Motor recovery after stroke: morphological and functional brain alterations

The aim of this study was to evaluate the relationships of morphological and CBF patterns with both the severity and the evolution of the motor deficit in the late phase of stroke and, in particular, to identify morphological and/or functional brain alterations associated with a persistent severe motor deficit or a poor, delayed motor recovery. We analysed CT/MRI and single photon emission tomography (SPET) findings from 37 patients studied in the chronic phase of stroke (mean duration +/- SD = 3.6 +/- 1.6 months), whom we were able to follow clinically for a period of 3 months. The eventual degree of motor recovery correlated significantly (negatively) with the time since stroke at entry, but not with the severity of neurological impairment at entry. The volume, side and location (cortical or subcortical) of the infarct did not correlate with either the severity or the evolution of the motor deficit. Patients with a CT/MRI lesion of the parietal lobe (n = 8) showed a more severe motor deficit than those with other cortical locations. The severity of the motor deficit correlated significantly (negatively) with CBF values in the supplementary motor area (SMA) and parietal areas of the damaged hemisphere, and in the contralateral undamaged primary motor cortex. The degree of motor improvement correlated significantly (positively) with CBF values in the contralateral undamaged thalamus, lentiform and caudate nuclei, and premotor cortex. In the late phase of stroke, the severity of the motor deficit may be positively associated with the functional impairment of associative parietal and frontal areas of the damaged hemisphere. The functional impairment of the basal ganglia-frontal network in the undamaged hemisphere seems to be related to a poor, delayed motor recovery.