Vestibular Patients Research Articles

Vestibular compensation: the neuro-otologist's best friend.

Why vestibular compensation (VC) after an acute unilateral vestibular loss is the neuro-otologist’s best friend is the question at the heart of this paper. The different plasticity mechanisms underlying VC are first reviewed, and the authors present thereafter the dual concept of vestibulo-centric versus distributed learning processes to explain the compensation of deficits resulting from the static versus dynamic vestibular imbalance. The main challenges for the plastic events occurring in the vestibular nuclei (VN) during a post-lesion critical period are neural protection, structural reorganization and rebalance of VN activity on both sides. Data from animal models show that modulation of the ipsilesional VN activity by the contralateral drive substitutes for the normal push–pull mechanism. On the other hand, sensory and behavioural substitutions are the main mechanisms implicated in the recovery of the dynamic functions. These newly elaborated sensorimotor reorganizations are vicarious idiosyncratic strategies implicating the VN and multisensory brain regions. Imaging studies in unilateral vestibular loss patients show the implication of a large neuronal network (VN, commissural pathways, vestibulo-cerebellum, thalamus, temporoparietal cortex, hippocampus, somatosensory and visual cortical areas). Changes in gray matter volume in these multisensory brain regions are structural changes supporting the sensory substitution mechanisms of VC. Finally, the authors summarize the two ways to improve VC in humans (neuropharmacology and vestibular rehabilitation therapy), and they conclude that VC would follow a “top-down” strategy in patients with acute vestibular lesions. Future challenges to understand VC are proposed.

Development of a Statistical Model for the Prediction of Common Vestibular Diagnoses.

Treatment of patients with vestibular disorders can be complex, requires lengthy clinic visit time, and uses greater clinical resources for diagnosis. A pre-encounter intake questionnaire may predict the most common disorders, allowing for more efficient allocation of resources and use of clinicians. To develop a statistical model for predicting vestibular diagnoses, prior to clinical evaluation, from an intake questionnaire. Retrospective review of 414 consecutive new vestibular patient intake questionnaires (September 2012 through January 2014) and associated medical records with performance of logistic regression analyses and development of predictive models (July 2013 through May 2015). Use of a vestibular intake questionnaire for triaging of new patients with complaints of dizziness. Predictors for the diagnosis of benign paroxysmal positional vertigo (BPPV), Ménière's disease, and vestibular migraine. Of the 414 questionnaires analyzed, 381 (92%) had clinician information necessary to define a final diagnosis. Patients were 34% male and had a mean (range) age of 57 (19-91) years. Of the diagnoses, 183 (48%) were ear related (including 103 BPPV and 49 Meniere's disease), 141 (37%) neurological (including 109 vestibular migraine), 36 (9%) medical, 8 (2%) of psychological origin, 46 (12%) of unknown etiology, and 33 (9%) other causes. The diagnosis of BPPV could be predicted from 4 variables with a sensitivity of 79% and specificity of 65%. The diagnosis of Ménière's disease could be predicted from 5 variables with a sensitivity of 81% and specificity of 85%. The diagnosis of vestibular migraine could be predicted from 4 variables with a sensitivity of 76% and specificity of 59%. A pre-encounter history questionnaire can provide useful diagnostic information for common vestibular disorders. This can help direct appointment scheduling to improve clinical efficiency, time to intervention, and use of resources. Further refinement may enable the use of shorter questionnaires or screening algorithms.

Definition of Balance and Cognition Related to Disability Levels in Vestibular Migraine Patients

Definition of Balance and Cognition Related to Disability Levels in Vestibular Migraine Patients

Vestibular Migraine: Vestibular Symptom May Identify Different Subgroups.

