Vascular inner ear partition: a concept for some forms of sensorineural hearing loss and vertigo

Cerebral Small Vessel Disease in Elderly Patients with Sudden Sensorineural Hearing Loss

BACKGROUND

The cause of sudden sensorineural hearing loss (SSNHL) is uncertain in a significant number of patients. A vascular etiology has been proposed because SSNHL increases the risk of developing a stroke. Cardiovascular risk factors can cause cerebral small vessel disease (CSVD). The presence of CSVD in turn raises the risk of stroke.

AIM

The aim of this study was to compare the presence of CSVD and cardiovascular risk factors in elderly patients with idiopathic SSNHL (iSSNHL) to a control cohort.

METHOD

Patients with iSSNHL of 50 years and older were compared with a control cohort with patients suspected of trigeminal neuralgia or vestibular paroxysmia. The primary outcome was the difference in the number of white matter hyperintensities using the ordinal Fazekas scale. Secondary outcomes were the presence of brain infarctions on MRI and the difference in cardiovascular risk factors.

RESULTS

In the SSNHL cohort, Fazekas score 2 was most frequently seen compared with Fazekas 1 in the control cohort. The distribution of Fazekas scores did not differ significantly. The sum of the Fazekas scores were 13,925 and 14,042 for iSSNHL and controls, respectively ( p = 0.908). Brain infarctions were seen in 8 patients with iSSNHL (n = 118) and in 13 patients in the control cohort (n = 118) ( p = 0.361). None of the cardiovascular risk factors were more frequently seen in the iSSNHL cohort.

CONCLUSION

Patients with iSSNHL did not exhibit more CSVD on MRI than controls. This result is in contrast with previous literature demonstrating a higher risk of stroke in patients with iSSNHL than in controls. A prospective analysis with a larger study population is therefore warranted.

Significance of Baseline Inferior Vestibular Function on the Prognosis of Patients with Labyrinthitis

OBJECTIVE

Acute spontaneous vertigo with idiopathic sudden sensorineural hearing loss (ISSNHL) can be diagnosed as labyrinthitis, which has a poorer prognosis than ISSNHL without vertigo. Thus, we aimed to identify the effect of the baseline vestibular function on the prognosis of labyrinthitis.

METHODS

A total of 23 patients with labyrinthitis was retrospectively divided into the recovered group (complete recovery, partial recovery) and the nonrecovered group (slight improvement, no improvement). Differences in caloric weakness and gain in the video head impulse test (vHIT) between the two groups were compared. In addition, the prognostic value of the vHIT on each of the three semicircular canals in predicting hearing recovery was analyzed using a linear regression model.

RESULTS

In final pure-tone audiometry, 2 patients (8.70%) exhibited complete recovery, 4 patients (17.39%) had partial recovery, and 17 patients (73.91%) had slight or no improvement. The initial ipsilesional posterior canal (iPC) gain and the contralesional anterior canal (cAC) gain were significantly decreased in the nonrecovered group (p < 0.013 for iPC and p < 0.007 for cAC, Mann-Whitney U test). The mean hearing gain was positively correlated with the iPC gain (R2 = 0.36, p = 0.003, Spearman correlation analysis).

CONCLUSION

An abnormal iPC gain may be a poor prognostic factor for hearing recovery. Additionally, the vHIT on the three semicircular canals can provide prognosis and insights into the pathophysiological mechanisms in patients with labyrinthitis.

Inner ear organoids: progress and outlook, with a focus on the vascularization

The inner ear is a complex organ that encodes sound, motion, and orientation in space. Given the complexity of the inner ear, it is not surprising that treatments are relatively limited despite the fact that, in 2015, hearing loss was the fourth leading cause of years lived with disability worldwide. Inner ear organoid models are a promising tool to advance the study of multiple aspects of the inner ear to aid the development of new treatments and validate drug-based therapies. The blood supply of the inner ear plays a pivotal role in growth, maturation, and survival of inner ear tissues and their physiological functions. This vasculature cannot be ignored in order to achieve a truly in vivo-like model that mimics the microenvironment and niches of organ development. However, this aspect of organoid development has remained largely absent in the generation of inner ear organoids. The current review focuses on three-dimensional inner ear organoid and how recent technical progress in generating in vitro vasculature can enhance the next generation of these models.

