LOCATION OF THE VERTEBRAL ARTERY FORAMEN ON THE ANTERIOR ASPECT OF THE LOWER CERVICAL-SPINE BY COMPUTED-TOMOGRAPHY

Axial computed tomography scans were performed on 14 cadaveric cervica l spines to determine the location of the vertebral artery foramen on the anterior aspect of the lower cervical spine. The best scan through the vertebral artery foramen from each level at C3-C6 was selected. M easurements of the vertebral artery foramen included the foramen depth , foramen width, interforaminal distance, the distance from the anteri or border of the transverse foramen to the anterior border of the tran sverse process, the distance from the posterior border of the transver se foramen to the posterior border of the lateral mass, and the distan ce from the medial border of the vertebral artery foramen to the later al border of the vertebral body. The results show that the average tra nsverse foramen width was 5.5 +/- 0.4 mm at C3, 5.7 +/- 1.0 mm at C4, 5.9 +/- 0.7 mm at C5, and 5.7 +/- 0.7 mm at C6. The average transverse foramen depth and average interforaminal distance gradually increased from C3 to C6. The distance from the anterior border of the vertebral artery foramen to the anterior border of the transverse process gradu ally increased from C3 (1.2 +/- 0.4 mm) to C6 (2.7 +/- 0.8 mm) as well . The average distance between the medial border of the transverse for amina and the lateral border of the vertebral body for C3-C6 ranged fr om 1.8 to 2.2 mm. The average distance between the anterior borders of the vertebral artery foramina and the anterior border of the vertebra l body gradually decreased from C3 (8.4 +/- 1.4 mm) to C6 (7.0 +/- 1.6 mm). This study suggested that the lateral border of the vertebral bo dy may be a reliable landmark during anterior cervical decompression. The vertebral artery foramen should be free of violation if vertebrect omy or subtotal vertebrectomy is performed medial to the lateral borde r of the vertebral body.