Analysis of intra-operative target location of subthalamic nucleus in deep brain stimulation surgery for Parkinson′s disease with bispectral index monitoring under general anesthesia

Abstract

Objective To explore the feasibility of using electrophysiology to locate STN targets in the treatment of Parkinson′s disease (PD) by deep brain stimulation (DBS) with bispectral index (BIS) monitoring under general anesthesia. Methods The data of 22 PD patients treated by bilateral STN-DBS at Department of Neurosurgery, the First Hospital of China Medical University from September 2017 to May 2019 were retrospectively analyzed. All patients completed surgery with BIS monitoring under general anesthesia. All STN nuclei were located based on microelectrode recording (MER). Postoperative MRI was fused with preoperative MRI to evaluate the accuracy of electrode implantation. Results The discharge in the sensory-motor area of STN were recorded by MER in all 44 sides during asleep DBS. Microelectrodes were implanted and STN electrophysiological signals were recorded for 40 sides when BIS value was maintained above 70. For the other 4 sides when BIS value was maintained between 30 and 60, and the discharge frequency and amplitude were only about 50% of those when BIS value was maintained above 70. The electrophysiological length of STN was 3.5-7.5(5.2±0.9) mm on the right side and 3.5-7.5(5.5±1.0)mm on the left side, respectively. After intracranial electrode was implanted and when BIS value ≥80, 18 patients could complete the stimulation test for clinical symptoms and side effects, and 4 patients could only complete the test for motor side effects. Postoperative MRI showed that all electrode targets were located in STN nucleus, and the radial error was (1.10±0.45)mm on the right side and (1.24±0.56)mm on the left side. No intracranial hemorrhage, infection or other complications occurred. Conclusions During the surgery of asleep STN-DBS, clear and typical STN discharge could be recorded in MER with BIS (≥70) monitoring. The target localization seems accurate. Key words: Parkinson disease; Anesthesia, general; Deep brain stimulation; Bispectral index; Microelectrode recording