Evaluation of vertebral artery anomaly in basilar invagination and prevention of vascular injury during surgical intervention: CTA features and analysis.

OBJECTIVE: To evaluate vertebral artery anomaly at the craniovertebral junction (CVJ) in patients with basilar invagination (BI) by computed tomographic angiography (CTA), and to discuss the prevention strategy of vascular injury.

METHODS: The primary axial, multiple planar reconstruction and volume-rendering cervicocranial CTA images of 39 BI patients were analysed to evaluate vertebral artery anomaly at the CVJ: persistent first intersegmental artery (PFIA), fenestrated vertebral artery (FEN), and extracranial C1/2 origin of posterior inferior cerebellar artery (PICA), high-riding vertebral artery, side-to-side asymmetry and irregular midline carotid artery loop was determined by subjective vision. 100 patients who underwent CTA for reasons other than CVJ deformity were enrolled as normal controls to evaluate the prevalence of vertebral artery anomaly in a normal population. Chi-square test was utilized for comparing the prevalence of vertebral artery anomaly between these two groups.

RESULTS: The incidence of PFIA was 25.6% (10/39), FEN was 7.7% (3/39), PICA was 5.1% (2/39), and the total incidence of extraosseous anomalous course of vertebral artery was 38.5% (15/39), significantly higher than that of control group, 7.0% (7/100) (P < 0.01). The incidence of high-riding vertebral artery and side-to-side asymmetry were 61.5% (24/39) and 30.8% (12/39), respectively. An irregular midline carotid artery loop was observed in five patients (12.8%).

CONCLUSION: Vertebral artery anomaly, which can be clearly depicted by CTA, is more frequent in BI patients. Preoperative CTA should be performed for this patient population to prevent vascular injury. These slides can be retrieved under Electronic Supplementary Material.