Authors: Carsten Kohlmeier, Peter Behrens, Andreas Böger, Brinda RamachandranAnthony CaparsoDirk Schulze, Philipp Stude, Max Heiland, Alexandre T. Assaf
Source: International Journal of Computer Assisted Radiology and Surgery, 12 January 2017, 1-10.
The ATI SPG microstimulator is designed to be fixed on the posterior maxilla, with the integrated lead extending into the pterygopalatine fossa to electrically stimulate the sphenopalatine ganglion (SPG) as a treatment for cluster headache. Preoperative surgical planning to ensure the placement of the microstimulator in close proximity (within 5 mm) to the SPG is critical for treatment efficacy. The aim of this study was to improve the surgical procedure by navigating the initial dissection prior to implantation using a passive optical navigation system and to match the post-operative CBCT images with the preoperative treatment plan to verify the accuracy of the intraoperative placement of the microstimulator.
Custom methods and software were used that result in a 3D rotatable digitally reconstructed fluoroscopic image illustrating the patient-specific placement with the ATI SPG microstimulator. Those software tools were preoperatively integrated with the planning software of the navigation system to be used intraoperatively for navigated placement. Intraoperatively, the SPG microstimulator was implanted by completing the initial dissection with CT navigation, while the final position of the stimulator was verified by 3D CBCT. Those reconstructed images were then immediately matched with the preoperative CT scans with the digitally inserted SPG microstimulator. This method allowed for visual comparison of both CT scans and verified correct positioning of the SPG microstimulator.
Twenty-four surgeries were performed using this new method of CT navigated assistance during SPG microstimulator implantation. Those results were compared to results of 21 patients previously implanted without the assistance of CT navigation. Using CT navigation during the initial dissection, an average distance reduction of 1.2 mm between the target point and electrode tip of the SPG microstimulator was achieved. Using the navigation software for navigated implantation and matching the preoperative planned scans with those performed post-operatively, the average distance was 2.17 mm with navigation, compared to 3.37 mm in the 28 surgeries without navigation.
Results from this new procedure showed a significant reduction (p = 0.009) in the average distance from the SPG microstimulator to the desired target point. Therefore, a distinct improvement could be achieved in positioning of the SPG microstimulator through the use of intraoperative navigation during the initial dissection and by post-operative matching of pre- and post-operatively performed CBCT scans.
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