently the investigative modality of choice to diagnose CVND. The aim of this study was to determine the outcomes in pediatric cochlear implant recipients with a diagnosis of CVND. The objectives included (1) to study the prevalence of CVND among children with prelingual congenital severe to profound hearing loss; (2) to assess post cochlear implantation (CI) outcomes in children with CVND using categories of auditory performance (CAP), speech intelligibility rating (SIR), and cortical auditory evoked potentials (CAEPs); and (3) to propose a management protocol for these children. MATERIALS AND METHODS: All CI procedures performed during the study period in children 5 years or younger were included in study. All patients who were older than 5 years or had syndromic associations, multiple disabilities, second side or revision CI were excluded from the study. Children with unilateral cochleovestibular nerve aplasia and all other cases of CVND (type IIa and IIb) were advised to undergo CI on side with more radiologically robust nerve and/or cochlea anatomy. Children with bilateral CVND were included in group A, and age-matched cochlear implant candidates with normal cochleovestibular nerve anatomy were included in group B for statistical comparison of outcomes. RESULTS: In group A, post CI CAP and SIR, CAEP amplitude and latency at 12 months showed statistically significant difference (p<0.05) compared with preoperative values. However, mean score of CAEP latency and amplitude and SIR score was worse for group A compared with group B at 12 months, which was statistically significant (p<0.05). CONCLUSION: This study supports the fact that CI is a viable option to be offered in children with CVND (type IIa and IIb) for the development of auditory perception and speech.

Perfil clínico y resultados obtenidos en los pacientes tratados mediante implante auditivo del tronco del encéfalo / Clinical Profile and Results Obtained in Patients Treated by Auditory Brainstem Implants

INTRODUCCIÓN: Los implantes cocleares han paliado algunas hipoacusias, pero las relacionadas con alteraciones del nervio coclear obligaron a buscar nuevas formas de tratamiento, dando lugar a los implantes auditivos del tronco cerebral (IATC). OBJETIVOS: Exponer el perfil clínico de los pacientes tratados mediante un IATC y los resultados entre los años 1997 y 2017. MATERIAL Y MÉTODOS: Se seleccionaron por un lado pacientes con tumores del nervio estatoacústico (VIII par craneal) y por otro lado pacientes sin tumores del VIII con malformaciones congénitas del oído interno. Previa y posteriormente a la colocación del IATC se evaluó la audición a través de audiometría tonal liminar, de la que se obtuvo el umbral tonal medio (UTM) y de la escala de rendimiento auditivo Categories Auditory Performance (CAP). RESULTADOS: Se incluyeron un total de 20 pacientes sometidos a una cirugía de IATC. Ocho de los casos fueron de causa tumoral (40%) y 12 no tumorales (60%). En 15 sujetos (75%) se realizó abordaje suboccipital y en 5 (25%) translaberíntico. La media de electrodos activos al inicio en los implantes de la casa comercial Cochlear® (Nucleus ABI24), la cual tiene un total de 21 electrodos, fue de 13 (61,90%) frente a 8,5 (70,83%) de los 12 electrodos que presenta el implante de la casa Med-el® (ABI Med-el). Se comprobó una mejora en el UTM medio de 118,49dB basal frente a 46,55 dB a los 2 años. En la escala CAP se parte en todos los casos de un valor de1, y en la revisión a los 2 años, de 2,57 (1-5). CONCLUSIÓN: Concluimos que el IATC es una opción segura y con buenos resultados auditivos cuando la indicación se hace de manera correcta

INTRODUCTION: Cochlear implants have been able to treat some types of hearing loss, but those related to cochlear nerve impairment made it necessary to find new ways to manage these deficits; leading to auditory brainstem implants (ABI). AIM: Our objective is to present the clinical profile of patients treated through an ABI and the results obtained from 1997 to 2017. MATERIAL AND METHODS: On the one hand, patients with statoacoustic nerve tumours (VIII cranial nerve) were selected, and on the other hand, patients withoutVIII tumours with congenital malformations of the inner ear. Before and after the placement of the ABI, hearing was assessed through tonal audiometry, from which the PTA (Pure Tone Average) and the CAP (Categories of Auditory Performance) scale were obtained. RESULTS: A total of 20 patients undergoing ABI surgery were included. Eight were of tumour cause (40%) and 12 non-tumour (60%). In 15 subjects (75%) a suboccipital approach was performed and in 5 (25%) translabyrinthine. The mean of active electrodes before the implantation of Cochlear® (Nucleus ABI24) was 13/21 (61.90%) versus 8.5/12 (70.83%) of the Med-el® (ABI Med-el). An improvement in the mean PTA of 118.49 dB was found against 46.55dB at 2 years. On the CAP scale, values of1 were obtained in the preimplantation and of 2.57 (1-5) in the 2-year revision. CONCLUSION: The ABI is a safe option, and with good hearing results when the indication is made correctly

