Monitoring Cognitive Functions During Deep Brain Stimulation Interventions by Real Time Neuropsychological Testing.

Objective: We monitored cognition in 14 Parkinson's disease (PD) patients during deep brain stimulation (DBS) surgery when the electrode was positioned at the target subthalamic nucleus (STN) (i.e., the STN motor area).

Methods: We present the DBS-real-time neuropsychological testing (DBS-RTNT) protocol and our preliminary experience with it; we also compared the intraoperative patient performance with the baseline data.

Results: Compared with the baseline data, patients undergoing DBS-RTNT in the target area demonstrated a significantly decreased performance on some tasks belonging to the memory and executive function domains. Patients undergoing right hemisphere DBS-RTNT had significantly lower short-term memory and sequencing scores than did patients undergoing left hemisphere DBS-RTNT.

Conclusion: PD patient cognitive performance should be monitored during DBS surgery, as STN-DBS may induce changes. These preliminary data contribute to improving our understanding of the anatomo-functional topography of the STN during DBS surgery, which will enable the identification of the best site for producing positive motor effects without causing negative cognitive and/or emotional changes in individual patients in the future. In principle, medications (i.e., patients who underwent surgery in a levodopa-off state) could have influenced our results; therefore, future studies are needed to address the possible confounding effects of levodopa use.