Paraneoplastic cochleovestibulopathy: clinical presentations, oncological and serological associations.

OBJECTIVE: Cochleovestibulopathy is a distinguishable paraneoplastic phenotype. In this study, we evaluate clinical presentation, serological/cancer associations and outcomes of paraneoplastic cochleovestibulopathy. METHODS: Retrospective chart review of patients with hearing impairment and/or vestibulopathy who underwent serological evaluations for paraneoplastic antibodies between January 2007 and February 2021 was performed. RESULTS: Twenty-six patients were identified (men, n=23; median age, 45 years, range: 28-70). Biomarkers detected included: KLHL11-IgG| |(n=20,| |77% (coexisting LUZP4-IgG, n=8)),| ||ANNA1-IgG| | |(n=3,| |12%),| |amphiphysin-IgG|| |(n=2,| |8%)| |and| |LUZP4-IgG|| |(n=1,| |4%). Most common neoplastic association was |testicular|/|extra-testicular| |seminoma| | (n=13,| |50%).|| Hearing| impairment (bilateral, 62%) was |present| |in| |all| |patients.| |Fifteen patients (58%) had cochleovestibular dysfunction as their initial presentation before rhombencephalitis/encephalomyelitis manifestations (hearing loss, four; acute vertigo, eight; both, three). |Brain| |MRI| |demonstrated| |internal| |auditory| |canal| |enhancement| |in| |four |patients.| Audiometry commonly revealed severe-profound bilateral sensorineural hearing loss. Most patients |had| a refractory course |despite| |immunotherapy| |and/or| |cancer| |treatment|. CONCLUSION: Cochleovestibulopathy commonly presents with rapidly progressive bilateral hearing loss and/or acute vertigo. However, in some patients, these symptoms present along with or following brainstem/cerebellar manifestations. KLHL11-IgG and seminoma are the most common serological and cancer associations, respectively. Recognition of this phenotype may aid in earlier diagnosis of paraneoplastic autoimmunity and associated cancer.

Clinical characteristics of patients with unilateral auditory neuropathy.

OBJECTIVE: To analyze the clinical characteristics of patients with unilateral auditory neuropathy (UAN), and to provide guidance for future clinical diagnosis and research. METHODS: Patients who were clinically diagnosed with UAN from 2004 to 2019 were included. Clinical characteristics, audiological features, imaging findings, genetic test results and management effect were summarized and followed. RESULTS: A total of 44 patients [mean age, 4.35 ± 4.39 years; 22 (50.00%) males and 22 (50.00%) females] were enrolled for analyses. Among the 38 patients who were tested by pure-tone or behavioral audiometry, the degree of hearing loss of the affected ear was characterized as mild in 2 ears (5.26%), moderate in 5 (13.16%), severe in 9 (23.68%) and profound in 22 (57.89%). For the 44 contralateral ears, 33 (75.00%) showed normal hearing and 11 (25.00%) presented with sensorineural hearing loss. Auditory brainstem responses were absent or abnormal in all 44 affected ears, while otoacoustic emissions and/or cochlear microphonics were present. Among the 18 patients who underwent magnetic resonance imaging (MRI), 7 (38.89%) presented cochlear nerve deficiency (CND). Nineteen candidate variants were found in 12 patients among the 15 UAN patients who were conducted targeted gene capture and next generation sequencing. Thirty patients were followed up by telephone to investigate their management effect. CONCLUSIONS: Our study demonstrates comprehensive audiological features of patients with UAN to improve the clinical understanding and diagnosis. Some patients with UAN could show ipsilateral CND and MRI is essential to evaluate if the nerve is deficient. No pathogenic variants that directly related to the pathogenesis of UAN have been found in this study currently.

Cochlear nerve canal stenosis and associated semicircular canal abnormalities in paediatric sensorineural hearing loss: a single centre study.

OBJECTIVE: This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis. METHOD: This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated. RESULTS: Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent). CONCLUSION: Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

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.

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).

Children with unilateral cochlear nerve canal stenosis have bilateral cochleovestibular anomalies.

