Neural substrates of good and poor recovery after hemiplegic stroke: a serial PET study

In this study, we used positron emission tomography (PET) at two different time points to study the temporal evolution of reorganization in patients with good and those without motor recovery from hemiplegia after the occurrence of a stroke. Ten hemiplegic patients with a first subcortical stroke and five healthy control subjects were scanned during passive and active movements at an interval of 8 weeks. PET1 was performed 22.8 ± 7.8 days after the index stroke. At PET2, 8 weeks later, patients were dichotomized to either good recovery or no recovery according to the upper extremity motor component of the Fugl-Meyer score. Increases of regional cerebral blood flow (rCBF) and comparison between groups at PET1 and PET2 were assessed using statistical parametric mapping. At PET 1, activation was found bilaterally in the inferior parietal cortex. Eight weeks later, patients with good recovery showed maximum activation in the contralateral primary somatosensory cortex and overactivation of the contralateral inferior parietal cortex. Patients with poor recovery showed bilateral activation with a maximum in the somatosensory cortex. Studies correlating activation patterns with quality of recovery may identify the neuroanatomical substrates that subserve improved motor function. Such studies may also guide the development of more effective rehabilitative interventions after the occurrence of stroke.