Audiological and Vestibular Measurements in Chronic Renal Failure Patients Receiving Hemodialysis Treatment.

BACKGROUND: The aim was to evaluate the changes in the audiovestibular system in adult patients with the diagnosis of chronic renal failure who were treated with hemodialysis. METHODS: Thirty-five patients diagnosed with chronic renal failure and receiving hemodialysis treatment 3 days a week and 35 healthy individuals were tested with pure tone audiometry, video head impulse test, and post-head shake nystagmus test. Dizziness Handicap Inventory was applied to all participants. RESULTS: The Dizziness Handicap Inventory scores of the patient groups are higher than the control groups (P=.001). In the video head impulse test, there is no statistically significant difference between the patient and control groups in terms of gain asymmetry. 17.1% of the patients had both left and right lateral saccades (P=.03). A statistically significant difference was also found after the post-head shake test (P=.025). In the patient group, an inverse relationship between the presence of left anterior right posterior saccades and blood urea nitrogen-creatinine ratio and a direct relationship between the presence of right anterior left posterior saccades and creatinine elevation were determined. The presence of saccades in the video head impulse test increased significantly as the disease duration of hemodialysis patients increased. CONCLUSION: It was determined that the overt and covert saccades in the video head impulse test increased significantly as the creatinine increased and the duration of the disease increased in the patients with chronic renal failure. The common clinical usage of video head impulse test in monitoring the vestibular side effects of creatinine elevation and disease duration in chronic renal failure patients may be possible with future studies.

Vestibular disorders following BNT162b2 mRNA COVID-19 vaccination: A retrospective case series.

BACKGROUND: There are few publications regarding manifestations of vestibular disorders (VDs) following BNT162b2 mRNA COVID-19 vaccination. PURPOSE: We describe cases of VD potentially related to BNT162b2 vaccination and calculate its reporting rate, in order to enlarge knowledge about this adverse effect. METHODS: A retrospective analysis of cases of VD following BNT162b2 vaccination reported to the pharmacovigilance centre of Georges-Pompidou European Hospital (France), in 2021 was performed. In order to identify these cases from the pharmacovigilance database containing all our registered cases, we used the Standardised MedDRA Query (SMQ) 'vestibular disorders'. Then we analysed cases with vestibular symptoms, based on the association of typical manifestations. The reporting rate was calculated based on the number of VD cases and the number of vaccinated patients. RESULTS: Among 6608 cases reported to our centre related to COVID-19 vaccines during 2021, 34 VDs associated with BNT162b2 administration were included. They were mainly reported in females (79%), 62% occurred after the first dose and 32% were serious. Symptoms had completely resolved in 13 cases (38%). Vertigo was the most common symptom followed by balance disorders. Three patients received second dose without reappearance of VD. The final diagnosis was reported in 10 patients (six cases of vestibular neuritis, two cases of central VD, two cases of benign paroxysmal positional vertigo). The regional reporting rate was 26 [95% CI: 17-34] cases of VD per 1 million persons vaccinated. CONCLUSION: Although the relationship between vaccination and VD cannot be established, clinicians should be aware of this rare adverse effect.

Comparing the recurrence of audio-vestibular disorders following breakthrough infection of COVID-19 vs. those following vaccine administration.

PURPOSE: The term "breakthrough infection" of COVID-19 indicates that subjects who previously received COVID-19 vaccination became infected with COVID-19. This study compared the recurrence of audio-vestibular disorders following breakthrough infection of COVID-19 vs. those following vaccine administration. PATIENTS AND METHODS: Fifty patients with previous known audio-vestibular disorders visited our clinic due to recurrence of inner ear symptoms following breakthrough infection of COVID-19 and were assigned to Group A. Another 50 patients who had recurrent inner ear symptoms following COVID-19 vaccination were assigned to Group B for comparison. The post-breakthrough infection interval is defined from date of breakthrough infection to the onset of inner ear symptoms, while the post-vaccination interval means the time from date of vaccination to the onset of inner ear symptoms. These two intervals were calculated and then compared. RESULTS: The time from latest vaccination to the breakthrough infection of COVID-19 was 4 m (median), likely due to waning of IgG response. To the onset of inner ear symptoms, the post-breakthrough infection interval was 40d (median) for Group A, which was significantly longer than 10d (median) of the post-vaccination interval for Group B. CONCLUSION: The post-breakthrough infection interval (median, 40d) is significantly longer than the post-vaccination interval (median, 10d) to exacerbate pre-existing audio-vestibular disorders. The reason is probably because an interval of 40d is related to IgG peak response following COVID-19 breakthrough infection, while that of 10d is responsible for IgG production after COVID-19 vaccination.

Vestibular dysfunction amongst adolescents: what do we know? A review.

BACKGROUND: Vestibular dysfunction in children is a debilitating condition that results in countless pernicious effects, such as motor development delay, poor academic performance and psychosocial impairment. Yet, research pertaining to vestibular and balance disorders amongst adolescents is still lacking and remains an enigma. METHODS: This paper outlines novel emerging aetiological factors contributing to vestibular dysfunction amongst adolescents by appraising published articles through a narrative review. RESULTS: Underlying aetiological factors of vestibular dysfunction can be identified among adolescents with thorough evaluation. Proper diagnostic evaluation of vestibular dysfunction is imperative in providing optimal care and guiding appropriate treatment strategies. The available literature demonstrated multifactorial aetiological factors that contribute to vestibular dysfunction in adolescents. CONCLUSION: Outlining the underlying aetiological factors of vestibular dysfunction is vital to ensure that patients receive appropriate care and treatment.

Four cases of audio-vestibular disorders related to immunisation with SARS-CoV-2 mRNA vaccines.

OBJECTIVE: To gain medical insight into the clinical course and safety of otolaryngologic disorders following immunisation with severe acute respiratory coronavirus (SARS-CoV-2) mRNA-based vaccines. DESIGN: Case description. STUDY SAMPLE: We report four cases of transient audio-vestibular symptoms, which occurred shortly after inoculation of two BNT162b2 (Pfizer-BioNTech®) and mRNA-1273 (Moderna®) vaccines. RESULTS: Hearing loss was unilateral in all cases and recovered at least partially: it was associated with persistent gait instability in two cases, after 1 and 7 months. Trigger mechanisms underpinning audio-vestibular impairment remain uncertain. Immune tolerance mechanisms with off-target innate activation of T-lymphocytes may be involved in vestibulocochlear nerve disorders, as for other cranial nerves involvement. CONCLUSIONS: The occurrence of audio-vestibular manifestations following mRNA-based vaccines needs ENT monitoring to support their causality in such rare vaccine-related adverse events. Audio-vestibular disorders appeared of transitory nature, including hearing loss, and should not deter further efforts in large-scale vaccination campaigns against SARS-CoV-2.

A prospective study on the application of HINTS in distinguishing the localization of acute vestibular syndrome.

BACKGROUND: Acute vestibular syndrome (AVS) is a common clinical syndrome in neurology clinics and emergency department. Canonical standard for AVS diagnosis requires the presence of persistent vertigo for more than 24 h. HINTS (head impulse-nystagmus-test of skew) is an emerging scheme in the diagnosis of AVS. In this prospective study, we evaluated the specificity and sensitivity of HINTS in distinguishing between central and peripheral AVS. METHODS: A cohort of 239 cases with complete clinical record was recruited in the study. All patients completed emergency brain CT examination to exclude hemorrhagic stroke. HINTS examination was conducted to distinguish between central AVS and peripheral AVS, and all patients completed head MRI, BAEP and vestibular function examinations within one week. Patients diagnosed as central AVS were subject to angiography (CTA/MRA/DSA), and patients with peripheral AVS were considered for a 3-month follow-up to correct the initial diagnosis. RESULTS: Patients with central AVS were associated with an elder age, higher incidences of hypertension, atrial fibrillation, family history of stroke and previous history of stroke. Posterior circulation cerebral infarction, vestibular migraine and cerebellitis were the dominant diseases associated with central AVS. The sensitivities of HIT, GE, and TS in the diagnosis of central AVS were 73.5%, 61.2%, and 26.5%, and the specificities were 97.9%, 92.6%, and 93.2% respectively. CONCLUSIONS: The sensitivity of HINTS for central AVS diagnosis is 89.8% and the specificity is 84.2%. HINTS is an easy-to-operate, low-cost, high-sensitivity and specific examination technique, which is practical in neurology outpatient clinics and emergency departments.

