title: Radiographic and anatomic basis of endoscopic anterior craniocervical decompression: a comparison of endonasal, transoral, and transcervical approaches.
abstract: OBJECTIVE
  To evaluate surgical access to the craniocervical junction using 3 endoscopic approaches: endonasal, transoral, and transcervical.
  
  
  METHODS
  Nine cadaveric specimens were used. Image guidance was used in 1 specimen for each approach; fluoroscopy was used in every case. The Vitrea imaging station (Vital Images Inc., Minnetonka, MN) was used to evaluate the angles and distances to the target of the approach, centered on the tip of the odontoid. The entry site was defined as: 1) the endonasal approach (inferior midline of the nasal bone), 2) the transoral approach (the tip of the upper incisor), and 3) the transcervical approach (the skin at the C4-C5 level).
  
  
  RESULTS
  Adequate lower clivus and craniocervical decompression was achieved using the endonasal and transoral approaches. Lower clivus decompression was not achieved with the transcervical approach. The average distance to the surgical target was as follows: endonasal (94 mm), transoral (102 mm), and transcervical (100 mm). The angle of attack was as follows: endonasal (28 degrees), transoral (30 degrees), and transcervical (15 degrees). The working area at the base of the field was as follows: endonasal (1305 mm2), transoral (1406 mm2), and transcervical (743 mm2).
  
  
  CONCLUSIONS
  The endonasal and transoral approaches allow wide exposure with large working angles to the craniocervical junction. The transcervical approach accesses the odontoid for resection from the body of C2 to the lip of the basion. The angles of attack in the transcervical approach when centered on the surgical target are limited, but this approach offers a clean, sterile operative field. Clinical investigation will be required to determine the optimal indications for each approach.
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. cbaird2@jhmi.edu
authors.forename: Clinton J
authors.initials: CJ
authors.lastname: Baird
authors.forename: James E
authors.initials: JE
authors.lastname: Conway
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sciubba
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Prevedello
authors.forename: Alfredo
authors.initials: A
authors.lastname: Quiñones-Hinojosa
authors.forename: Amin B
authors.initials: AB
authors.lastname: Kassam
mesh_terms: D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D001368:Axis, Cervical Vertebra / Q000000981:diagnostic imaging / Q000601:surgery; D002102:Cadaver; D001270:Cervical Atlas / Q000000981:diagnostic imaging / Q000601:surgery; D019299:Decompression, Surgical / Q000379:methods*; D004210:Dissection / Q000379:methods; D004724:Endoscopy / Q000379:methods*; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009055:Mouth / Q000033:anatomy & histology / Q000601:surgery; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000601:surgery; D009333:Neck / Q000033:anatomy & histology / Q000601:surgery; D038361:Neuronavigation; D019635:Neurosurgical Procedures / Q000379:methods*; D009777:Occipital Bone / Q000000981:diagnostic imaging / Q000601:surgery; D009809:Odontoid Process / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D011183:Postoperative Complications / Q000517:prevention & control; D018570:Risk Assessment; D013117:Spinal Cord Compression / Q000517:prevention & control / Q000601:surgery; D013530:Surgical Wound Infection / Q000517:prevention & control; D016896:Treatment Outcome