OBJECTIVES/HYPOTHESIS: To investigate the cochleovestibular apparatus bilaterally in children with isolated unilateral bony cochlear nerve canal (bCNC) stenosis. STUDY DESIGN: Retrospective review. METHODS: Imaging studies of children with unilateral bCNC stenosis (<1.0 mm) on computed tomography imaging (N = 36) were compared with controls imaged due to trauma without temporal bone injury (N = 32). Twenty-six measurements were obtained in each ear, assessing the bony internal auditory canal (IAC), cochlea, and vestibular end-organs, and were analyzed using one-way analysis of variance for intersubject comparisons and paired t tests for intrasubject comparisons with a Bonferroni adjustment for multiple comparisons (P = .0006). RESULTS: Patients with bCNC stenosis had a smaller IAC (P < .000) and cochlea (P < .000) on the stenotic side as compared with controls. Although the vestibular end-organ was also smaller in bCNC ears, this difference was not significant. The contralateral ear also had a smaller bCNC (P < .000) and cochlea (P < .000) as compared with controls, although to a lesser degree than the stenotic side. CONCLUSIONS: Children with unilateral bCNC stenosis have abnormal biometry of both the cochlea and the vestibular end-organ in the affected and the normal contralateral ear as compared with controls. LEVEL OF EVIDENCE: 3b Laryngoscope, 129:2403-2408, 2019.

Extremely common radiographic finding of cochlear nerve deficiency among infants with prelingual single-sided deafness and its clinical implications.

OBJECTIVES: To clarify the common radiographic findings of audiologically documented prelingual single-sided deafness (SSD) and identify the prevalence of cochlear nerve deficiency (CND) in SSD infants referred from the newborn hearing screening program. METHODS: Between March 2012 and March 2017, the records of all infants referred to our otology clinic after undergoing newborn hearing screening program were retrospectively reviewed. Twenty-four consecutive well infants without risk factors who had a confirmed diagnosis of prelingual SSD under the age of 1 year and who underwent internal auditory canal (IAC) magnetic resonance imaging (MRI) were included. The sizes of cochlear nerve (CN), IAC, and cochlear nerve canal (CNC) were measured on MRI. The presence of CND was visually determined by comparing the CN size to the ipsilateral facial nerve (FN) in the affected side via an oblique sagittal view of IAC MRI and defined when CN was absent or smaller than FN. RESULTS: CND was seen in all 24 deaf ears (100%) on MRI. There was one with incomplete partition type I, and another with combined cochleovestibular nerve absence. Twenty-four subjects demonstrated either an absent (20/24, 83.3%) or small (4/24, 16.7%) CN. When the absent and small CN groups were compared, the former group had a higher prevalence of narrow CNC and narrow IAC. Of the 20 infants without identifiable CN on the affected side, 17 (85%) had narrow IAC and 17 (85%) had narrow CNC. In the 20 ears with absent CN, only one had both normal-sized IAC and CNC. CONCLUSION: The contribution of CND to prelingual SSD in Korean infants reached 100%, according to IAC MRI alone.

Cochlear Nerve Aplasia with Detectable Olivocochlear Efferent Function: A Distinct Presentation of Auditory Neuropathy Spectrum Disorder.

BACKGROUND: Cochlear nerve aplasia (CNA) may present with features of auditory neuropathy spectrum disorder (ANSD), having detectable otoacoustic emissions (OAE) but profound hearing loss. We propose that some children with CNA have a distinct form of afferent ANSD in which efferent cochlear nerve function can be detected using contralateral suppression of OAE. METHODS: Children were prospectively enrolled with MRI and auditory brainstem response evidence of unilateral CNA, a normal contralateral ear, and detectable OAE bilaterally. Distortion product OAE (DPOAE) levels were recorded in real time with default primary tone settings: frequency (f)2 = 4.5 kHz and f2/f1 = 1.22 kHz, with level (L)1 = 65 dB SPL and L2 = 55 dB SPL. Recordings were made over 2 min with simultaneous application of an intermittent contralateral broadband noise (CBBN) stimulus at 60 dB SPL. RESULTS: Three girls, aged 4.5, 7, and 8 years, participated. Suppression of DPOAE of 0.15-1.3 dB was detected in all 3 ears with CNA in response to CBBN stimulation. No response was detected in the normal ears. CONCLUSIONS: Children with unilateral ANSD can have normal efferent cochlear nerve function despite MRI evidence of ipsilateral CNA. The importance of these findings for newborn hearing screening and cochlear implantation is discussed.

A comparison of semi-automated volumetric vs linear measurement of small vestibular schwannomas.

