The anterior spinal artery origin: A microanatomical study

Backround: Detailed knowledge of the pattern of origin of the anterior spinal artery is critical as surgical and endovascular procedures involving the area of the ventral medulla and the vertebrobasilar junction are commonplace. We conducted a detailed microanatomical study to elucidate the site and pattern of origin of this critically important artery. Method: Nine adult cadaveric heads (18 sides) were examined after injection of colored silicon. In every specimen, the site of origin of the rami of the anterior spinal artery, their course, branching pattern and anastomoses, external diameters, and the distance from neighbor critical vessels were recorded. The dissections were performed with the aid of both the surgical microscope and a 0 degree endoscope. Findings: The pattern and site of origin of the anterior spinal artery show great variability. Also the distance of the origin of the two rami (right and left) forming the anterior spinal artery from the vertex of the vertebrobasilar junction and from the origin of the posterior inferior cerebellar artery is highly variable. Conclusions: Knowledge of the different pattern of origin and course of the proximal portion of the anterior spinal artery is critically important when planning and executing endovascular and surgical procedures involving the distal vertebral artery, the vertebrobasilar junction and the ventral medulla. On the basis of our and other authors' findings, we propose an overall classification of the pattern of origin and distribution of the proximal anterior spinal artery, which has clinical repercussions.