Covert Saccade Triggers in Bilateral Vestibular Hypofunction (CS-TRIGGER)

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.

Study Overview

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

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Bron, France, 69500
    • Hospices Civils de Lyon

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 88 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Patients; Patients suffering from chronic bilateral vestibular hypofunction	Other: Covert Saccades and Virtual Reality; During this intervention, patients will undergo head impulse testing while wearing virtual reality Headsets. During the head impulse tests the visual information will be modified in order to create a conflict between head rotation and rotation of the visual scene. Recording of head and eye movement will be done during these head impulses in order to verify if visual information modifies compensatory eye movements during head impulses.; Other: Actives versus passives Head Impulses; Patients will undergo classic passive head rotation as well as active head rotation in order to compare latencies of covert saccades in both conditions.; Other: Visually guided saccades; Patients as well as healthy control subjects will undergo testing of visually guided saccades in different conditions (step, gap, overlap) in order to compare latencies of covert saccades between both groups.
Active Comparator: healthy subject group	Other: Covert Saccades and Virtual Reality; During this intervention, patients will undergo head impulse testing while wearing virtual reality Headsets. During the head impulse tests the visual information will be modified in order to create a conflict between head rotation and rotation of the visual scene. Recording of head and eye movement will be done during these head impulses in order to verify if visual information modifies compensatory eye movements during head impulses.; Other: Actives versus passives Head Impulses; Patients will undergo classic passive head rotation as well as active head rotation in order to compare latencies of covert saccades in both conditions.; Other: Visually guided saccades; Patients as well as healthy control subjects will undergo testing of visually guided saccades in different conditions (step, gap, overlap) in order to compare latencies of covert saccades between both groups.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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 1

Secondary 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 1
Velocity of covert-saccades	Velocity of covert saccades correspond to the maximal velocity of the first covert-saccade	day 1
Amplitude of covert-saccades	Amplitude of covert saccades correspond to amplitude of the first covert-saccade	Day 1
Latency of visually-guided saccades	Latency of visually guided saccades correspond to the time between the appearance of target and the initiation of the first saccade	Day 1

Collaborators and Investigators

• Sponsor: Hospices Civils de Lyon
• Investigators: Principal Investigator: Caroline FROMENT, MD, Hospices Civils de Lyon

Study record dates

Study Major Dates

• Study Start (Actual): December 15, 2020
• Primary Completion (Actual): March 21, 2022
• Study Completion (Actual): March 21, 2022

Study Registration Dates

• First Submitted: February 11, 2020
• First Submitted That Met QC Criteria: February 12, 2020
• First Posted (Actual): February 13, 2020

Study Record Updates

• Last Update Posted (Actual): July 28, 2022
• Last Update Submitted That Met QC Criteria: July 27, 2022
• Last Verified: July 1, 2022

More Information

Terms related to this study

• Keywords: Saccadic Eye Movements; Bilateral Vestibulopathy; Bilateral Vestibular Hypofunction
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Otorhinolaryngologic Diseases; Labyrinth Diseases; Ear Diseases; Vestibular Diseases; Bilateral Vestibulopathy; Reflex, Abnormal
• Other Study ID Numbers: 69HCL19_0998; 2020-A00184-35 (Other Identifier: ID-RCB)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No