Covert Saccade Triggers in Bilateral Vestibular Hypofunction

Healthy Volunteers Clinical Trial

— CS-TRIGGER  

Official title:

Covert Saccade Triggers in Bilateral Vestibular Hypofunction

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04268615
• Other study ID #: 69HCL19_0998
• Secondary ID: 2020-A00184-35
• Status: Completed
• Phase: N/A
• Start date: December 15, 2020
• Est. completion date: March 21, 2022

Study information

• Verified date: July 2022
• Source: Hospices Civils de Lyon
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 32
• Est. completion date: March 21, 2022
• Est. primary completion date: March 21, 2022
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 90 Years

Eligibility

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

Related Conditions & MeSH terms

• Bilateral Vestibulopathy
• Healthy Volunteers
• Reflex, Abnormal

Intervention

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.
• 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.
• 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.

Locations

Country	Name	City	State
France	Hospices Civils de Lyon	Bron

Sponsors (1)

Lead Sponsor	Collaborator
Hospices Civils de Lyon

Country where clinical trial is conducted

France, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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	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
Secondary	Velocity of covert-saccades	Velocity of covert saccades correspond to the maximal velocity of the first covert-saccade	day 1
Secondary	Amplitude of covert-saccades	Amplitude of covert saccades correspond to amplitude of the first covert-saccade	Day 1
Secondary	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