Fine motor control in adults with and without chronic hemiparesis: baseline comparison to nondisabled adults and effects of bilateral arm training.

OBJECTIVES: To characterize fine motor control through finger tapping in both arms of 10 patients with chronic stroke, to make baseline comparisons with matched controls, and to examine the responsiveness of deficits seen in stroke patients after 6 weeks of bilateral arm-based training.
DESIGN: Nonrandomized controlled, cohort before-after trial.
SETTING: Research institution. PARTICIPANTS: Ten people from the community with chronic unilateral ischemic stroke and 10 age- and sex-matched healthy controls. Participants with hemiparesis had completed all conventional care and were more than 6 month poststroke. Inclusion criteria were at least 6 months since a unilateral stroke, ability to follow simple instructions and 2-step commands, volitional control of the nonparetic arm, and at least minimal antigravity movement in the shoulder of the paretic arm.
INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measurements included rate and timing consistency of unilateral tapping at a preferred and a maximal rate and the accuracy and stability of interlimb coordination in bilateral simultaneous (inphase) and alternating (antiphase) tapping at a preferred rate.
RESULTS: Nonparetic finger control was similar to that of the nondisabled participants except under bilateral conditions, where it was less consistent. A subgroup with residual paretic finger function, had slower and less consistent paretic finger tapping, as well as less accurate and more variable interlimb coordination; however, basic bilateral coupling relationships were preserved. Bilateral arm-based training improved bilateral nonparetic consistency but slowed unilateral preferred tapping. Training also improved paretic fine motor control in 2 of 4 participants with mild stroke severity. The 2 responders, with dominant hemisphere lesions, indicated a possible recovery advantage with bilateral training for such lesions.
CONCLUSIONS: In general, nonparetic finger control for tapping was preserved but paretic finger control was compromised. Disruption of nonparetic control of tapping, particularly consistency of tapping, occurred during bilateral tapping tasks but was responsive to 6 weeks of bilateral arm-based training. Despite the apparent lack of training specificity, the generalizable effects of bilateral arm training to fine motor interlimb coordination may reflect central motor control mechanisms for upper-extremity coordination, which may be accessed and may influence the recovery of arm function after stroke.