Early Rehabilitation Using Head Impulse Test for Acute Vestibular Deficit

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.


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