Motor impairment in Wilson's disease. 3: The clinical impact of pyramidal tract involvement

Magnetic brain stimulation was performed on 24 patients with Wilson's disease (WD). Responses to the right and left first dorsal interosseus muscle (FDI) and to the right and left tibialis anterior muscle (TA) were analysed. In 45% of the patients prolonged central motor conduction times (CCTs) to the FDIs were found, whereas only 12% of the patients presented with prolonged CCTs to the TA muscles. No consistent significant correlations between copper metabolism and pyramidal tract function tested by magnetic brain stimulation were found. An improvement of CCTs and response amplitudes with copper elimination therapy was observed only at early phases of therapy. There was no correlation with duration of therapy or neurological symptoms. Thus magnetic brain stimulation turns out to be sensitive to detect subclinical pyramidal tract impairment in WD but seems to test a too specific aspect of motor impairment in WD to reflect the overall neurological status of the patients. Therefore, it has to be combined with other tests to be used for therapy control.