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.

Ataxia in a Young Female.

Neurofibromatosis type 2 (NF2) is a genetically inherited disorder characterized by the presence of multiple central nervous system tumours, most pathognomonic being bilateral vestibular schwannomas with or without peripheral manifestations in the form of cataract or cutaneous neurofibromas. NF2 is an uncommon disorder compared to NF1. We describe a classical case of neurofibromatosis type 2 with florid clinical manifestations and characteristic neuroimaging features. We also briefly describe the literature pertaining to this rare disorder. The case also emphasizes the fact that NF2 should be considered in the list of differentials for ataxia especially when it is associated with sensory neural hearing loss.

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 neuropathy in the rat exposed for a long period to moderate-intensity noises.

Damaging effects on the cochlea of high-intensity acoustic overexposures have been extensively documented, but only few works have focused on the danger of moderate noise levels. Using scanning and transmission electron microscopy, we explored the noise-induced neuroepithelial changes that occur in the cochlea of rats subjected to moderate intensities, 70 and 85 dB SPL, for an extended period of time (6 hr/day over 3 months). Although the full quota of outer and inner sensory hair cells remained present, we detected discrete abnormalities, likely resulting from metabolic impairment, in both types of hair cell within the basal region of the cochlea. In contrast, important noise-dependent losses of spiral ganglion neurons had occurred. In addition, we found cytoplasmic accumulations of lipofuscin-like aggregates in most of the surviving cochlear neurons. These results strongly suggest that noise levels comparable to those of certain working environments, with sufficient exposure duration, pose a severe risk to the cochlea. Moreover, our data support the notion that long-duration exposure to moderate noise is a causative factor of presbycusis.

Phase II study of mTORC1 inhibition by everolimus in neurofibromatosis type 2 patients with growing vestibular schwannomas.

Neurofibromatosis type 2 (NF2) is a genetic disorder with bilateral vestibular schwannomas (VS) as the most frequent manifestation. Merlin, the NF2 tumor suppressor, was identified as a negative regulator of mammalian target of rapamycin complex 1. Pre-clinical data in mice showed that mTORC1 inhibition delayed growth of NF2-schwannomas. We conducted a prospective single-institution open-label phase II study to evaluate the effects of everolimus in ten NF2 patients with progressive VS. Drug activity was monitored every 3 months. Everolimus was administered orally for 12 months and, if the decrease in tumor volume was >20 % from baseline, treatment was continued for 12 additional months. Other patients stopped when completed 12 months of everolimus but were allowed to resume treatment when VS volume was >20 % during 1 year follow-up. Nine patients were evaluable. Safety was evaluated using CTCAE 3.0 criteria. After 12 months of everolimus, no reduction in volume ≥20 % was observed. Four patients had progressive disease, and five patients had stable disease with a median annual growth rate decreasing from 67 %/year before treatment to 0.5 %/year during treatment. In these patients, tumor growth resumed within 3-6 months after treatment discontinuation. Everolimus was then reintroduced and VS decreased by a median 6.8 % at 24 months. Time to tumor progression increased threefold from 4.2 months before treatment to > 12 months. Hearing was stable under treatment. The safety of everolimus was manageable. Although the primary endpoint was not reached, further studies are required to confirm the potential for stabilization of everolimus.

Vestibular paroxysmia in children: a treatable cause of short vertigo attacks.

Vestibular paroxysmia due to neurovascular compression is a syndrome consisting of frequent short episodes of vertigo in adults that can be easily treated. Here we describe the initial presentation and follow-up of three children (one female, 12y; two males, 8y and 9y) who experienced typical, brief, vertiginous attacks several times a day. Nystagmus was observed during the episodes. Cranial magnetic resonance imaging revealed arterial compression of the eighth cranial nerve. The attacks ceased after administration of low-dose carbamazepine (2-4mg/kg daily). Vestibular paroxysmia must be considered in the differential diagnosis of children with brief vertiginous episodes.

Indications and contraindications of auditory brainstem implants: systematic review and illustrative cases.