MRI surveillance following concurrent cochlear implantation in cases of vestibular schwannoma resection.

OBJECTIVE: Cochlear nerve preserving translabyrinthine vestibular schwannoma (VS) resection enables concurrent cochlear implantation. Implantation in patients with VS raises important concerns including the ability to undergo postoperative magnetic resonance imaging (MRI) monitoring of residual tumor growth or tumor recurrence, specifically with a retained magnet. We aim to assess the feasibility of MRI monitoring and the impact on image quality with retained cochlear implant (CI) magnets. METHODS: Retrospective review of post-operative head MRI scans in CI recipients with a retained CI magnet, after cochlear nerve preserving translabyrinthine excision of VS. The ability to visualize the ipsilateral and contralateral internal auditory canal (IAC) and cerebellopontine angle (CPA) were assessed. RESULTS: A total of eight surveillance head MRI were performed in six patients. In one case, in which the receiver was positioned lower, the view of the ipsilateral IAC and CPA was distorted. In all other cases, the views of both the ipsilateral and contralateral IAC and CPA were overall unimpaired. DISCUSSION: Imaging artifact only very rarely impedes adequate visualization of the ipsilateral IAC or CPA in CI recipients. In anticipation of the need for further IAC and CPA imaging, it would be advisable to place the receiver in an exaggerated superior-posterior position to further decrease obscuring artifact. Thus, serial monitoring of VS tumors can be performed safely with preservation of image quality with a retained receiver magnet. CONCLUSIONS: When placing the CI receiver-stimulator farther posterior-superiorly, excellent visualization of the IAC and CPA can be accomplished without significantly impairing the image quality.

Clinical long-term observation of the keyhole microvascular decompression with local anesthesia on diagnosis and treatment of vestibular paroxysmia.

Background: The pathophysiology and etiology of vestibular paroxysmia (VP) remains unclear, moreover, due to the lack of reliable diagnostic features for VP, the clinical diagnosis will be made mainly by exclusion.Aims/objectives: To evaluate the diagnostic value and curative effect of keyhole microvascular decompression with local anesthesia for VP.Material and methods: 54 patients with trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia underwent keyhole microvascular decompression with local anesthesia, twelve of whom were coexistent with VP. The evaluation of the vertigo after operation was performed with symptom report card for 12 patients with VP and the mean follow-up period was 116 months (range 114-118 months).Results: The cochleovestibular neurovascular compression at the root zone of vestibular nerve was found in 12 patients with VP, of whom 11 patients had the neurovascular compressive vertigo induced intra-operatively and the vertigo disappeared postoperatively, moreover, one patient had no neurovascular compressive vertigo induced intra-operatively and the vertigo was not improved significantly after operation. Of 12 patients with VP during the mean 116-month follow-up, 11 patients had no recurrence of neurovascular compressive vertigo and the effective control rate of vertigo was 91.7%.Conclusions and significance: Keyhole microvascular decompression with local anesthesia is not only an effective method for treating VP and controlling neurovascular compressive vertigo, but also has definite clinical significance in the diagnosis of VP.

Clinical Profile and Results Obtained in Patients Treated by Auditory Brainstem Implants. / Perfil clínico y resultados obtenidos en los pacientes tratados mediante implante auditivo del tronco del encéfalo.

