Location of the vertebral artery at C1 in children: how far out laterally can one safely dissect?

BACKGROUND: There is little information available on the anatomic location of the vertebral artery in pediatric patients undergoing a posterior cervical arthrodesis involving the first cervical vertebra (C1). The purpose of this study was to define how far laterally one can safely dissect posteriorly without risk to the vertebral artery in pediatric patients.

METHODS: A subset of computed tomography angiograms of the neck that had been previously obtained in patients at our institution was evaluated. The location of the vertebral artery was identified on both the right and the left side at the vertebral artery groove.

RESULTS: A total of 549 patients were included. The vertebral artery was an average of 13.97 mm (standard deviation, 1.89 mm) from the midline. Ninety-seven percent of the vertebral arteries were more than 1 cm lateral to the midline, and none were less than 8 mm from the midline. There was a significant difference among the age groups in the location of the vertebral artery, with the vertebral artery closer to the midline in younger patients (p < 0.001). In patients eight years of age or older, the average distance from the midline equaled the value reported for adults.

CONCLUSIONS: Patients under the age of eight years had vertebral arteries that were significantly closer to the midline compared with those of older patients; nonetheless, 97% of the vertebral arteries in the younger patients were more than 1 cm lateral to the midline.

CLINICAL RELEVANCE: Increased care must be taken when dissecting out laterally on C1 in younger patients, as the vertebral artery tends to be closer to the midline than has been described in adults.