Subacute Combined Degeneration

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Diagnosis & Tests

An examination usually shows symmetrical sensorimotor polyneuropathy, with muscle weakness and sensation disturbance. Reflexes are often abnormal. Muscles may develop spasticity. There is a loss of position sense (awareness of body position) and sense of touch, pain, and temperature may be diminished.

Mental changes are variable, from mild forgetfulness to complete dementia or psychosis. Severe dementia is uncommon, but in some cases, it is the initial symptom of the disorder. An eye examination may indicate damage to the optic nerve (optic neuritis), with abnormal pupil responses, inflammation or atrophy of the optic nerve (visible on retinal exam), decreased visual acuity, and other changes.

• CBC (complete blood count) may show anemia. If folic acid has been used to treat anemia, neurologic symptoms may develop even if the anemia is no longer evident and this may make diagnosis difficult.
• Serum (blood) levels of vitamin B-12 are low.