Motor Evoked Potentials in Newly Diagnosed and Treated Patients With Wilson Disease

To investigate whether patients with Wilson disease have abnormal motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation.

In a prospective, observational, single-center study, transcranial magnetic stimulation was used to examine MEPs recorded from the abductor digiti minimi in 24 newly diagnosed treatment-naive patients and 21 treated patients with Wilson disease.

Motor evoked potentials were recorded in 22 (91.7%) newly diagnosed treatment-naive patients and in 20 (95.2%) treated patients. Abnormal MEP parameters were found in a similar proportion of newly diagnosed and treated patients: MEP latency (38% vs. 29%), MEP amplitude (21% vs. 24%), central motor conduction time (29% vs. 29%), and resting motor threshold (68% vs. 52%). Abnormal MEP amplitude (P = 0.044) and resting motor threshold (P = 0.011) were more frequent in treated patients with brain MRI abnormalities but not in newly diagnosed patients. We did not observe significant improvement in MEPs parameters after 1 year of treatment introduction in eight examined patients. However, in one patient where MEPs were initially nondetectable, they were present 1 year after treatment introduction with zinc sulfate, although MEPs were not in the normal range.

Motor evoked potential parameters did not differ between newly diagnosed and treated patients. There was no significant improvement in MEP parameters one year after treatment introduction. Further studies conducted on large cohorts are necessary to determine the usefulness of MEPs in detecting pyramidal tract damage and improvement after anticopper treatment introduction in Wilson disease.