Monitoring cognitive functions during deep brain stimulation (DBS) interventions by Real Time Neuropsychological Testing (DBS-RTNT).

Objective: We monitored cognition during Deep brain stimulation (DBS) surgery, when the electrode is positioned at the target subthalamic nucleus (i.e., STN motor area) in 14 PD patients.

Methods: We present the Real Time Neuropsychological Testing (DBS-RTNT) protocol, our preliminary experience, along with patients' performance comparing intraoperative results with baseline data.

Results: Compared to baseline, DBS-RTNT in the target area showed a significantly decreased performance at some tasks belonging to memory and executive functions domains. Significantly decreased short-term memory and sequencing scores were found for right (vs. left) hemisphere DBS-RTNT.

Conclusions: PD patients' performance should be monitored during DBS surgery as STN-DBS may induce changes in cognitive performance. These preliminary data contribute to improve, during DBS-surgery the anatomo-functional topography of the STN in order to identify, in future approaches, in the individual patient the best site producing positive motor effects, without causing negative cognitive and/or emotional changes. Medications (i.e., the patients underwent surgery in a levodopa off state) could in principle have influenced our results therefore future studies are needed to address possible confounding effect of levodopa use.