Article

The relationship between structural and functional integrity of
descending motor pathways can predict the potential for motor recovery after
stroke. The authors examine the relationship between brain imaging biomarkers
within contralesional and ipsilesional hemispheres and hand function in
well-recovered patients after subcortical stroke at the level of the internal
capsule. OBJECTIVE: MEASURES of functional activation and integrity of the
ipsilesional corticospinal tract might predict paretic hand function. METHODS: A
total of 14 patients in the chronic stable phase of motor recovery after
subcortical stroke and 24 healthy age-matched individuals participated in the
study. Functional MRI was used to examine BOLD contrast during passive wrist
flexion-extension and paced or maximum-velocity active fist clenching. Functional
integrity of the corticospinal pathway was assessed by transcranial magnetic
stimulation to obtain motor-evoked potentials (MEPs) in the first dorsal
interosseus muscle of the paretic and nonparetic hands. Fractional anisotropy and
the proportion of traces between hemispheres in the posterior limb of both
internal capsules were quantified using diffusion-weighted MRI. RESULTS: Patients
with smaller MEPs had a weaker paretic hand and more primary motor cortex
activation in their affected hemisphere. Asymmetry between white matter tracts of
either hemisphere was associated with reduced precision grip strength and
increased BOLD activation within the contralesional dorsal premotor cortex for
demanding hand tasks. CONCLUSION: There may be beneficial reorganization in
contralesional secondary motor areas with increasing damage to the corticospinal
tract after subcortical stroke. Associations between clinical, functional, and
structural integrity measures in chronic stroke may lead to a better
understanding of motor recovery processes.

Langue : ANGLAIS