December 15, 2014
A 55-year-old man with megaloblastic anemia, progressive weakness of lower limbs, gait disturbance, and ataxia
Subacute Combined Degeneration
- Subacute combined degeneration is an acquired myelopathy caused by vitamin B12 deficiency, and is a rare cause of demyelination of the dorsal columns of the spinal cord.
- Clinical Presentation: Profound neurologic déficits, including progressive sensory abnormalities, ascending paresthesias, weakness, ataxia, loss of sphincter control, and gait impairment. Megaloblastic anemia is a common early symptom leading to the diagnosis; although, neurologic symptoms may occur in the absence of haematologic abnormalities.
- Key Diagnostic Features:
- Symmetric increased signal seen on T2 and STIR images within the dorsal (and less commonly, lateral) columns: "inverted V" sign in axial plane.
- Mild mass effect and mild contrast enhancement may be present.
- DDx:
- Dorsal column myelopathy
- HIV myelopathy
- Nitrous oxide toxicity
- Copper deficiency
- Cyanide toxicity
- Spinal cord infarction
- Demyelination
- Other causes of transverse myelitis
- Rx: Vitamin B12 therapy
