Evolution of functional reorganization in hemiplegic stroke: A serial positron emission tomographic activation study

We used serial positron emission tomography (PET) to study the evolution of functional brain activity within 12 weeks after a first subcortical stroke , Six hemiplegic stroke patients and three normal subjects were scanned twi ce (PET 1 and PET 2) by using passive elbow movements as an activation para digm. Increases of regional cerebral blood flow comparing passive movements and rest and differences of regional cerebral blood flow between PET 1 and PET 2 in patients and normal subjects were assessed by using statistical p arametric mapping. In controls, activation was found in the contralateral s ensorimotor cortex, supplementary motor area, and bilaterally in the inferi or parietal cortex with no differences between PET 1 and PET 2. In stroke p atients, at PET 1, activation was observed in the bilateral inferior pariet al cortex, contralateral sensorimotor cortex, and ipsilateral dorsolateral prefrontal cortex, supplementary motor area, and cingulate cortex. Ar PET 2 , significant increases of regional cerebral blood flow were found in the c ontralateral sensorimotor cortex and bilateral inferior parietal cortex. A region that was activated at PET 2 only was found in the ipsilateral premot or area. Recovery from hemiplegia is accompanied by changes of brain activa tion in sensory and motor systems. These alterations of cerebral activity m ay be critical for the restoration of motor function.