The number of non-neurofibromatosis type 2 (NF2) indications for auditory brainstem implant (ABI) in the literature is increasing. The objective of this study was to analyze and discuss the indications for ABI. Retrospective chart review and systematic review were conducted at Quaternary referral skull base center and referring centers. Analysis of ABI cases with non-NF2 indications and systematic review presenting non-NF2 ABI cases were performed. Fourteen referred cases with ABI were identified. All cases had unsatisfactory results of ABI and all could have been rehabilitated with a cochlear implant (CI). Of these 14 cases, 9 improved with a cochlear implant, and 2 with a hearing aid, two are still planned for CI, one received bilateral CI, no ABI. In literature, we found 31 articles presenting 144 non-NF2 ABI cases with at least 7 different indications other than NF2. ABI should be restricted to those patients who have no other rehabilitation options. Patency of the cochlea and evidence of an intact cochlear nerve should be examined with imaging and electrophysiologic testing. Sometimes a CI trial should be planned prior to proceeding with ABI. We have shown that in many cases a CI is still possible and CI provided better results than ABI. In vestibular schwannoma in the only hearing ear, cochlear otosclerosis, temporal bone fractures, (presumed) bilateral traumatic cochlear nerve disruption, auto-immune inner ear disease and auditory neuropathy primarily CI are indicated. Traumatic bilateral cochlear nerve disruption is exceptionally unlikely. In cochlear nerve aplasia, testing should be performed prior to meeting indications for ABI. In malformations, ABI is indicated only in severe cochlear hypoplasia or cochlear aplasia.

Vestibular involvement in peripheral neuropathy: a review.

OBJECTIVE: This paper reviews the current literature on involvement of the vestibular division of the eighth cranial nerve in peripheral neuropathies. The literature abounds with references to auditory neuropathy, which is frequently related to more generalized neuropathies, but there is a marked paucity of work regarding vestibular neuropathy. A brief overview of neuropathies and the anatomy of the vestibulocochlear nerve provide the background for a review of the literature of vestibular nerve involvement in a range of neuropathies. DESIGN: A literature search including textbooks, and peer-reviewed published journal articles in online bibliographic databases was conducted. STUDY SAMPLE: Two databases for medical research were included in this review. RESULTS: The review of the literature indicates that vestibular involvement is a common and consistent finding in many peripheral neuropathies of different aetiologies. Specifically, if patients present unsteadiness/ataxia out of proportion to objective signs of somatosensory loss or muscle weakness. CONCLUSION: This review concludes that vestibular neuropathy, is common in peripheral neuropathy and should be identified to optimize patient management and rehabilitation.

Noise-induced cochlear neuropathy is selective for fibers with low spontaneous rates.

Acoustic overexposure can cause a permanent loss of auditory nerve fibers without destroying cochlear sensory cells, despite complete recovery of cochlear thresholds (Kujawa and Liberman 2009), as measured by gross neural potentials such as the auditory brainstem response (ABR). To address this nominal paradox, we recorded responses from single auditory nerve fibers in guinea pigs exposed to this type of neuropathic noise (4- to 8-kHz octave band at 106 dB SPL for 2 h). Two weeks postexposure, ABR thresholds had recovered to normal, while suprathreshold ABR amplitudes were reduced. Both thresholds and amplitudes of distortion-product otoacoustic emissions fully recovered, suggesting recovery of hair cell function. Loss of up to 30% of auditory-nerve synapses on inner hair cells was confirmed by confocal analysis of the cochlear sensory epithelium immunostained for pre- and postsynaptic markers. In single fiber recordings, at 2 wk postexposure, frequency tuning, dynamic range, postonset adaptation, first-spike latency and its variance, and other basic properties of auditory nerve response were all completely normal in the remaining fibers. The only physiological abnormality was a change in population statistics suggesting a selective loss of fibers with low- and medium-spontaneous rates. Selective loss of these high-threshold fibers would explain how ABR thresholds can recover despite such significant noise-induced neuropathy. A selective loss of high-threshold fibers may contribute to the problems of hearing in noisy environments that characterize the aging auditory system.

Loss of osteoprotegerin expression in the inner ear causes degeneration of the cochlear nerve and sensorineural hearing loss.

