Ability to adjust reach extent in the hemiplegic arm.

OBJECTIVE: Insufficient information exists about the ability of hemiparetic patients to adjust reach extent during early recovery from stroke. Further knowledge may suggest guidance for therapy intervention. The objective of this study was to investigate the ability of hemiparetic subjects to adjust reach extent within 6 months after stroke. DESIGN: Repeated-measures design experiment with two factors-group and target position. SETTING: Physiotherapy department. PARTICIPANTS: Nine hemiparetic and nine age- and gender-matched healthy subjects. METHODS: Participants performed 15 reaching movements in the sagittal plane, five to each target of 8, 13 and 18 cm from the starting position. MAIN OUTCOME MEASURES: Motion analysis was used to collect information on the kinematic variables of distance moved, movement duration, peak velocity, average velocity and the timing of peak velocity. These variables were compared between the different target positions and between groups. RESULTS: The stroke group demonstrated a longer movement duration, lower peak and average velocity, and a later time to peak velocity compared with the healthy group. In response to the change in target position, both groups increased peak velocity for each increase in target position with no significant increase in movement duration, and showed a longer deceleration phase for the 18-cm target position. There was no significant difference between scaling of distance moved and peak velocity to target position between the groups. However, stroke subjects tended to overshoot the closer target and undershoot the more distant targets. The mean difference between groups was 12 mm [95% confidence interval (CI): -17 to 50] for the 8-cm position, 5mm (95% CI: -34 to 23) for the 13-cm position, and 9 mm (95% CI: -39 to 22) for the 18-cm position. The difference in peak velocity between each target position was smaller in the stroke subjects compared with the healthy subjects. The mean difference between groups was 103 mm/second (95% CI: -171 to -34) for the 8-cm position, 157 mm/second (95% CI: -231 to -82) for the 13-cm position, and 171 mm/second (95% CI: -262 to -80) for the 18-cm position. CONCLUSIONS: Some aspects of the movement organisation of stroke subjects were similar to that of healthy subjects. However, stroke subjects showed errors in adjusting reach extent and velocity appropriately for different distances.

Coordination between reaching and grasping in patients with hemiparesis and healthy subjects.

OBJECTIVE: To investigate the coordination of reach-to-grasp components in hemiparetic and healthy subjects. DESIGN: Split-plot repeated-measures design with 3 factors (group, object size, movement speed). SETTING: Movement laboratory. PARTICIPANTS: Twelve hemiparetic and 12 age-matched healthy subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We used motion analysis to collect information on the kinematic variables of movement duration, peak velocity, peak deceleration, and maximum aperture, and the time of peak velocity, peak deceleration, and maximum aperture expressed as a percentage of movement duration during 32 reaching movements by each subject. We examined the coordination between the 2 components in 2 ways. First, we investigated the correlation between time of hand opening and start of hand transport, and between time of maximum aperture and time of peak deceleration. Second, we compared movements at preferred and fast speeds (manipulation of transport component) and to 2 different-sized cups (manipulation of grasp component). RESULTS: Both groups demonstrated a temporal coupling between grasp and transport components at the start of the reach and at the time of maximum aperture. Both groups increased the aperture of grasp for larger cups and increased the maximum grip aperture, and had a shorter deceleration phase for faster movements. The deceleration phase of the hemiparetic patients was longer than that of the healthy subjects, however, and the components were not as tightly coupled. CONCLUSIONS: The hemiparetic patients, who had a moderate amount of functional recovery, were similar to healthy subjects in their ability to control reach-to-grasp components. Their performance was not as skilled, however.