Transient peripheral vestibular hypofunction measured with vestibular short-latency evoked potentials following noise exposure in rats.

Exposure to 120 dB sound pressure level (SPL) band-limited noise results in delayed onset latency and reduced vestibular short-latency evoked potential (VsEP) responses. These changes are still present 4 wk after noise overstimulation. Noise-induced hearing loss (NIHL) has been shown to vary in extent and duration based on the noise intensity. This study investigated whether noise-induced peripheral vestibular hypofunction (NPVH) would also decrease in extent and/or duration with less intense noise exposure. In the present study, rats were exposed to a less intense noise (110 dB SPL) but for the same duration (6 h) and frequency range (500-4,000 Hz) as used in previous studies. The VsEP was assessed 1, 3, 7, 14, 21, and 28 days after noise exposure. In contrast to 120 dB SPL noise exposure, the 110 dB SPL noise exposures produced smaller deficits in VsEP responses that fully recovered in 62% (13/21) of animals within 1 wk. These findings suggest that NPVH, a loss or attenuation of VsEP responses with a requirement for elevated stimulus intensity to elicit measurable responses, is similar to NIHL, that is, lower sound levels produce a smaller or transient deficit. These results show that it will be important to determine the extent and duration of vestibular hypofunction for different noise exposure conditions and their impact on balance.NEW & NOTEWORTHY This is the first study to show a temporary noise-induced peripheral vestibular hypofunction that recovers following exposure to continuous noise.

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.

Cervical and ocular vestibular evoked myogenic potentials in determining nerve division involvement in patients with a tumor located in the internal auditory canal.

OBJECTIVES: The study aimed at the analysis of the parameters of acoustic cervical and ocular vestibular evoked myogenic potentials (AC-cVEMP and AC-oVEMP) response in patients with a confirmed tumor located in the internal auditory canal. It also aimed to assess to what degree a combination of these tests may be of benefit in the preoperative indication of the affected nerve division via preoperative determination whether the tumor originated from the superior or inferior division of the vestibular nerve, both divisions, or if it originated from a different nerve in the internal auditory canal. METHODS: The study group included 50 patients. Preoperative MRI scans were used to measure tumor diameter. AC-cVEMP and AC-oVEMP testing were performed before tumor resection. The surgeon was asked for a detailed description of the tumor origin. RESULTS: The corrected amplitude of cVEMP was significantly lower on the tumor side than on the non-affected side and in the control group. The corrected Asymmetry Ratio (AR) of cVEMPs in patients with the tumor was significantly elevated above the reference values with the mean being 58.29% and the mean AR of oVEMPs in patients the tumor was 71.78% which made both results significantly higher than in the control group. Neither cVEMP nor oVEMP latency was significantly correlated with tumor size. Data obtained from cVEMP and oVEMP tests was an effective indicator of tumor origin in 74% of patients showing which division (or both divisions) of the VIIIth nerve was affected in comparison with information obtained from the surgeon. CONCLUSIONS: The combined use of AC-cVEMP and AC-oVEMP tests may be useful in surgical planning in patients the tumor located in the internal auditory canal, providing a highly probable determination of the division of the affected nerve. Such information is valuable for the surgeon as it offers additional knowledge about the tumor before the procedure. cVEMP and oVEMP results may not be used as the basis for the calculation of tumor size in patients.

Cranial Nerve Disorders Associated With Immune Checkpoint Inhibitors.