Osteoprotegerin (OPG) is a key regulator of bone remodeling. Mutations and variations in the OPG gene cause many human diseases that are characterized by not only skeletal abnormalities but also poorly understood hearing loss: Paget's disease, osteoporosis, and celiac disease. To gain insight into the mechanisms of hearing loss in OPG deficiency, we studied OPG knockout (Opg(-/-)) mice. We show that they develop sensorineural hearing loss, in addition to conductive hearing loss due to abnormal middle-ear bones. OPG deficiency caused demyelination and degeneration of the cochlear nerve in vivo. It also activated ERK, sensitized spiral ganglion cells (SGC) to apoptosis, and inhibited proliferation and survival of cochlear stem cells in vitro, which could be rescued by treatment with exogenous OPG, an ERK inhibitor, or bisphosphonate. Our results demonstrate a novel role for OPG in the regulation of SGC survival, and suggest a mechanism for sensorineural hearing loss in OPG deficiency.

[The influence of otolithic afferentation on the vestibulo-ocular interaction in the patients presenting with an unilateral lesion in a peripheral vestibular neuron].

The objective of the present work was to study the influence of otolithic afferentation on the vestibulo-ocular interaction in 20 patients with vestibular neuronitis (at the stages of decompensation and subcompensation) and in 30 healthy subjects by the electronystagmographic technique. The sinusoidal (program 1) and eccentric (program 2) rotation was applied with the angular velocity of 10 degrees/s (stimulus 1, rotation rate 0.04 Hz), 30 degrees/s (stimulus II, rotation rate 0.12 Hz), 60 degrees/s (stimulus III) and oscillation periods of 18, 6, and 3 s respectively. No significant changes in the parameters of the vesicular reflex were observed in the patients with vestibular neuronitis and control subjects studied in the phase of decompensation under programs 1 and 2 . The study of the patients presenting with vestibular neuronitis in the subcompensation phase (program 2) revealed a significant increase of nystagmus intensity on the affected side compared with the respective parameters estimated in the framework of program 1 (p<0.001). The enhancement of stimulation did not result in any significant changes in the character of vestibuloocular interactions. The results of the study indicate that otolithic afferentation influences the process of compensation of peripheral vestibular labyrinth dysfunction in the patients presenting with vestibular neuronitis at the stage of decompensation.

Electrophysiologic and behavioral outcomes of cochlear implantation in children with auditory nerve hypoplasia.

OBJECTIVES: Hypoplasia of the auditory nerve (AN) refers to significant narrowing of the VIIIth cranial nerve which could compromise stimulation of the nerve by electrical pulses delivered from a cochlear implant (CI), thereby hindering activity in other parts of the auditory pathways. To compensate, high current levels or increased charge may be required to elicit auditory perception causing current to spread to other cranial nerves and potentially resulting in unwanted myogenic responses. Deficits in central auditory activity could reduce perception of speech and language. In the present study, we measured auditory brainstem responses in children with and without hypoplasia of the AN to answer the following questions. In children with hypoplastic ANs, (a) can CI stimulation evoke typical patterns of activity from the AN and brainstem?, (b) do brainstem responses change with CI experience?, (c) are evoked responses dependent on the size of the AN pathway?, and (d) does auditory development measured by behavioral tests of speech perception develop more slowly than in peers with normal AN diameter? DESIGN: Of 807 children using CIs in our program, 20 (2.5%) were identified as having AN hypoplasia using high-resolution computed tomographic scan and/or magnetic resonance imaging. An age-matched control group of children using CIs with normal AN diameter were recruited to compare electrophysiological and behavioral measures. Radiologic imaging was used to measure the diameter of the internal auditory canal (IAC), auditory nerve canal (ANC), and AN. Electrophysiological testing of the evoked compound action potential and auditory brainstem response was performed at CI activation and every 3 mo after initial testing up to 2 yr. Peak latency and waveform morphology were compared between study and control groups. Tests of speech perception and discrimination were attempted every 12 mo after device activation up to 10 yr. RESULTS: : Hypoplastic AN was identified as moderate to critical stenosis of the IAC, ANC, and AN. Initial electrically evoked compound action potential responses were mostly absent in children with AN hypoplasia. In the time window when electrically evoked auditory brainstem responses would be expected, some responses included single amplitude peaks at normal wave eV latencies, but the majority were abnormal, with peaks at atypical latencies or with no observable wave peaks. All evoked responses were inconsistent over time and did not reflect a typical pattern of auditory brainstem development. Speech perception scores were significantly poorer in the study group compared with controls and did not improve with CI experience. The type of abnormal evoked waveform response was independent of IAC, ANC, or AN diameter and also independent of behavioral outcome measures. CONCLUSIONS: : Evoked responses recorded in CI children with AN hypoplasia indicate a high incidence of nonauditory activity with CI use. The range of abnormal responses was not predicted by the severity of the hypoplastic AN or associated structures. This, along with poorer auditory development compared with peers with normal AN diameters, suggests that children with hypoplasia of the AN are poor candidates for cochlear implantation.

