Images in Clinical Medicine
Kim Eagle, M.D., Editor
Wallerian Degeneration of the Pyramidal Tract
N Engl J Med 1994; 331:88July 14, 1994
- Article
Figure 1 Wallerian Degeneration of the Pyramidal Tract.
Coronal views of the brain of a 41-year-old man with the acquired immunodeficiency syndrome and right-sided spastic hemiplegia, aphasia, and hemianopia were obtained by magnetic resonance imaging (MRI) eight months after the patient had an intracerebral hemorrhage. The consecutive T2 weighted coronal MRI slices show the old hematoma as an irregular lesion, which is hypointense because of hemosiderin deposition; dilatation of the left lateral ventricle is also evident. In addition, a long band of increased signal intensity traces the anatomical course of the pyramidal tract from the lesion in the internal capsule (left panel, solid arrow) down to the left cerebral peduncle (open arrow), reaching the pons (arrowhead) and the medulla oblongata (right panel, curved arrow). This finding is compatible with wallerian degeneration of the pyramidal tract. Wallerian degeneration is the descending destruction of axons and myelin sheaths resulting from neuronal damage, such as that due to ischemic infarction or hemorrhage. The degeneration leads to an increase in extracellular water, producing increased signal intensity on T2 weighted MRI scans.
Kim Eagle, M.D.
Johan A. Dol, M.D.
Elisabeth S. Louwerse, M.D.
Academic Medical Center, 1105 AZ Amsterdam, the Netherlands
