Remote depressions of cerebral metabolism in hemiparetic stroke: Topography and relation to motor and somatosensory functions

Depressions of regional cerebral glucose metabolism (rCMRGlu) as measured with positron emission tomography in 28 patients with first hemiparetic stroke were mapped anatomically and related to the involvement of the cortico‐spinal tract and the somatosensory pathway. Cortico‐spinal tract and somatosensory pathway status were examined by magnetic evoked motor potentials (MEP) and somatosensory evoked potentials (SSEP), respectively. Patients were grouped with respect to the stroke lesions as assessed by magnetic resonance images into striatocapsular, thalamocapsular, and corticosubcortical groups. In spite of identical clinical presentation, the topography of significant remote rCMRGlu depressions varied in the affected cerebral hemisphere among the three groups, involving also the contralateral hemisphere in the thalamocapsular and cortico‐subcortical group. The thalamus was the only area with a significant mean rCMRGlu depression in all groups, although it was structurally spared in striatocapsular and cortico‐subcortical strokes. The remote rCMRGlu depressions in the primary sensorimotor cortex were associated with significantly abnormal MEPs in striatocapsular stroke, while both the MEPs and SSEPs were significantly abnormal in the cortico‐subcortical group. Further, depressed rCMRGlu in the putamen of the lesion side and in the cerebellar hemisphere ipsilateral to the hemiparesis correlated with motor impairment. Our data suggest that, in addition to damage of the efferent cortico‐spinal or afferent somatosensory tract, impairment of other circuits may contribute to the severe hemiparesis initially observed after stroke. We hypothesize that the chronic remote rCMRGlu depressions described in the present study result from axonal damage interfering with connectivity patterns. © 1994 Wiley‐Liss, Inc.