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

Civil Hospices of Lyon

Status: Completed

Conditions: Healthy Volunteers; Bilateral Vestibulopathy; Reflex, Abnormal

Treatments: Other: Covert Saccades and Virtual Reality; Other: Visually guided saccades; Other: Actives versus passives Head Impulses

Study type: Interventional

Funder types: Other

Identifiers

NCT04268615

69HCL19_0998

2020-A00184-35 (Other Identifier)

Details and patient eligibility

About

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.

Enrollment: 32 patients

Sex: All

Ages: 18 to 90 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Non-Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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32 participants in 2 patient groups

Patients

Experimental group

Description:

Patients suffering from chronic bilateral vestibular hypofunction

Treatment:

Other: Actives versus passives Head Impulses

Other: Visually guided saccades

Other: Covert Saccades and Virtual Reality

healthy subject group

Active Comparator group

Treatment:

Other: Actives versus passives Head Impulses

Other: Visually guided saccades

Other: Covert Saccades and Virtual Reality