Cerebral Small Vessel Disease in Elderly Patients With Vestibular Neuritis

Background

Acute audiovestibular loss is a neurotologic emergency of which the etiology is frequently unknown. In vestibular neuritis a viral genesis is expected, although there is insufficient evidence to support viruses as the only possible etiological factor. In sudden deafness, a vascular etiology has been proposed in elderly patients, since cardiovascular risk factors are more frequently present and a higher risk of developing a stroke was seen compared to the general population. So far, very little research has been carried out on vascular involvement in elderly patients with vestibular neuritis. Cardiovascular risk factors have a positive correlation with cerebral small vessel disease, visible as white matter hyperintensities, brain infarctions, microbleeds and lacunes on MRI. The presence of these characteristics indicate a higher risk of developing a stroke.

Aim

We investigated whether elderly patients with vestibular neuritis have a higher prevalence of vascular lesions on MRI compared to a control cohort.

Materials and Methods

Patients of 50-years and older, diagnosed with vestibular neuritis in a multidisciplinary tertiary referral hospital, were retrospectively reviewed and compared to a control cohort. The primary outcome was the difference in cerebral small vessel disease on MRI imaging, which was assessed by the number of white matter hyperintensities using the ordinal Fazekas scale. Secondary outcomes were the presence of brain infarctions on MRI and the difference in cardiovascular risk factors.

Results

Patients with vestibular neuritis (N = 101) had a 1.60 higher odds of receiving a higher Fazekas score than the control cohort (N = 203) (p = 0.048), there was no difference in presence of brain infarctions (p = 1.0). Hyperlipidemia and atrial fibrillation were more common in patients experiencing vestibular neuritis.

Conclusion

We found a positive correlation of white matter hyperintensities and VN which supports the hypothesis of vascular involvement in the pathophysiology of vestibular neuritis in elderly patients. Further prospective research is necessary to confirm this correlation.

Towards maturation of human otic hair cell-like cells in pluripotent stem cell-derived organoid transplants

Human otic organoids generated from pluripotent stem cells (PSCs) provide a promising platform for modeling, drug testing, and cell-based therapies of inner ear diseases. However, providing the appropriate niche that resembles inner ear development and its vasculature to generate otic organoids is less conspicuous. Here, we devised a strategy to enhance maturation of otic progenitor cells toward human hair cell-like cells (HCLCs) by assembling three-dimensional (3D) otic organoids that contain human PSC-derived otic cells, endothelial cells, and mesenchymal stem cells (MSCs). Heterotopic implantation of otic organoids, designated as grafted otic organoids (GOs), in ex ovo chick embryo chorioallantoic membrane (CAM) stimulated maturation of the HCLCs. Functional analysis revealed the presence of voltage-gated potassium currents without detectable sodium currents in these cells in the GOs. Our results demonstrated that implantation of 3D heterotypic cell mixtures of otic organoids improved maturation of human HCLCs. This GO-derived HCLCs could be an attractive source for drug discovery and other biomedical applications.

Usefulness of the Video Head Impulse Test for the Evaluation of Vestibular Function in Patients With Otitis Media With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVES

To investigate usefulness of the video Head Impulse Test (vHIT) as a method for evaluating semicircular canal function in patients with otitis media with antineutrophil cytoplasmic antibody-associated vasculitis (OMAAV).

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Fourteen patients with OMAAV underwent vestibular examination.

MAIN OUTCOME MEASURES

The gain in vestibulo-ocular reflex (VOR) and the presence of catch-up saccade were examined for each semicircular canal.

RESULTS

Seven (50.0%) of the 14 patients felt subjective symptoms of disequilibrium. Dysfunction in at least one semicircular canal was detected in all ears of the OMAAV patients evaluated by vHIT. Dysfunction in posterior semicircular canal was detected more frequently than that in the anterior or horizontal canal. There were no significant correlations between the gain in VOR and hearing loss.