The objective of this study was to evaluate patients with vestibular migraine and analyze whether different vestibular symptoms were able to discriminate different subgroups. Eighty-three patients (73 women, mean age 42 yr) who fulfilled the criteria for vestibular migraine were selected. Participants were divided into two groups according to their vestibular symptoms: spontaneous vertigo (SV) or triggered vertigo (TV). In each group, migraine subtype (migraine with aura and migraine without aura) was further analyzed. The SV group comprised 40 patients (35 women, mean age 42.6 yr) of which 26 had migraine with aura. The TV group comprised 43 patients (38 women, mean age 41.3 yr) of which 34 had migraine without aura. A significant difference in the presence of spontaneous vertigo was noted, proving more frequent in the migraine with aura group, whereas TV was more frequent in the migraine without aura group (χ(2) test, p < 0.0001). Spontaneous rotatory vertigo was more frequent in migraine with aura, whereas triggered nonrotatory vertigo was more frequent in migraine without aura. This finding suggests a broad spectrum of clinical symptomatology in vestibular migraine patients. All of these patients are classified as vestibular migraine but they may represent two extremes of a disease spectrum.

Negative prognostic factors for psychological conditions in patients with audiovestibular diseases.

To examine the backgrounds of patients with audiovestibular disease regarding what influences their psychological state. During a 12-year period, 375 successive patients with audiovestibular diseases were enrolled in this study. Diseases included unilateral (n=174) and bilateral (n=51) Menière's disease, sudden deafness with vertigo (n=70), and vestibular neuritis (n=80). Diagnosis, sex, age, duration of disease, vertigo frequency, persistent nystagmus, and ipsilateral/contralateral hearing levels were recorded. Cornell Medical Index (domains III-IV=neurosis) and Self-Rating Depression Scale (score>40=depression) were applied during acute vertigo remissions in all patients. Neurosis and depression, respectively, were diagnosed in 62.7% and 82.4% of bilateral Menière's, 32.7% and 48.9% of unilateral Menière's, 15.7% and 38.6% of sudden deafness/vertigo, and 12.7% and 31.3% of vestibular neuritis patients. Multivariable logistic regression analysis showed that Menière's disease with longer disease duration (Oz 1.212; P=0.021) and worse hearing in the secondary affected ear (Oz 1.131; P=0.042); sudden deafness/vertigo with persistent nystagmus (Oz 1.895; P=0.005); and vestibular neuritis with longer disease duration (Oz 1.422; P=0.019) and persistent nystagmus (Oz 1.950; P=0.0003) had mental illness significantly more often than those with shorter-duration disease, better hearing and no persistent nystagmus. Mental disorder increased in accordance with solo vertigo, vertigo/hearing loss, repeated symptoms, and bilateral lesions. Treatment strategies should be carefully constructed for patients with persistent nystagmus, long disease duration, and hearing loss in the secondary affected ear to avoid psychological disorders.

The activities-specific balance confidence scale and berg balance scale: Reliability and validity in Arabic-speaking vestibular patients

Persons with vestibular disorders are susceptible to imbalance. The Activities-specific Balance Confidence (ABC) scale and Berg Balance Scale (BBS) have been validated in persons with vestibular disorders. The purpose of this study was to examine the reliability and validity of the Arabic versions of ABC and BBS among Arabic-speaking persons with vestibular disorders in Jordan and Saudi Arabia. Therefore, the A-ABC and A-BBS were administered to a convenience sample of 82 persons with vestibular disorders (age = 43 ± 14), (56% female). The test-retest reliability of the A-ABC item and total score as well as the inter-rater and intra-rater reliability of the A-BBS total score reflected high agreement. Significant and large correlations were found between the A-ABC and the A-BBS (r= 0.54, P< 0.05), the A-ABC and the Arabic Dizziness Handicap Inventory (A-DHI) (r= -0.76, P< 0.05), and the A-BBS and the A-DHI (r= -0.56, P< 0.05). The A-ABC and the A-BBS demonstrated good reliability and validity and can be utilized with Arabic-speaking persons with vestibular disorders.

The Use of Computer-Assisted Home Exercises to Preserve Physical Function after a Vestibular Rehabilitation Program: A Randomized Controlled Study.

