Hand Dominance Influences Motor Recovery Trajectories Following Stroke: A Longitudinal Study.

Stroke often causes persistent upper extremity (UE) motor deficits, affecting reaching and grasping and impacting daily activities. Recovery may depend on whether the dominant or non-dominant hand is affected, a distinction that remains understudied. This pilot study aimed to characterize longitudinal UE recovery post-stroke. Twenty participants post-stroke (ten with the dominant hand affected, ten with the non-dominant hand affected) performed reach-to-grasp-and-lift tasks (1-inch cube, 2.5-inch circular object), plus clinical assessments, five times over six months with the initial testing around 15 days post-stroke (mean = 14.9). Kinematic measurements included Time to Peak Velocity, Time After Peak Velocity, Reach Duration, Reaching Trajectory Smoothness, Path Linearity, and Grasp Duration. Piecewise linear mixed-effects models evaluated longitudinal trends. Clinical measures improved significantly within 45 days post-stroke, while most kinematics improved significantly in the first 30 days but plateaued thereafter. A secondary exploratory analysis examining effects of hand dominance on UE recovery showed significant clinical improvements in both groups, but significant kinematic improvements were only demonstrated in the affected dominant hand group. Findings suggest kinematic improvements may be driven by dominant hand impairment, possibly reflecting motor control differences or greater reliance on the dominant hand. These results highlight the need for targeted rehabilitation strategies tailored to the non-dominant hand's functional role.