Impact of internal capsule lesions on outcome of motor hand function at one year post-stroke

Objective: To investigate the association between damage to different levels of the corticofugal tract and long-term hand motor recovery. Design: Prospective cohort study. Patients: Seventy-five first-ever middle cerebral artery stroke survivors. Methods: Hand motor function was assessed with the Fugl-Meyer Motor Assessment Scale at one year post-stroke. Localization of the corticofugal tract was assessed on axial magnetic resonance imaging slices using a corticofugal mask defining involvement of the motor cortex, corona radiata or internal capsule and combinations of these structures, adjusted for lesion volume. Results: Longitudinal involvement of all 3 levels of the corticofugal tract and partial involvement of the internal capsule were associated with a significant probability of poor motor hand function recovery. The probability of regaining hand function ranged from 54% if the corticofugal tract was only partly affected to 13% if both motor cortex and internal capsule were affected. Conclusion: At one year post-stroke, lesions of the internal capsule were associated with a significantly lower probability of return of isolated hand motor function than lesions of the cortex, subcortex and corona radiata. Since recovery of isolated hand and finger movements is important for regaining a functional upper limb in everyday living, these patients should be identified early post-stroke in order to evaluate specific hand function training.