INTRODUCTION: Cochlear implants have been able to treat some types of hearing loss, but those related to cochlear nerve impairment made it necessary to find new ways to manage these deficits; leading to auditory brainstem implants (ABI). AIM: Our objective is to present the clinical profile of patients treated through an ABI and the results obtained from 1997 to 2017. MATERIAL AND METHODS: On the one hand, patients with statoacoustic nerve tumours (VIIIcranial nerve) were selected, and on the other hand, patients withoutVIII tumours with congenital malformations of the inner ear. Before and after the placement of the ABI, hearing was assessed through tonal audiometry, from which the PTA (Pure Tone Average) and the CAP (Categories of Auditory Performance) scale were obtained. RESULTS: A total of 20 patients undergoing ABI surgery were included. Eight were of tumour cause (40%) and 12 non-tumour (60%). In 15 subjects (75%) a suboccipital approach was performed and in 5 (25%) translabyrinthine. The mean of active electrodes before the implantation of Cochlear® (Nucleus ABI24) was 13/21 (61.90%) versus 8.5/12 (70.83%) of the Med-el® (ABI Med-el). An improvement in the mean PTA of 118.49dB was found against 46.55dB at 2years. On the CAP scale, values of1 were obtained in the preimplantation and of 2.57 (1-5) in the 2-year revision. CONCLUSION: The ABI is a safe option, and with good hearing results when the indication is made correctly.

Microvascular Decompression and Transposition of the 8th Cranial Nerve Using a Fenestrated Clip.

Neurovascular compression is a potential, yet rare cause of vertigo and unilateral tinnitus. Despite the high success rate of microvascular decompression (MVD) in other vascular compression syndromes, the outcome reported after MVD of the vestibulocochlear nerve is variable.1,2 The presence of combined symptoms of tinnitus and vertigo treated by MVD has demonstrated a higher predictive value for success.3 In this video, we present the case of a 68-year-old male who presented with vertigo and tinnitus refractory to medical management and vestibular therapy. Audiologic evaluation was normal apart from mild sensorineural hearing loss. Vestibular testing was suggestive of uncompensated right peripheral vestibulopathy. Magnetic resonance imaging with fast imaging employing steady-state acquisition sequences revealed vascular compression by the right anteroinferior cerebellar artery (AICA) at the cisternal component of vestibulocochlear nerve. After a multidisciplinary discussion, a microvascular decompression was performed through a right retrosigmoid craniotomy. The AICA was mobilized off the vestibulocochlear nerve and was secured to the petrous dura using a fenestrated clip. Indocyanine green angiography with Glow-800 was conducted before and after AICA transposition to confirm adequate flow through the mobilized vessel. Postoperatively, the patient's vestibular symptoms improved significantly. This case demonstrates that microvascular decompression can provide a satisfactory outcome in patients with unilateral tinnitus and vertigo associated with vascular compression in appropriately selected cases (Video 1).

Management of jugular bulb injury during drilling of the internal auditory canal (ICA) for vestibular schwannoma surgery.

The retrosigmoid approach for vestibular schwannoma surgery has remained the standard approach by most neurosurgeons. Drilling the posterior wall of the internal auditory meatus (IAM) is an essential step in removing the intrameatal tumor. During IAM drilling, three anatomical structures can be encountered, including the posterior semicircular canal, vestibular aqueduct, and jugular bulb. Any of these can be injured during drilling, especially if the jugular bulb lies above the inferior edge of the IAM. Although IAM drilling is performed in most vestibular schwannoma surgeries, information on how to manage complications such as jugular bulb injury is lacking. Here we use an intraoperative video to demonstrate how to manage the inadvertent injury to the jugular bulb in order to avoid massive blood loss. We present a case of a 39-year-old woman with hearing loss, diagnosed with a cerebellopontine angle mass extending into the IAM. Surgery was required due to tumor progression. We used the retrosigmoid approach to access the tumor. During IAM drilling, the jugular bulb was injured. A thin layer of bone wax was applied under continuous suction. The margins of the wax were then gently compressed with a dissector; great care was taken to avoid pushing the wax into the jugular bulb. Excess bone wax was removed (video 1). A small diamond drill (2 mm) was used for further drilling. Our instructional video shows the surgical approach, microsurgical anatomy, and technical aspects of managing massive bleeding from jugular bulb injury. It should therefore be helpful for young neurosurgeons.

A Predictive Model for Cochlear Implant Outcome in Children with Cochlear Nerve Deficiency.

