Changes in processing of proprioceptive information in Parkinson’s disease and multiple system atrophy

Objective Changes in processing of proprioceptive information are known in idiopathic Parkinson’s disease (IPD) and may contribute to motor deficits. This study used transcranial magnetic stimulation (TMS) to investigate the processing of proprioceptive information induced by muscle vibration (MV) in 10 patients with IPD and 10 patients with multiple system atrophy of the parkinsonian type (MSA-P) in comparison to 10 controls. Methods Single and paired-pulses were used, and motor evoked potentials (MEPs) were recorded in the extensor and flexor carpi radialis muscles (ECR and FCR) without and with MV (80 Hz) to the ECR. Cortical silent periods (SP) were also studied. Results Controls showed the known MV-induced focal MEP augmentation which was lacking in IPD and intermediate and less focal in MSA-P. Intracortical inhibition and facilitation were not influenced by MV. SP was not changed by MV in controls and IPD while it was significantly prolonged in MSA-P. Conclusions Processing of proprioceptive information is differently changed in IPD and MSA-P. Cortical facilitation by MV is more impaired in IPD than MSA-P, and these changes are less focal in MSA-P than in controls. Significance Our results support the view that changes in processing of proprioceptive information may contribute to motor deficits in patients with IPD and MSA-P.