Postural instability in patients with chronic stroke.

PURPOSE It is known that visuospatial orientation and the extent of spontaneous recovery vary between right or left hemisphere affected stroke patients. We hypothesized that the right hemisphere affected chronic patients would show more impaired static balance than left hemisphere affected patients. The purpose of the study was to assess displacement of the center of pressure (COP) of ambulatory patients with either left or right hemiparesis. METHODS Forty-five patients and thirty healthy subjects participated and static balance was measured while standing on a force plate. RESULTS The patients showed more than four times higher mean velocity moment and two times faster anterior-posterior (AP) and medial-lateral (ML) speed of COP displacement than healthy subjects. The patients with left hemiparesis, and affected right hemisphere, had higher power peak magnitudes of COP displacements than patients with right hemiparesis both in ML and AP directions at low frequencies. The patients had higher power peak magnitudes of COP displacements than healthy subjects in both ML and AP directions at all separately analyzed frequency ranges. More weight bearing on the paretic side was associated with less COP displacement in ML and AP directions. CONCLUSIONS Patients with left hemiparesis have more low frequency COP movements from side to side and from front to back than patients with right hemiparesis. Patients with right or left hemiparesis sway more than the healthy subjects. The affected hemisphere and the disturbed cerebral networks likely produce different postural deficits in right or left hemiparetic patients.