Subacute combined degeneration of the cord

Case Discussion

Subacute combined degeneration of the cord (SACD) is a myelopathy that is a neurological consequence of hypovitaminosis B12 ¹. It results in the degeneration of the dorsal columns, lateral corticospinal, and lateral spinothalamic tracts of the spinal cord ².

The initial symptoms are usually paresthesia in the extremities, and numbness which may further progress to sensory loss, unsteady gait, distal weakness, predominantly in the legs, and bladder or bowel dysfunction ^2,3. It can lead to ataxic paraplegia if left untreated ^2,3.

MRI findings of SACD are characterized by dorsal spinal cord hypointensity on T1W images and hyperintensity on T2W images which correspond with the demyelination. On sagittal images, there is a minimal widening of the affected spinal cord with increased signal intensity on T2W images for a variable segment at the posterior aspect ⁴. On axial images, paired T2 hyperintensities are seen bilaterally as “inverted V” or “inverted rabbit ears” patterns in the expected anatomic location of the dorsal columns ^2,3.

The differential diagnosis of bilateral dorsal column myelopathy includes infarction of spinal cord, infectious and inflammatory demyelination including multiple sclerosis, acute disseminated encephalomyelitis (ADEM), and neoplasm ⁴.

On suspicion, the treatment with intramuscular injections of vitamin B12 should be started promptly to prevent any irreversible damage to neurons ^1,3. Indeed, this patient recovered with such therapy.