Transcranial magnetic stimulation for differential diagnostics in patients with parkinsonism

Objective - We investigated transcranial magnetic stimulation (TMS) parameters in patients with parkinsonism, particularly in the early stages of the disease. Subjects and methods - We performed TMS in 48 patients with PD, progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). We measured motor threshold (MT), latency (L), motor-evoked potential amplitude and central motor conduction time (CMCT) and cortical silent period (CSP). Furthermore, we selected and compared 27 patients with a disease duration of less than 3 years. Results - CMCT, MT, L and CSP were different among the three groups. Post hoc analyses revealed that CMCT and CSP were the shortest in PD, and that MT was significantly lower in PD than in MSA. In patients whose disease duration was less than 3 years, CMCT and CSP were different among the three groups. Post hoc analyses showed significantly shorter CMCT in PD. Conclusions - TMS can detect the pathophysiological difference among the groups in the early stages of the disease.