Introduction: DBS electrode placement using intraoperative CT scan for planning and confirmation of electrode placement under general anesthesia without microelectrode recording and with the use of NexFrame is a new method for DBS electrode placement. This new method has been performed at our institution for the last 12 months. We report on the accuracy of DBS electrode placement using this method for the past 51 patients.

Methods: Prospective data were collected from the first 51 patients who underwent this method for DBS electrode placement. The accuracy of placement was calculated as the inverse of a linear distance between the center of the (Target) contact on the DBS electrode and the intended target. Immediate postoperative CT images were merged with preoperative CT/MRI planning scans and the distance was electronically calculated. A correlation between the above mentioned distance and the closest distance of the DBS electrode from the ventricle was also performed.

Results: 51 patients participated in the study. Their mean age was 64 ± 9.5. There were 31 Parkinson Disease patients, 19 with Essential Tremor and 1 dystonia patient. All patients had bilateral electrode implantation as followed: 19 Vim , 10 STN, 22 GPi. The mean accuracy of DBS placement was 1.524 mm ± 1.04 mm. The mean deviation from plane distance was 1.254 mm ± 0.9 mm. There was a slight trend of less accuracy on the right side (the second operated side) of 1.68 mm vs 1.36 mm on the left side with a p=0.07. There was a moderate negative correlation between the distance of the electrode from the ventricle and the accuracy of placement (Pearson correlation coefficient of -0.40). Electrode trajectories passing >4.0 mm from the ventricle wall were more accurate than those whose approach was <4.0 mm. (p=< 0.05). There was no statistically significant difference between distances from the ventricle on either side.

Conclusions: DBS electrode placement using Ceretom CT scanner and NexFrame has high accuracy, and is comparable to the reported accuracy of frame-based MRI guided stereotaxy. There is also a higher accuracy of placement with increased distance of the electrode trajectory from the ventricle.

Patient Care: Using general anesthesia during DBS placement greatly improves patients satisfaction and shortens operative time. Use of intraoperative CT scan improves spatial accuracy and confirms adequate placement in the OR and could potential allow for a shorter and safer surgery.

Learning Objectives: 1- Identify methods of DBS electrode placement guidance 2- Determine the accuracy of placement of DBS electrode using a novel method 3- Identify factors impacting accuracy of placement

References: Thani NB, Bala A and Lind CRP. Accuracy of magnetic resonance imaging-directed frame-based stereotaxy. Neurosurgery 70[ONS Suppl 1]:ons114–ons124, 2012