The outcome of cochlear implantation (CI) in patients with cochlear nerve deficiency (CND) is variable, resulting in a wide range of speech perception performance, from degrees of environmental sound perception to conversation without lip-reading. Twenty-five cochlear implantees with CND were enrolled retrospectively to determine the factors correlated with CI outcome in patients with CND and to develop a predictive model for CI outcome. CI outcome was evaluated using the Categories of Auditory Performance (CAP) score at 2 years after CI. Patients with negative auditory brainstem response (ABR) showed a significantly lower CAP score than those with positive ABR (2.5 ± 1.7, 4.8 ± 0.7; p = 0.001). The area ratio of vestibulocochlear nerve (VCN) to facial nerve (FN) at the cerebellopontine angle on magnetic resonance images was positively correlated with CI outcome (p < 0.001). With multiple regression analysis, a predictive equation accounting for 66% of variance of CAP score at 2 years after CI was [Formula: see text]. We found that preoperative ABR and area ratio of VCN to FN at the cerebellopontine angle could predict CI outcome in patients with CND. Preoperative counselling based on our predictive model might be helpful to determine treatment modality for auditory rehabilitation and which ear to implant.

Outcomes after cochlear implant provision in children with cochlear nerve hypoplasia or aplasia.

INTRODUCTION: Cochlear nerve aplasia or hypoplasia is found in up to a half of patients with unilateral or bilateral hearing loss. There is an ongoing discussion regarding the indication of cochlear implants for hearing rehabilitation in cases with radiologically-defined aplasia or hypoplasia of the cochlear nerve in those patients, especially in children. At present there is conflicting evidence whether the audiological outcomes of those children with a CI are comparable to those of children with a CI and a radiologically-normal cochlear nerve. The primary aim of this study was to assess the audiological abilities before and after CI provision in children with cochlear nerve hypoplasia or aplasia. Additionally, we aimed to determine if audiological outcomes differed in children with aplasia from those with hypoplasia. Such data should be helpful in determining if CI provision is appropriate for such children. METHODS: This retrospective study presents 7 children who were diagnosed with cochlear nerve aplasia or hypoplasia and received a CI. The pre- and postoperative audiological performance and the hearing and speech development of the children were examined. RESULTS: 4 children were unilateral CI users and 3 were bilateral CI users. Hearing reactions could be detected in all children. Already at first fitting, prompt responses and reactions to songs were observed. The aided thresholds in free field in children with hypoplasia were between 30 and 60 dB. Even in children with aplasia, the results in free field with CI averaged between 30 and 70 dB. Therefore the aided thresholds in children with hypoplasia and in children with aplasia of the CN are similar. It could be demonstrated that hearing reactions improve with the long term use of the implant. Improvement in general development could be observed in all children despite the very heterogeneous conditions and the accompanying handicaps. CONCLUSION: The results of this study support the hypothesis that children with radiologically-defined CN hypoplasia or aplasia and detectable responses to electrical or acoustical stimuli can improve their sound detection thresholds and their awareness of sound when provided with a CI.

Clinical role of electrocochleography in children with auditory neuropathy spectrum disorder.

OBJECTIVES: To assess electrocochleography (ECochG) to tones as an instrument to account for CI speech perception outcomes in children with auditory neuropathy spectrum disorder (ANSD). MATERIALS & METHODS: Children (<18 years) receiving CIs for ANSD (n = 30) and non-ANSD (n = 74) etiologies of hearing loss were evaluated with ECochG using tone bursts (0.25-4 kHz). The total response (TR) is the sum of spectral peaks of responses across frequencies. The compound action potential (CAP) and the auditory nerve neurophonic (ANN) in ECochG waveforms were used to estimate nerve activity and calculate nerve score. Performance on open-set monosyllabic word tests was the outcome measure. Standard statistical methods were applied. RESULTS: On average, TR was larger in ANSD than in non-ANSD subjects. Most ANSD (73.3%) and non-ANSD (87.8%) subjects achieved open-set speech perception; TR accounted for 33% and 20% of variability in the outcomes, respectively. In the ANSD group, the PTA accounted for 69.3% of the variability, but there was no relationship with outcomes in the non-ANSD group. In both populations, nerve score was sensitive in identifying subjects at risk for not acquiring open-set speech perception, while the CAP and the ANN were more specific. CONCLUSION: In both subject groups, the TRs correlated with outcomes but these measures were notably larger in the ANSD group. There was also strong correlation between PTA and speech perception outcome in ANSD group. In both subject populations, weaker evidence of neural activity was related to failure to achieve open-set speech perception.

