Initial motor impairment influences activation pattern of motor recovery

OBJECTIVES: We investigated the functional magnetic resonance imaging (fMRI) activation pattern of a motor task in patients with acute subcortical lesions to examine the relationship between activation pattern and recovery of motor impairment. METHODS: Five patients (one with subcortical infarction and four with thalamic hemorrhage) were examined using fMRI 1 month after the insult. Impairment was assessed by the Medical Research Council motor strength classification (MRC). One patient with severe motor deficits was also studied at 4 months when her motor deficits improved up to MRC grade 4. RESULTS: Three patients with relatively mild deficits (MRC grade 3 or 4) at their onsets, improved fully up to grade 5 within 1 month. FMRI performed at 1 month showed activation in the contralateral primary motor cortex and supplementary motor area (SMA), but no significant activation was seen on the ipsilateral unaffected side. Two patients with severe motor impairment (MRC grade 1) improved up to 3 and 4 of MRC at 1 month or later. They showed activation of the ipsilateral premotor area as well as contralateral primary motor cortex and SMA. One of them, whose severe motor deficit improved at 4 month, also showed activation of the ipsilateral postcentral gyrus and the activated area expanded longitudinally corresponding with her functional recovery. DISCUSSION: Our study demonstrates that the fMRI pattern varies according to functional recovery, suggesting the importance of the ipsilateral premotor area and postcentral gyrus especially for those patients with severe motor impairment initially.