Reliance on visual information after stroke. Part I: Balance on dynamic posturography

Abstract

Objective: To test the hypothesis that postural imbalance after stroke may be caused by inability to use pertinent somatosensory, vestibular, or visual information.

Design: Description of the sensory organization of patients with hemiplegia.

Setting: Public rehabilitation center in France.

Participants: Forty patients with hemiplegia after a single hemisphere stroke who were at least 12 months post stroke.

Interventions: Not applicable.

Main outcome measures: The patients performed computerized dynamic posturography (EquiTest), which is designed to assess a patient's ability use sensory inputs separately and to effectively suppress inaccurate inputs in case of sensory conflict. Body stability under each of 6 sensory conditions was assessed by an equilibrium score (ES).

Results: In conditions of altered somatosensory information, with visual deprivation (ES5) or visuovestibular conflict (ES6), the median scores for patients with hemiplegia (ES5-43; ES6-20) were significantly lower than those for normal subjects (ES5-69; ES6-67).

Conclusions: Many patients with hemiplegia seem to rely on visual input. The mechanism of this excessive visual reliance is discussed. Rehabilitation programs of postural control for the patients with hemiplegia should take into account the possible impairment of sensory organization and should include exercises to be performed under conditions of sensory input deprivation and sensory conflict.