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Abstract

Two patients with congenital hemiparesis (#5 and #7 in reference1) showed a striking discrepancy between large, pre- and perinatally acquired middle cerebral artery infarctions and relatively preserved sensorimotor functions. Despite the large cystic lesions, the affected hemispheres possessed spino-thalamo-cortical somatosensory afferents as well as cortico-spinal motor efferents. This was shown by magnetoencephalography during repetitive tactile finger stimulation and focal transcranial magnetic stimulation. Accordingly, magnetic resonance (MR) diffusion tensor tractography2 (figure) visualized numerous trajectories passing through the narrow bridge of preserved white matter between the lateral ventricle and the infarcted area, providing extensive structural connectivity of fronto-parietal areas with the brainstem and the cerebellum. Although these findings are suggestive of a superior reorganizational capability of the developing human brain, further studies (including tractography data from patients with similar lesions acquired later in life) will be needed to clarify this point.