Thalamic metabolism and corticospinal tract integrity determine motor recovery in stroke

We studied the role of remote metabolic depressions and pyramidal tract involvement regarding motor recovery following a first hemiparetic ischemic stroke. In 23 patients the regional cerebral glucose metabolism (rCMRGlu) was measured with positron emission tomography and the location and spatial extent of the stroke lesions were assessed by magnetic resonance imaging. Motor impairment during the acute and chronic stages (4 weeks after stroke) was determined by a motor score and recordings of magnetic evoked motor potentials. Twelve patients recovered significantly, whereas 11 patients retained a disabling hemiparesis. In contrast to patients with good motor recovery, rCMRGlu was severely depressed in the thalamus on the lesion side in patients with poor motor recovery. This patient group also showed more severe damage to the pyramidal tract on magnetic resonance images and a more pronounced reduction of the magnetic evoked motor potential amplitude. Neither the size of the stroke lesions nor the spatial extent of the lesional and remote rCMRGlu depressions outside the thalamus correlated with the thalamic hypometabolism and the improvement of the motor score. We conclude that preservation both of parts of the pyramidal tract and of the thalamic circuitry is a major determinant for the quality of hand motor recovery following acute brain ischemia in the adult.