OBJECTIVE: To describe the spectrum, treatment, and outcome of cranial nerve disorders associated with immune checkpoint inhibitor (Cn-ICI). METHODS: This nationwide retrospective cohort study on Cn-ICI (2015-2019) was conducted using the database of the French Refence Center. In addition, a systematic review of the literature (MEDLINE, Scopus, and Web of Science) for records published between 2010 and 2019 was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the search terms cranial nerve or neuropathy or palsy and immune checkpoint inhibitors. RESULTS: Among 67 cases with ICI-related neurologic toxicities diagnosed in our reference center, 9 patients with Cn-ICI were identified (7 men, 78%, median age 62 years [range 26-82 years]). Patients were receiving a combination of anti-cytotoxic T-lymphocyte antigen 4 and anti-programmed cell death 1 (PD-1)/PD-1 ligand (n = 5, 56%) or anti-PD-1 antibodies alone (n = 4, 44%). Cn-ICI involved optic (n = 3), vestibulocochlear (n = 3), abducens (n = 2), facial (n = 2), and oculomotor (n = 1) nerves. Two patients had involvement of 2 different cranial nerves. Treatment comprised corticosteroids (n = 8, 89%), ICI permanent discontinuation (n = 7, 78%), plasma exchange (n = 2, 22%), and IV immunoglobulin (n = 1, 11%). Median follow-up was 11 months (range 1-41 months). In 3 cases (33%), neurologic deficit persisted/worsened despite treatment: 2 optic and 1 vestibulocochlear. Among cases from the literature and the present series combined (n = 39), the most commonly affected cranial nerves were facial (n = 13, 33%), vestibulocochlear (n = 8, 21%), optic (n = 7, 18%), and abducens (n = 4, 10%). Trigeminal, oculomotor, and glossopharyngeal nerves were less frequently affected (total n = 7). CONCLUSION: Cranial nerve disorders can complicate treatment with ICIs. Approximately one-third of the patients had persisting deficits, most frequently involving hearing and vision loss.

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.

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

Quantitative Analysis of Saccade Gain in Video Head Impulse Testing.

OBJECTIVE: To quantitatively analyze corrective saccade (CS) gain and further characterize the specific relationship between vestibulo-ocular reflex (VOR) gain and CS gain in patients with vestibular loss and healthy controls. STUDY DESIGN: Prospective combined with retrospective study. SETTING: Affiliated Sixth People's Hospital, Shanghai Jiao Tong University. SUBJECTS AND METHODS: Forty patients with unilateral vestibular loss and 40 participants with normal vestibular function were subjected to video head impulse testing (vHIT). The analysis of the horizontal semicircular canal VOR and CS gains was based on individual head impulses. RESULTS: The patient group had significantly higher CS gain and lower VOR gain than the control group (P < .001). While there was no significant correlation between VOR and CS gains in the control group after adjusting for age and sex (P = .689), VOR gain negatively correlated with CS gain in the patient group (r = -0.853, P < .001). The specific relationship between VOR and CS gains was characterized as y = -1.17x + 1.12 (x: VOR gain, y: CS gain; r2 = 0.732, P < .001) in the patient group. CONCLUSIONS: In healthy participants, CS was not correlated with VOR gain, suggesting that CS is not due to VOR hypofunction. In patients with unilateral vestibular loss, CS was closely associated with VOR gain and can almost correct gaze position errors required for visual stabilization. CS gain could be an important indicator to diagnose vestibular loss and help physicians identify abnormal vHIT curves caused by artifacts and irregular practices.

The Evidence for Selective Loss of Otolithic Function.

Recent advances in vestibular testing now permit functional testing of all peripheral vestibular sense organs (all three semicircular canals, utricle, and saccule). This makes it possible to identify patients with isolated dysfunction of the utricle or saccule, even though parallel pathways for vestibular information are ultimately integrated centrally. Selective, isolated unilateral loss of utricular function as measured by ocular vestibular-evoked myogenic potentials (VEMPs) has been observed in patients with normal semicircular canal function as measured by the video head impulse test of all six semicircular canals, and normal bilateral saccular function as determined by symmetrical cervical VEMPs. How these patients present clinically and how they recover is discussed and contrasted with acute vestibular neuritis. In some patients, the unilateral loss of otolith organ (utricle or saccule) function persists and yet the patient recovers functionally to their usual lifestyle. Until the testing of all peripheral vestibular sense organs is routine, the frequency of isolated loss of otolith function cannot be gauged.

Quality of life related to symptomatic outcomes in patients with vestibular schwannomas: A Canadian Centre perspective.

Patients with vestibular schwannomas (VS) typically present with hearing loss and tinnitus as well as variable cranial nerve dysfunctions. Surgical resection, stereotactic radiotherapy and/or conservative management employing serial magnetic resonance or computed tomography imaging serve as the main treatment options. Quality of life (QoL) may be impacted by the extent of tumour burden and exacerbated or relieved by treatment. Subjective assessment and quality of life inventories provide valuable information in client centered approaches with important implications for treatment. The intention of QoL measurements affecting VS patients within a clinical setting is to facilitate discussions regarding treatment options and objectively evaluate patient- centered clinical outcomes in a naturalistic setting.

