title: Anomalous vertebral arteries in the extra- and intraosseous regions of the craniovertebral junction visualized by 3-dimensional computed tomographic angiography: analysis of 100 consecutive surgical cases and review of the literature.
abstract: METHODS
  Consecutive case series and literature review.
  
  
  OBJECTIVE
  To describe the utility of 3-dimensional computed tomographic angiography (3D CTA) for evaluating vertebral artery (VA) anomalies before surgery.
  
  
  BACKGROUND
  Recent advances in instrumentation surgery at the craniovertebral junction (CVJ) enable us to perform rigid internal fixation. However, the risk of VA injury as a complication of the surgery has become a major problem. Thus, the importance of preoperative evaluation of the VA course has been emphasized.
  
  
  METHODS
  Cases of 100 consecutive patients who underwent CVJ instrumentation surgery since July 1998 were analyzed. Occipitocervical/thoracic or C1-C2 posterior fusion was performed for atlantoaxial subluxation (AAS) in 59 patients and cervical fixation including C2 was required for middle-to-lower cervical lesions in 41 patients. Twenty-seven patients with AAS had a congenital skeletal anomaly (CSA) at the CVJ including os odontoideum and occipitalization of C1 (AAS-CSA[+] group). Anomalous VAs at the extra- and intraosseous regions were evaluated by 3D CTA.
  
  
  RESULTS
  No neurovascular injury occurred during surgery. Abnormal courses of the VA at the extraosseous region were detected in 10 cases: 2 had fenestration and 8 had a persistent first intersegmental artery. All 10 cases were in the AAS-CSA(+) group. A high-riding VA was detected in 31 cases. Fourteen out of the 31 cases were in the AAS-CSA(+) group, indicating 51.9% of the AAS-CSA(+) group had high-riding VA. In the AAS-CSA(+) group, a C1-C2 transarticular screw and C2 pedicle screw were actually inserted in 58% and 31% of the planned insertions, respectively.
  
  
  CONCLUSIONS
  The present findings suggest that the frequency of an abnormal VA at the extra- and intraosseous regions is increased when patients have AAS and CSA at the CVJ. Using preoperative 3D CTA, we can precisely identify anomalous VAs and thereby reduce the risk of their intraoperative injury.
authors: Department of Orthopaedic Surgery, The Spine Section, Chiba University Graduate School of Medicine, Inohana, Chuo-ku, Chiba, Japan. masashiy@faculty.chiba-u.jp
authors: Masashi
authors: M
authors: Yamazaki
authors: Akihiko
authors: A
authors: Okawa
authors: Takeo
authors: T
authors: Furuya
authors: Tsuyoshi
authors: T
authors: Sakuma
authors: Hiroshi
authors: H
authors: Takahashi
authors: Kei
authors: K
authors: Kato
authors: Takayuki
authors: T
authors: Fujiyoshi
authors: Chikato
authors: C
authors: Mannoji
authors: Kazuhisa
authors: K
authors: Takahashi
authors: Masao
authors: M
authors: Koda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000792:Angiography / Q000379:methods*; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery; D001270:Cervical Atlas / Q000000981:diagnostic imaging* / Q000601:surgery; D002675:Child, Preschool; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D007796:Laminectomy; D008297:Male; D008875:Middle Aged; D009777:Occipital Bone / Q000000981:diagnostic imaging* / Q000601:surgery; D015995:Prevalence; D013123:Spinal Fusion; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014711:Vertebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging*