Center-of-pressure responses to optokinetic stimulation in patients with stroke and age-matched healthy adults:...

Visual dependence and optokinetic stimulation (OKS) modulate sensory weighting for postural control and may be altered after stroke. However, the center-of-pressure (COP) measures that most sensitively index OKS-related changes during quiet standing, compared with age-matched older adults, have not been clearly defined.

To explore which COP measures are most responsive to OKS during quiet standing in patients with stroke versus older adults, and to interpret these responses using visual dependence and frequency-domain COP measures.

This was a retrospective secondary analysis of a cross-sectional dataset. Thirty patients with subacute stroke and 30 age-matched healthy adults underwent stabilometry under eyes-open and rotating-visual conditions induced through OKS. COP measures were derived; frequency-domain features indexed sensory weighting. Visual dependence was defined as dynamic minus static Subjective Visual Vertical. Two-way mixed analysis of variance evaluated group and condition effects.

Significant group × condition interactions were observed for sway path, mediolateral amplitude, and mediolateral sway velocity (p < 0.01, partial η² ≈0.08-0.09). In the stroke group, these indices were higher under both rotating-visual conditions than in the eyes-open condition (p < 0.01, Hedges' $g_{\mathrm{av}}$ ≈0.76-1.33). Visual dependence was greater in patients with stroke than in healthy controls (20.1 ± 10.0° vs. 15.1 ± 8.0°, p < 0.05, r = 0.29).

Under OKS, group-by-condition interactions appeared mainly in mediolateral-direction COP measures, and visual dependence was higher in patients with stroke than in healthy controls, suggesting greater susceptibility to visually induced imbalance.