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.

AUNA2: A Novel Type of Non-Syndromic Slowly Progressive Auditory Synaptopathy/Auditory Neuropathy with Autosomal-Dominant Inheritance.

BACKGROUND: Auditory synaptopathy/neuropathy (AS/AN) is a heterogeneous disorder, which may be caused by environmental factors like postnatal hyperbilirubinemia or by genetic factors. The genetic forms are subdivided into syndromic and non-syndromic types, and show different inheritance patterns with a strong preponderance of autosomal-recessive forms. To date, only a single locus for non-syndromic autosomal-dominant AS/AN (AUNA1) has been reported in a single family, in which a non-coding DIAPH3 mutation was subsequently described as causative. MATERIALS AND METHODS: Here, we report detailed clinical data on a large German AS/AN family with slowly progressive postlingual hearing loss. Affected family members developed their first symptoms in their second decade. Moderate hearing loss in the fourth decade then progressed to profound hearing impairment in older family members. Comprehensive audiological and neurological tests were performed in the affected family members. Genetic testing comprised linkage analyses with polymorphic markers and a genome-wide linkage analysis using the Affymetrix GeneChip® Human Mapping 250K. RESULTS AND CONCLUSION: We identified a large family with autosomal-dominant AS/AN. By means of linkage analyses, the AUNA1 locus was excluded, and putatively linked regions on chromosomal bands 12q24 and 13q34 were identified as likely carrying the second locus for autosomal-dominant AS/AN (AUNA2). AUNA2 is associated with a slowly progressive postlingual hearing loss without any evidence for additional symptoms in other organ systems.

Hearing impairment in a female infant with interstitial deletion of 2q24.1q24.3.

Patients with interstitial deletions in 2q24.1q24.3 are rarely reported. These patients manifest a variety of clinical features in addition to intellectual disability, depending on the size and location of the deletion. We report a female patient with interstitial deletion of 5.5 Mb in 2q24.1q24.3, who showed intrauterine growth retardation, hypotonia, global developmental delay, microcephaly, and characteristic facial appearance. In addition, she had hearing impairment, with no auditory brainstem response. Case of 2q24.1q24.3 deletion with hearing impairment is quite rare. We suspect that hearing impairment is caused by bilateral cochlear nerve deficiency due to cochlear nerve canal stenosis. Further studies are necessary to evaluate hearing impairment as a clinical feature in patients with de novo heterozygous 2q24.1q24.3 deletion.

Auditory Brainstem Response Altered in Humans With Noise Exposure Despite Normal Outer Hair Cell Function.

OBJECTIVES: Recent animal studies demonstrated that cochlear synaptopathy, a partial loss of inner hair cell-auditory nerve fiber synapses, can occur in response to noise exposure without any permanent auditory threshold shift. In animal models, this synaptopathy is associated with a reduction in the amplitude of wave I of the auditory brainstem response (ABR). The goal of this study was to determine whether higher lifetime noise exposure histories in young people with clinically normal pure-tone thresholds are associated with lower ABR wave I amplitudes. DESIGN: Twenty-nine young military Veterans and 35 non Veterans (19 to 35 years of age) with normal pure-tone thresholds were assigned to 1 of 4 groups based on their self-reported lifetime noise exposure history and Veteran status. Suprathreshold ABR measurements in response to alternating polarity tone bursts were obtained at 1, 3, 4, and 6 kHz with gold foil tiptrode electrodes placed in the ear canal. Wave I amplitude was calculated from the difference in voltage at the positive peak and the voltage at the following negative trough. Distortion product otoacoustic emission input/output functions were collected in each participant at the same four frequencies to assess outer hair cell function. RESULTS: After controlling for individual differences in sex and distortion product otoacoustic emission amplitude, the groups containing participants with higher reported histories of noise exposure had smaller ABR wave I amplitudes at suprathreshold levels across all four frequencies compared with the groups with less history of noise exposure. CONCLUSIONS: Suprathreshold ABR wave I amplitudes were reduced in Veterans reporting high levels of military noise exposure and in non Veterans reporting any history of firearm use as compared with Veterans and non Veterans with lower levels of reported noise exposure history. The reduction in ABR wave I amplitude in the groups with higher levels of noise exposure cannot be accounted for by sex or variability in outer hair cell function. This change is similar to the decreased ABR wave I amplitudes observed in animal models of noise-induced cochlear synaptopathy. However, without post mortem examination of the temporal bone, no direct conclusions can be drawn concerning the presence of synaptopathy in the study groups with higher noise exposure histories.

