MEP latency shift after implantation of deep brain stimulation systems in the subthalamic nucleus in patients with advanced Parkinson's disease.

Deep brain stimulation (DBS) into the subthalamic nucleus (STN) is a highly effective treatment for advanced Parkinson's disease (PD). The consequences of STN stimulation on intracortical and corticospinal excitability have been addressed in a few studies using transcranial magnetic stimulation (TMS). Although excitability measurements were compared between the STN stimulation OFF and ON condition, in these experiments, there are no longitudinal studies examining the impact of electrode implantation per se on motor excitability. Here, we explored the effects of STN electrode implantation on resting motor thresholds (RMT), motor evoked potential (MEP) recruitment curves, and MEP onset latencies on 2 consecutive days before and shortly after STN surgery with the stimulator switched off, thus avoiding the effects of chronic DBS on the motor system, in 8 PD patients not taking any dopaminergic medication. After surgery, RMT and MEP recruitment curves were unchanged. In contrast, MEP onset latencies were significantly shorter when examined in relaxed muscles but were unchanged under preactivation. We hypothesize that postoperatively TMS pulses induced small currents in scalp leads underneath the TMS coil connecting the external stimulator with STN electrodes leading to inadvertent stimulation of fast-conducting descending neural elements in the vicinity of the STN, thereby producing submotor threshold descending volleys. These "conditioning" volleys probably preactivated spinal motor neurons leading to earlier suprathreshold activation by the multiple corticospinal volleys produced by TMS of the motor cortex. These TMS effects need to be considered when interpreting results of excitability measurements in PD patients after implantation of STN electrodes.

Hidding U ，Bäumer T ，Siebner HR ，Demiralay C ，Buhmann C ，Weyh T ，Moll C ，Hamel W ，Münchau A ... -  《MOVEMENT DISORDERS》

The nature and time course of cortical activation following subthalamic stimulation in Parkinson's disease.

Kuriakose R ，Saha U ，Castillo G ，Udupa K ，Ni Z ，Gunraj C ，Mazzella F ，Hamani C ，Lang AE ，Moro E ，Lozano AM ，Hodaie M ，Chen R ... -  《-》

Effects of DBS, premotor rTMS, and levodopa on motor function and silent period in advanced Parkinson's disease.

Bäumer T ，Hidding U ，Hamel W ，Buhmann C ，Moll CK ，Gerloff C ，Orth M ，Siebner HR ，Münchau A ... -  《-》

Effects of subthalamic nucleus stimulation on motor cortex excitability in Parkinson's disease.

Fraix V ，Pollak P ，Vercueil L ，Benabid AL ，Mauguière F ... -  《-》

Single pulse stimulation of the human subthalamic nucleus facilitates the motor cortex at short intervals.

Hanajima R ，Ashby P ，Lozano AM ，Lang AE ，Chen R ... -  《JOURNAL OF NEUROPHYSIOLOGY》