Copper deficiency myelopathy produces a clinical picture like subacute combined degeneration.

BACKGROUND

Copper deficiency in ruminants is known to cause an ataxic myelopathy. Copper deficiency as a cause of progressive myelopathy in adults is underrecognized.

OBJECTIVE

To describe the clinical, biochemical, electrophysiologic, and imaging characteristics in 13 patients with myelopathy associated with copper deficiency.

METHODS

The records of patients with a copper deficiency-associated myelopathy were reviewed. Clinical characteristics, laboratory investigations, and responses to therapeutic intervention were summarized.

RESULTS

Thirteen such patients were found, 11 of them in a 15-month period. All patients presented with prominent gait difficulty, reflecting a sensory ataxia due to dorsal column dysfunction and lower limb spasticity. All patients had polyneuropathy. A high or high-normal serum zinc level was seen in 7 of the 11 patients for whom this information was available. Somatosensory evoked potential studies done in eight patients showed impaired conduction in central proprioceptive pathways. Dorsal column signal change on spine MRI was present in three patients. An initial clue to the diagnosis was a very low ceruloplasmin level; further tests of copper metabolism excluded Wilson disease. The cause remained unexplained in most patients. Oral copper supplementation restored normal or near-normal copper levels in 7 of the 12 patients in whom adequate follow-up data were available; parenteral supplementation restored normal level in 3 further patients. Copper supplementation prevented further neurologic deterioration, but the degree of actual improvement was variable.

CONCLUSIONS

Unrecognized copper deficiency appears to be a common cause of idiopathic myelopathy in adults. The clinical picture bears striking similarities to the syndrome of subacute combined degeneration associated with vitamin B12 deficiency. Early recognition and copper supplementation may prevent neurologic deterioration.