Tractography of persistent ipsilateral hemiparesis following subdural hematoma.

lesion or by secondary damage to the cerebral peduncle contralateral to the lesion, a so-called Kernohan-Woltman notch phenomenon (KWNP). A possible mechanism of ipsilateral hemiparesis is that morphological changes in the brainstem associated with KWNP are accompanied by irreversible damage to the adjacent corticospinal tract (CST).1-3 A few reports dealing with the acute and sub-acute stages of this paradoxical phenomenon have appeared in the literature.1,2,4,5 In the case reported here, the patient presented with longstanding ipsilateral hemiparesis following traumatic subdural hematoma 16 years previous. We investigated and visualized using fiber tractography (FT) permanent reconfiguration of the CST contralateral to the lesioned side with midbrain atrophy.