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Worsening of Ipsilateral Hemiparesis After Recurrent Stroke

Recurrent stroke in the opposite hemisphere from the first stroke can worsen the original hemiparesis, providing insights about poststroke brain reorganization.

These authors report three cases in which a recurrent stroke in the hemisphere opposite the original stroke unexpectedly caused worsening of hemiparesis ipsilateral to the recurrent stroke. The hemiparesis had resulted from an earlier stroke due to cerebral large-vessel disease. In all cases, the recurrent stroke did not produce contralateral hemiparesis because the recurrent stroke was small-sized (lacunar), was localized in the "extrapyramidal" motor pathway (including the thalamus, globus pallidus, and corona radiata), and spared the internal capsule. The authors speculate that the extrapyramidal motor pathway connected to the uncrossed cerebrospinal tract (CST) ipsilateral to the hemiparesis had been reorganized after the first stroke and contributed to the recovery from the initial hemiparesis. They further speculate that the recurrent stroke may damage this pathway and cause ipsilateral worsening of the hemiparesis.

Comment: Worsening of hemiparesis caused by a recurrent stroke that occurs in the hemisphere opposite to an initial stroke has been reported previously and, thus, may not be a rare event. One of the most plausible explanations could be that damage to the uncrossed CST ipsilateral to the hemiparesis contributes to hemiparesis exacerbation. Reorganization of the contralateral cortical motor area after a stroke has been demonstrated using recently developed modalities, such as functional MRI. Therefore, an emerging concept is that the uncrossed CST may be intensified as a compensatory mechanism during stroke recovery. In this context, the authors could have used functional MRI to examine whether cortical reorganization had occurred in their patients.

The phenomenon of hemiparesis exacerbation after recurrent stroke has two important implications. First, if a second stroke occurring in the opposite hemisphere is large enough to damage some crossed as well as uncrossed CST fibers, it would cause contralateral hemiparesis as well as worsen the ipsilateral hemiparesis. Physicians should be aware of this possibility and correctly evaluate changes in the severity of the existing hemiparesis, because the worsening of ipsilateral hemiparesis could easily be missed. Second, ipsilateral exacerbation caused by a recurrent stroke indirectly suggests that, after an initial stroke, reorganization can take place in the unaffected hemisphere. Elucidating the molecular mechanism of the cortical reorganization and identifying medications or rehabilitation techniques to facilitate this process may be very important to aid functional recovery of stroke patients.

— Tetsuro Ago, MD, PhD

Dr. Ago is a Fellow at the Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine & Dentistry of New Jersey, New Jersey Medical School, Newark.

Published in Journal Watch Neurology April 10, 2007

Citation(s):

Yamamoto S et al. Deterioration of hemiparesis after recurrent stroke in the unaffected hemisphere: Three further cases with possible interpretation. Cerebrovasc Dis 2007 Jan; 23:35-9.

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