Characterization of nerve biopsy in copper deficiency peripheral neuropathy due to over-treatment of Wilson's disease: A case report.

Background: Copper deficiency peripheral neuropathy caused by excessive treatment in Wilson's disease has been reported. But its pathological characteristics are rarely reported. Here, we report a case of copper deficiency peripheral neuropathy in Wilson's disease and present the characteristics of its nerve biopsy.

Case description: A 44-year-old female patient diagnosed with Wilson's disease was on long-term oral administration of zinc gluconate and copper chelators. In June 2022, she developed symptoms of peripheral neuropathy, accompanied by anemia and neutropenia. The 24-hour urinary copper excretion was 53.85 µg. Serum copper was 66.6 µg/L, and ceruloplasmin was 0.01 g/L. Electromyography showed length-dependent axonal damage in peripheral nerves. Sural nerve biopsy showed mainly axonal damage and decreased density of nerve fibres of all classes (large and small myelinated and unmyelinated), accompanied by demyelination. Ultimately, the diagnosis of copper deficiency peripheral neuropathy caused by excessive treatment of Wilson's disease was established. After discontinuing copper chelation therapy, she experienced mild alleviation of symptoms.

Conclusion: The pathological features of copper deficiency peripheral neuropathy in Wilson's disease include the formation of axonal vacuoles, the presence of myelin ovoids, and a reduced number of large and small myelinated and unmyelinated nerve fibers. This case emphasizes the importance of monitoring copper metabolism during the stable phase of treatment for patients with Wilson's disease.