CONCLUSIONS

vHIT is thought to be the most suitable method for evaluating semicircular canal function in patients with OMAAV as vHIT is not influenced by middle ear pathology and was able to evaluate vertical canal function including the posterior canal.

Efficacy of the additional effect of hyperbaric oxygen therapy in combination of systemic steroid and prostaglandin E1 for idiopathic sudden sensorineural hearing loss

PURPOSE

The efficacies of hyperbaric oxygen therapy (HBO), systemic steroid, prostaglandin E₁, or the combination of any two modalities have been reported in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). However, little is known about the combined efficacy of HBO, systemic steroid, and prostaglandin E₁ for this disorder. We aimed to investigate the efficacy of HBO combined with systemic steroids and prostaglandin E₁ as triple therapy in patients with ISSNHL.

MATERIALS AND METHODS

We retrospectively evaluated the records of 67 patients with ISSNHL who were treated with systemic steroid and prostaglandin E₁, with (n = 38) or without (n = 29) HBO. The inclusion criteria included a diagnosis of ISSNHL within 14 days of symptom onset, age ≥15 years, treatment according to the protocol, and clinical follow-up of at least 1 month. The patients' hearing levels were evaluated 1 month after hearing loss onset. The primary outcome was hearing improvement on pure tone audiometry. We also evaluated the demographic profiles of patients.

RESULTS

Patients treated with triple therapy showed significantly greater hearing improvement (p < 0.01) than those treated without HBO, despite some differences between the two treatment groups. Multivariate logistic regression analysis revealed a significant positive correlation between pure tone audiometry improvement and hyperbaric oxygen therapy, after adjustment for confounding factors (odds ratio = 7.42; 95% and confidence interval = 2.37-23.3; p = 0.001).

CONCLUSION

HBO with systemic steroid and prostaglandin E₁ administration conferred significant therapeutic benefits for ISSNHL. Therefore, routine use of triple therapy is recommended for patients with ISSNHL.

Different prognoses in patients with profound sudden sensorineural hearing loss

Background: Inner ear hemorrhage is increasingly recognized as a cochlear lesion that can cause profound sudden sensorineural hearing loss (SSNHL). Objectives: To investigate changes of cochlear and vestibular function and to compare therapeutic recovery from profound SSNHL induced by different etiologies. Material and methods: Eighty patients with profound SSNHL (≥90 dB) were divided into an inner ear hemorrhage group and a non-inner ear hemorrhage group by MRI. Statistical analysis was performed to compare the therapeutic effects from vertigo and hearing loss and the outcomes of follow-up in the two groups. Results: There were significant differences between the two groups in terms of the overall 14-day therapeutic response rate (20 vs. 48%), the incidence of imbalance (26.7 vs. 6%), the incidence of semicircular canal dysfunction on the affected side (60 vs. 20%), the incidence of abnormal C-VEMP and O-VEMP on the affected side (63.3 vs. 38%; and 60 vs. 30%, respectively), the average hearing threshold (74.2 ± 10.7 vs. 53.6 ± 11.4 dB), and the word recognition score (65.5 ± 21.7 vs. 83.5 ± 24.5%) at a 12-month follow-up. Conclusions and significance: A higher percentage of patients with profound SSNHL induced by inner ear hemorrhage were associated with vertigo and had a poor prognosis.

The Intimate Relationship between Vestibular Migraine and Meniere Disease: A Review of Pathogenesis and Presentation

Vestibular migraine (VM) has only recently been recognized as a distinct disease entity. One reason is that its symptoms overlap greatly with those of other vestibular disorders, especially Meniere disease (MD). The pathophysiology of neither VM nor MD is entirely elucidated. However, there are many theories linking migraine to both disorders. We reviewed the current understanding of migraine, VM, and MD and described how VM and MD are similar or different from each other in terms of pathophysiology and presentation, including hypotheses that the two share a common etiology and/or are variants of the same disease.

