Factors associated with neuropsychiatric side effects after STN-DBS in Parkinson's disease.

Neurostimulation of the subthalamic nucleus is an established treatment for advanced Parkinson's disease, and it might be the second milestone in treatment of Parkinson's disease after the introduction of L-dopa and dopamine agonists. However there are cognitive and psychiatric adverse effects have attracted increasing attention. In this context the subthalamic nucleus (STN) and the stimulation of the STN has been highlighted. The STN is part of the basal ganglia that are considered as part of distributed cortico-subcortical networks, which are involved in the selection, facilitation and inhibition of movements, emotions, behaviors and thoughts. Within this conception of the basal ganglia as a global "Go-/No-go-system" the STN is viewed as a central regulator. Those behavioral or cognitive effects of STN high frequency stimulation which can be modulated by changes in stimulation are therefore likely reflecting the intrinsic role of the STN in non-motor domains. However, there is insufficient knowledge about which proportion of Neuropsychiatric effects directly relates to such a modulation of the intrinsic basal ganglia state or which individual susceptibility factors may contribute to their clinical presentation. In this review the role of the preoperative factors and also the relevance of the intraoperative and postoperative management is analyzed.