Objective. The purpose of this study was to evaluate whether elderly patients with vestibular dysfunction are able to preserve physical functional level, reduction in dizziness, and the patient's quality of life when assistive computer technology is used in comparison with printed instructions. Materials and Methods. Single-blind, randomized, controlled follow-up study. Fifty-seven elderly patients with chronic dizziness were randomly assigned to a computer-assisted home exercise program or to home exercises as described in printed instructions and followed for tree month after discharge from an outpatient clinic. Results. Both groups had maintained their high functional levels three months after finishing the outpatient rehabilitation. No statistically significant difference was found in outcome scores between the two groups. In spite of moderate compliance levels, the patients maintained their high functional level indicating that the elderly should not necessarily exercise for the first three months after termination of the training in the outpatient clinic. Conclusion. Elderly vestibular dysfunction patients exercising at home seem to maintain their functional level, level of dizziness, and quality of life three months following discharge from hospital. In this specific setup, no greater effect was found by introducing a computer-assisted training program, when compared to standard home training guided by printed instructions. This trial is registered with NCT01344408.

Oscillatory neural responses evoked by natural vestibular stimuli in humans.

While there have been numerous studies of the vestibular system in mammals, less is known about the brain mechanisms of vestibular processing in humans. In particular, of the studies that have been carried out in humans over the last 30 years, none has investigated how vestibular stimulation (VS) affects cortical oscillations. Here we recorded high-density electroencephalography (EEG) in healthy human subjects and a group of bilateral vestibular loss patients (BVPs) undergoing transient and constant-velocity passive whole body yaw rotations, focusing our analyses on the modulation of cortical oscillations in response to natural VS. The present approach overcame significant technical challenges associated with combining natural VS with human electrophysiology and reveals that both transient and constant-velocity VS are associated with a prominent suppression of alpha power (8-13 Hz). Alpha band suppression was localized over bilateral temporo-parietal scalp regions, and these alpha modulations were significantly smaller in BVPs. We propose that suppression of oscillations in the alpha band over temporo-parietal scalp regions reflects cortical vestibular processing, potentially comparable with alpha and mu oscillations in the visual and sensorimotor systems, respectively, opening the door to the investigation of human cortical processing under various experimental conditions during natural VS.

Ocular vestibular evoked myogenic potentials in response to air-conducted 500 Hz short tones: Effect of stimulation procedure (monaural or binaural), age and gender.

The ocular vestibular myogenic potentials (oVEMP) can be elicited by monaural air-conducted sound stimulation, and are usually recorded from the contralateral eye. In clinical setting a binaural stimulation would save time and require less effort from the subjects. We evaluated the differences between monaural and binaural stimulation, and the possible effect of age and gender on oVEMP parameters. Air-conducted oVEMP were recorded by binaural and by monaural stimulation in a group of 54 normal subjects, aged from 12 to 83 years, and in 50 vestibular patients. From each side, we measured the latency of the N1 component, and the peak-to-peak N1-P1 amplitude. For both parameters we also computed the asymmetry ratio. In normal subjects binaural stimulation produced slightly larger responses than monaural stimulation; detectability, latency and amplitude ratio were the same for the two techniques. We found no differences related to gender, and the age-induced amplitude decline was likely to be negligible.oVEMP recorded not in an acute phase of their disorder, proved to be abnormal in about 20% of the patients, and the normal or abnormal findings obtained either with monaural or with binaural stimulation were always concordant. The oVEMP obtained after binaural and monaural stimulation are very similar, and they are largely independent from age and gender.

Diagnosing Stroke in Acute Vertigo: The HINTS Family of Eye Movement Tests and the Future of the "Eye ECG".