Correlation between afferent rearrangements and behavioral deficits after local excitotoxic insult in the mammalian vestibule: a rat model of vertigo symptoms

Damage to inner ear afferent terminals is believed to result in many auditory and vestibular dysfunctions. The sequence of afferent injuries and repair, as well as their correlation with vertigo symptoms, remains poorly documented. In particular, information on the changes that take place at the primary vestibular endings during the first hours following a selective insult is lacking. In the present study, we combined histological analysis with behavioral assessments of vestibular function in a rat model of unilateral vestibular excitotoxic insult. Excitotoxicity resulted in an immediate but transient alteration of the balance function that was resolved within a week. Concomitantly, vestibular primary afferents underwent a sequence of structural changes followed by spontaneous repair. Within the first two hours after the insult, a first phase of pronounced vestibular dysfunction coincided with extensive swelling of afferent terminals. In the next 24 h, a second phase of significant but incomplete reduction of the vestibular dysfunction was accompanied by a resorption of swollen terminals and fiber retraction. Eventually, within 1 week, a third phase of complete balance restoration occurred. The slow and progressive withdrawal of the balance dysfunction correlated with full reconstitution of nerve terminals. Competitive re-innervation by afferent and efferent terminals that mimicked developmental synaptogenesis resulted in full re-afferentation of the sensory epithelia. By deciphering the sequence of structural alterations that occur in the vestibule during selective excitotoxic impairment, this study offers new understanding of how a vestibular insult develops in the vestibule and how it governs the heterogeneity of vertigo symptoms.

Summary: Early sequence of afferent injury and repair in vestibular sensory epithelium that correlates with balance disorders and functional restoration is detailed in a rodent model of excitotoxicity.

Migraine features in patients with Meniere's disease

OBJECTIVES/HYPOTHESIS

To better understand the features of migraine in Meniere's disease (MD).

STUDY DESIGN

Retrospective review of prospectively obtained surveys in an outpatient clinic of a tertiary medical center.

METHODS

Detailed questionnaires on headaches and dizziness were given to consecutive patients presenting with dizziness. The responses were verified by the clinician with the patient. The data, in addition to the clinical history and audiogram, were used to diagnose patients with migraine headaches and MD using criteria set by the International Headache Society (IHS) and the American Academy of Otolaryngology-Head and Neck Surgery, respectively. The prevalence of migraine-like symptoms in those patients with MD, who did not fit the diagnostic criteria for migraine, was evaluated.

RESULTS

Thirty-seven patients with definite MD were included. There was a predominance of females (female/male:26/11). Mean age of patients was 52 ± 14 years. Nineteen patients (51%) had migraine headaches. Fifteen patients fulfilled the criteria for definite vestibular migraine. Of those who did not fulfill the IHS migraine criteria, a majority had characteristics such as a family history of migraine, visual motion sensitivity, or lifelong motion sickness that were highly suggestive of a migraine disorder.

CONCLUSIONS

A majority of patients with MD have migraine headaches as defined by the IHS. Sensitivity to visual motion, light and sound, head motion, smells, weather changes, or medication was present in 95% of all patients with definite MD and 82% of non-IHS migraine MD patients. This may suggest that MD may be an atypical variant of migraine.

[Isolated functional loss of the lateral semicircular canal in vestibular neuritis]

Today, modern tools in vestibular testing are feasible to provide information about functional status of all five peripheral vestibular receptors. Isolated or combined loss of crista and macula receptor function can be determined in the diagnostic process. We describe a seldom case of isolated functional loss of lateral semicircular canal receptor function in a 55-year-old patient. Whereas there was no ispilateral caloric response and video head impulse test revealed a catch-up saccade, air-conducted (AC) cervical and ocular vestibular-evoked myogenic potentials (cVEMP, oVEMP), subjective visual vertical and MRI were normal.

Attenuating Cardiac Pulsations within the Cochlea: Structure and Function of Tortuous Vessels Feeding Stria Vascularis

The mammalian ear has an extraordinary capacity to detect very low-level acoustic signals from the environment. Sound pressures as low as a few μ Pa (-10 dB SPL) can activate cochlear hair cells. To achieve this sensitivity, biological noise has to be minimized including that generated by cardiovascular pulsation. Generally, cardiac pressure changes are transmitted to most peripheral capillary beds; however, such signals within the stria vascularis of the cochlea would be highly disruptive. Not least, it would result in a constant auditory sensation of heartbeat. We investigate special adaptations in cochlear vasculature that serve to attenuate cardiac pulse signals. We describe the structure of tortuous arterioles that feed stria vascularis as seen in corrosion casts of the cochlea. We provide a mathematical model to explain the role of this unique vascular anatomy in dampening pulsatile blood flow to the stria vascularis.

