Non-motor effects of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: preliminary physiological results

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain l argely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiol ogy. Nine patients affected by PD undergoing chronic DBS of the STN have be en studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent perio d and sympathetic skin response (SSR) studies with DBS ON and OFF To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N2 0 and the VEP P100 component increased significantly in amplitude whereas t he SSR decreased in amplitude and increased in latency. Although plasma ren in activity tended to increase with DBS OFF, its modification induced by po stural changes and blood pressure values did not significantly differ with DBS ON and OFF We conclude that DBS of the STN in PD, besides inducing a cl inical improvement, induces several non-motor effects.