[Nonmotor symptoms in Parkinson's disease and deep brain stimulation].

INTRODUCTION

The efficacy of deep brain stimulation (DBS) for the motor symptoms of advanced Parkinson's disease (PD) is well established. However, the effects of DBS on nonmotor symptoms (NMS) are less clear.

AIM

To review the published literature on nonmotor aspects of DBS for PD.

DEVELOPMENT

The outcome of NMS after DBS in PD varies across studies. Some symptoms improve -sleep disorders, pain or sensory complaints, obsessive-compulsive disorder- and other aspects decline or appear -word fluency, apathy, body weight gain-. Isolated studies note mild improvements in working memory, visuomotor sequencing and conceptual reasoning, some gastrointestinal, urogenital, sweating and olfactory disturbances; whereas other studies have reported declines in verbal memory (long delay recall), visuospatial memory, processing speed and executive function; orthostatic hypotension remains without changes. The reasons for such a range of symptoms observed is due to the multifactorial etiology of the NMS, including preoperative vulnerability, changes in dopaminergic medications, surgical and stimulation effects, underlying PD-related factors and psychosocial effects. Specific patient subgroups may be at greater risk of cognitive deficits -e.g., those older than 69 years or with cognitive impairment prior to surgery- or depression, mania and suicide -e.g., those ones with preoperative psychiatric symptoms-.

CONCLUSIONS

Patients who undergo DBS must be well-selected, weighing the risks and benefits, in order to obtain the best results with this treatment. Further multicentre studies are necessary to understand the role of DBS on NMS.