title: Experience with intraoperative navigation and imaging during endoscopic transnasal spinal approaches to the foramen magnum and odontoid.
abstract: OBJECTIVE
  In this study the authors share their experience using intraoperative spinal navigation and imaging for endoscopic transnasal approaches to the odontoid in 5 patients undergoing C1-2 surgery for basilar invagination at Stanford Hospital and Clinics from 2010 to 2013.
  
  
  METHODS
  Of these 5 patients undergoing C1-2 surgery for basilar invagination, 4 underwent a 2-tiered anterior C1-2 resection with posterior occipitocervical fusion during a first stage surgery, followed by endoscopic endonasal odontoidectomy in a separate setting. Intraoperative stereotactic navigation was performed using a surgical navigation system in all cases. Navigation accuracy, characterized as target registration error, ranged between 0.8 mm and 2 mm, with an average of 1.2 mm. Intraoperative imaging using a CT scanner was also performed in 2 patients.
  
  
  RESULTS
  Endoscopic decompression of the brainstem was achieved in all patients, and no intraoperative complications were encountered. All patients were extubated within 24 hours after surgery and were able to swallow within 48 hours. After appropriate initial reconstruction of the defect at the craniocervical junction, no postoperative CSF leakage, arterial injury, or need for reoperation was encountered; 1 patient developed mild postoperative velopharyngeal insufficiency that resolved by the 6-month follow-up evaluation. There were no deaths and no patients required tracheostomy placement. The average inpatient stay after surgery varied between 72 and 96 hours, without extended intensive care unit stays for any patient.
  
  
  CONCLUSIONS
  Technologies such as intraoperative CT scanning and merged MRI/CT can provide the surgeon with detailed, virtual real-time information about the extent of complex endoscopic vertebral segment resection and brainstem decompression and lessens the prospect of revision or secondary procedures in this challenging surgical corridor. Moreover, patients experience limited morbidity and can tolerate early oral intake after transnasal endoscopic odontoidectomy. Essential to the successful undertaking of these endoscopic adventures is 1) an understanding of the endoscopic nasal, skull base, and neurovascular anatomy; 2) advanced and extended-length instrumentation including navigation; and 3) a team approach between experienced rhinologists and spine surgeons comfortable with endoscopic skull base techniques.
authors.affiliation: Departments of Neurosurgery and.
authors.forename: Omar
authors.initials: O
authors.lastname: Choudhri
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Mindea
authors.forename: Abdullah
authors.initials: A
authors.lastname: Feroze
authors.forename: Ethan
authors.initials: E
authors.lastname: Soudry
authors.forename: Steven D
authors.initials: SD
authors.lastname: Chang
authors.forename: Jayakar V
authors.initials: JV
authors.lastname: Nayak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical / Q000379:methods; D004724:Endoscopy / Q000379:methods; D005260:Female; D005539:Foramen Magnum / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D038361:Neuronavigation / Q000379:methods; D009809:Odontoid Process / Q000601:surgery*; D012086:Reoperation; D013123:Spinal Fusion / Q000379:methods