Plasma very long-chain n-3 polyunsaturated fatty acids and age-related hearing loss in older adults

OBJECTIVES

Age-related hearing loss is a common social and health problem in the older adult population. Up until now, very little scientific attention has been given to the potential role of fatty acids in age-related hearing loss. In this study we investigated whether plasma very long-chain n-3 polyunsaturated fatty acids (PUFAs) are associated with age-related hearing loss over three years.

DESIGN

Cross-sectional and 3-year longitudinal analyses.

SETTING

Wageningen, the Netherlands.

PARTICIPANTS

720 men and postmenopausal women (50-70 years of age) without middle ear dysfunction or unilateral hearing loss.

MEASUREMENTS

Fatty acid proportions were measured in plasma cholesteryl esters. Hearing thresholds (in decibels, dB) at baseline and after three years were measured with pure-tone audiometry. Hearing loss was calculated as the increase in mean hearing thresholds in the low (0.5-kHz, 1-kHz, and 2-kHz) and high (4-kHz, 6-kHz, and 8-kHz) frequencies over three years.

RESULTS

Subjects in the highest quartile of plasma very long-chain n-3 PUFA had less hearing loss in the low frequencies over three years than subjects in the lowest quartile (p < 0.01, ANCOVA, difference in mean adjusted hearing thresholds= -1.2 dB). There were no significant differences between the quartiles of plasma very long-chain n-3 PUFA in hearing loss in the high frequencies (p=0.49, ANCOVA). These associations are adjusted for baseline mean hearing thresholds, age, sex, level of education and alcohol consumption.

CONCLUSION

This study is the first to show an inverse association between plasma very long-chain n-3 PUFAs and age-related hearing loss. These results are encouraging, but require confirmation from future studies.

The vascularization of the human cochlea: its historical background

The history of vascularization of the human cochlea began with the first anatomical description of the cochlea in the 16th century. Three different periods are recognizable in the development of knowledge concerning this subject: the macroscopic period, with the description of the structure of the cochlea from the 16th to the 19th century; the microscopic period, with the description of the part of the organ of Corti in the 19th century; and the injection period, with the description of the fine vascularization of the cochlea in the 20th century. Various techniques were used during these three periods, which will be presented here, using only original references. This historical study reveals the ingenuity of the researchers in using different aspects of technological progress to enhance their performance in research.

Evaluation of vardenafil for the treatment of subjective tinnitus: a controlled pilot study

Background

Vardenafil (Levitra^®) represents a potent and highly selective phosphodiesterase type 5 (PDE5) inhibitor, which is established for treatment of various diseases. There are several unpublished reports from patients stating that vardenafil has a considerable therapeutic effect on their concomitant tinnitus. This pilot study was conducted to specifically assess the effect of vardenafil in patients with chronic tinnitus.

Methods

This trial was based on a prospective, randomized, double-blind, placebo-controlled, parallel group design. Fourty-two consecutive subjects with mon- or binaural chronic tinnitus received 10 mg vardenafil (N = 21) or matching placebo tablets (N = 21) administered orally twice a day over a period of 12 weeks. Clinical examination and data acquisition took place at each visit: at baseline, after 4 weeks, after 12 weeks (end of treatment with study medication), and at non-medicated follow-up after 16 weeks. Assessment of clinical effectiveness was based on a standardized tinnitus questionnaire (TQ), the Short Form 36 health survey (SF-36), audiometric measurements (mode, pitch and loudness of tinnitus; auditory thresholds) and biomarkers of oxidative stress in patients' blood (malondialdehyde, protein carbonyl, homocysteine and total antioxidative status). Therapeutic efficacy was evaluated by comparison of subjective and objective parameters with baseline data between both treatment groups (ANCOVA).