Neuromuscular choristoma of the internal auditory meatus.

Choristomas of the internal auditory meatus are exceedingly rare tumors. In most cases, neuromuscular choristomas have initially been misdiagnosed as vestibular schwannomas (VS). No known characteristics in the clinical presentation or in imaging exist distinguishing these tumors from VS, which are the most common tumors at this location [Smith et al.: AJNR Am J Neuroradiol 1997;18:327-329]. We present a case of a neuromuscular choristoma of the 8th cranial nerve that was operated because of growth demonstrated on two MRI scans 3 months apart. We were convinced that this young patient would require treatment sometime in the future, and we believed that an operation at that time had higher chances to preserve the anatomical structures. Histomorphological examination of the tumor revealed a nodular lesion with fascicular and nodular assembled smooth muscle cells, connective tissue and nerve fibers.

Structural brain changes following peripheral vestibulo-cochlear lesion may indicate multisensory compensation.

BACKGROUND: Do central mechanisms account for the variability of clinical recovery following peripheral vestibulo-cochlear lesions? OBJECTIVE: To investigate structural (morphological) plasticity in the human brain following unilateral vestibulo-cochlear lesions which might contribute to central vestibular compensation. METHODS: The authors compared regional grey matter volume (GMV) changes in patients after surgical removal of unilateral acoustic neuroma with age-matched control subjects, and hypothesised morphometric changes in the vestibular and auditory cortices which may be related to functional disability scores. Patients were examined with a battery of neuro-otological tests and clinical scores to assess vestibular and auditory disability. RESULTS: Voxel-based morphometry was used for categorical comparison between patients and age- and gender-matched controls. GMV increase was found bilaterally in primary somatosensory cortices and motion-sensitive areas in the medial temporal gyrus (MT). Simple regression analysis revealed a GMV increase (1) in the contralesional superior temporal gyrus/posterior insula to be correlated with decreasing clinically assessed vestibular deficits; (2) in the contralesional inferior parietal lobe with decreasing functional impairment of daily living activities; and (3) in the contralesional auditory cortex (Heschl gyrus) with decreasing hearing impairment. CONCLUSIONS: These data may suggest structural cortical plasticity in multisensory vestibular cortex areas of patients with unilateral peripheral vestibulo-cochlear lesion after surgical removal of acoustic neuroma. As changes of GMV were related to vestibular function, structural brain changes may reflect central mechanisms of vestibular compensation.

Brain stem responses evoked by stimulation with an auditory brain stem implant in children with cochlear nerve aplasia or hypoplasia.

