Deep Brain Stimulation and Nonmotor Symptoms.

Deep brain stimulation (DBS) is currently the treatment of choice for advanced Parkinson's disease (PD). Several brain targets, including the subthalamic nucleus and the globus pallidus internus, have been successfully employed, with excellent motor outcomes. Despite less established knowledge, DBS may be a powerful tool for managing a wide variety of nonmotor symptoms (NMS) in PD patients, either directly or indirectly due to motor benefit or reduction of dopaminergic drug load. After an assessment of global nonmotor outcomes of DBS, as measured by currently available clinical scales and questionnaires, this chapter will address DBS effects on four main NMS categories: neurobehavioral, including cognitive and neuropsychiatric symptoms, autonomic dysfunction, including orthostatic hypotension, constipation, and urinary dysfunction, sleep disturbances, including insomnia, REM sleep behavior disorder, and restless leg syndrome, to conclude with sensory symptoms, mainly focusing on pain. An overall positive impact of DBS on most NMS emerges from the reviewed studies. However, current opinion on the effect of DBS on NMS in PD needs to be tempered by the relatively low number of cases and the lack of large, controlled, specifically designed studies for most NMS categories.