The role of diaschisis in stroke recovery

Background and Purpose-Recovery from hemiparesis after stroke has been show n to involve reorganization in motor and premotor cortical areas. However, whether poststroke recovery also depends on changes in remote brain structu res, ie, diaschisis, is as yet unresolved. To address this question, we stu died regional cerebral blood now in 7 patients (mean+/-SD age, 54+/-8 years ) after their first hemiparetic stroke. Methods-We analyzed imaging data voxel by voxel using a principal component analysis by which coherent changes in functional networks could be disclos ed. Performance was assessed by a motor score and by the finger movement ra te during the regional cerebral blood flow measurements. Results-The patients had recovered (P<0.001) from severe hemiparesis after on average 6 months and were able to perform sequential finger movements wi th the recovered hand. Regional cerebral blood flow at rest differentiated patients and controls (P<0.05) by a network that was affected by the stroke lesion. During blindfolded performance of sequential finger movements, pat ients were differentiated from controls (P<0.05) by a recovery-related netw ork and a movement-control network. These networks were spatially incongrue nt, involving motor, sensory, and visual cortex of both cerebral hemisphere s, the basal ganglia, thalamus, and cerebellum. The lesion-affected and rec overy-related networks overlapped in the contralesional thalamus and extras triate occipital cortex. Conclusions-Motor recovery after hemiparetic brain infarction is subserved by brain structures in locations remote from the stroke lesion. The topogra phic overlap of the lesion-affected and recovery-related networks suggests that diaschisis may play a critical role in stroke recovery.