Differences in standing balance by level of upper extremity motor impairment after stroke

Postural instability is a common and disabling consequence of stroke. Emerging evidence suggests that the upper extremities may also contribute to postural control - even during quiet stance.

To investigate whether varying levels of UE motor impairment are associated with distinct postural control profiles in individuals with chronic stroke.

A cross-sectional observational study was conducted in outpatient neurorehabilitation centers. Sixty-five individuals with chronic stroke (mean age 56.77 ± 12.86 years; 56.92% male), all able to stand and walk independently, were included. Participants were stratified by upper extremity motor impairment severity using the Fugl-Meyer Assessment for the Upper Extremity (FMA-UE). Postural sway was evaluated with instrumented posturography employing a Wii Balance Board and open-source software. Center of pressure displacement and mean sway velocity were recorded under four sensory conditions. Clinical balance scales complemented the instrumented assessment.

Significant differences in mediolateral sway were found across severity groups in three of the four sensory conditions (p < 0.01), with the severe group showing greater sway than the mild group - particularly under the most challenging condition (eyes closed on foam: 3.05 cm, 95% CI: 1.40-4.70; p < 0.001). Regarding sway velocity, the severe group exhibited higher values than the severe-moderate group under reduced sensory input (e.g. eyes closed: mean difference = 1.11 cm/s; p = 0.016).

Upper extremity motor impairment was associated with greater mediolateral instability during quiet standing in chronic stroke, supporting the clinical relevance of considering upper extremity function in balance-focused rehabilitation.