Wilson's disease: normalisation of cortically evoked motor responses with treatment.

A newly diagnosed patient with Wilson's disease is reported in whom the only clearly pathological neurophysiological findings before treatment were abnormal electromyographic (EMG) responses evoked by transcranial magnetic brain stimulation. Serial examinations over 10 months following commencement of treatment with D-penicillamine revealed normalisation of EMG responses. Pathophysiologically, the initially abnormal EMG responses probably resulted from reversible impairment of impulse propagation along cortico-motor-neuronal pathways and/or a reduced excitability of cortical cells due to impaired function of the basal ganglia.