Background: Microelectrode recording (MER) is used to confirm targeting accuracy during deep brain stimulation (DBS) surgery. We describe a technique using intraoperative computed tomography (CT) extrapolation (iCTE) to predetermine and adjust the trajectory of the guide tube to improve microelectrode targeting accuracy. We hypothesized that this technique would decrease the number of MER tracks and operative time, while increasing the recorded length of the subthalamic nucleus (STN).
Methods: Thirty-nine patients with Parkinson's disease who underwent STN DBS before the iCTE method were compared with 33 patients undergoing STN DBS using iCTE. Before dural opening, a guide tube was inserted and rested on dura. Intraoperative computed tomography (iCT) was performed, and a trajectory was created along the guide tube and extrapolated to the target using targeting software. If necessary, headstage adjustments were made to correct for error. The guide tube was inserted, and MER was performed. iCT was performed with the microelectrode tip at the target. Coordinates were compared with planned/adjusted track coordinates. Radial error between the MER track and the planned/adjusted track was calculated. Cases before and after implementation of iCTE were compared to determine the impact of iCTE on operative time, number of MER tracks and recorded STN length.
Results: The use of iCTE reduced the average radial MER track error from 1.90 ± 0.12 mm (n = 54) to 0.84 ± 0.09 mm (n = 49) (P < 0.001) while reducing the operative time for bilateral lead placement from 272 ± 9 minutes (n = 30) to 233 ± 10 minutes (n = 24) (P < 0.001). The average MER tracks per hemisphere was reduced from 2.24 ± 0.13 mm (n = 66) to 1.75 ± 0.09 mm (n = 63) (P < 0.001), whereas the percentage of hemispheres requiring a single MER track for localization increased from 29% (n = 66) to 43% (n = 63). The average length of recorded STN increased from 4.01 ± 0.3 mm (n = 64) to 4.75 ± 0.28 mm (n = 56) (P < 0.05).
Conclusion: iCTE improves microelectrode accuracy and increases the first-pass recorded length of STN, while reducing operative time. Further studies are needed to determine whether this technique leads to less morbidity and improved clinical outcomes.
Keywords: Accuracy; Deep brain stimulation; Parkinson disease; Subthalamic nucleus.
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