Comparison of electrode location between immediate postoperative day and 6 months after bilateral subthalamic nucleus deep brain stimulation.

Abstract

We compared the electrode positions of subthalamic nucleus (STN) deep brain stimulation (DBS) estimated at the immediate postoperative period with those estimated 6 months after surgery. Brain CT scans were taken immediately and 6 months after bilateral STN DBS in 53 patients with Parkinson's disease. The two images were fused using the mutual information technique. The discrepancies of electrode positions in three coordinates were measured in the fused images, and the relationship with the pneumocephalus was evaluated. The average discrepancy of x- and y-coordinates of electrode positions at the level of STN (3.5 mm below the anterior commissure-posterior commissure line) were 0.6 ± 0.5 mm (range, 0~2.1 mm) and 1.0 ± 0.8 mm (range, 0~5.2 mm), respectively. The average discrepancy of z-coordinates of the electrode tips of the fused images was 1.0 ± 0.8 mm (range, 0.1~4.0 mm). The volume of pneumocephalus (range, 0~76 ml) was correlated with the y-coordinate discrepancies (p < 0.005). The electrode positions in the immediate postoperative CT might have significant discrepancies with those in the CT taken at a stable period after STN DBS especially when there is a large amount of pneumocephalus.