Results

Vardenafil had no superior efficacy over placebo in the treatment of chronic tinnitus during this study. The primary efficacy criterion 'TQ total score' failed to demonstrate significant improvement compared to placebo. Subjective reports of TQ subscales and general quality of life areas (SF-36), objective audiometric examinations as well as investigated biomarkers for oxidative stress did not reveal any significant treatment effects. The safety profile was favorable and consistent with that in other vardenafil studies.

Conclusion

Although hypoxia and ischemia play a special role in the pathogenesis of tinnitus, the PDE5-inhibitor-induced increase of nitric oxide-mediated vasodilatation exerted no specific influence on tinnitus symptomatology. Considering the unclear risk of rarely associated hearing impairment, systemic application of vardenafil or other PDE5 inhibitors prove to be not appropriate for therapy of chronic tinnitus.

Prognostic factors for vestibular impairment in sensorineural hearing loss

The clinical course and prognosis in sensorineural hearing loss (SNHL) may be even worse if vestibular system is also involved, especially due to near location of anatomical structures in the inner ear. The aim of the study was to determine prognostic value of some clinical, audiological and demographic factors associated with SNHL in predicting a possibility of vestibular impairment. The study was conducted on 124 consecutive patients (183 ears) diagnosed for sensorineural hearing loss during 1 year in our department. In all of them, audiological (pure-tone, speech and impedance audiometry, ABR) and ENG examinations (visual ocular-motor, positional, kinetic and caloric tests) were performed. The correlations between ENG outcome and the following variables associated with sensorineural hearing loss were investigated: audiological (degree and location of hearing loss, audiogram configuration), clinical (tinnitus, vertigo, dizziness) and demographic (age, sex) factors. Normal ENG was recorded in 26.6%, vestibular impairment of peripheral type in 38.7%, and central type in 34.7% of the patients. In a multivariate stepwise linear regression analysis, the degree of hearing loss was the main variable correlating with abnormal ENG result. Tinnitus and location of hearing loss were also found to be the two other variables which, to some minor extent, can influence the ENG outcome. Peripheral vestibular impairment was observed more frequently in patients with residual hearing/deafness. The degree of hearing loss, presence of tinnitus and location of hearing loss are factors predicting the possibility of abnormal ENG outcome in sensorineural hearing loss.

Evaluation of patients with acute vestibular syndrome

Acute vestibular syndrome is characterized by a rapid unilateral injury to either peripheral or central vestibular structures. It consists of severe vertigo, nausea and vomiting, spontaneous nystagmus, and postural instability. In many cases, a peripheral etiology is considered although it may be due to an underlying serious central pathology. The present study was designed to investigate the feasibility of differentiating the cause of acute vestibular syndrome in such patients using clinical, audiovestibular and radiologic tools. We performed a case series study of patients complaining of acute vertigo at a university referring center for hearing and balance disorders. Thirty patients with history of acute vertigo within 3 days onset with no history of previous otological or neurological disorders. Eighteen patients were due to acute peripheral vestibular lesion, 1 due to psychiatric illness under antidepressant drugs and 11 were of central vestibular lesion. The most important step in the diagnosis of acute vertigo is a thorough and detailed history. The common error of carrying out investigations in place of a detailed history is to be avoided. The clinical evaluation has the highest sensitivity and specificity in differentiating central from peripheral vestibular lesions.

The expression of VIP and SP in the cochlea of spontaneously hypertensive rats and its implication

