Raphael Maire

Vestibulo-ocular reflex characteristics in patients with unilateral Ménière's disease.

Objective: The pathophysiologic concept of Ménières disease assumes that endolymphatic hydrops is the cause of the symptoms via increased pressure in the endolymphatic space and/or ionic disorder due to ruptured membrane. The goal of this study was to assess whether the vestibulo-ocular reflex (VOR) properties in patients with Ménières disease were consistent with the classical theory. Material and Methods: We studied 34 patients (19 women, 15 men) presenting with unilateral Ménières disease divided into 2 groups according to the duration of the disease: 18 were in the early stage (<12 mo), and 16 were in the late stage (≥12 mo). Nineteen patients were examined during an attack. Eight of them and the 15 other patients were tested during the interval between attacks. Their characteristics were compared with those of a group of 22 normal subjects. The VOR function was evaluated via standard caloric and impulse rotatory tests (velocity step). A mathematic model of vestibular function was used to characterize the VOR response to rotational stimulation. Dynamic VOR parameters (sensitivity coefficient, time constant, gain, and asymmetries between the 2 directions of rotation) were statistically compared between the 2 groups of patients during and between attacks and between the patients and controls. Results: All dynamic VOR parameters showed no statistically significant difference both with normal controls and among the patients during and between attacks (p > 0.05) except for gain asymmetry (p ≤ 0.008). During attacks, patients with early Ménières disease displayed a higher gain in rotation toward the affected ear, the opposite being observed in patients with late disease. Caloric test revealed a moderate canal paresis on the affected side during the crisis and a slight asymmetry between attacks. Conclusion: During attacks in patients with early Ménières disease, the VOR gain toward the affected side is higher than that toward the intact side, supporting the fact that that the sensitivity of the cupuloendolymphatic system on the affected ear is increased. This observation is in agreement with a mechanical pressure effect of hydrops on the vestibular organs.

Chronic subjective dizziness

Conclusion. Chronic subjective dizziness (CSD) is frequent and affects twice as many women as men. Anxiety is a strong predisposing factor. The pathophysiologic concept of this disorder assumes that balance function and emotion share common neurologic pathways, which might explain that the balance disorder can provoke fear and vice versa, giving rise to a problem in perception of space and motion. In anxious patients this can turn into a space and motion phobia, with avoidance behaviour. Objective. CSD is a diagnosis based on the hypothesis of an interaction between the vestibular system and the psychiatric sphere. Patients complain of chronic imbalance, worsened by visual motion stimulation, and frequently suffer from anxiety. Vestibular examination reveals no anomalies. We evaluated the incidence and characteristics of CSD in patients referred to our neuro-otology centre (tertiary hospital outpatient clinic). Subjects and methods. This was a retrospective study of 1552 consecutive patients presenting with vertigo. CSD was diagnosed in 164 patients (female:male=111:53). Results. CSD represents 10.6% of the dizzy patients in our clinic. Psychiatric disorder, mainly anxiety, was found in 79.3% of the cases. Other frequently associated factors were fear of heights and former vestibular lesion (healed). In all, 79.0% of the patients with CSD had poor balance performance on dynamic posturography testing.

Dynamic asymmetry of the vestibulo-ocular reflex in unilateral peripheral vestibular and cochleovestibular loss.

Objective: Rotatory tests in the horizontal plane have shown various degrees of vestibulo‐ocular reflex (VOR) asymmetry in patients after surgical deafferentation of one labyrinth. The purpose of this work was to characterize dynamic horizontal VOR responses among patients presenting with a unilateral peripheral labyrinthine deficit of nonsurgical origin and to compare results in isolated vestibular loss versus cochleovestibular loss.

Horizontal vestibulo-ocular reflex dynamics in acute vestibular neuritis and viral labyrinthitis: evidence of otolith-canal interaction.

Objective To evaluate the dynamic properties of the horizontal vestibulo-ocular reflex (h-VOR) in the acute stage of two common labyrinthine diseases that provoke severe attacks of vertigo with spontaneous nystagmus: vestibular neuritis (vestibular loss alone) and viral labyrinthitis (cochleovestibular loss). Material and Methods Sixty-three patients were investigated: 42 were diagnosed with vestibular neuritis and 21 with viral labyrinthitis. The h-VOR function was evaluated by conventional caloric and impulsive testing. A simplified model of vestibular function was used to analyze the vestibulo-ocular response to rotational stimulation. Results The results showed a significant difference in h-VOR characteristics between the two pathologies. Patients with vestibular neuritis exhibited a strong horizontal semicircular canal deficit, but no h-VOR asymmetry between the two rotational directions. In contrast, patients with viral labyrinthitis demonstrated moderate canal paresis and a marked h-VOR deficit in rotation toward the affected ear. Conclusions These findings support the hypothesis that the h-VOR dynamic asymmetry that occurs after an acute unilateral inner ear lesion is not due to canal dysfunction alone, but involves complex adaptive changes in the central VOR that may implicate the otolith system. Based on histopathologic and clinical differences in the two pathologies reported in the literature, we postulate that this otolith-canal interaction is mainly linked to the loss of saccular function.

