The main objective of this study is to test the effectiveness of a rehabilitation program with cervical vibration and/or prism adaptation in patients with left hemiplegia on balance.

Imbalance is particularly severe after a Cerebral Vascular Accident because they not only limit the capacity of transfer and are a source of falls but also represent an obstacle to the acquisition of autonomy.

When the brain lesion is located in the right hemisphere, the prognosis in terms of equilibrium is worse probably because of the presence of disorders of spatial cognition. These disorders of spatial cognition are manifested by a distortion of the mental representation of space and body in space that probably cause a deviation of the position of the center of pression on platform. This component of balance disorders secondary to disruption of spatial cognition, do not benefit at present from specific rehabilitative treatment despite the severity of the consequences.

But the application of sensory manipulations has proven its effectiveness on visuospatial neglect that is another disorder of spatial cognition closed to the pathophysiology of balance disorders after right brain lesion. Sensory manipulations decrease the distortion of internal representations of the body in space by restoring the symmetry of sensory inputs. Some of these manipulations (visual manipulation by wearing prisms and proprioceptive manipulations) are also effective on the immediate correction of postural imbalances on force platform and disorders of spatial perception.

We therefore believe that the approach by repeated sensory manipulation is a new promising way of research for the rehabilitative treatment of balance disorders secondary to disorders of spatial cognition. As the mechanisms of action and the structures involved during proprioceptive vibration of neck muscles and during visual prism adaptation are different, we believe that the combination of these two types of sensory manipulations will permit to obtain a greater and longer lasting effect than a lonely manipulation. The concomitant evaluation of the bias on postural platform and the perception of the body axis will allow us to assess the impact of such rehabilitation on the disorders of spatial representation and so better understand the mechanisms of action of sensory manipulations.

The main objective of this study is to test the effectiveness of a rehabilitation program with cervical vibration (V) and / or prism adaptation (P) in patients with left hemiplegia on balance at the end of the intervention (day14).

Secondary objectives are to test:

• The immediate effect (day 0) on force platform evaluation of balance,
• Maintaining the gain at 3 months and 6 months on balance,
• Effectiveness at day 14 on negligence
• Maintaining the gain at 3 months and 6 months on neglect,
• Effectiveness at day 14 on functional abilities,
• Maintaining the gain at 3 months and 6 months on functional abilities,
• Understanding the mechanisms of action of each of the sensory manipulations by assessing changes in perceptions of space, after rehabilitation programs (day 14) and at 3 months and 6 months.
• To evaluate the evolution of motility, sensitivity and spasticity in the various assessments.

During the 15 days rehabilitation performed for the study, the upper and lower limbs motor rehabilitation will last less than one hour and a half, and will exclude instrumental techniques of balance rehabilitation, sensory manipulations, virtual reality, strain-induced therapy.

Moreover, an ancillary study will be performed to study the immediate neurofunctional effect of vibratory stimulation, in right brain-damaged patients with imbalance and in healthy volunteers, through the assessment of cerebral activation changes in MRI. The secondary objectives of this ancillary study are to test the neurofunctional effect of repeated vibratory stimulation in right brain-damaged patients, describe the relationship between cerebral activation changes and evolution of balance, and describe the areas of the brain activated by vibratory stimulation.

Inclusion Criteria:

• Right unilateral supratentorial ischemic or hemorrhagic lesion

• Adult (age ≥ 18 years) under 80 years

• Stroke

  • older than 9 months
  • with or without hemianopsia
  • with or without visuospatial hemineglect

• The first symptomatic episode

• Standing balance ≥ 30 sec unaided

• Percentage of weight rests on the hemiplegic lower limb below 40% of body weight (on a platform of strength)

• Written informed consent of the patient or a member of his entourage (in the case of patients with motor difficulties)

Exclusion Criteria:

• Orthopedic, rheumatologic or visual disorders affecting the distribution of the center of pressure while standing
• Visual disorder that does not allow assessment of the longitudinal axis or visual straight ahead
• Ischemic or hemorrhagic brain stem lesion
• Trouble for understanding protocol procedures

Inclusion Criteria for the healthy volunteers (ancillary study) :

• Age ≥ 18 years, right-handed, sex and age-matched (+/- 5 years) to the patients of the coordinating center
• Able to get an MRI
• With no imbalance
• With no visual disorder impacting the repartition of the center of pression when standing up, or that does not allow assessment of the longitudinal axis or visual straight ahead
• Written informed consent