Accurate localization of the subthalamic nucleus (STN) is important for proper placement of the electrodes in deep brain stimulation (DBS) surgery for patients with advanced Parkinson disease. The authors evaluated the accuracy of our modified composite targeting method and the value of using high-field MR imaging for targeting the STN.
Thirteen patients with advanced Parkinson disease underwent bilateral STN DBS based on 3-T MR imaging, and 13 patients underwent surgery based on 1.5-T MR imaging. By sequentially referring to the postmammillary commissure, the red nucleus, the mammillothalamic tract, and the STN, the modified composite targeting method determined the stereotactic coordinates for targeting the STN. The accuracy and efficacy of the composite targeting method and 3-T MR imaging were evaluated by using the intraoperative microelectrode recording, the postoperative imaging study, and the postoperative clinical improvement.
The landmark structures for targeting the STN were visualized clearly with 3-T MR imaging. The mean (± SD) path length through the STN of the central track was 4.9 ± 1.1 mm in the 3-T group and 3.1 ± 2.0 mm in the 1.5-T group (p < 0.001). Twenty-one (81%) of 26 electrodes were placed in the central track in the 3-T group, whereas 8 (31%) of 26 electrodes were placed in the central track in the 1.5-T group (p = 0.006). The rest of the electrodes were placed in the noncentral optimum track for alleviating parkinsonian motor symptoms. The mean Unified Parkinson's Disease Rating Scale motor part score during off period was reduced by 53% in the 3-T group and by 41% in the 1.5-T group (p = 0.14). The mean reductions of levodopa equivalent daily doses were 48.6% in the 3-T group and 43.7% in the 1.5-T group (p = 0.61).
The use of the modified composite targeting method referring to the multiple landmarks with 3-T MR imaging offers reliable and clinically effective target for STN DBS surgery.