Continuous vs. intermittent neurofeedback to regulate auditory cortex activity of tinnitus patients using real-time fMRI - A pilot study

The emerging technique of real-time fMRI neurofeedback trains individuals to regulate their own brain activity via feedback from an fMRI measure of neural activity. Optimum feedback presentation has yet to be determined, particularly when working with clinical populations. To this end, we compared continuous against intermittent feedback in subjects with tinnitus. Fourteen participants with tinnitus completed the whole experiment consisting of nine runs (3 runs × 3 days). Prior to the neurofeedback, the target region was localized within the auditory cortex using auditory stimulation (1 kHz tone pulsating at 6 Hz) in an ON-OFF block design. During neurofeedback runs, participants received either continuous (n = 7, age 46.84 ± 12.01, Tinnitus Functional Index (TFI) 49.43 ± 15.70) or intermittent feedback (only after the regulation block) (n = 7, age 47.42 ± 12.39, TFI 49.82 ± 20.28). Participants were asked to decrease auditory cortex activity that was presented to them by a moving bar. In the first and the last session, participants also underwent arterial spin labeling (ASL) and resting-state fMRI imaging. We assessed tinnitus severity using the TFI questionnaire before all sessions, directly after all sessions and six weeks after all sessions. We then compared neuroimaging results from neurofeedback using a general linear model (GLM) and region-of-interest analysis as well as behavior measures employing a repeated-measures ANOVA. In addition, we looked at the seed-based connectivity of the auditory cortex using resting-state data and the cerebral blood flow using ASL data. GLM group analysis revealed that a considerable part of the target region within the auditory cortex was significantly deactivated during neurofeedback. When comparing continuous and intermittent feedback groups, the continuous group showed a stronger deactivation of parts of the target region, specifically the secondary auditory cortex. This result was confirmed in the region-of-interest analysis that showed a significant down-regulation effect for the continuous but not the intermittent group. Additionally, continuous feedback led to a slightly stronger effect over time while intermittent feedback showed best results in the first session. Behaviorally, there was no significant effect on the total TFI score, though on a descriptive level TFI scores tended to decrease after all sessions and in the six weeks follow up in the continuous group. Seed-based connectivity with a fixed-effects analysis revealed that functional connectivity increased over sessions in the posterior cingulate cortex, premotor area and part of the insula when looking at all patients while cerebral blood flow did not change significantly over time. Overall, these results show that continuous feedback is suitable for long-term neurofeedback experiments while intermittent feedback presentation promises good results for single session experiments when using the auditory cortex as a target region. In particular, the down-regulation effect is more pronounced in the secondary auditory cortex, which might be more susceptible to voluntary modulation in comparison to a primary sensory region.

Progressive hearing loss in Fabry’s disease: a case report

Fabry’s disease is a chromosomal X-linked inherited disease, which causes a lack of the lysosomal alpha-galactosidase A enzyme leading to a cellular accumulation of glycosphingolipids. This accumulation leads to various clinical disorders, including inner ear lesions, with sensorineural hearing loss and dizziness. This article proposes to describe a clinical case of a patient suffering from Fabry’s disease with inner ear associated problems and to review the literature focusing on this subject.

European Society for Clinical Evaluation of Balance Disorders: Discussion about dual‐task conditions combining postural control with cognitive tasks

INTRODUCTION Since 2005, the European Society for Clinical Evaluation of Balance Disorders (ESCEBD) has met annually in Nancy, France. The ESCEBD includes specialists who have a specific interest in balance disorders with the following background: neurophysiology; ear, nose, and throat; neurology; ophthalmology; physical medicine and rehabilitation; geriatrics; cardiology; sport medicine; and physiotherapy. Each year, the society focuses on one or two problematic themes related to equilibrium and aims to obtain the standardization of balance testing and clinical recommendations. A panel of experts leads the proceedings, synthesizes the most relevant opinions of the discussion, and suggests solutions. The main topic of the 4th Annual Meeting held on June 6, 2008, was the dual-task condition in balance evaluation. Concurrently performing tasks, in situations such as using a handheld phone when driving or managing organizational and environmental constraints in occupational activities, have broader implications in understanding motor coordination degradation. Performance is more affected with the novelty of the task, especially in elderly persons. Our purpose was to discuss the paradigm of the dual-task during postural control and the clinical application of such a condition in the assessment of balance. We report here a brief summary of our discussion.

Localization of static positional nystagmus with the ocular fixation test

Objective: Characteristics of static positional nystagmus (SPN) (i.e., persistency, direction fixed, direction changing) are observed in both peripheral and central disturbances and possess no localizing value for vestibular lesions. Our objective was to investigate whether the ocular fixation test as applied to SPN could assist in localizing vestibular lesions.

Audiological monitoring in Swiss childhood cancer patients

Full audiological monitoring is the best strategy to detect hearing loss early and to provide timely intervention in the absence of a clinical method of otoprotection. Full monitoring requires audiological evaluation before, and then during and after ototoxic cancer treatment. In a worldwide context of monitoring protocols that vary substantially, we analyzed the audiological monitoring of childhood cancer patients over the last decade across treatment centers in Switzerland.

Letter: Cystic Vestibular Schwannomas Respond Best to Radiosurgery

To the Editor: We have read with great interest the recent articles published inNeurosurgery, related to the response after radiosurgery (RS) for cystic vestibular schwannomas (VSs).1,2 During the past 20 yr, a noteworthy reflection and dilemma have been ongoing whether surveillance, microsurgery, or RS should be performed in patients with newly diagnosed VSs.3 Particularly, tumor volume and cystic component have been considered related to tumor response and control after RS.1 VSs (small to medium size tumors) represent nowadays a common indication of RS and particularly of GammaKnife surgery (GKS). The former is related to high rates of tumor control, ranging between 89% and 98%4-7 at 5 yr, with facial nerve preservation rates between 84% and 100%.3,4,6,8-12 The prescribed doses are currently low, ranging between 11 and 13 Gy in most of the