Early Rehabilitation Using Head Impulse Test for Acute Vestibular Deficit

Summary

The vestibulo-ocular reflex (VOR) induces a compensatory movement in the eye when the head is rotated, to maintain stable vision when we move. It originates in the peripheral vestibular system, which detects head movements. It is particularly effective for rapid head movements, as tested in the Head Impulse Test (HIT). In acute unilateral vestibular deficit (AUVD), the VOR deficit is compensated for by a substitution saccade, more commonly known as catch up saccade, that contribute to refocus the gaze and maintain vision during head rotations.

Recent technological advances have made it possible to make high-quality recordings during HIT (video Head Impulse Test, vHIT), leading to the identification of substitution saccades of variable latency. Our team has shown that saccades of shorter latency lead to better visual function (Hermann et al., 2017) and that the cerebellum is involved in the development of these saccades (Hermann et al., 2023), suggesting a learning effect rather than the de novo appearance of particular saccades.

The main hypothesis of this study is that the mechanisms underlying short-latency substitution saccades, which seems to guarantee good functional recovery, depend on learning occurring from the first days after an acute unilateral vestibular deficit. We also hypothesise that early physiotherapeutic rehabilitation of the VOR under Head Impulse Test conditions would promote this learning process and the development of early catch-up saccades.

One of the causes of AVD is the resection of cochleovestibular schwannomas. This procedure involves a neurotomy, i.e. complete vestibular deafferentation, which is precisely known due to the scheduled nature of the surgery. The exact moment of onset of vestibular damage is therefore known, unlike other vestibular pathologies. Hospitalisation is necessary in the immediate aftermath of surgery, with the presence of physiotherapists on the wards. In addition, there is no spontaneous recovery of the vestibular deficit. These patients therefore represent the ideal acute unilateral vestibular deficit model for testing our hypothesis. Two studies using vHIT in the aftermath of vestibular schwannoma resection surgery (Pogson et al. 2022; Mantokoudis et al. 2014) also allow us to confirm the safety and feasibility of our protocol in this patient population.

Conditions

• Vestibular Schwannoma
• Unilateral Vestibular Deficit

Interventions

PROCEDURE

Experimental treatment: Head movements

These are gaze stabilisation exercises under vHIT control, between post-operative days 1 to 6. The patient sits facing a wall 2 metres away. The investigator places the vHIT device on the participant's head and ensures that it fits properly. This is followed by an initial calibration phase (the patient must follow a laser dot with his eyes). Then comes stimulation phase: the investigator, standing behind the patient, places his hands on the sides of the patient's lower jaw, which he is asked to clench. The investigator asks the subject to stare at a visual target on the wall in front of the patient. The investigator then performs a series of low-amplitude, high-speed head movements in the plane of the lateral canals and on the side of the vestibular deficit. The patient is encouraged to resume fixation of the visual target as quickly as possible. For each treatment session, patients should perform a minimum of 10 impulses and a maximum of 30 impulses on the deafferented side. Each

PROCEDURE

Sham treatment: only eye movements

These are visually guided saccade exercises under vHIT device control but without head movements (saccade module), between post-operative days 1 to 6. For this sham treatment, the modalities are identical to the experimental treatment session, up to the calibration phase described above. For the stimulation phase, the investigator, standing behind the patient, places his hands on the sides of the patient's lower jaw, which he is asked to clench. The investigator asks the subject to stare at a visual target on the wall in front of the patient. The target then jumps horizontally to trigger visually guided saccades or slides horizontally to trigger an eye-tracking movement. The investigator stabilises the patient's head to prevent any head movement. The patient is encouraged to resume or maintain fixation of the visual target as quickly as possible. A minimum of 5 horizontal saccade sequences and 5 horizontal eye-tracking sequences will be performed. Each training session lasts approxi

Sponsors & Collaborators

• Hospices Civils de Lyon

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-05-13

Primary Completion

2027-05-31

Completion

2027-05-31

Countries

• France

Study Locations