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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
20
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.
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.
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.
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
Oscillopsia severity questionnaire is a 9 items questionnaires that identify oscillopsia in different circumstances.
Unité de Neuro-Ophtalmologie Hôpital Neurologique
Bron, France
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.
Time frame: Day 0
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
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: Day 0
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