Support-specific modulation of grip force in individuals with hemiparesis

Objective: To investigate whether use of auxiliary sensory input will result in modulated grip force. Design: Case-control study. Setting: Free-standing acute inpatient rehabilitation hospital. Participants: Six people with unilateral hemiparesis due to unilateral stroke and 6 control subjects without neurologic disorders. Interventions: Seated subjects lifted and transported the same object under 3 different conditions: with no support, with the target arm positioned on a freely moving skateboard, and with a finger from the subject's contralateral hand lightly touching the wrist of the target arm. Main Outcome Measures: Peak grip force and temporal coupling between the grip force and lift-off of the object. Results: All subjects were able to better regulate grip force when provided with additional sensory input. Light finger touch resulted in decreased grip force, as did skateboard use (P < .05). Subjects with hemiparesis showed 2 times longer latency between grip-force application and lift-off of the object (P < .05). Conclusions: Statistically significant grip-force reduction was noted with both support aids. These findings could have implications in clinical and rehabilitative areas. (c) 2005 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation