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  • Stereotactic Accuracy and Surgical Utility of the O-arm in DBS Surgery

    Final Number:

    Jonathan Dennis Carlson MD, PhD; Katie McLeod BA; Pamela PA McLeod

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: The development of intraoperative imaging such as MRI, CT, and O-arm in deep brain stimulation has led to “ asleep” surgery. The accuracy of these imaging techniques is critical when neurophysiological methods are bypassed. There remains uncertainty as to the accuracy of the O-arm at predicting DBS electrode positions. There also is debate about the importance of microelectrode recording when intraoperative imaging is used. The objective of this study was to measure the accuracy of the O-arm, and to evaluate the utility of microelectrode recording when intraoperative imaging is used in an “awake” protocol.

    Methods: O-arm images of the implanted DBS electrodes were collected during implantation in the subthalamic nucleus using microelectrode mapping in patients with Parkinson's disease. These images were fused to postoperative MRI and postoperative CT scans. The stereotactic coordinates for the tip of the electrode were measured. The Euclidean radial distances between the modalities were compared. The impact of microelectrode mapping on final DBS electrode positioning was evaluated.

    Results: In 71 consecutive DBS electrodes the average radial difference of the tip of the DBS electrode between the O-arm and MRI was 1.55 ± 0.58 mm. The average radial distance between the O-arm and CT was 1.03 ± 0.61. In 1 out of 4 cases the microelectrode recording did not confirm the optimum region of the STN, and additional microelectrode passes were needed to neurophysiologically identify the STN. If the DBS electrode was inserted to target, and O-arm confirmed its expected location, then 15% of the electrode would have been neurophysiologically outside the core of the STN. The O-arm assisted in determining the cause of targeting error, and in choosing more optimal trajectories.

    Conclusions: Intraoperative O-arm images accurately depict the location of the DBS electrode compared to postoperative CT and MRI. Microelectrode mapping and intraoperative imaging are both effective tools that can be combined for more accurate DBS electrode placement.

    Patient Care: Patient care will be improved by adoption of intraoperative imaging techniques

    Learning Objectives: By the conclusion of the session, participants should be able to: 1) understand the use of the O-arm in DBS surgery, 2) Discuss in small groups the accuracy and limitations of the O-arm, 3) Discuss the synergistic value of neurophysiological techniques and intraoperative imaging in DBS surgery.


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