26B. Subacute combined degeneration of the spinal cord

Subacute combined degeneration of the spinal cord, also called funicular myelosis, is a degeneration of the dorsal and lateral white matter of the spinal cord which occurs due to chronic B12 deficiency. Some conditions, like chronic nitrous oxide abuse, can cause a functional B12 deficiency.

The spinocerebellar, lateral corticospinal, and dorsal columns are affected.

Clinical features

The patient has loss of deep sensation, vibration, and position sense. Sensory ataxia is also present.

Diagnosis and evaluation

Megaloblastic anaemia may be present, as well as low serum B12 and high MMA and homocysteine.

Treatment

Treatment is B12 supplementation. It may take a long time for the symptoms to improve, and they may not completely resolve.