• Masashi Yamazaki, Akihiko Okawa, Takeo Furuya, Tsuyoshi Sakuma, Hiroshi Takahashi, Kei Kato, Takayuki Fujiyoshi, Chikato Mannoji, Kazuhisa Takahashi, and Masao Koda.
• Department of Orthopaedic Surgery, The Spine Section, Chiba University Graduate School of Medicine, Inohana, Chuo-ku, Chiba, Japan. masashiy@faculty.chiba-u.jp
• Spine. 2012 Oct 15;37(22):E1389-97.

Study DesignConsecutive case series and literature review.ObjectiveTo describe the utility of 3-dimensional computed tomographic angiography (3D CTA) for evaluating vertebral artery (VA) anomalies before surgery.Summary Of Background DataRecent 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.MethodsCases 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.ResultsNo 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.ConclusionThe 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.

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