Sensory stimulation promotes normalization of postural control after stroke

Abstract

Background and purpose: In a randomized study of hemiparetic stroke patients with a median age of 75 years, functional recovery was significantly better in those who received additional sensory stimulation (n = 38), including electrostimulation, than in control patients (n = 40) given the same physiotherapy and occupational therapy; group differences for balance, mobility, and activities of daily living were significant. The present study was designed to investigate postural control in patients who survived more than 2 years after stroke onset.

Methods: The 48 survivors (mean, 2.7 years; range, 2.0 to 3.8 years), 22 from the treatment group and 26 from the control group, were compared with 23 age-matched healthy subjects. Subjects were perturbed by vibrators applied to calf muscles or with galvanic vestibular stimulation. We evaluated postural control in terms of sway variances or sway velocities and the dynamics of postural control as a feedback system using system identification with a model previously validated for human postural control.

Results: Significantly more patients of the treatment group than of the control group maintained stance during perturbations (P < .01). Among patients capable of maintaining stance during perturbation, the control patients were characterized by significant divergence from normal values in two of the three characteristic parameters of dynamic postural control (ie, swiftness and stiffness; P < .05) compared with the treatment subgroup or age-matched subjects.

Conclusions: The course of sensory stimulation enhanced recovery of postural function, an enhancement still significant 2 years after the lesion and treatment. The differences and near normalization of characteristic parameters of dynamic postural control among treated patients suggest that improved recovery after sensory stimulation may be achieved by patients regaining normal or near normal dynamics of human postural control.