Perception of vertical and postural control following stroke: a clinical study

Abstract

Objectives To investigate the relationship between subjective visual vertical (SVV) and trunk alignment following stroke. Setting Stroke unit of a large general hospital. Participants Twelve stroke patients and nine controls were assessed. One patient was assessed at 14, 23, 30, 37 and 58 days post-stroke. Outcome measures SVV assessment involved viewing a line, rotating in the frontal plane, through goggles that restricted field of vision. Participants estimated when the line was vertical; the median of 10 estimates was taken to be the SVV. Postural alignment was classified as upright or leaning to the left or right. Results The stroke group was less accurate in perception of vertical than the control group ( P < 0.001). In the stroke group, nine participants had SVV ≥ 2.5° from true vertical. Two of these participants leaned towards their SVV in sitting. Seven participants could sit upright, but six of these leaned towards their SVV in standing. Two participants had SVV < 2.5°; both maintained upright posture in sitting and standing. The case study demonstrated gradual improvement in SVV and posture; upright posture was regained in sitting whilst SVV was −7°. Discussion Postural problems were associated with SVV tilt; however, upright sitting posture was possible despite SVV tilt. We propose that leaning in sitting is due to inaccurate representation of the support surface. Conclusion Postural problems following stroke are related to inaccurate spatial representation. Further studies using perceptual assessments to reveal spatial representation are recommended.