title: Improved surgical procedure using intraoperative navigation for the implantation of the SPG microstimulator in patients with chronic cluster headache.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg Eppendorf, University of Hamburg, Martinistr. 52, 20246, Hamburg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kohlmeier
authors.affiliation: Interdisciplinary Pain Center, University Hospital Freiburg, University of Freiburg, Breisacherstraße 64, 79106, Freiburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Behrens
authors.affiliation: Department of Neurology, Pain Clinic, Red Cross Hospital Kassel, Hansteinstrasse 29, 34121, Kassel, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Böger
authors.affiliation: Autonomic Technologies, Inc., Redwood City, CA, USA.
authors.forename: Brinda
authors.initials: B
authors.lastname: Ramachandran
authors.affiliation: Autonomic Technologies, Inc., Redwood City, CA, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Caparso
authors.affiliation: Digitales Diagnostikzentrum Breisgau, Kaiser-Joseph-Straße 263, 79098, Freiburg, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Schulze
authors.affiliation: Department of Neurology, University Hospital Bergmannsheil, University of Bochum, Buerkle-de-la-Camp Platz 1, 44789, Bochum, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Stude
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg Eppendorf, University of Hamburg, Martinistr. 52, 20246, Hamburg, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Heiland
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg Eppendorf, University of Hamburg, Martinistr. 52, 20246, Hamburg, Germany. a.assaf@uke.uni-hamburg.de.
authors.forename: Alexandre T
authors.initials: AT
authors.lastname: Assaf
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003027:Cluster Headache / Q000175:diagnosis / Q000601:surgery*; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D005726:Ganglia, Parasympathetic / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007432:Intraoperative Period; D008297:Male; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
keywords: Cluster headache (CH); Cone beam computed tomography (CBCT); Microstimulator; Navigated surgery; Pterygopalatine fossa (PPF); Sphenopalatine ganglion (SPG)