Commentary on the regulatory implications of noise-induced cochlear neuropathy.

OBJECTIVE: A discussion on whether recent research on noise-induced cochlear neuropathy in rodents justifies changes in current regulation of occupational noise exposure. DESIGN: Informal literature review and commentary, relying on literature found in the authors' files. No formal literature search was performed. STUDY SAMPLE: Published literature on temporary threshold shift (TTS) and cochlear pathology, in humans and experimental animals, as well as the regulations of the US Occupational Safety and Health Administration (OSHA). RESULTS: Humans are less susceptible to TTS, and probably to cochlear neuropathy, than rodents. After correcting for inter-species audiometric differences (but not for differences in susceptibility), exposures that caused cochlear neuropathy in rodents already exceed OSHA limits. Those exposures also caused "pathological TTS" (requiring more than 24 h to recover), which does not appear to occur with human broadband noise exposure permissible under OSHA. CONCLUSION: It would be premature to conclude that noise exposures permissible under OSHA can cause cochlear neuropathy in humans.

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.

Hearing and Vestibular Function After Preoperative Intratympanic Gentamicin Therapy for Vestibular Schwanomma as Part of Vestibular Prehab.

OBJECTIVE: To evaluate auditory and vestibular function after presurgical treatment with gentamicin in schwannoma patients. BACKGROUND: The vestibular PREHAB protocol aims at diminishing the remaining vestibular function before vestibular schwannoma surgery, to ensure less acute symptoms from surgery, and initiate a more efficient vestibular rehabilitation already before surgery. However, the potential cochleotoxicity of gentamicin is a concern, since modern schwannoma surgery strives to preserve hearing. STUDY DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: Seventeen patients diagnosed with vestibular schwannoma between 2004 and 2011, and took part in vestibular PREHAB program. The patients were of age 21 to 66 years (mean 48.8), 9 females and 8 males. INTERVENTION: Intratympanic gentamicin installations before surgery as part of the vestibular PREHAB. MAIN OUTCOME MEASURES: Hearing thresholds, word recognition score, caloric response, subjective visual vertical and horizontal, cVEMP, and vestibular impulse tests. RESULTS: Combined analysis of frequency and hearing threshold showed a significant decrease after gentamicin therapy (p < 0.001). Pure-tone average decreased with 7.1 ± 8.5 dB (p = 0.004), and speech recognition with 10%. The treatment resulted in unilateral vestibular deafferentation with no notable reaction to bithermal caloric irrigation (reduction 64%, p < 0.001), loss of the vestibulo-ocular response measured by the head-impulse test, and deviation of subjective horizontal/vertical to the side of the lesion (+2.2 degrees, p = 0.010). CONCLUSIONS: Intratympanic installations of gentamicin, as part of the vestibular PREHAB, result in unilateral vestibular deafferentation, but constitute a definite risk for high-frequency hearing loss. The hearing results are in line with those reported upon when treating Menière's disease.

Comparison of three diagnostic tests in detecting vestibular deficit in patients with peripheral vestibulopathy.

OBJECTIVES: This study aimed to evaluate the results of the video head impulse test and of the caloric and rotatory chair tests in patients with dizziness. Agreement between test results was assessed and the best protocol for detecting peripheral vestibulopathy was identified. METHODS: Participants comprised 116 patients, 75 with a peripheral vestibulopathy and 41 with non-peripheral vestibulopathy. The main outcome measures were classified as normal or abnormal according to our laboratory data. RESULTS: Agreement between tests was low. Vestibulopathy testing that required all three results to be abnormal had a sensitivity of 0.547, a specificity of 0.878, and positive and negative predictive values of 0.891 and 0.514, respectively. Vestibulopathy testing that required just one result to be abnormal had a sensitivity of 0.933, a specificity of 0.292, and positive and negative predictive values of 0.701 and 0.705, respectively. CONCLUSION: In peripheral vestibulopathy, there was weak concordance in the assessment of horizontal semicircular canal function among the different tests. However, the video head impulse test had sufficient statistical power to be recommended as the first-line test.