Patients who present to the emergency department with symptoms of acute vertigo or dizziness are frequently misdiagnosed. Missed opportunities to promptly treat dangerous strokes can result in poor clinical outcomes. Inappropriate testing and incorrect treatments for those with benign peripheral vestibular disorders leads to patient harm and unnecessary costs. Over the past decade, novel bedside approaches to diagnose patients with the acute vestibular syndrome have been developed and refined. A battery of three bedside tests of ocular motor physiology known as "HINTS" (head impulse, nystagmus, test of skew) has been shown to identify acute strokes more accurately than even magnetic resonance imaging with diffusion-weighted imaging (MRI-DWI) when applied in the early acute period by eye-movement specialists. Recent advances in lightweight, high-speed video-oculography (VOG) technology have made possible a future in which HINTS might be applied by nonspecialists in frontline care settings using portable VOG. Use of technology to measure eye movements (VOG-HINTS) to diagnose stroke in the acute vestibular syndrome is analogous to the use of electrocardiography (ECG) to diagnose myocardial infarction in acute chest pain. This "eye ECG" approach could transform care for patients with acute vertigo and dizziness around the world. In the United States alone, successful implementation would likely result in improved quality of emergency care for hundreds of thousands of peripheral vestibular patients and tens of thousands of stroke patients, as well as an estimated national health care savings of roughly $1 billion per year. In this article, the authors review the origins of the HINTS approach, empiric evidence and pathophysiologic principles supporting its use, and possible uses for the eye ECG in teleconsultation, teaching, and triage.

Construction and Validation of the Vestibular Screening Tool for Use in the Emergency Department and Acute Hospital Setting

ObjectivesTo construct a new vestibular screening tool to identify likely vestibular disorders and guide referral of dizzy patients presenting to hospital and to test the vestibular screening tool for construct and discriminative validity and reliability of physiotherapy assessors. DesignMethodologic study. SettingEmergency and acute hospital wards of a metropolitan hospital. ParticipantsAdults (N=114) presenting to hospital with dizziness (mean age, 67.36±14.88y; 57% women). InterventionNot applicable. Main Outcome MeasuresThree vestibular screening tools (3, 4, and 5 items) were investigated. Physiotherapy vestibular diagnostic tests categorized patients as vestibular or nonvestibular patients. Subsets of patients were assessed twice by 2 physiotherapists (n=20) and twice by the same physiotherapist (n=30). ResultsEach of the vestibular screening tools had a good fit to the Rasch measurement model. Factor analysis demonstrated individual items loaded across 1 factor, confirming unidimensionality of the 3 vestibular screening tools, and Cronbach α determined internal consistency. The 4-item vestibular screening tool had the greatest area under the curve using receiver operator curve analysis (.894), with highest sensitivity (83%) and specificity (84%) for identifying vestibular disorders (cutoff value ≥4/8). Sensitivity of the 3- and 5-item versions was lower than the 4-item vestibular screening tool (80%). The 4-item vestibular screening tool scores showed high intrarater (κ item scores, .831–1; intraclass correlation coefficient [ICC] total, .988) and interrater (κ item scores, .578–.921; ICC total, .878) reliability. ConclusionsThe 4-item vestibular screening tool is a reliable, valid tool for screening dizzy patients presenting to hospital, with unidimensional construct validity, high sensitivity, and specificity for identifying likely vestibular disorders. The vestibular screening tool could be used clinically to streamline referrals of dizzy patients to vestibular clinics.

International Classification of Headache Disorders 3rd edition beta-based field testing of vestibular migraine in China: Demographic, clinical characteristics, audiometric findings and diagnosis statues.

