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[A case with pyramidal tract lesion suggesting Wallerian degeneration--analysis with diffusion coefficient]
Abstract:
We reported a 55-year-old man, whose T2-weighted MR images disclosed abnormal high signal band along the left pyramidal tract 6 months after cerebral infarction of the left centrum semiovale. Brain CT revealed low intensity areas in the centrum semiovale, the posterior limb of the internal capsule on left side. On T2-weighted MR images, there were an irregular high signal area on the left centrum semiovale, a high signal band from the left centrum semiovale to the medullary pyramid, and a high signal band from the left centrum semiovale to the cerebral cortex. These lesions were observed as high signal areas on proton weighted images and low signal areas on T1-weighted MR images. Diffusion coefficient perpendicular to the pyramidal tract in the patient, which was calculated from diffusion weighted images at the posterior limb of the internal capsule, was higher than that in normal individuals. Diffusion anisotropy at the lesion, which is the rate between the diffusion coefficient parallel and perpendicular to nerve fiber, was higher than that of normal individuals. These data suggested that the lesion had demyelinating process, which was consistent with the pathology at stage 2 of the Wallerian degeneration.
Insights
This study details a case of Wallerian degeneration in a 55-year-old man following a cerebral infarction. MRI and CT scans revealed demyelination along the pyramidal tract, consistent with advanced degeneration.
Area of Science:
- Neuroimaging
- Neuropathology
Background:
- Cerebral infarction can lead to secondary degeneration of white matter tracts.
- Wallerian degeneration is a process of axonal and myelin breakdown distal to an injury.
Observation:
- A 55-year-old male presented with imaging findings 6 months post-left centrum semiovale infarction.
- T2-weighted MRI showed abnormal high signal intensity along the left pyramidal tract, extending from the centrum semiovale.
- CT revealed hypodensities in the left centrum semiovale and posterior limb of the internal capsule.
Findings:
- MRI demonstrated lesions consistent with demyelination, including high signal on T2/proton-weighted and low signal on T1-weighted images.
- Diffusion tensor imaging revealed increased diffusivity perpendicular to the pyramidal tract and altered diffusion anisotropy.
- These imaging characteristics suggest stage 2 Wallerian degeneration.
Implications:
- This case highlights the utility of advanced MRI techniques in characterizing white matter degeneration.
- Understanding the imaging patterns of Wallerian degeneration is crucial for diagnosing and managing post-stroke complications.
- The findings contribute to the neuropathological understanding of secondary tract degeneration.