Exclusive endoscopic transcanal transpromontorial approach: a new perspective for internal auditory canal vestibular schwannoma treatment.

OBJECTIVE The aim of this study was to describe the first case series in which an exclusive endoscopic transcanal transpromontorial approach (EETTA) was used to treat small vestibular schwannomas (VSs) and meningiomas of the internal auditory canal (IAC). METHODS The authors performed a retrospective review of patients who had undergone surgery using an EETTA to the IAC at 2 university tertiary care referral centers during the period from November 2011 to January 2015. RESULTS Ten patients underwent surgery via an EETTA for the treatment of VS in the IAC at the University Hospital of Modena or the University Hospital of Verona. The patients had Koos Grade I or II tumors and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Class D hearing status preoperatively. Gross-total resection was achieved in all patients. No major complications such as cerebrospinal fluid leakage or hemorrhage were reported. In 7 of 10 (70%) patients, facial nerve function was normal immediately after surgery (Rough Grading System [RGS] Grade I). Two patients presented with a transitory facial palsy immediately after surgery (RGS Grade II-III) but experienced complete recovery during the follow-up period. The mean follow-up was 10 months. CONCLUSIONS The EETTA proved to be successful for the removal of VS or meningioma involving the cochlea, fundus, and IAC, with possible lower complication rates and less invasive procedures than those for traditional microscopic approaches. The potential for the extensive and routine use of this approach in lateral and posterior skull base surgery will depend on the development of technology and surgical refinements and on the diffusion of skull base endoscopic skills among the otolaryngological and neurosurgical communities.

Deficiencia del nervio coclear: logros obtenidos y expectativas con el implante coclear / Coclear nerve deficiency: achievements and expectations with the coclear implant / Deficiência de nervos coculares: realizações e expectativas como implante cocular

Introducción: la deficiencia del nervio coclear se define como un nervio coclear hipoplásico o aplásico, presente en más del 18% de los niños con hipoacusias neurosensoriales profundas y cuya indicación de implante coclear sigue generando controversias. Objetivo: Analizar el protocolo de estudio en pacientes con sospecha de deficiencia del nervio coclear y exponer los resultados clínico-audiológicos pos-implante coclear en nuestro servicio. Material y método: Estudio retrospectivo de historias clínicas en el período 2011-2017, analizando los estudios solicitados dentro de la evaluación preimplante coclear y el estudio extendido en pacientes con sospecha de deficiencia del nervio coclear. Resultados: Dentro de la población, un caso correspondió a un paciente con hipoacusia neurosensorial profunda bilateral con sospecha de deficiencia del nervio coclear (Birman: GRADO I y Casselman: TIPO I/IIa bilateral). El potencial evocado auditivo de tronco encefálico eléctrico permitió determinar el oído a implantar, mostrando mejor configuración de ondas para el oído derecho. Actualmente, presenta una óptima adaptación al implante (categoría de performance auditivo: 2-categoría de Moog-Geers: 3), con una puntuación de 8/40 en el cuestionario IT-MAIS. Conclusión: El protocolo de estudio prequirúrgico extendido es aplicable a pacientes con sospecha de deficiencia del nervio coclear. Estudios funcionales aportan datos de utilidad para determinar cuál de estos pacientes podrían beneficiarse tras la colocación del mismo. El asesoramiento familiar sobre las limitaciones y los objetivos reales es fundamental.

