The effect of deep brain stimulation on the frontal N30 component of somatosensory evoked potentials in advanced Parkinson's disease patients

Objectives: In the present study we investigated whether in advanced Parkin son's disease (PD) patients the frontal component of short somatosensory ev oked potentials (SEPs) to median nerve stimulation may be modified by basal ganglia deep brain stimulation (DBS). Methods: We recorded the SEPs in 6 PD patients undergoing bilateral functio nal neurosurgery in the internal globus pallidus (GPi) (4 patients) and in the nucleus subthalamicus (STN) (two patients) during ineffective and effec tive bilateral BDS. Pre-operatively, the SEPs were also recorded in off the rapy and during apomorphine infusion. Results: From the evaluation of the latency and the amplitude characteristi cs of the major parietal (N20 and P25) and frontal (N30) components, we obs erved that whereas the parietal waves did not vary in any condition, the N3 0 potential showed a remarkable amplitude increase during apomorphine as we ll as during effective bilateral GPi or STN DBS. Furthermore, after the sti mulators were turned off we noticed that the N30 amplitude potential progre ssively faded almost in parallel with the attenuation of DBS clinical effec ts. Conclusions: Our results lead to the conclusion that the bilateral DBS of b oth GPi and STN is really effective in producing a selective increase of fr ontal N30 amplitude probably improving the supplementary motor area functio nal activity, but these results do not clarify whether this amelioration is due to a central or a 'long loop' mechanism. (C) 1999 Published by Elsevie r Science Ireland Ltd. All rights reserved.