Observing the time course of early long pyramidal tract Wallerian degeneration after acute ischemic stroke: a case report

A 75-year-old man was found lying prostrate in a hot room in the middle of summer. On admission, he had high fever, dehydration, and multiple decubitus, in addition to right hemiparesis and total aphasia. Brain CT showed subacute ischemic stroke in the territory of left middle cerebral artery. Brain MRI diffusion-weighted imaging (DWI) 4 days after admission detected high signal intensity lesions in the left pyramidal tract from the midbrain cerebral peduncle to the lower pons, indicating early Wallerian degeneration. The lesions were found to extend to the contralateral pyramidal decussation by MRI DWI day 12, but they had disappeared on day 28. On the other hand, brain MRI FLAIR images detected the lesions clearly day 44. Also, diffusion tensor tractography detects fewer left cerebral pyramidal tracts. No previous reports have documented the time course of such long Wallerian degeneration. This case suggests that dehydration may promote the onset of early and long Wallerian degeneration.