Introduction: cochlear nerve deficiency is defined as a hypoplastic or aplastic cochlear nerve present in more than 18% of children with profound sensorineural hearing loss. Cochlear implant indication continues to generate controversy. Objective: Analyze the study protocol in patients with suspected cochlear nerve deficiency and expose the clinical-audiological results after cochlear implant in our service. Material and method: Retrospective study of medical records in the period 2011-2017. Analyzing the studies requested within the cochlear pre-implant evaluation and the extended study in patients with suspected cochlear nerve deficiency. Results: Within the population, one case corresponded to a patient with bilateral profound sensorineural hearing loss with suspicion of Cochlear nerve deficiency (Birman GRADE I and Casselman TYPE I/IIa bilateral). The auditory evoked potentials by electrical stimulation allowed to determine the ear to be implanted, showing better configuration of waves for the right ear. Currently, it presents an optimal adaptation to the implant (Auditory per formance category: 2- Category of Moog-Geers: 3), with a score of 8/40 in the IT-MAIS questionnaire. Conclusion: The extended preoperative study protocol is appropriate for patients with suspected cochlear nerve deficiency. Functional studies provide useful data to determine which patients could benefit. Family counseling about real limitations and goals is critical.

Introdução: a deficiência do nervo coclear é definida como um nervo coclear hipoplásico ou aplástico presente em mais de 18% das crianças com perda auditiva neurossensorial profunda onde a indicação do implante coclear continua a gerar polêmica. Objetivo: Analisar o protocolo do estudo em pacientes com suspeita de deficiência do nervo coclear e apresentar os resultados clínico-audiológicos após o implante coclear em nosso serviço. Material e método: Estudo retrospectivo dos registros clínicos no período de 2011-2017, analisando os estudos solicitados na avaliação pré-implante coclear e o estudo prolongado em pacientes com suspeita de deficiência de nervo coclear. Resultados: Dentro da população, um caso correspondeu a um paciente com perda auditiva neurossensorial profunda bilateral com suspeita de deficiência do nervo coclear (Birman: GRADO I e Casselman: TIPO bilateral I/IIa). O potenciais evocados auditivos elétrico permitiu determinar a orelha a ser implantada, mostrando melhor configuração de ondas para a orelha direita. Atualmente, apresenta uma ótima adaptação ao implante (categoria de desempenho auditivo: 2- categoria de Moog-Geers: 3), com uma pontuação de 8/40 no questionário IT-MAIS. Conclusão: O protocolo de estudo pré-operatório estendido é aplicável a pacientes com suspeita de deficiência do nervo coclear. Estudos funcionais fornecem dados úteis para determinar quais pacientes poderiam se beneficiar do implante coclear. O aconselhamento familiar sobre limitações e metas reais é crítico.

[Tinnitus in patients with hemifacial spasm: a treatable combination?] / Tinnitus bij patiënten met hemifaciale spasmen.

BACKGROUND: About 5-15% of people in the Western world will suffer from an extended period of tinnitus during their lifetime. This is often a non-treatable, disabling disorder. Tinnitus can be classified as pulsatile or non-pulsatile. Pulsatile tinnitus can be caused by a treatable neurovascular compression. CASE DESCRIPTION: Here we describe two patients, a 68-year old woman and 40-year old man suffering from pulsatile tinnitus and hemifacial spams due to neurovascular compression of the facial and acoustic nerve in the anterior cranial fossa. After microvascular decompression using the Jannetta procedure, in which a sponge was placed between the blood vessel and the nerve, the tinnitus and hemifacial spasm disappeared. CONCLUSION: Recognition of hemifacial spasm in patients with tinnitus is important because the symptoms are treatable when it is due to neurovascular compression. Because hemifacial spasm can manifest in subtle forms - for instance unilateral blinking - this important symptom can easily be overlooked.

Cochleovestibular Nerve Compression Syndrome Caused by Intrameatal Anterior Inferior Cerebellar Artery Loop: Synthesis of Best Evidence for Clinical Decisions.

INTRODUCTION: Intrameatal cochleovestibular neurovascular conflict is a rare condition with specific clinical and therapeutic implications. Although surgery is commonly indicated in other neurovascular conflicts, for this subset of patients there is little evidence to guide treatment decisions. Moving from a case description, we performed a review of the literature on this topic to systematically present the best available evidence to guide clinical decisions. METHODS: We performed a literature review on reported cases of surgically treated intrameatal anterior inferior cerebellar artery (AICA)-cochleovestibular nerve neurovascular conflict, analyzing preoperative clinical data, surgical techniques, and outcomes. We analyzed the levels of evidence using the King's College guidelines. DISCUSSION: We found 35 studies of neurovascular compression of the cochleovestibular nerve by AICA for 536 patients operated on to resolve their neurovascular conflict. Only 4 of these studies describe intrameatal AICA neurovascular conflicts, for 9 cases, including our own. Tinnitus was the most frequent symptom (9/9), followed by vertigo (2/9). Our case was the only one showing unilateral hearing loss. Surgery consisted of microsurgical mobilization of the AICA loop performed through a retrosigmoid craniotomy. Tinnitus and vertigo resolved after surgery in all cases, whereas hearing loss did not improve after surgery. CONCLUSIONS: Surgical treatment offers the best results for tinnitus and vertigo, but it seems to have no effect on hearing loss, not even at long-term follow-up. Microvascular decompression should be proposed to intrameatal symptomatic patients before the onset of hearing loss.

