Comparison of corticospinal tract and extrapyramidal motor system involvement in patients with Wilson's disease

Introduction: Wilson's disease is a rare autosomal recessive disorder of hepatic copper transport characterized by varying hepatic and extrapyramidal motor symptoms. Clinical signs of corticospinal tract involvement are rare. Materials: To elucidate corticospinal tract involvement in Wilson's disease motor evoked potentials (MEP) were recorded in 34 patients undergoing long-term treatment with diagnosed Wilson's disease (25 with a neurological and 9 with a non-neurological form). Results: 5 patients with a neurological form exhibited clinical signs of corticospinal tract involvement. However, motor evoked potentials revealed corticospinal tract abnormalities with delayed latencies in 12 patients with a neurological form. In patients with a non-neuro logical form there were almost no abnormalities in MEP. In patients with a neurological form of Wilson's disease, abnormalities of motor evoked potentials are characterized by delayed latencies more than by loss of amplitudes. Discussion: These results explain that corticospinal tract involvement occurs in the absence of clinically apparent central paresis because axonal damage is not present. The delay of latencies correlates with the degree of extrapyramidal involvement but not with the extent of clinical impairment. Conclusion: While extrapyramidal motor involvement is caused by neuronal death following copper intoxication in basal ganglia, the corticospinal tract abnormalities could be explained more by a glial pathology due to hepatic failure.