Behavioural changes after bilateral subthalamic stimulation in advanced Parkinson disease: a systematic review

The long-lasting beneficial effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on motor function have now largely been acknowledged. Whereas behavioural changes have been demonstrated in certain case reports and small case series, some authors have not observed behavioural changes at all. The extent to which these changes occur has not yet been established. The aim of the present study was to systematically analyse behavioural changes of bilateral STN DBS.

A structured Medline search was conducted using previously described methods. Studies were selected according to specific in- and exclusion criteria. Data on patients, surgical technique, outcome and complications were collected and pooled.

In total 1,398 patients who underwent bilateral STN DBS were included. The total cumulative follow-up period was 1,480 patient-years. Cognitive problems were seen in 41%, depression in 8%, and (hypo)mania in 4% of the patients. Anxiety disorders were observed in less than 2%, and personality changes, hypersexuality, apathy, anxiety, and aggressiveness were observed in less than 0.5% of the group studied. About half of the patients did not experience behavioural changes.

Caregivers should be aware of the extent of these behavioural changes and a risk/benefit evaluation should be performed for individual patients.