Electrically Evoked Auditory Event-Related Responses in Patients with Auditory Brainstem Implants: Morphological Characteristics, Test-Retest Reliability, Effects of Stimulation Level, and Association with Auditory Detection.

OBJECTIVE: This study aimed to (1) characterize morphological characteristics of the electrically evoked cortical auditory event-related potentials (eERPs) and explore the potential association between onset eERP morphology and auditory versus nonauditory stimulation; (2) assess test-retest reliability of onset eERPs; (3) investigate effects of stimulation level on onset eERPs; and (4) explore the feasibility of using the onset eERP to estimate the lowest stimulation level that can be detected for individual stimulating electrodes in patients with auditory brainstem implants (ABIs). DESIGN: Study participants included 5 children (S1 to S5) and 2 adults (S6 to S7) with unilateral Cochlear Nucleus 24M ABIs. Pediatric ABI recipients ranged in age from 2.6 to 10.2 years (mean: 5.2 years) at the time of testing. S6 and S7 were 21.2 and 24.6 years of age at the time of testing, respectively. S6 and S7 were diagnosed with neurofibromatosis II (NF2) and implanted with an ABI after a surgical removal of the tumors. All pediatric subjects received ABIs after being diagnosed with cochlear nerve deficiency. The lowest stimulation level that could be detected (behavioral T level) and the estimated maximum comfortable level (C level) was measured for individual electrodes using clinical procedures. For electrophysiological measures, the stimulus was a 100-msec biphasic pulse train that was delivered to individual electrodes in a monopolar-coupled stimulation mode at stimulation levels ranging from subthreshold to C levels. Electrophysiological recordings of the onset eERP were obtained in all subjects. For studies evaluating the test-retest reliability of the onset eERP, responses were measured using the same set of parameters in two test sessions. The time interval between test sessions ranged from 2 to 6 months. The lowest stimulation level that could evoke the onset eERP was defined as the objective T level. RESULTS: Onset eERPs were recorded in all subjects tested in this study. Inter- and intrasubject variations in morphological characteristics of onset eERPs were observed. Onset eERPs with complex waveforms were recorded for electrodes that evoked nonauditory sensations, based on feedback from subjects, as well as for electrodes without any indications of nonauditory stimulations. Onset eERPs in patients with ABIs demonstrated good test-retest reliability. Increasing stimulation levels resulted in increased eERP amplitudes but showed inconsistent effects on response latencies in patients with ABIs. Objective and behavioral T levels were correlated. CONCLUSIONS: eERPs could be recorded in both non-NF2 and NF2 patients with ABIs. eERPs in both ABI patient groups show inter- and intrasubject variations in morphological characteristics. However, onset eERPs measured within the same subject in this study tended to be stable across study sessions. The onset eERP can potentially be used to estimate behavioral T levels in patients with ABIs. Further studies with more adult ABI recipients are warranted to investigate whether the onset eERP can be used to identify electrodes with nonauditory stimulations.

Usefulness of radiological findings for predicting cochlear implantation outcomes in children with cochlear nerve deficiency: a pilot study.