Trajectories of Visual and Vestibular Markers of Youth Concussion.

Visual and vestibular deficits, as measured by a visio-vestibular examination (VVE), are markers of concussion in youth. Little is known about VVE evolution post-injury, nor influence of age or sex on trajectory. The objective was to describe the time trend of abnormal VVE elements after concussion. Two cohorts, 11-18 years, were enrolled: healthy adolescents (n = 171) from a high school with VVE assessment before or immediately after their sport seasons and concussed participants (n = 255) from a specialty care concussion program, with initial assessment ≤28 days from injury and VVE repeated throughout recovery during clinical visits. The primary outcome, compared between groups, is the time course of recovery of the VVE examination, defined as the probability of an abnormal VVE (≥2/9 abnormal elements) and modeled as a cubic polynomial of days after injury. We explored whether probability trajectories differed by: age (<14 years vs. 14+ years), sex, concussion history (0 versus 1+), and days from injury to last assessment (≤28 days vs. 29+ days). Overall, abnormal VVE probability peaked at 0.57 at day 8 post-injury, compared with an underlying prevalence of 0.083 for uninjured adolescents. Abnormal VVE probability peaked higher for those 14+ years, female, with a concussion history and whose recovery course was longer than 28 days post-injury, compared with their appropriate strata subgroups. Females and those <14 years demonstrated slower resolution of VVE abnormalities. VVE deficits are common in adolescents after concussion, and the trajectory of resolution varies by age, sex, and concussion history. These data provide insight to clinicians managing concussions on the timing of deficit resolution after injury.

Is Inadequate Water Intake a Risk Factor for Vestibular Disorders?

BACKGROUND: Water is a vital nutrient for the human body system and failing to consume enough water could cause health problems. The purpose of this study is to investigate the relationship between water intake and vestibular system disorders. METHODS: Data from 93 patients (aged between 20 and 76 years) with vestibular disorders were analyzed in the study. The mean age of the patients was 46.96 ±13.94 years (female: 45.68 ±13.45, male: 49.96 ±14.85), and 69.9% (n=65) were female. Participants were sub-categorized into diagnostic groups as follows: benign paroxysmal positional vertigo, Meniere's disease, vestibular neuritis, vestibular migraine, and persistent postural perceptual dizziness. The water intake information was analyzed for total water, plain water, and caffeinated beverages separately and compared between groups. RESULTS: There was a significant difference between vestibular neuritis and benign paroxysmal positional vertigo (P < .001) and also between vestibular neuritis and Meniere's disease (P = .021) in terms of the intake values of plain water and total water. No significant difference was found between groups in caffeinated beverages intake (P = .151), and it was found that there is no statistically significant difference in plain water and total water intake in terms of gender (P > .05). CONCLUSION: The most significant result of this study is that inadequate water intake can be a risk factor for some forms of peripheral vestibular disorders. People should be informed about the importance of drinking water and be encouraged to increase their water intake.

Neuro-Visual and Vestibular Manifestations of Concussion and Mild TBI.

