Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 4, 2011, pp. 630-631

Neurology India, Vol. 59, No. 4, July-August, 2011, pp. 630-631

Letter to Editor

An unusual case of copper myelopathy

Dinesh Singh¹, Sourya Acharya¹, Abhishek Vikram Singh¹, Sachin Parakh¹, Pankaj Banode²

¹ Department of Medicine, J.N. Medical College/DMIMSU, Sawangi (M), Wardha, India
² Department of Radiology, J.N. Medical College/DMIMSU, Sawangi (M), Wardha, India
Correspondence Address: Sourya Acharya, Department of Medicine, J.N. Medical College/DMIMSU, Sawangi (M), Wardha, India, souryaacharya@yahoo.co.in

Date of Submission: 30-Apr-2011
Date of Decision: 03-May-2011
Date of Acceptance: 01-May-2011

Code Number: ni11188

PMID: 21891951

DOI: 10.4103/0028-3886.84355

Sir,

Copper is a component of numerous metalloenzymes and proteins maintaining the structure and function of the nervous system. Its wide distribution in foods and low daily requirement makes dietary deficiency unusual. Hypocuprism can present as myeloneuropathy and resembles subacute combined degeneration (SACD) both clinically and radiologically. ^[1] The literature on copper myeloneuropathy due to hypcuprism is limited. ^[2]

A 35-year-old female presented with 2 years history of progressive gait ataxia more at night, with numbness in both lower limbs and hands. Her past history was insignificant. Drug history suggested intake of multivitamins containing chromium, selenium, and zinc over a period of 4 years. She was pale and neurological examination revealed spasticity in both the lower limbs, hyperreflexia in both upper and lower limbs with absent ankle reflexes. The vibration sense was impaired up to the iliac spine bilaterally; the joint position sense was impaired up to the ankle joint in the lower limbs and finger movements in the upper limbs. Both plantars were extensors. She had a spastic ataxic gait with positive rombergism. Investigations: hemoglobin 7.7 gm/dL, MCV 100/uL, WBC 3800 mm ³ , normal platelet count, and normal renal and liver profile. Serum iron studies and B12 levels were normal. Serology for HIV was negative. Magnetic resonance imaging (MRI) of spine revealed non enhancing contiguous hyperintense signal in the posterior columns of the cervical cord from C1-C6 suggesting degeneration [Figure - 1]. Nerve conduction studies showed axonal type of sensori-motor neuropathy in the lower limbs. Serum copper was 40 ug/dL (80-155 ug/dL) and serum zinc was 188 ug/dL (70-150 ug/dL). Multivitamins were stopped. Oral copper supplementation equivalent to 8 mg of elemental copper per day resulted in prompt hematological recovery but without functional improvement after 2 months of follow-up.

Copper is a micronutrient essential for the function of the nervous system and bone marrow as a prosthetic group in many key enzymes, including cytochrome oxidase, superoxide dismutase, dopamine hydroxylase, and methionine synthase. ^[1] Copper deficiency myeloneuropathy is a distinct entity, but rarely recognized. It presents as a progressive syndrome with clinical, electrophysiological, and radiographic evidence of myelopathy with predilection for the posterior columns and corticospinal tracts resembling SACD due to vitamin B12 deficiency. ^[2] Reduction in cytochrome oxidase activity is the likely basis for neurological dysfunction associated with the copper deficiency. Causes of copper deficiency include malnutrition, prematurity, parenteral, or enteral feeding without copper supplementation, gastrectomy, ingestion of copper-chelating agents, and excessive zinc therapy. ^[3]

Hyperzincemia in our patient may be due to prolonged intake of zinc containing multivitamin. Zinc induces the expression of the intracellular chelator metallothionein in enterocytes. Copper has a higher affinity for metallothionein, and thus displaces zinc from metallothionein. Copper remains bound in the enterocytes which are then sloughed into the lumen and eliminated causing hypocupremia. Treatment involves stopping excessive zinc intake, and administering copper supplements. Oral supplementation is more practical than parenteral supplements. The neurological progression can only be halted but not reversed. Where neurological recovery occurs, it tends to be limited to a subjective improvement in sensory symptoms. Prompt recognition is essential, as early institution of therapy might prevent neurological deterioration. ^[3],[4]

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