Early Abnormalities Related to Postinfarction Wallerian Degeneration: Evaluation with MR Diffusion-Weighted Imaging

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Abstract
Wallerian degeneration (WD) is most commonly seen after cerebral infarctions and results in persistent neurological deficits. MRI may detect changes related to WD as early as 4 weeks after the insult. We sought to determine if MR diffusion-weighted imaging (DWI) detects changes of WD during the acute period that follows a cerebral infarction. Eleven patients with cerebral infarctions underwent DWI within 72 h of the onset of symptoms. DWI was performed using a high diffusion gradient strength (B = 1,000) in a single axis and trace imaging. We reviewed all images with special attention to the signal intensity in the location of the corticospinal tracts. Ten patients harbored 11 middle cerebral artery (MCA) infarcts, and one patient had an anterior cerebral artery (ACA) infarction. Only one patient with an MCA infarct showed a subtle abnormality in the ipsilateral corticospinal tract. The patient with the ACA infarct showed an abnormality in the region of the corticopontine tract. As used in this study, DWI depicted presumed early WD in only 20% of instances.