VERY EARLY DEMONSTRATION OF SECONDARY PYRAMIDAL TRACT DEGENERATION BYCOMPUTED-TOMOGRAPHY

Background While magnetic resonance imaging has revealed progressive c hanges in the pyramidal tract in accordance with histopathologic stage s of wallerian degeneration secondary to a supratentorial lesion, comp uted tomography (CT) has only demonstrated a shrinkage of the pyramida l tract in the midbrain or pens during the chronic stage. We present a patient with frontoparietal subcortical hemorrhage in whom serial CT scans clearly demonstrated wallerian degeneration along the axis of th e pyramidal tract early in the acute stage. Case Description A 63-year -old man with a history of hypertension suddenly developed a deteriora tion of consciousness, transcortical mixed aphasia, and dense hemipleg ia on the right side. CT scans revealed a massive intracerebral hemato ma in the frontoparietal subcortices of the left hemisphere. Although initial CT did not detect any hypodense areas along the left pyramidal tract below the hematoma, ill-defined areas of decreased density appe ared in the posterior limb of the internal capsule, cerebral peduncle of the midbrain, and pontine base of the left side on day 13 after the stroke. These areas became well demarcated on day 22 and persisted th ereafter. Conclusions An extensive hematoma can interrupt the pyramida l tract fibers that arise not only from the motor cortex and caudal pr emotor cortex but also from the somatosensory and parietal cortices, a llowing very early CT demonstration of wallerian degeneration of the p yramidal tract.