OBJECTIVE: Accurate and precise measurement of vestibular schwannoma (VS) size is key to clinical management decisions. Linear measurements are used in routine clinical practice but are prone to measurement error. This study aims to compare a semi-automated volume segmentation tool against standard linear method for measuring small VS. This study also examines whether oblique tumour orientation can contribute to linear measurement error. STUDY DESIGN: Experimental comparison of observer agreement using two measurement techniques. SETTING: Tertiary skull base unit. PARTICIPANTS: Twenty-four patients with unilateral sporadic small (< 15 mm maximum intracranial dimension) VS imaged with 1 mm-thickness T1-weighted Gadolinium enhanced MRI. MAIN OUTCOME MEASURES: (1) Intra and inter-observer intraclass correlation coefficients (ICC), repeatability coefficients (RC), and relative smallest detectable difference (%SDD). (2) Mean change in maximum linear dimension following reformatting to correct for oblique orientation of VS. RESULTS: Intra-observer ICC was higher for semi-automated volumetric when compared with linear measurements, 0.998 (95% CI 0.994-0.999) vs 0.936 (95% CI 0.856-0.972), p < 0.0001. Inter-observer ICC was also higher for volumetric vs linear measurements, 0.989 (95% CI 0.975-0.995) vs 0.946 (95% CI 0.880-0.976), p = 0.0045. The intra-observer %SDD was similar for volumetric and linear measurements, 9.9% vs 11.8%. However, the inter-observer %SDD was greater for volumetric than linear measurements, 20.1% vs 10.6%. Following oblique reformatting to correct tumour angulation, the mean increase in size was 1.14 mm (p = 0.04). CONCLUSION: Semi-automated volumetric measurements are more repeatable than linear measurements when measuring small VS and should be considered for use in clinical practice. Oblique orientation of VS may contribute to linear measurement error.

Paroxismia vestibular: reporte de un caso / Vestibular paroxysmia: case report

Presentamos el caso de un paciente joven quien presenta 4 a 5 crisis diarias de vértigo espontáneo de segundos de duración, todos o casi todos los días desde hace 9 meses. Estas crisis no tienen gatillo posicional, y hay completa ausencia de sintomatologia entre crisis. Como discutimos en el artículo, este cuadro coíncide con los recientemente publicados criterios para una paroxismia vestibular, entidad supuestamente secundaria a la compresión neurovascular del nervio vestibular. El paciente respondió de forma inmediata y completa a carbamazepina a dosis bajas, el tratamiento de elección en la paroxismia vestibular.

We present the case of a young patient, with a 9-month long history of 4 to 5 daily spells of spontaneous vertigo, each lasting only seconds. There is no positional trigger, and there is a complete lack of symptoms between attacks. As is discussed in the article, this matches the recently published criteria for Vestibular Paroxysmia, an entity allegedly secondary to neurovascular compression of the vestibular nerve. The patient responded immediately and completely to carbamazepine at low dosage, the preferred treatment for vestibular paroxysmia.

Etiologic and Audiologic Characteristics of Patients With Pediatric-Onset Unilateral and Asymmetric Sensorineural Hearing Loss.

Importance: Pediatric-onset unilateral and asymmetric sensorineural hearing loss (SNHL) is a common condition, but in most patients, the cause remains unclear; thus, determination of the hearing outlook is difficult. Objective: To analyze the etiologic and audiologic characteristics of pediatric-onset unilateral and asymmetric SNHL. Design, Setting, and Participants: In this retrospective cohort study performed from January 1, 2008, through December 31, 2016, patients at a tertiary referral center who were diagnosed with pediatric-onset unilateral or asymmetric SNHL were divided into 3 groups according to their hearing levels: unilateral hearing loss with scaled-out levels (UHL-SO), unilateral hearing loss with residual hearing (UHL-RH), and asymmetric hearing loss (AHL). Main Outcomes and Measures: Basic demographic data, family and medical histories, audiologic results, imaging findings, and genetic results were ascertained and compared among patients of the 3 groups. Results: A total of 133 patients (mean [SD] age, 9.1 [10.9] years; 63 [47.4%] male and 70 [52.6%] female), including 50 with UHL-SO, 42 with UHL-RH, and 41 with AHL, were enrolled for analyses. Of 50 patients with UHL-SO, 49 (98.0%) had stable hearing levels with time, whereas 10 of 42 patients with UHL-RH (23.8%) and 18 of 41 patients with AHL (43.9%) revealed progressive or fluctuating hearing loss. Inner ear malformations detected with temporal bone high-resolution computed tomography, particularly cochlear aperture stenosis, were detected at higher rates in patients with UHL-SO (9 of 31 [29.0%]) and UHL-RH (6 of 24 [25.0%]) than in those with AHL (1 of 30 [3.3%]). In contrast, screening for mutations in 3 common deafness genes-GJB2, SLC26A4, and MTRNR1-achieved definite diagnosis in a higher percentage of patients with AHL (10 of 37 [27.0%]) than patients with UHL-SO (0 of 33) and UHL-RH (1 of 25 [4.0%]). Conclusions and Relevance: The UHL-SO and UHL-RH conditions share a common or similar etiopathogenesis different from that of AHL. Imaging studies and genetic testing might be prioritized during the respective general etiologic workups for patients with UHL and AHL. Regular hearing checkups are warranted for patients with UHL and AHL because a certain proportion of patients might sustain progression in SNHL.

