Posturographic assessment of sitting balance recovery in the subacute phase of stroke

Although early sitting balance is a well-known predictor of functional outcome after stroke, it is still unknown which aspects of normal upright sitting balance are most sensitive to subsequent recovery. This study used an adjustable chair mounted on a force platform to assess the recovery of quiet-sitting balance in 16 patients with a first supratentorial stroke during their inpatient rehabilitation. The patients underwent three posturographic assessments at 6-week intervals from the moment of their admission, on average 5.6 weeks after stroke. Each quiet-sitting balance assessment consisted of two series of four 30-s test conditions: sitting with eyes open and closed, on both a stable and unstable (air cushion) surface. The RMS of the center-of-pressure (COP) velocities was used as the primary measure of lateral and anteroposterior balance control. It was found that, compared to 10 healthy elderly, lateral balance was more affected by stroke than balance in the anteroposterior direction, especially during visual deprivation, and most sensitive to subsequent functional changes induced by spontaneous recovery or rehabilitation. Furthermore, lateral balance control showed the strongest association with the Berg Balance Scale as a clinical measure of balance capacity. Hence, (lateral) trunk control seems to be a primary target for rehabilitation. Since an unstable support was necessary to obtain significant effects of stroke, recovery and visual deprivation, it may be important to use an unstable support during sitting balance training as well.