Recovery of Visual Acuity in People With Vestibular Deficits

Study Overview
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Brief Summary
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The purpose of this study is to determine whether exercises relieve the symptoms of dizziness and imbalance in people with vestibular deficits and improves the ability to see clearly during head movements. We hypothesize that the performance of specific adaptation and substitution exercises will result in an improvement in visual acuity during head movements while those patients performing placebo exercises will show no improvement.

Detailed Description
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Decrements in visual acuity during head movement in patients with vestibular hypofunction are potentially serious problems. This deficit could contribute to decreased activity level, avoidance of driving with resultant diminished independence and, ultimately, limited social interactions and increased isolation. Oscillopsia occurs because of inadequate vestibulo-ocular reflex (VOR) gain and suggests that compensation for the vestibular loss has not occurred. The purpose of this study was to examine the effect of an exercise intervention on visual acuity during head movement in patients with unilateral and bilateral vestibular hypofunction. We hypothesized that 1) patients performing vestibular exercises would have improved visual acuity during head movement compared to patients performing placebo exercises; 2) there would be no correlation between dynamic visual acuity (DVA) and the patients' subjective complaints of oscillopsia; and 3) improvement in DVA would be reflected by changes in residual vestibular function as indicated by an increase in VOR gain. Patients are assigned randomly to either the vestibular exercise or placebo exercise group. The randomization schedule is generated using a computer program for 2-sample randomization. The sequence was not concealed from the investigator who obtained consent from the subjects and supervised the exercises (SJH). The group assignment (vestibular exercise or placebo exercise) was concealed from the participants and from the investigator who performed the outcome measures. The vestibular exercise group practiced exercises that consisted of adaptation exercises and eye-head exercises to targets (Table 1), which were designed to improve gaze stability 16. They also performed gait and balance exercises. The placebo exercise group performed exercises designed to be 'vestibular-neutral'.

Official Title
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Recovery of Visual Acuity in Vestibular Deficits

Conditions
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Vestibular Neuronitis, Vestibular Neuronitis, Bilateral, Vestibular Schwannoma

Intervention / Treatment
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* Other: Control exercises
* Other: gaze stabilization exercises


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient had to have either a unilateral vestibular or bilateral vestibular hypofunction defined as follows: Unilateral vestibular deficits were defined by a > 25% difference in slow phase eye velocity between right and left sides on either the caloric or rotary chair test. Bilateral vestibular deficits were defined included refixation saccades made in response to unpredictable head thrusts to the right and left, a gain < .1 on rotary chair step test and a peak slow phase eye movement of <5 degrees/sec during irrigation of each ear on bithermal water caloric testing Healthy subjects with normal vestibular function test results must be able to complete DVA test Exclusion Criteria: Patients with central lesions will be omitted from the study because vestibular adaptation or other compensatory mechanisms may be compromised and Patients with visual acuity when the head is stationary of 20/60 or worse. Patients on medication that suppress or facilitate vestibular function will not be excluded from the study but data will be analyzed to assess the effect of medication. Patient who do not understand the purpose of the study and what it involves

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: exercises for gaze stabilization<br>Experimental group performed vestibular adaptation and substitution exercises | Other: gaze stabilization exercises<br>* adaptation and substitutin exercises encorporating retinal lsip and head movements<br>|
| Placebo Comparator: Control exercises<br>Saccadic eye movements against a Ganzfeld to prevent retinal slip error signal; no head movements | Other: Control exercises<br>* saccadic eye movements against a plain background; no head movements<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Visual Acuity During Head Movement From Baseline to Discharge | visual acuity is measured using a computerized system first with the head stationary and then with the head moving in yaw plane. Head velocity is measured using a rate sensor and optotype is displayed only when head velocity is between 120 and 180 degrees per second. The change in visual acuity was calculated from subtracting the discharge measurement from the baseline measurement (pre-intervention). | pre-intervention and at discharge | 
| Subjective Complaints: (All Pre- and Post-intervention): | questionnaire | pre-intervention, 2 weeks, 4 weeks and at discharge | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Disability Scale | questionnaire | pre-intervention, 2 weeks, 4 weeks and at discharge | 
| Activities Specific Balance Confidence Scale | questionnaire | pre-intervention, 2 weeks, 4 weeks and at discharge | 
| Symptoms Intensity for Dizziness, Oscillopsia, Disequilibrium | visual analoque scales | pre-intervention, 2 weeks, 4 weeks and at discharge | 
| Balance and Gait | gait speed | pre-intervention, 2 weeks, 4 weeks and at discharge | 
| Fall Risk (Dynamic Gait Index) | performance test | pre-intervention, 2 weeks, 4 weeks and at discharge | 
| Eye Movements: Scleral Search Coil | eye movements are measured by having the participant sit within an electromagnetic field while wearing a scleral coil (like a contact lens but only in contact with the sclea, not the cornea); te coil moves with eye movement and distorts the electrimagnetic field | pre- and post-treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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vestibular rehabilitation, vestibular hypofunction