PURPOSE OF REVIEW: Mild traumatic brain injury, or concussion, is a major cause of disability. Vestibular and visual dysfunction following concussion is common and can negatively affect patients' well-being and prolong recovery. Etiologies of visual and vestibular symptoms are numerous, including ocular, neuro-ophthalmic, otologic, and neuro-vestibular conditions. Some etiologies are benign and may be treatable, while others are potentially vision or life-threatening, making a focused history and examination essential. This review offers an approach to the evaluation and treatment of the most common neuro-visual and vestibular impairments that may result from concussion. RECENT FINDINGS: Treatment of concussion including exercise, computerized programs, transcranial magnetic stimulation, gene therapy, stem cell therapy, and nanoparticles has shown promise. Many novel therapies are in the pipework for visual and vestibular recovery after concussion; however, the treatment mainstay remains therapy and evaluation for co-existing diseases.

Examination of risk factors for postoperative vestibular symptoms in patients with cholesteatoma.

BACKGROUND: In cholesteatoma, the prognosis of tympanoplasty has been well discussed in terms of hearing outcomes and residual or recurrent lesions. Postoperative dizziness and vertigo are major complications of tympanoplasty; however, few reports are available. AIMS/OBJECTIVES: We investigated each condition of cholesteatoma postoperative vestibular risk using the STAM system and staging published by EAONO/JOS, as well as findings on bony destruction. MATERIAL AND METHODS: From April 2010 to March 2021, 156 patients (166 ears) with cholesteatoma who underwent primary microscopic tympanoplasty at our hospital were registered. Subjective vestibular symptoms were recorded the day after surgery. RESULTS: Postoperative vestibular symptoms were observed in 13.9% of subjects. All of them were stage II and had both attic and mastoid lesions. Attic (p < .05) and mastoid (p < .01) lesions were risk factors. Multivariate analysis showed that significant differences were found in past histories of vestibular symptoms (p < .05) and exposure of the dura mater (p < .01). CONCLUSIONS AND SIGNIFICANCE: In the exposed dura group, the length of the prominence of the lateral semicircular canal to the middle cranial fossa dura was significantly shorter than that of the non-exposed group (p < .01). Narrow working space and downward operation may increase vestibular risk.

Subjective versus objective tests of dizziness and vestibular function in epidemiologic screening research.

BACKGROUND: Many epidemiologic studies of vestibular disorders are based on responses to questionnaires which have not been tested against objective tests of the vestibular system. OBJECTIVE: The goal was to determine if the dizziness and balance questions used in the National Health Interview Survey (NHIS) are valid and predict performance on objective tests of the vestibular system (VNG). METHODS: Data from 367 participants recruited from the community, aged 21.4 to 87.6 years, were collected in the Otolaryngology department at a tertiary care center. They were asked the eight NHIS questions twice, at least 30 minutes apart and were tested on VNG. RESULTS: Question responses changed from Test 1 to Test 2 and differed between males and females. "Yes" responses did not predict abnormal VNG responses, for the total group and when the group was categorized into younger (<60 years) and older (>60 years) subjects. The sensitivity and specificity of all questions was low. CONCLUSION: The NHIS questions provide some information about what people recall of their experiences, but they may not provide insight into the diagnostic prevalence of vestibular and balance disorders because the sensitivity and specificity are too low. Questionnaire-based epidemiologic studies should be interpreted with caution.

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (canvas): an important cause of late-onset ataxia with unique clinical features.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, slowly progressive disorder characterized by cerebellar ataxia, sensory neuropathy and bilateral vestibulopathy. Recently, a biallelic intronic AAGGG repeat expansion, (AAGGG)exp, in the Replication Factor C1 (RFC1) gene was identified as the cause of this disorder. In this study, we describe the phenotypic features of five patients from five different families diagnosed as CANVAS. The mean age at onset was 49.00 ± 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. The mean age at onset was 49.00 ± 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. Our study describes clinical findings, histopathological features and diagnostic clues of CANVAS from Turkey, a country with a high consanguineous marriage rate. Repeat expansion in the RFC1 gene should be considered in all cases with late-onset ataxia, especially when sensory disturbances, vestibular involvement and persistent coughing coexist.