The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus.

BACKGROUND AND PURPOSE: Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus. MATERIALS AND METHODS: Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation. RESULTS: The anatomic location of the vascular loop was not significantly different among the 3 groups (all, P > .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 (P = .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed. CONCLUSIONS: Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve.

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.

The internal acoustic canal--another review area in paediatric sensorineural hearing loss.

Morphological abnormalities of the internal acoustic canal (IAC), albeit rare, are sometimes associated with hearing loss in children. We present an illustration of the spectrum of IAC abnormalities together with a brief review of the embryology and anatomy of the IAC and the techniques used when imaging the petrous temporal bone. This review focuses on morphological abnormalities of the IAC together with their clinical implications and impact on clinical management.

Cochlear nerve deficiency and associated clinical features in patients with bilateral and unilateral hearing loss.

OBJECTIVE: To clarify the prevalence and clinical characteristics of cochlear nerve deficiency (CND) in patients with congenital bilateral and unilateral hearing loss. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: One hundred fourteen children with bilateral and 56 children with congenital unilateral sensoneural hearing loss. MAIN OUTCOME MEASURES: Review of medical records, audiologic tests, and imaging studies. Imaging studies were evaluated for the presence or absence of abnormalities in the bony cochlear nerve canal (BCNC), internal auditory canal (IAC), and inner ear. RESULTS: The prevalence of CND, whether unilateral or bilateral, was much higher in the unilateral than in the bilateral hearing loss group: 50% (28/56) versus 5.3% (6/114). Among the 6 children with bilateral hearing loss and CND, 2 had bilateral BCNC stenosis alone, 2 had bilateral BCNC stenosis and unilateral IAC stenosis, 1 had unilateral BCNC stenosis alone, and 1 had unilateral IAC stenosis alone. All 28 children with unilateral hearing loss and CND had BCNC stenosis, whereas 9 (32.1%) also had concurrent IAC stenosis. Three of the 6 children with CND and bilateral hearing loss and 5 of the 28 children with CND and unilateral hearing loss also had other inner ear abnormalities. CONCLUSION: Our results suggest differences in the causes and mechanisms of CND in children with bilateral versus unilateral hearing loss.

Implication of bony cochlear nerve canal on hearing in patients with congenital unilateral sensorineural hearing loss.

This study was designed to evaluate the dimensions of the bony cochlear nerve canal (BCNC) in congenital unilateral sensorineural hearing loss (USNHL) patients with normal inner ears, and to analyze the correlation between BCNC and hearing status. Medical records and temporal bone computed tomography (TBCT) findings of 380 patients who visited Seoul National University Hospital between January 1999 and December 2007 were reviewed retrospectively. The length and width of the BCNC at the fundus of the internal auditory canal were measured in millimeters based on the axial view of TBCT for three ear groups: normal inner ears of control group subjects (group A, 179 ears), normal inner ears on the contralateral side of USNHL patients (group B, 201 ears), and the affected inner ears in USNHL (group C, 201 ears). The mean values of length and width in group C (0.79 ± 0.36 and 1.58 ± 0.83 mm, respectively) were significantly smaller than those in group A (1.07 ± 0.10 and 2.38 ± 0.28 mm, respectively; p < 0.001) and group B (1.04 ± 0.23 and 2.33 ± 0.39 mm, respectively; p < 0.001). The receiver operating characteristic curves for BCNC were conducted to estimate the cutoff values from which the proportions of profound hearing loss increased, compared to those of mild to severe hearing loss. The areas under the curve were 0.487 ± 0.044 (p = 0.781) and 0.622 ± 0.041 (p = 0.011) for length and width, respectively. The cutoff value of width with a sensitivity of 90% for profound USNHL was 1.16 mm in otherwise normal inner ears. Clinicians would be recommended to take a close look at BCNC as one of the possible causes of hearing loss in otherwise normal inner ears of USNHL on TBCT.

