title: Preoperative evaluation of the vertebral arteries and posterior portion of the circle of Willis for cervical spine surgery using 3-dimensional computed tomography angiography.
abstract: METHODS
  A retrospective analysis using prospectively collected data from 3-dimensional computed tomography angiography (3D-CTA).
  
  
  OBJECTIVE
  To investigate the frequency of anomalous vertebral arteries (VA) and variations of the posterior portion of the circle of Willis (PPCW) using 3D-CTA for preventing perioperative iatrogenic vascular complications.
  
  
  BACKGROUND
  Some studies have reported that preoperative 3D-CTA is useful for determining the VA blood flow in the cervical spine. However, preoperative 3D-CTA has not been used for evaluating PPCW, which functions as vessels collateral to the basilar artery in the case of iatrogenic VA injury.
  
  
  METHODS
  The study included 100 consecutive patients (61 males and 39 females; mean age, 60.4 ± 15.4 yr; range, 11-86 yr) who underwent cervical decompression and/or instrumentation between April 2008 and May 2012. We measured the diameters of the VA (VAD), posterior communicating artery (PCOMD), first segment of the posterior cerebral artery (P1D), and basilar artery (BAD) twice and determined the frequency of anomalous VA and PPCW variations.
  
  
  RESULTS
  Hypoplastic VA, hypoplastic PCOM, and hypoplastic P1 were detected in 11 (11.0%), 81 (81.0%), and 13 patients (13.0%), respectively. Hypoplastic PCOM-P1 and hypoplastic basilar artery were observed in 87 (87.0%) and 3 patients (3.0%), respectively. Overall, 47 patients (47.0%) possessed some degree of abnormal VA blood flow.There were 7 patients (7.0%) with both unilaterally hypoplastic VA and bilaterally hypoplastic PCOM-P1s, in whom iatrogenic VA injury on the dominant side could have caused lethal vascular complications. We termed the hypoplastic VA of the contralateral side without collateral vessels as "critical VA."
  
  
  CONCLUSIONS
  The VAs and PPCW vary considerably. Preoperative 3D-CTA provides important information for preventing tragic vascular complications caused by iatrogenic VA injury. Taking the risk of radiation into consideration, we recommend this method for patients at the highest risk for iatrogenic VA injury.
authors.affiliation: Department of Orthopaedic Surgery, Niigata University Medical and Dental General Hospital, Niigata, Japan. cbe90900@pop06.odn.ne.jp
authors.forename: Atsuki
authors.initials: A
authors.lastname: Sano
authors.forename: Toru
authors.initials: T
authors.lastname: Hirano
authors.forename: Kei
authors.initials: K
authors.lastname: Watanabe
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Izumi
authors.forename: Naoto
authors.initials: N
authors.lastname: Endo
authors.forename: Takui
authors.initials: T
authors.lastname: Ito
authors.forename: Shoichi
authors.initials: S
authors.lastname: Inagawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D002574:Cervical Vertebrae / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000601:surgery; D002648:Child; D002941:Circle of Willis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control; D057234:Preoperative Period; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014652:Vascular Diseases / Q000175:diagnosis; D014711:Vertebral Artery / Q000000981:diagnostic imaging*; D055815:Young Adult