Influence of vision conditions on postural control in right and left hemispheric lesions

Abstract

Objective Postural regulation is a prerequisite of executing functional activities in various environments. The integration of sensory inputs is weighted differently according to the situation and the required motor strategies. Stroke impairs postural regulation and production of motor strategies, and visual inputs might have different influence depending on the side of the lesion. The main objective of this study was to determine whether side of hemispheric lesion influences the effects of visual inputs on postural regulation in the medial-lateral and anterior-posterior axes when self-imposed disturbances occur in the seated position. Material/Patients and methods We assessed 22 chronic stroke participants (12 with right and 10 with left side lesions; > 6 months) who had a single hemispheric stroke. Participants were asked to maintain their balance in a sitting position on a seesaw placed on a force platform that recorded at 40 Hz. Four conditions were tested: eyes open and closed; with alteration of the right and left visual field using goggles. The area, length and speed of the Centre of Pression (COP) in the medial-lateral and anterior-posterior axes were analyzed with two-way ANOVAs to assess the effects of vision and group. Results The effects of the occlusion of visual field on postural control differed depending on the side of the lesion. In both the medial-lateral and anterior-posterior axes, the left visual field occlusion perturbed stability in the participants with the right lesion while the right visual field occlusion perturbed stability in the participants with the left lesion. In addition, the visual effect differed for these two groups of patients with greater destabilization on the medial-lateral axis for those having a right side lesion. Discussion/Conclusion Our findings emphasized the dominant role of the right hemisphere on postural control under vision conditions, particularly in the medial-lateral axis where greater instability was observed in people with a right hemispheric lesion.