Kinematic Measures of Bimanual Performance are Associated With Callosum White Matter Change in People With Chronic Stroke.

The study only tested symmetrical bimanual tasks, such as lifting a box with both hands. It did not test asymmetrical tasks, like opening a jar, which are common in daily life and may rely on different neural mechanisms. The sample size was small, with only 15 participants in the kinematic analysis, limiting the generalizability of the correlations. Stroke lesion locations were highly variable, and some lesions extended beyond the motor network, potentially affecting attention or visual-spatial skills that also influence movement. Because this was a cross-sectional study, it shows association but cannot prove that reduced white matter integrity caused the movement problems.

The authors declared no conflicts of interest. The study was supported by grants from the National Institute on Disability, Independent Living, and Rehabilitation Research, the American Heart Association, and the National Institute of Neurological Disorders and Stroke.

Do not interpret the lack of correlation between the corticospinal tract and bimanual kinematics as evidence that the tract is unimportant. The study found it correlated with single-limb motor scores, so it remains critical for basic movement, even if it does not explain the specific coordination deficits seen in two-handed tasks.