This study explored the clinical characteristics of vestibular migraine in Chinese subjects and performed a field test of the criteria of the International Classification of Headache Disorders 3rd edition beta version. Consecutive patients with vestibular migraine were surveyed and registered in a headache clinic during the study period. The diagnosis of vestibular migraine was made according to International Classification of Headache Disorders 3rd edition beta version. Assessments included standardized neuro-otology bedside examination, pure-tone audiogram, bithermal caloric testing, neurological imaging, cervical X-ray or magnetic resonance imaging, Doppler ultrasound of cerebral arteries and laboratory tests. A total of 67 patients (62 female/five male, 47.8 ± 10.3 years old) were enrolled in this study. The mean ages of migraine and vertigo onset were 32.2 ± 11.5 and 37.9 ± 10.1 years, respectively. The most common migraine subtype was migraine without aura (79%), followed by migraine with aura (12%) and chronic migraine (9%). The duration of vertigo attacks varied from seconds to days and 25% of patients had attacks that lasted less than 5 minutes. Among the patients with short-lasting attacks, 75% of these patients had ≥5 attacks per day within 72 hours. Auditory symptoms were reported in 36% of the patients. Migraine prophylactic treatments were effective in 77% of the patients. Our study showed that the clinical features of vestibular migraine in China were similar to those of Western studies. The definition of vertigo episodes and migraine subtypes of vestibular migraine in International Classification of Headache Disorders 3rd edition beta version might be modified further. More than five vertigo attacks per day within 72 hours might be helpful as far as identifying vestibular migraine patients with short-lasting attacks.

Sensory substitution in bilateral vestibular a-reflexic patients.

Patients with bilateral vestibular loss have balance problems in darkness, but maintain spatial orientation rather effectively in the light. It has been suggested that these patients compensate for vestibular cues by relying on extravestibular signals, including visual and somatosensory cues, and integrating them with internal beliefs. How this integration comes about is unknown, but recent literature suggests the healthy brain remaps the various signals into a task-dependent reference frame, thereby weighting them according to their reliability. In this paper, we examined this account in six patients with bilateral vestibular a-reflexia, and compared them to six age-matched healthy controls. Subjects had to report the orientation of their body relative to a reference orientation or the orientation of a flashed luminous line relative to the gravitational vertical, by means of a two-alternative-forced-choice response. We tested both groups psychometrically in upright position (0°) and 90° sideways roll tilt. Perception of body tilt was unbiased in both patients and controls. Response variability, which was larger for 90° tilt, did not differ between groups, indicating that body somatosensory cues have tilt-dependent uncertainty. Perception of the visual vertical was unbiased when upright, but showed systematic undercompensation at 90° tilt. Variability, which was larger for 90° tilt than upright, did not differ between patients and controls. Our results suggest that extravestibular signals substitute for vestibular input in patients’ perception of spatial orientation. This is in line with the current status of rehabilitation programs in acute vestibular patients, targeting at recognizing body somatosensory signals as a reliable replacement for vestibular loss.

Effects of haptic supplementation on postural stability in unilateral vestibular loss patients

The effects of haptic supplementation on postural stability during upright standing with vision were investigated in 11 unilateral vestibular loss (UVL) patients and compared to 12 age-marched controls. All the participants were instructed to grip a fixed or mobile stick. In the mobile conditions, the lower extremity of the stick was in contact with a slippery or a rough surface. Postural stability was assessed by the root mean square (RMS) and the velocity of the center of foot pressure (CoP) displacements in both antero–posterior (AP) and medio-lateral (ML) directions. Results showed that RMS was larger in UVL patients than in aged-matched participants in AP direction. However, in the mobile stick conditions, only the rough surface improved postural stability. In addition, RMS was more sensitive to haptic supplementation than CoP velocity. The present study confirms the importance of haptic information in the multi-sensory (re) weighting process underlying postural control in UVL patients.

The significance of neutrophil to lymphocyte ratio and platelet to lymphocyte ratio in vestibular neuritis.

