Grip force regulation during pinch grip lifts under somatosensory guidance: Comparison between people with stroke and healthy controls

Objectives: To compare the timing and grip force application in a pinch grip task performed under somatosensory guidance in stroke and matched controls and to identify characteristics of impaired grip force regulation after stroke. Design: Matched-pairs control group. Setting: University research laboratory. Participants: Forty-five people with stroke who could pick up a pen lid using a pinch grip and actively participated in rehabilitation and 45 adults without neurologic conditions or musculoskeletal or skin impairments affecting the hand, matched for age, sex, and hand dominance. Interventions: Not applicable. Main Outcome Measures: Timing and magnitude of grip forces applied during pinch grip lift and bold. Results: Prolonged time to grip and lift objects, and excessive grip force prior to commencing the lift occurred in approximately half of the contralesional (involved) hands of people with stroke. Fluctuating irregular forces and reduced adaptation of the grip safety margin were also observed. Excessive safety margins were not predominant after stroke. Extreme slowing and disorganized sequencing of the grip and lifting forces and difficulty maintaining a stable grip characterized severe dysfunction. Conclusions: Delayed grip formulation and variable grip force application are key characteristics of grip dysfunction after stroke.