Covert-saccades, Dynamic Visual Acuity and Quality of Life

Study Overview
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Brief Summary
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Patients with chronic bilateral vestibular hypofunction may suffer from a visual instability during head movement called oscillopsia. Visual consequence of vestibular deficit can lead to a severe impairment of their quality of life. However, correcting saccades during rapid head movement, called covert-saccades, have been more recently identified. These saccades, which occur during the head movement in patients with vestibular hypofunction, present a very short latency. They could compensate for the lack of vestibular-ocular reflex and greatly decrease oscillopsia and visual impairment. The objective of this study is to evaluate the potential functional benefice of these compensatory movements in a population of 20 patients with chronic bilateral areflexia, in a cross-sectional study.

Official Title
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Quality of Life and Dynamic Visual Acuity in Patients With Bilateral Vestibulopathy: the Impact of Covert-saccades

Conditions
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Vestibular Diseases

Intervention / Treatment
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* Other: Head Impulse Tests
* Other: Dynamic visual acuity Test (DVAT)
* Other: VEMPs & VEMPo
* Other: Dizziness Handicap Inventory
* Other: Oscillopsia severity questionnaire


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Bilateral Vestibular Hypofunction (BVH) with at least two of the tree following criteria Mean peak slow phase velocity of 5°/s or less in bilateral bithermal (30 and 44°C) caloric irrigations Pathologic Head-impulse test VOR gain of <0.25 on rotatory chair tests Disorder present for over 6 month Comprehension of the experiments instructions Patient consent Exclusion Criteria: Corrected Visual Acuity lower than 5/10 Other conditions leading to oscillopsia or ataxia Oculomotor palsy, ocular instability in primary position Cervical rachis pathology with instability Cochlear Implants Non-stabilized medical disease Pregnant women Patients under tutelage

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bilateral vestibular hypofunction<br>Patients suffering from chronic bilateral vestibular hypofunction. | Other: Head Impulse Tests<br>* Head Impulse Tests are performed by the clinician who holds the patient's head in his hands, while he is looking straight at an earth-fixed target; then by turning the patient's head abruptly and unpredictably to the left or right, up or down through a small angle (only 10-20 degrees - not a large angle). 20 impulses in each directions (6) will be performed.<br>Other: Dynamic visual acuity Test (DVAT)<br>* Dynamic visual acuity Test (DVAT) assesses visual acuity during head movement relative to baseline static visual acuity. DVA will be assessed actively during self-generated rotations of the head in different directions.<br>Other: VEMPs & VEMPo<br>* VEMPs & VEMPo are sound evoked muscular contractions of the neck or eye. They are recorded using an evoked response computer, a sound generator, and surface electrodes to pick up neck or eye muscle activation.<br>Other: Dizziness Handicap Inventory<br>* Dizziness Handicap Inventory is a questionnaire that identify difficulties that patient may be experiencing because of dizziness, yielding to a score ranging from 0 to 100<br>Other: Oscillopsia severity questionnaire<br>* Oscillopsia severity questionnaire is a 9 items questionnaires that identify oscillopsia in different circumstances.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of covert-saccades | Frequency of covert saccades corresponds to the total amount of covert-saccades divided by the total amount of head impulse tests multiplied by 100. | Day 0 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Quality of life assessed with the Dizziness Handicap Inventory | Dizziness Handicap Inventory is a questionnaire that identify difficulties that patient may be experiencing because of dizziness, yielding to a score ranging from 0 to 100 | Day 0 | 
| Dynamic visual acuity | Dynamic visual acuity is a measure of threshold for binocular reading of letters that are presented on a screen during head impulse test | day 0 | 
| Oscillopsia severity questionnaire score | Oscillopsia severity questionnaire is a 9 items questionnaires that identify oscillopsia in different circumstances. A mean item score gives an oscillopsia severity score ranging from 1 to 5, yielding to a total score ranging from 0 to 45 | day 0 | 
| Latency of covert-saccades | Latency of covert saccades correspond to the time between the beginning of head impulse and the initiation of the first covert-saccade | Day 0 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bilateral vestibular hypofunction, Video Head Impulse Test, Covert-saccades, Quality of life, Dynamic visual acuity