VIrtual Reality Glasses Use to Improve Lateropulsion and the Post-stroke Postural Vertical

VIRGIL is a monocentric interventional study aiming to investigate the effect of immersion in a virtual tilted room on modulation of the verticality representation (postural vertical \[PV\] and visual vertical \[VV\]), which in turn might affect body orientation (head and trunk). To this end, the investigators will conduct a within-person randomized trial including post-stroke patients and healthy participants.

This project proposes to test the effect of immersion in a tilted virtual reality on verticality representation in hemisphere stroke patients showing lateropulsion and in healthy participants. The idea is to use the virtual reality as a tool to recalibrate the internal reference of verticality (contralesionally biased) in stroke patients and to experimentally create a bias in verticality perception of healthy participants, then to investigate how this modulation of the internal model of verticality might affect the erect posture. The investigators hypothesize that, in stroke patients, the recalibration of the verticality perception might ameliorate their lateropulsion, whereas in healthy participants, the experimental verticality bias introduced might induce a transient experimental lateropulsion. A transmodal modulation of the verticality perception, both on PV and VV, would imply a modulation by the virtual reality not only at the level of perception but also at the internal model of verticality, advocating for a powerful effect of this technology. The analysis of a post-effect (on verticality perception) that would continue after the intervention (immersion in the virtual titled room) would be a supplementary argument advocating for its clinical use in rehabilitation of post-stroke lateropulsion. To judge the effect of the immersion in tilted virtual reality, the following measures will be considered: (a) PV perception, (b) VV perception, (c) body orientation measured by inertial captors, and (d) weight-bearing asymmetry in erect posture assessed by posturography.

Eligibility Criteria:
Inclusion Criteria:

* 20 stroke participants

  * Hospitalized in neurorehabilitation
  * Hemisphere stroke (Right or left)
  * Stroke delay \< 6 months
  * Presence of lateropulsion assessed by the Scale for Contraversive Pushing (SCP) \> 0.5
* 20 healthy participants

  * No history of stroke or others neurological pathologies
  * No balance disorders
  * No history of vestibular or dizzissness disorders

Exclusion Criteria:

* All

  * History of psychiatric disorders
  * Nyctophobia
  * Advanced heart failure
  * Severe trunk deformation with C7 lateral \> 30 mm due to a independant cause beyond the stroke (i.e., scoliosis) or history of postural disorder
* 20 Stroke participants

  * Medical instability making the assessment impossible
  * Comprehension deficits with Boston Diagnostic Aphasia Examination gravity score ≥3
  * History of vestibular or dizzissness disorders
  * No previous neurological history interfering with balance
  * Inability to understand and execute simple orders
  * Severe untreated depression (Aphasic Depression Rating Scale (ADRS) score \>15)