Influence of gaze distance and downward gazing on postural sway in hemiplegic stroke patients.

Gaze distance and head flexion suppress postural sway in healthy subjects. However, the effects of these factors on stroke patients have not been fully elucidated. In this study, we aimed to evaluate the effects of gaze distance and downward gazing on postural sway in stroke patients. We examined 15 stroke patients and 14 elderly controls. Postural sway was measured in the subjects under the following 5 conditions: eyes fixed forward on a marker located 600 cm ahead (600-cm condition); eyes fixed forward on a marker located 150 cm ahead (150-cm condition); eyes fixed downward (downward condition); the subject facing straight ahead but with eyes closed (closed-forward condition); and the subject facing downward but with eyes closed (closed-downward condition). The root mean squares of the anteroposterior (A-P RMS) and the mediolateral (M-L RMS) directions were determined. The results showed that the short gaze distance decreased the M-L RMS in both the stroke patients and controls (p < 0.001, r = 0.66; p = 0.024, r = 0.43, respectively). In the control group, the downward condition increased the M-L RMS when compared with the 600-cm condition (p = 0.011, r = 0.48). The downward condition decreased the A-P and M-L RMS in the stroke patients when compared with the 600-cm condition (A-P RMS: p < 0.001; r = 0.66, M-L RMS: p = 0.001; r = 0.59). Our results showed that the short gaze distance decreased postural sway in both groups, and downward gazing decreased it only in the stroke group.