To investigate the significance of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) in vestibular neuritis. Retrospective, case-control study. The study subjects were patients who received treatment for vestibular neuritis between January 2009 and December 2013, and a control group composed of 70 age- and sex-matched healthy subjects who received laboratory testing as part of a routine health checkup. The subjects underwent a complete blood cell count and counts of the various cell subtypes to compare NLR and PLR in the vestibular neuritis patients and controls. The associations between laboratory test results and values of the vestibular function test and clinical information were examined. In addition, a subgroup analysis according to the duration of spontaneous nystagmus was performed. The mean NLR and PLR values of the patient group were significantly higher than those of the control group. Although caloric test outcomes and hospitalization period were not significantly correlated with blood profiles, the duration of dizziness needing antivertiginous drugs was positively correlated with NLR and PLR (P = .021, P = .020, respectively). In addition, NLR was negatively correlated with the length of time between symptom start and blood sampling (P = .005). The NLR and PLR value of patients with nystagmus for more than 5 days were significantly higher than those of patients whose nystagmus ceased within 5 days. This is the first report to evaluate the significance of NLR and PLR in vestibular neuritis. NLR and PLR should be taken into consideration as simple and reliable parameters for predicting the cause and severity of the disease.

Interaction between Vestibular Compensation Mechanisms and Vestibular Rehabilitation Therapy: 10 Recommendations for Optimal Functional Recovery.

This review questions the relationships between the plastic events responsible for the recovery of vestibular function after a unilateral vestibular loss (vestibular compensation), which has been well described in animal models in the last decades, and the vestibular rehabilitation (VR) therapy elaborated on a more empirical basis for vestibular loss patients. The main objective is not to propose a catalog of results but to provide clinicians with an understandable view on when and how to perform VR therapy, and why VR may benefit from basic knowledge and may influence the recovery process. With this perspective, 10 major recommendations are proposed as ways to identify an optimal functional recovery. Among them are the crucial role of active and early VR therapy, coincidental with a post-lesion sensitive period for neuronal network remodeling, the instructive role that VR therapy may play in this functional reorganization, the need for progression in the VR therapy protocol, which is based mainly on adaptation processes, the necessity to take into account the sensorimotor, cognitive, and emotional profile of the patient to propose individual or “à la carte” VR therapies, and the importance of motivational and ecologic contexts. More than 10 general principles are very likely, but these principles seem crucial for the fast recovery of vestibular loss patients to ensure good quality of life.

Horizontal and Vertical vHIT in Acute Unilateral Vestibular Neuritis Patients.

Objectives : Vestibular neuritis (VN) is an acute peripheral vestibulopathy that manifests with acute spontaneous vertigo, nausea and sometimes vomiting, and postural imbalance. Video head impulse test (vHIT) is an objective measure of responses of semicircular canals using high speed video measures of eye movement response to head impulses. The purpose of this study was to measure and analyze horizontal and vertical vestibular canals responses measured by vHIT in acute unilateral VN and to compare the results with the un-affected sides in those patients. Design : The responses of vHIT were obtained from 31 patients with acute VN (16 females and 15 males) ranging in age from 24 to 54 years. Audiological and vestibular assessments were done to all participants that include pure tone, speech audiometry, tympanometry, acoustic reflexes, vestibular bed side evaluation and caloric testing. Results : The mean age of VN patients were 38.03 ± 7.96 years. The right side was affected in 14 and left in 17 patients. The gain of vHIT was reduced in the affected side of VN which was statistically significant when compared with the un-affected side. Isolated horizontal canal was observed in 15 patients whereas mixed horizontal and vertical canals were observed in 9 patients. Vertical canals were affected in 7 out of 31 patients. Discussion and Conclusion : Acute VN patients do have single or multi-semicircular canals affection which can be objectively measured for each canal by vHIT. The lesion is manifested by reduction in amplitude response for affected canal which can affect the superior division mainly and to less extent the inferior vestibular division.

Deficient recovery response and adaptive feedback potential in dynamic gait stability in unilateral peripheral vestibular disorder patients.