To investigate the expression of vasoactive intestinal peptide (VIP) and substance P (SP) in the cochlea of spontaneously hypertensive rat (SHR), and to assess the function of VIP and SP in the cochlea following the damage of hypertension, hearing thresholds of ABR were observed and the fixative (4% paraformaldehyde) was pumped through the circulatory system. Adult Wistar rats (3 months, n=20) served as the control group and SHRs (3 months, n=20) as the hypertension group. Bullas were taken out and cochleas were irrigated in vitro with the same fixative. The number of base turn's spiral ganglions in the sections was counted. The expression of VIP and SP were detected by SABC method and the images of the sections were analyzed. The number of base turn's spiral ganglsons in the hypertension group was significantly less than in the normal group (P<0.01). VIP and SP were expressed in the spiral ganglion cytoplasma and stria vascularis of the two groups. There were no significant difference in the expression of VIP and SP in spiral ganglion cytoplasma (P>0.05) between the two groups. However, in stria vascularis the expression of VIP in the hypertension group was higher than in the normal group (P<0.05), and no significant difference in SP was found between the two groups. It was suggested that VIP not only contributed to the regulation of the cochlea microcirculation, but also made the neurotransmitter in the pathway of the auditory system. However, SP made only the neurotransmitter in the pathway of the auditory system.

[Idiopathic sudden deafness]

PURPOSE

Sudden idiopathic deafness is a sensorineural hearing loss with no recognized causes at the time of onset. The impairment site is usually localized in the cochlea, but some cases of retrocochlear lesions (e.g., cerebellopontine angle tumors, degenerative neural diseases, neuraxial ischemic lesions) can induce sensorineural deafness. The medical management of patients presenting with sudden deafness aims at detecting a causal mechanism, and at administering emergency therapeutic drugs. The diagnosis of idiopathic sudden deafness can be definitely made when no causes are found. Usually, the impairing mechanism involves the cochlea. The pathophysiology of this sensorineural alteration is still unknown. It is most likely that several mechanisms are associated together, their common point being an impairment to the feedback loop of the organ of Corti.

CURRENT KNOWLEDGE AND KEY POINTS

It is very likely that reactivation of neurotropic viruses and/or cochlear ischemia are frequent etiologies. Whatever the cause, the treatment is to be administered urgently, and consists of a high-dose corticotherapy at the least. Other treatments have never really proven to be effective. It is secondarily checked that no retrocochlear pathological processes, such as a cerebellopontine angle tumor, is present, in particular in young people.

FUTURE PROSPECTS AND PROJECTS

One of the current objectives is to determine when cochlear ischemia is involved, in a mini-invasive manner, such as with laser Doppler flowmetry, so that the treatment can be optimized. From a therapeutic point of view, early acoustic protection has been proven to be effective in cases of cochlear ischemia in small laboratory animals. Its efficacy in case of sudden deafness, non-exclusive of other causes than ischemia, is being assessed in a multicentric project.

Acute vestibulopathy

Acute vestibulopathy is characterized by the acute or subacute onset of vertigo, dizziness or imbalance with or without ocular motor, sensory, postural or autonomic symptoms and signs, and can last for seconds to up to several days. Acute vestibular lesions may result from a hypofunction or from pathological excitation of various peripheral or central vestibular structures (labyrinth, vestibular nerve, vestibular nuclei, cerebellum or ascending pathways to the thalamus and the cortex). This update focuses on new aspects of the aetiology, pathophysiology, epidemiology, and treatment of (i) acute peripheral disorders (benign paroxysmal positioning vertigo, vestibular neuritis, Menière's disease, perilymph fistula, especially 'superior canal dehiscence syndrome', vestibular paroxysmia); and (ii) acute central vestibular disorders (especially 'vestibular migraine'). Finally, the clinical relevance of recent diagnostic tools (three-dimensional analysis of eye movement, imaging techniques) is discussed.

Vascular variations of the inner ear

Vascular anomalies of the inner ear have been documented in only a few isolated case reports. The goal of our study was to describe, qualify and quantify vascular variations of the inner ear in 122 temporal bones from 64 pediatric subjects aged between 0 and 10 years. The average age was 11.6 months. Horizontal sections of the temporal bone, examined by light microscopy, revealed vessels coursing freely through the perilymphatic space of the cochlea, especially in the apical turn. Other findings included abnormally wide vessels in the stria vascularis as well as a vascular malformation of the internal auditory canal. Our study demonstrated more atypical vessels in the cochlea than in the vestibular labyrinth. We found a statistically significant positive correlation between vascular variations of the inner ear and concomitant cardiac anomalies or endolymphatic hydrops. We also discuss the possible etiology and potential significance of these findings in terms of disturbances of the function of the inner ear.