Vestibular dysfunction in cochlear implant candidates: Prevalence and outcomes.

PURPOSE: Cochlear implantation (CI) has been shown to reduce vestibular function postoperatively in the implanted ear. The objective of this study was to identify the prevalence of preoperative vestibular weakness in CI candidates and identify any risk factors for postoperative dizziness. STUDY DESIGN: Retrospective cohort study. MATERIALS AND METHODS: Patients who underwent CI and had preoperative videonystagmography (VNG) at the Silverstein Institute from January 1, 2017 to May 31, 2020 were evaluated. The primary endpoint was dizziness lasting more than one month postoperatively. RESULTS: One hundred and forty nine patients were evaluated. Preoperative VNG revealed that 46 (30.9%) had reduced vestibular response (RVR) on one side and 32 (21.5%) had bilateral vestibular hypofunction (BVH). Postoperative dizziness occurred in 14 (9.4%) patients. Patients with postoperative dizziness were more likely to have abnormal preoperative VNG (RVR or BVH), compared to patients without postoperative dizziness (78.6% versus 49.6%, p = 0.0497). In cases of RVR, implantation of the weaker or stronger vestibular ear did not affect the postoperative dizziness (16.1% versus 6.7%, p = 0.38). Postoperative VNG in patients with dizziness showed decreased caloric responses in the implanted ear (28.4 to 6.4 degrees/s, p = 0.02). CONCLUSION: Preoperative caloric weakness is prevalent in CI candidates and abnormal preoperative vestibular testing may be a predictor of postoperative dizziness. CI has the potential to cause vestibular injury and preoperative testing may aid in both counseling and decision-making.

[Dizziness in Parkinson's disease]. / Golovokruzhenie pri bolezni Parkinsona.

OBJECTIVE: To study clinical features of vestibular disorders in patients with Parkinson's disease (PD) and to develop methods of their treatment. MATERIAL AND METHODS: The study included 90 patients with PD who were divided into two groups: the main group (60 patients with PD and vestibular symptoms (VS)) and the control group (30 patients with PD without VS). All patients underwent clinical neurological examination, assessment of cognitive functions, affective and autonomic disorders as well as neurovestibular examination. RESULTS: In some cases, dizziness was due to concomitant diseases of the vestibular system. Among the rest of the patients of the main group, signs of disorders of the central mechanisms of gaze control, otolith dysfunction, anxiety disorder and visuospatial dysfunction were recorded significantly more often than in the control group. The addition of vestibular rehabilitation to the complex treatment of patients of the main group helped to reduce postural instability and decreased the risk of falls. CONCLUSION: Vestibular disorders are significantly more common in patients with PD who complain of dizziness. An early detection of these disorders is feasible with the help of neurovestibular research. It is reasonable to add individually selected vestibular exercises to the complex treatment of these disorders.

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.

Cognitive and Central Vestibular Functions Correlate in People With Multiple Sclerosis.

Background. Cognitive impairment is common, but poorly managed in people with multiple sclerosis (MS). Balance has been correlated with cognition in people with MS, potentially through shared utilization of central sensory integration pathways. Objective. This study characterized the relationship between central vestibular integration and cognition in people with MS through measurement of several clinical vestibular functions requiring central sensory integration and multiple cognitive domains. Methods. Forty people with MS and 20 controls completed a battery of vestibular and cognitive examinations targeting different central vestibular integration measures and different domains of cognition, respectively. Performance on these measures was compared between people with MS and controls, and then correlational analyses were undertaken between the vestibular and cognitive measures in the MS sample. Results. People with MS performed worse than controls on all vestibular and cognitive measures. There were consistent correlations between vestibular and cognitive measures in the MS sample. Factor analysis of vestibular functions yielded a single factor hypothesized to represent central vestibular integration that demonstrated a significant relationship with a composite cognitive measure in people with MS. Discussion. Our results suggest that vestibular and cognitive dysfunction may both arise from central sensory processing pathways in people with MS. This connection could be targeted through vestibular rehabilitation techniques that improve central sensory processing and both balance and cognition in people with MS.

