Covert Saccade Triggers in Bilateral Vestibular Hypofunction

Not Applicable

Completed

• Conditions: Reflex, Abnormal; Bilateral Vestibulopathy; Healthy Volunteers
• Interventions: Other: Covert Saccades and Virtual Reality; Other: Actives versus passives Head Impulses; Other: Visually guided saccades

• Registration Number: NCT04268615
• Lead Sponsor: Hospices Civils de Lyon

Brief Summary

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 triggering of these covert-saccade is still not known. They could be of visual origin but the short latency is unusual. The objective of this study is to evaluate the potential role of visual trigger in 12 patients with chronic bilateral areflexia, using different visuo-vestibular conditions. The latency of simple visually guided saccades will also be tested in the group of patients and a group of 12 healthy controls.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2020-02-11
• Study First Submitted QC: 2020-02-12
• Study First Posted: 2020-02-13
• Study Start: 2020-12-15
• Primary Completion: 2022-03-21
• Study Completion: 2022-03-21
• Status Verified: 2022-07
• Last Update Submitted: 2022-07-27
• Last Update Posted: 2022-07-28

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 32

Inclusion Criteria

• For all :

  • Age from 18 to 90
  • Understanding of the experimental instructions
  • Informed Consent

• For Patients :

Bilateral vestibular hypofunction with regards to the criteria of the of the Barany Society A. Chronic vestibular syndrome with at least three of the following symptoms

1. Postural imbalance

2. Unsteadiness of gait

3. Movement-induced blurred vision or oscillopsia during walking or quick head/body movements

4. Worsening of postural imbalance or unsteadiness of gait in darkness and/or on uneven ground B. No symptoms while sitting or lying down under static conditions C. Bilaterally reduced or absent angular VOR function documented by

   • bilaterally pathological horizontal angular VOR gain < 0.6, measured by the video-HIT5or scleral-coil technique and/or
   • reduced caloric response (sum of bithermal max. peak SPV on each side < 6°/sec7)and/or
   • reduced horizontal angular VOR gain < 0.1 upon sinusoidal stimulation on a rotatorychair (0.1 Hz, Vmax = 50°/sec).

D. Not better accounted for by another disease

* For Healthy control No ENT or neurological disorders

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Exclusion Criteria

• Corrected Visual Acuity lower than 5/10
• Other conditions leading to oscillopsia or ataxia
• Oculomotor palsy, ocular instability in primary position
• Treatment that may affect ocular motility (psychotropes)
• Cervical rachis pathology with instability
• Cochlear Implants
• Non-stabilized medical disease
• Pregnant women
• Patients under tutelage
• Patient without social security

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Patients	Covert Saccades and Virtual Reality	Patients suffering from chronic bilateral vestibular hypofunction
Patients	Actives versus passives Head Impulses	Patients suffering from chronic bilateral vestibular hypofunction
Patients	Visually guided saccades	Patients suffering from chronic bilateral vestibular hypofunction
healthy subject group	Covert Saccades and Virtual Reality	-
healthy subject group	Actives versus passives Head Impulses	-
healthy subject group	Visually guided saccades	-

Primary Outcome Measures

Name	Time	Method
Latency of covert-saccades	Day 1	Latency of covert saccades correspond to the time between the beginning of head impulse and the initiation of the first covert-saccade

Secondary Outcome Measures

Name	Time	Method
Frequency of covert-saccades	Day 1	Frequency of covert saccades corresponds to the total amount of covert-saccades divided by the total amount of head impulse tests multiplied by 100.
Velocity of covert-saccades	day 1	Velocity of covert saccades correspond to the maximal velocity of the first covert-saccade
Amplitude of covert-saccades	Day 1	Amplitude of covert saccades correspond to amplitude of the first covert-saccade
Latency of visually-guided saccades	Day 1	Latency of visually guided saccades correspond to the time between the appearance of target and the initiation of the first saccade

Trial Locations

Locations (1)

Hospices Civils de Lyon; 🇫🇷 Bron, France