Deterioration of hemiparesis after recurrent stroke in the unaffected hemisphere: Three further cases with possible interpretation

Background: The concept of neural reorganization after brain damage is already well established, and many previous studies have successfully reported the translocation of the neural activation in the motor-related cortices during motor tasks using functional imaging modalities. Several primate and human studies have suggested the formation of newly reorganized tracts in the ipsilesional or contralesional hemisphere, but the mechanism for the formation of these tracts is still largely unknown. Methods: Three acute stroke patients who presented with abrupt deterioration of their right-sided hemiparesis due to the infarcts following a recurrent stroke in the originally unaffected hemisphere were studied using magnetic resonance imaging ( MRI), MR angiography and single- photon emission CT. The relationship between the neurological symptom on admission and the precise location of the new infarct was carefully investigated from the perspective of reorganization. Results: Diffusion-weighted MRI showed a new subcortical infarct in the right hemisphere contralateral to the initial stroke in all patients. These new lesions involved the thalamus, globus pallidus or corona radiata, sparing the area of the internal capsule. T-2-weighed MRI on admission showed an old infarct in the left middle cerebral artery territory, which had caused the original right-sided hemiparesis. Conclusion: It is proposed that the 'extrapyramidal' motor pathway in the unaffected hemisphere is associated with poststroke neural reorganization. Copyright (c) 2007 S. Karger AG, Basel