OBJECTIVES: The inclusion criteria for an auditory brain stem implant (ABI) have been extended beyond the traditional, postlingually deafened adult with Neurofibromatosis type 2, to include children who are born deaf due to cochlear nerve aplasia or hypoplasia and for whom a cochlear implant is not an option. Fitting the ABI for these new candidates presents a challenge, and intraoperative electrically evoked auditory brain stem responses (EABRs) may assist in the surgical placement of the electrode array over the dorsal and ventral cochlear nucleus in the brain stem and in the postoperative programming of the device. This study had four objectives: (1) to characterize the EABR by stimulation of the cochlear nucleus in children, (2) to establish whether there are any changes between the EABR recorded intraoperatively and again just before initial behavioral testing with the device, (3) to establish whether there is evidence of morphology changes in the EABR depending on the site of stimulation with the ABI, and (4) to investigate how the EABR relates to behavioral measurements and the presence of auditory and nonauditory sensations perceived with the ABI at initial device activation. DESIGN: Intra- and postoperative EABRs were recorded from six congenitally deaf children with ABIs, four boys and two girls, mean age 4.2 yrs (range 3.2 to 5.0 yrs). The ABI was stimulated at nine different bipolar sites on the array, and the EABRs recorded were analyzed with respect to the morphology and peak latency with site of stimulation for each recording session. The relationship between the EABR waveforms and the presence or absence of auditory electrodes at initial device activation was investigated. The EABR threshold levels were compared with the behavioral threshold (T) and comfortably loud (C) levels of stimulation required at initial device activation. RESULTS: EABRs were elicited from all children on both test occasions. Responses contained a possible combination of one to three peaks from a total of four identifiable peaks with mean latencies of 1.04, 1.81, 2.61, and 3.58 msecs, respectively. The presence of an EABR was a good predictor of an auditory response; however, the absence of the EABR was poor at predicting a site with no auditory response. The morphology of EABRs often varied with site of stimulation and between EABR test occasions. Postoperatively, there was a trend for P1, P3, and P4 to be present at the lateral end of the array and P2 at the medial end of the array. Behavioral T and C levels showed a good correlation with postoperative EABR thresholds but a poor correlation with intraoperative EABR thresholds. CONCLUSIONS: The presence of an intraoperative EABR was a good indicator for the location of electrodes on the ABI array that provided auditory sensations. The morphology of the EABR was often variable within and between test sessions. The postoperative EABR thresholds did correlate with the behavioral T and C levels and could be used to assist with initial device fitting.

Protective effect of lutein against acrolein-induced ototoxicity in rats.

BACKGROUND: Acrolein is a reactive aldehyde that forms during burning of wood and other fuels. It is also a product of lipid peroxidation (LPO) reactions and is present in cigarette smoke. Acrolein is known to cause oxidative stress and inflammatory nerve tissue damage. Lutein is a tetraterpenoid molecule with antioxidant and anti-inflammatory properties. There appear to be no studies on the effect of lutein on vestibulocochlear nerve damage induced by acrolein. The aim of this study was to investigate the effect of lutein on vestibulocochlear nerve damage induced by acrolein in rats using biochemical and histopathological methods. METHODS: The rats were divided into three groups (n = 6, for each group) a healthy control group (HG), an acrolein (ACR) group and a lutein and acrolein (LACR) group. In the LACR group, lutein was administered (1 mg/kg) via oral gavage. The ACR and HG groups received saline via oral gavage. Then, 1 h after the administration of lutein and saline, the LACR and ACR groups were treated with 3 mg/kg of acrolein via oral gavage. This procedure was repeated once a day for 30 days. RESULTS: The results of biochemical experiments showed that in the vestibulocochlear nerve tissues of the animals treated with acrolein, the levels of malondialdehyde, total oxidants, nuclear factor kappa b, tumor necrosis factor alpha and interleukin 1 beta significantly increased, whereas the levels of total glutathione and total antioxidants decreased as compared to those in the HG and LACR groups. In addition, severe histopathological damage was observed in vestibulocochlear nerve tissue of the acrolein group, whereas this damage was alleviated in the lutein group. CONCLUSION: Lutein protected vestibulocochlear nerve tissue from acrolein-associated oxidative and proinflammatory damage. This suggests that lutein might be useful in preventing or treating acrolein-induced ototoxicity.

The ventrolateral surgical approach to labyrinthectomy in rats: anatomical description and clinical consequences.

UNLABELLED: Destruction of the inner ear in rats for medical research has been performed since 1936. Nevertheless, descriptions of the technique used and clinical analysis are poor and often involve coagulation of the stapedial artery. We suggest a description of a surgical ventrolateral approach to labyrinthectomy in rats, with preservation of the stapedial artery. METHODS: Twenty-five Wistar rats were operated on via a right ventrolateral approach to the bulla, followed by labyrinthectomy with preservation of the stapedial artery. Clinical observation and tests were carried out from the time of the surgery until day one. Twenty-four hours after the surgery on the right side, the same surgery was performed on the left side, followed by clinical observation. Twenty-five other rats were used as controls, with sham surgery. Histologic analysis of the vestibular nerve with silver staining was performed in six rats 3 or 7 days after the labyrinthectomy. RESULTS: The ventrolateral approach made it possible to reach the middle- and inner-ear with preservation of nervous and vascular elements such as the facial nerve and stapedial artery. Unilateral labyrinthectomy induced ocular skew deviation, head torsion and limb asymmetry. Dynamic signs were first rolling, then rotation, which increased considerably during tail suspension. Bilateral labyrinthectomy produces instability with major body oscillation. Animals show head and neck dorsiflexion with limb extension, sometimes followed by fast backward walking. CONCLUSION: The ventrolateral approach is an efficient technique for surgical labyrinthectomy with stapedial artery preservation. Clinical analysis shows a wide range of signs to evaluate the functional destruction of the vestibular organ.