A Randomized Controlled Trial of Precision Vestibular Rehabilitation in Adolescents following Concussion: Preliminary Findings.

OBJECTIVE: To compare the effectiveness of a 4-week precision vestibular rehabilitation intervention compared with a behavioral management control intervention for adolescents with vestibular symptoms/impairment within 21 days of a concussion. STUDY DESIGN: This study used double-blind, randomized controlled trial design involving adolescent (12-18 years) patients with a diagnosed sport/recreation-related concussion with vestibular symptoms/impairment from a concussion-specialty clinic between October 2018 and February 2020. Eligible participants were randomized in a 1:1 to either a 4-week vestibular intervention group (VESTIB) or a behavioral management control group (CONTROL). CONTROLS (n = 25) were prescribed behavioral management strategies (eg, physical activity, sleep, hydration, nutrition, stress management) and instructed to perform stretching/physical activity (eg, walking, stationary cycle) 30 minutes/day. VESTIB (n = 25) were prescribed precision vestibular rehabilitation exercises and instructed to perform at-home exercises for 30 minutes/day. Primary outcomes were improvement in Vestibular/Ocular Motor Screening vestibular items (ie, horizontal/vertical vestibular-ocular reflex, visual motion sensitivity) at 4 weeks postenrollment. RESULTS: We screened 310 and enrolled a total of 55 (18%) adolescent patients who were randomized to one of the interventions. Fifty of fifty-five (91%) participants completed all aspects of the study protocol. Participants in VESTIB improved significantly across the intervention period in horizontal (mean difference-1.628; 95% CI [-3.20, -0.06]; P = .04) and vertical (mean difference-2.24; 95% CI [-4.01, -0.48]; P = .01) vestibular-ocular reflex, but not visual motion sensitivity (mean difference-2.03; 95% CI [-4.26, 0.19]) of the Vestibular/Ocular Motor Screening score compared with CONTROLS. CONCLUSIONS: Overall, the vestibular intervention group experienced greater clinical improvements in vestibular symptoms/impairment than controls across the 4-week intervention. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03555370.

SARS-CoV-2 (COVID-19) and audio-vestibular disorders.

To describe the audio-vestibular disorders related to the newly SARS-CoV-2 infection, including the possible ototoxicity side-effects related to the use of drugs included in the SARS-CoV-2 treatment protocols. A systematic review was performed according to the PRISMA protocol. The Medline and Embase databases were searched from March 1, 2020 to April 9, 2021. Initially the search yielded 400 manuscripts, which were reduced to 15, upon the application of inclusion criteria. Sensorineural hearing loss (SNHL) is the most frequent audio-vestibular symptom described, occurring alone or in association with tinnitus and vertigo. The etiopathogenesis of the inner ear disorders related to COVID-19 infection is still poorly understood. The number of reports of COVID-19 infections associated to audio-vestibular disorders is increasing; even if the quality of the studies available is often insufficient, audio-vestibular disorders should be considered as possible manifestations to be included among the symptoms of this infection.

Progress in protecting vestibular hair cells.

Vestibular hair cells are mechanosensory receptors that are capable of detecting changes in head position and thereby allow animals to maintain their posture and coordinate their movement. Vestibular hair cells are susceptible to ototoxic drugs, aging, and genetic factors that can lead to permanent vestibular dysfunction. Vestibular dysfunction mainly results from the injury of hair cells, which are located in the vestibular sensory epithelium. This review summarizes the mechanisms of different factors causing vestibular hair cell damage and therapeutic strategies to protect vestibular hair cells.