Hypoperfusion without stroke alters motor activation in the opposite hemisphere, Annals of Neurology 56

To specifically investigate the effect that large-vessel disease may have on cortical reorganization, we used functional magnetic resonance imaging to study patients with unilateral hemispheric hypoperfusion and impaired vasomotor reac-tivity from critical internal carotid or middle cerebral artery disease but without stroke. We hypothesized that when these patients used the hand contralateral to the hypoperfused hemisphere they would show unique activation in motor-related areas of the normally perfused hemisphere, that is, ipsilateral activation. We found that normal performance of two motor tasks was associated with increased ipsilateral hemispheric activation in the patients compared with age-matched controls. In addition, although task difficulty had an effect on ipsilateral activation, the increased ipsilateral activation seen in patients was not dependent on task difficulty. Our findings demonstrate that hemodynamic compromise alone is sufficient to cause atypical ipsilateral activation. This activation may serve to maintain normal motor performance. Ann Neurol 2004;56:796–802 Over the past decade, functional brain imaging has been used increasingly to investigate mechanisms of motor recovery after stroke. A consistent finding in the earlier studies was that patients showed prominent ac-tivation in the ipsilateral hemisphere during the execu