Vestibular mapping in patients with unilateral peripheral-vestibular deficits.

OBJECTIVE: To test the hypothesis that patterns of semicircular canal (SCC) and otolith impairment in unilateral vestibular loss depend on the underlying disorders, we analyzed peripheral-vestibular function of all 5 vestibular sensors. METHODS: For this retrospective case series, we screened the hospital video-head-impulse test database (n = 4,983) for patients with unilaterally impaired SCC function who also received ocular vestibular-evoked myogenic potentials and cervical vestibular-evoked myogenic potentials (n = 302). Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus) was analyzed with hierarchical cluster analysis and correlated with the underlying etiology. RESULTS: Acute vestibular neuropathy (AVN) (37.4%, 113 of 302), vestibular schwannoma (18.2%, 55 of 302), and acute cochleovestibular neuropathy (6.6%, 20 of 302) were most frequent. Horizontal SCC impairment (87.4%, 264 of 302) was more frequent (p < 0.001) than posterior (47.4%, 143 of 302) and anterior (37.8%, 114 of 302) SCC impairment. Utricular damage (58%, 175 of 302) was noted more often (p = 0.003) than saccular impairment (32%, 98 of 302). On average, 2.6 (95% confidence interval 2.48-2.78) vestibular sensors were deficient, with higher numbers (p ≤ 0.017) for acute cochleovestibular neuropathy and vestibular schwannoma than for AVN, Menière disease, and episodic vestibular syndrome. In hierarchical cluster analysis, early mergers (posterior SCC/sacculus; anterior SCC/utriculus) pointed to closer pathophysiologic association of these sensors, whereas the late merger of the horizontal canal indicated a more distinct state. CONCLUSIONS: While the extent and pattern of vestibular impairment critically depended on the underlying disorder, more limited damage in AVN and Menière disease was noted, emphasizing the individual range of loss of function and the value of vestibular mapping. Likely, both the anatomic properties of the different vestibular end organs and their vulnerability to external factors contribute to the relative sparing of the vertical canals and the sacculus.

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.

[Functional assessment of cochlear nerve and hearing]. / Exploration fonctionnelle du nerf cochléaire et de l'audition.

BACKGROUND/PURPOSE: Since otoneurosurgical pathologies are being diagnosed increasingly early, the functional prognosis of surgery is gaining in importance. Hearing and cochlear nerve exploration can be carried out using three principal methods: pure-tone and speech audiometry, evoked otoacoustic emissions (EOAEs), and brainstem auditory evoked potentials (BAEPs). The aim of this paper is to present the current knowledge on auditory functional assessment. MATERIALS AND METHODS: The medical and scientific literature from the Pubmed-Medline database was reviewed. Recently published related books were also included. RESULTS/DATA SYNTHESIS: Preoperative audiological evaluation makes it possible to assess pathology consequences on hearing. Depending on auditory status, conservative surgery, including intraoperative auditory monitoring, can be planned. From this perspective, prognostic factors for hearing preservation - such as the speech intelligibility score, the presence of transient EOAEs, and the presence of the BAEPs wave III - were identified. However, several surgical teams argue for a systematic conservative procedure, particularly when EOAEs are present, whatever the patient's preoperative hearing status. Postoperative audiological evaluation provides the opportunity for monitoring: in the short term, to detect complications early, through BAEPs recorded in the nonoperated ear; in the long term, to detect recurrence of the pathology. Moreover, the consequences of surgery on hearing can be assessed and long-term follow-up of auditory function can be carried out. Finally, the comparison of pre- and postoperative audiological status provides inductive feedback on surgery and electrophysiological monitoring, giving the otoneurosurgeon and neurophysiologist the opportunity to improve the entire procedure. CONCLUSION: Auditory functional assessment is essential for optimal care of tumor or functional pathologies involving the cochlear nerve and/or the cerebellopontine angle.