CONCLUSION: Children with CND received limited benefits from CIs and their results varied. The size of the vestibulocochlear nerve relative to the facial nerve could potentially be used as a predicator for CI outcomes in children with CND. OBJECTIVE: This study aimed to (1) retrospectively review the outcomes of cochlear implants (CIs) in children with cochlear nerve deficiency (CND) and (2) evaluate the clinical usefulness of radiological findings as predictors for post-implantation outcomes. METHODS: Study participants included 10 children with bilateral CND and profound sensorineural hearing loss. The preoperative magnetic resonance imaging and temporal bone computed tomography scans were evaluated. Auditory processing capability and speech perception performance were measured with Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scales. Aided hearing thresholds with CI were measured. The relationships between CI outcomes and the sizes of vestibulocochlear nerve and cochlear nerve canal (CNC) were analysed. RESULTS: Although post-operative CAP scores and hearing thresholds significantly improved in children with CND, their results were worse than those measured in implanted children with normal cochlear nerve. No significant correlation was found between the CI outcomes and the vestibulocochlear nerve diameters or the CNC diameters in children with CND. However, children with larger vestibulocochlear-nerve-to-facial-nerve-ratios got better results.

Nervus Intermedius Guides Auditory Brainstem Implant Surgery in Children with Cochlear Nerve Deficiency.

OBJECTIVE: To investigate the anatomic features of the nervus intermedius and cranial nerve VII in children with cochlear nerve deficiency and to verify whether the nervus intermedius can provide an additional landmark to help guide placement of the auditory brainstem implant electrode. STUDY DESIGN: Case series with chart review. SETTING: Tertiary referral center. SUBJECTS AND METHODS: High-definition video was captured during retrosigmoid surgery in 64 children (mean age, 3.91 ± 2.83 years) undergoing auditory brainstem implant placement. These videos were examined with particular reference to the number and variety of nervus intermedius bundles and any associated facial nerve anomalies. RESULTS: Absence of cranial nerves VI, VII, and VIII was observed in 3, 6, and all 64 children, respectively. Fifteen children had several abnormalities of the facial nerve in the cerebellopontine angle. Anatomic identification of the facial nerve and the bundles composing the nervus intermedius was possible in 46 children. In 12 children, identification was possible with the assistance of intraoperative monitoring. The number of bundles composing the nervus intermedius varied from 1 to 6. The nervus intermedius and cranial nerve IX were useful landmarks for identifying the foramen of Luschka of the lateral recess. CONCLUSION: The nervus intermedius provides an additional landmark during auditory brainstem microsurgery since it was identified in all subjects. The nervus intermedius anatomy and its topographic relationship with the neurovascular structures around the foramen of Luschka have been described for the first time in children with cochlear nerve deficiency.

[The neurovascular conflict of the vestibulocochlear nerve. Etiology, diagnostics, the methods for the surgical and conservative treatment].

The present review of the current literature concerning pathogenesis, formation of neurovascular conflict of the vestibulocochlear nerve, its epidemiology, clinical manifestations, diagnostics, and the methods for the surgical and conservative treatment is focused on the indications for decompression of the vestibulocochlear nerve and its effectiveness in the patients presenting with the neurovascular conflict of the vestibulocochlear nerve.

Solitary Metastasis to the Facial/Vestibulocochlear Nerve Complex: Case Report and Review of the Literature.

BACKGROUND: Distant metastasis of mucinous adenocarcinoma from the gastrointestinal tract, ovaries, pancreas, lungs, breast, or urogenital system is a well-described entity. Mucinous adenocarcinomas from different primary sites are histologically identical with gland cells producing a copious amount of mucin. This report describes a very rare solitary metastasis of a mucinous adenocarcinoma of unknown origin to the facial/vestibulocochlear nerve complex in the cerebellopontine angle. CASE DESCRIPTION: A 71-year-old woman presented with several month history of progressive neurological decline and a negative extensive workup performed elsewhere. She presented to our institution with complete left facial weakness, left-sided deafness, gait unsteadiness, headache and anorexia. A repeat magnetic resonance imaging scan of the head revealed a cystic, enhancing abnormality involving the left cerebellopontine angle and internal auditory canal. A left retrosigmoid craniotomy was performed and the lesion was completely resected. The final pathology was a mucinous adenocarcinoma of indeterminate origin. Postoperatively, the patient continued with her preoperative deficits and subsequently died of her systemic disease 6 weeks after discharge. CONCLUSIONS: The facial/vestibulocochlear nerve complex is an unusual location for metastatic disease in the central nervous system. Clinicians should consider metastatic tumor as the possible etiology of an unusual appearing mass in this location causing profound neurological deficits. The prognosis after metastatic mucinous adenocarcinoma to the cranial nerves in the cerebellopontine angle may be poor.