P043 Deep brain stimulation of Subthalamic nucleus and L-dopa modulate TMS-evoked cortical activity in Parkinson's disease patients. Issue 3 (March 2017)

• Record Type: Journal Article
• Authors: Casula, E.P.; Pellicciari, M.C.; Ponzo, V.; Bassi, M. Stampanoni; Veniero, D.; Peppe, A.; Brusa, L.; Stefani, A.; Koch, G.
• Is Part Of: Clinical neurophysiology. Volume 128:Issue 3(2017:Mar.)
• Page Start: e28
• Publication Date: 2017-03
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2016.10.169
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Question: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) represents an effective therapy in Parkinson's disease (PD). The effects of STN-DBS on cortical reactivity are still poorly understood. By combining transcranial magnetic stimulation (TMS) and electroencephalography (EEG), we explored the effects of STN-DBS either alone or in combination with levodopa (LD), on cortical activity evoked by TMS of the primary motor cortex (M1) in a sample of PD patients chronically treated with STN implantation. Methods: Six advanced PD patients treated with STN-DBS were tested in three clinical conditions on distinct days: (i) on therapy/on DBS; (ii) off therapy/on DBS; (iii) off therapy/off DBS. In each condition, 80 single TMS pulses were delivered over left M1 while simultaneously acquiring EEG. We evaluated TMS-induced changes in the time domain and in the time/frequency domain. Results: In the OFF/ON condition there was a significant increase of GMFP peaking at 60–70 ms (P2) compared to OFF/OFF condition. In ON/ON condition a significant increase of GMFP peaking at 60–70 ms (P2) and at 100 ms (P3) was observed compared to OFF/OFF condition. Time/frequency analysis showed a synchronization of activity in the 10–17 Hz range over central-posterior region within the P2 time window in the OFF/ON condition compared to OFF/OFF. The same analysis conducted on the P3 time window revealed a synchronization of activity in the 11–16 Hz range of frequency over central regions when comparing OFF/ON condition to ON/ON. Conclusions: Our data reveal that bilateral STN-DBS induces a significant modulation of cortical global reactivity at early components. The association of LD therapy produces additional distinct modulation of later components. These findings could be related to cortical induced modulation of GABAergic intracortical activity.