The cortical excitability profile of patients with the G209A SNCA mutation versus patients with sporadic Parkinson's disease: A transcranial magnetic stimulation study.

Mutations in the α-synuclein gene are a rare cause of Parkinson's disease. We investigated, by single-pulse TMS, the cortical excitability profile of nine α-synuclein patients in comparison with 24 idiopathic PD patients, subdivided into "akinetic" (n=17) and "tremor-dominant" (n=7) subgroups. The comparative assessment of rest motor threshold, active MEP and Silent Period Input/Output curves indicated that the cortical excitability of α-Synuclein patients is similar to patients with the "akinetic" form of PD. Both groups of patients exhibited differences in excitatory and inhibitory brain circuits from "tremor-dominant" patients indicating that varying clinical phenotypes are associated with differential profiles of corticospinal excitability.