Unilateral peripheral vestibular disorder (UPVD) causes deficient locomotor responses to novel environments due to a lack of accurate vestibular sensory information, increasing fall risk. This study aimed to examine recovery response (stability recovery actions) and adaptive feedback potential in dynamic stability of UPVD‐patients and healthy control subjects during perturbed walking. 17 UPVD‐patients (>6 months since onset) and 17 matched healthy control participants walked on a treadmill and were subjected to eight unexpected perturbations during the swing phase of the right leg. For each perturbation, the margin of stability (MS; state of body's centre of mass in relation to the base of support), was determined at touchdown of the perturbed leg and during the following six recovery steps. The first perturbation caused a reduced MS at touchdown for the perturbed leg compared to baseline, indicating an unstable position, with controls requiring five recovery steps to return to MS baseline and UPVD‐patients not returning to baseline level within the analyzed six recovery steps. By the eighth perturbation, control subjects needed two steps, and UPVD‐patients required three recovery steps, both thereby improving their recovery response with practice. However, MS at touchdown of the perturbed leg increased only for the controls after repeated perturbations, indicating adaptive feedback‐driven locomotor improvements for the controls, but not for the UPVD‐patients. We concluded that UPVD‐patients have a diminished ability to control dynamic gait stability during unexpected perturbations, increasing their fall risk, and that vestibular dysfunction may inhibit the neuromotor system adapting the reactive motor response to perturbations.

Pilot study of a new rehabilitation tool: improved unilateral short-term adaptation of the human angular vestibulo-ocular reflex.

Unilateral vestibulo-ocular reflex (VOR) short-term adaptation training causes some increase toward the nonadapting side (~30% of increase on adapting side). We conducted a pilot study to determine if the increase could be reduced by providing a visual stimulus during rotations to the nonadapting side. Unilateral vestibular short-term adaptation is a technique that could increase the ipsilesional VOR response of vestibular patients with unilateral hypofunction. However, this technique results in the VOR response increasing for rotations toward the nonadapting (normal) side, which is undesirable because the VOR will be overcompensatory (causing nonstable vision) during head rotations toward the normal side. We built a portable helmet device that sensed horizontal angular head velocity to generate a visual target that required a preset VOR gain (eye velocity/head velocity) for optimal image stabilization that could be set differently for leftward and rightward head rotations. We tested 10 subjects (six controls and four patients with vestibular hypofunction). We measured the active and passive VOR gain during high-peak-acceleration, unilateral, transient head rotations (head impulses) before and after unilateral VOR adaptation training. In control subjects, for rotations toward the adapting side (target gain = 1.5), the VOR gain increased because of training by 26.1% ± 23.4% during active head impulses and by 14.6% ± 13.0% during passive head impulses. In contrast, for rotations toward the nonadapting side, there were no statistically significant increases. A visual stimulus driving the VOR gain to unity toward the nonadapting side aids unilateral adaptation more so than no visual stimulus.

Visual dependency and dizziness after vestibular neuritis.

Symptomatic recovery after acute vestibular neuritis (VN) is variable, with around 50% of patients reporting long term vestibular symptoms; hence, it is essential to identify factors related to poor clinical outcome. Here we investigated whether excessive reliance on visual input for spatial orientation (visual dependence) was associated with long term vestibular symptoms following acute VN. Twenty-eight patients with VN and 25 normal control subjects were included. Patients were enrolled at least 6 months after acute illness. Recovery status was not a criterion for study entry, allowing recruitment of patients with a full range of persistent symptoms. We measured visual dependence with a laptop-based Rod-and-Disk Test and severity of symptoms with the Dizziness Handicap Inventory (DHI). The third of patients showing the worst clinical outcomes (mean DHI score 36–80) had significantly greater visual dependence than normal subjects (6.35° error vs. 3.39° respectively, p = 0.03). Asymptomatic patients and those with minor residual symptoms did not differ from controls. Visual dependence was associated with high levels of persistent vestibular symptoms after acute VN. Over-reliance on visual information for spatial orientation is one characteristic of poorly recovered vestibular neuritis patients. The finding may be clinically useful given that visual dependence may be modified through rehabilitation desensitization techniques.