Effects of Subthalamic Nucleus Deep Brain Stimulation on Parkinsonian Resting Tremor : An MEG Study

Objective: The pathophysiological mechanisms of Parkinsonian movement disorders are still not fully understood. We have studied the MEG signals and EMG signals of the upper limbs during isometric motor task from a Parkinsonian patient who has undergone bilateral STN DBS implantation. We compared the EMG and MEG oscillatory patterns when the DBS was both 'On' from both isometric find the differences in the coherent frequencies between M1 and resting tremor EMG and associative powers. Method: Whole head MEG recordings and EMG were obtained from a 62 year old male patient in both DBS 'On' and 'Off'. Coherence and power were calculated in the frequency bands of 1-30Hz. Raw data were studied also. Results: M1 - EMG coherence in the rolandic area is prominent around 8Hz when DBS is 'Off'. Coherence diminishes when the DBS is 'On'. Raw data shows that regular tremor still exists when DBS is 'On'. Power spectrum is bigger in M1 than EMG when DBS is 'On', and vice versa when DBS is 'Off'. Conclusions: Although tremor still exists when DBS is 'On', seeing that the coherence has almost vanished between the M1-EMG, it is speculated that DBS effects the low-frequency M1-EMG synchronization which is thought to be responsible for the Parkinsonian resting tremor.