Radiographic analysis of cochlear nerve vascular compression.

OBJECTIVES: We analyzed whether radiographically demonstrated anterior inferior cerebellar artery (AICA) vascular compression of the cochleovestibular nerve in asymmetric hearing loss could be correlated to either the symptomatic ear or to cochlear nerve diameter. METHODS: We undertook a retrospective case-control study in which patients were enrolled into a database if audiometry demonstrated asymmetry of 20 dB at one frequency, asymmetry of 10 dB at two frequencies, or a difference of 20% on word recognition scores. If AICA vascular contact was demonstrated on subsequent magnetic resonance imaging of the cerebellopontine angle, patients were included in the study. Patients with vestibular schwannoma or Meniere's disease were excluded. The AICA contact was graded by a blinded neuroradiologist according to criteria proposed by McDermott et al. The cross-sectional area of the cochlear nerve was measured. RESULTS: Symptomatic ears could be correlated to a decreased cochlear nerve diameter, but not to the degree of AICA penetration into the internal auditory canal. CONCLUSIONS: AICA vascular compression of the cochleovestibular nerve does not appear to correlate to hearing loss or to cochlear nerve diameter. The finding of decreased cochlear nerve diameter in symptomatic ears implies an alternative mechanism for asymmetric hearing loss.

Pathology of the vestibulocochlear nerve.

Imaging of the vestibulocochlear nerve has evolved dramatically over the past few decades. The imaging specialist now is involved in the diagnosis of far more diagnostic entities than ever before. With this increased involvement comes the responsibility to increase collective knowledge regarding the pathophysiology of these diagnostic entities. This article is organized in a conventional way and covers congenital deformity of the internal auditory canal, neoplastic and pseudoneoplastic lesions, with special detailed emphasis on schwannoma of the eight cranial nerves (acoustic neuroma), nonneoplastic IAC/CPA pathology, including vascular loops, and numerous additional differential diagnostic entities, with particular emphasis on non-neoplastic meningeal disease. Lesions of the auditory pathway and an overview of cochlear implant surgery are also included in this discussion.

Clinical and audiological features in auditory neuropathy.

OBJECTIVE: To medically and audiologically characterize a population of children diagnosed as having auditory neuropathy (AN). STUDY DESIGN: Retrospective medical chart review. SETTING/SUBJECTS: We identified 22 patients from a pediatric otology clinic in a tertiary care pediatric hospital setting. RESULTS: A genetic factor in AN is suggested by our identification of 3 families with 2 affected children and 2 other children with family histories that were positive for hearing loss. Clinical features common among our population included a history of hyperbilirubinemia (n = 11 [50%]), prematurity (n = 10 [45%]), ototoxic drug exposure (n = 9 [41%]), family history of hearing loss (n = 8 [36%]), neonatal ventilator dependence (n = 8 [36%]), and cerebral palsy (n = 2 [9%]). Full clinical and audiological data were available for 18 of the 22 children, including otoacoustic emissions, auditory brainstem responses with cochlear microphonics, and age-appropriate audiometric findings. Significantly, 9 of these 18 patients showed improvement in behavioral thresholds over time, indicating that a subset of children with AN may recover useful hearing levels. Also significant was the success of cochlear implantation in 4 children. CONCLUSIONS: Management of AN in children requires serial clinical and audiometric evaluations, with a prominent role for behavioral testing. Prematurity, genetics, and hyperbilirubinemia appear to be significant factors in the development of AN; hyperbilirubinemia can be associated with spontaneous improvement of hearing thresholds. For those children not benefiting from amplification or FM systems, cochlear implantation remains a potentially successful method of habilitation.