Presentation
Progressive weakness of the lower limbs.
Patient Data
Bilateral and relatively symmetrical and continuous high T2 signal within the dorsal columns and lateral corticospinal tracts involving the entirety of the spinal cord up to the conus medullaris. No enhancement seen on postcontrast sequences.
Case Discussion
MRI features are highly suggestive of subacute combined degeneration of the cord, involving the dorsal columns and corticospinal tracts, the latter presumably accounting for the patient's weakness. In this case, the serum vitamin B12 was normal, but there was a high homocysteine level.
The subacute combined degeneration of the cord is secondary to vitamin B12 deficiency. However, the vitamin B12 level may be normal in up to 30% of patients, and in such cases other more sensitive and specific biomarkers may be used:
- holotranscobalamin or active vitamin B12 (low)
- methylmalonic acid (high)
- homocysteine (high)
Additional contributor: ZE, Boudiaf, MD
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