# The graded effect of propofol in electrophysiology-guided navigation during deep brain stimulation surgery

## TL;DR

Propofol anesthesia during DBS surgery affects electrode placement accuracy, but careful control and use of burst index can help maintain precision.

## Contribution

Identifies burst index as a novel biomarker for DBS navigation under propofol anesthesia.

## Key findings

- Propofol dosages >4 mg/kg/h lead to deeper electrode placements in DBS surgery.
- Burst index (BI) correlates with proximity to the DBS sweetspot and distinguishes the STN region.
- MER data remain useful under GA if propofol levels are carefully managed.

## Abstract

Propofol is widely used for general anesthesia (GA) during deep brain stimulation (DBS) surgery targeting the subthalamic nucleus (STN) in Parkinson’s disease (PD), yet its effects on intra-operative spatial navigation, critical for electrode placement, remain contentious. We performed multimodal analysis on 583 microelectrode recordings (MER) from PD patients undergoing DBS surgery under local anesthesia (LA) and GA. Deep sedation interfered with the identification of the dorsal STN border, and propofol dosages >4 mg/kg/h resulted in deeper final electrodes. While firing rate (FR) and burst index (BI) differed between LA and GA, only BI distinguished imaging-defined STN and correlated negatively with the proximity to the DBS sweetspot across conditions. Thus, propofol-based GA complicates navigation in DBS surgery, but MER remain informative if propofol levels are carefully controlled. BI emerges as a potential biomarker when MER are “polluted” by high levels of propofol, offering critical feedback during DBS surgery under GA.