Early Rehabilitation Using Head Impulse Test for Acute Vestibular Deficit

Overview

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.

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
• 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

Primary outcome measures

• First Substitution Saccade Latency after treatment [Time frame: Day 7]

Secondary outcome measures (6)

• First Substitution Saccade Latency during the First Week [Time frame: Everyday from post-surgery Day 1 to Day 6]
• First Saccade Latency after treatment (follow-up) [Time frame: At post-surgery Day 45 and 3rd month]
• First saccades amplitude after treatment [Time frame: Post surgery Day 7, Day 45 and 3rd month]
• First saccades amplitude during first week [Time frame: Everyday from post-surgery Day 1 to Day 6]
• Balance and gait assessment [Time frame: At Day -1 (pre-surgery), and post-surgery Day 7, Day 45 and 3rd Month]
• Quality of Life Assessment [Time frame: At Day -1 (pre-surgery), and post-surgery Day 7, Day 45 and 3rd Month]

Eligibility criteria

Inclusion criteria

• patients with unilateral vestibular schwannoma and programmed surgery
• vestibulo-ocular reflex gain :

• on pathological side > 0.50
• on healthy side > 0.80
• all information's concerning the study given more than 15 days before surgery and consent collected the day before surgery

Exclusion criteria

• Radiotherapy treatment prior to surgery.
• Resumption of surgery
• Presence of bilateral vestibular schwannomas
• Normal or Corrected to normal distance visual acuity < 5/10
• Presence of other aetiologies that may explain the ataxic syndrome and/or oscillopsias
• Oculomotor paralysis, ocular instability in primary position
• Use of medications that compromise eye movement (psychotropic drugs)
• Cervical spinal pathology with instability (contraindication for vHIT)
• Cochlear implantation
• Non-stabilized medical condition
• Pregnant women. This exclusion criterion will be investigated by questioning the patient.
• Patient under guardianship
• Patient not affiliated to a social security scheme
• Patient participating any other interventional study

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Double blind

Primary purpose

Treatment

Study locations

France · 1 center

• Pierre Wertheimer Hospital - Neurological Hospital — Bron

Identifiers

NCT: NCT06660082 · 69HCL24_0718 · 2024-A02268-39

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