Rehabilitation Program Dedicated to Post-stroke Lateropulsion Including Exoskeleton Assisted Exercises

Lateropulsion is a deficit in the body orientation with respect to the vertical in the coronal plane, defined by the presence of one of the three signs: lateral body tilt, active pushing from the sound limbs, and resistance to passive corrections. The lateral body tilt is the cardinal sign, the frequency of the 2 other signs increasing with lateropulsion severity (most dramatic forms called pusher syndrome in the past). Lateropulsion is frequent after stroke, and represents the main factor underpinning balance and gait disorders at the subacute phase. After hemisphere stroke lateropulsion is caused by a bias in the internal model of the verticality in the frontal plane, individuals unconsciously aligning their body posture on a tilted verticality representation. Pilot studies suggested the possibility to recalibrate the internal model of verticality, biased by stroke, and to improve individuals' uprightness. The investigators expect that a specific rehabilitation program combining technics devoted to lateropulsion, and comprising exoskeleton (Atalante) assisted balance exercises could help recalibrate the internal model of verticality and alleviate lateropulsion. The primary objective is to test the hypothesis that a 3-week specific lateropulsion rehabilitation program (15 sessions of 30 minutes including exoskeleton and a rehabilitation focused on the vertical body orientation in the frontal plane) improves the visual vertical (VV), the most used test to assess verticality perception.

Inclusion Criteria: * Right hemispheric first and unique ischemic stroke between 2 weeks and 6 months old (subacute phase) ; * Presence of lateropulsion, assessed by the Scale for Contraversive Pushing (2 ≤ SCP \< 5) * Presence of contralesional VV bias (VV \> 4°) * Right handedness defined by a Edinburgh score ≥0,39 * Being hospitalized in a Physical Medicine and Neurological Rehabilitation (PMR) facility. * Have given a written and informed consent Exclusion Criteria: * Medical instability making evaluation impossible, * Comprehension or cognitive or behavioral disorders, or depressive symptoms that compromise participation in the program * Postural disorders or body geometry disorders that interfere with balance for a reason that is independant of the stroke * Morphological contraindications to the use of the Atalante® robot (segment length or joint ranges; height \100kg), * Severe spasticity (\>3 on the modified Ashworth scale) in the adductors, quadriceps, hamstrings and triceps surae * Presence of a pressure sore at the areas of contact with the Atalante® robot, * History of osteoporotic fractures. * Pregnancy and breastfeeding