Description of the Microsurgical Anatomy and Intramedullary Tumor Resection in the Anterior Part of the Spinal Cord

During resection of an intramedullary spinal cord tumor, dissection of the ventro-central part of the tumor is most difficult because of the close anatomical relationship between the spinal branches of central vessels to be preserved and the tumor feeding arteries. The central vessels run anteroposteriorly through the anterior median septum(AMS), and a pair comprising a central artery and vein forms a vascular bundle that runs into the spinal cord from the tip of the AMS. These vascular bundles are covered with thin folds of the AMS, named septal sleeves, until they enter the spinal cords. Furthermore, the feeding arteries of the tumor arising from the spinal branches of the central arteries at the tip of the AMS are contained in thick septal sleeves; these thick sleeves indicate the position of the feeding arteries to be excised. To control brisk bleeding from the stump of the feeding artery at the top of the AMS, pinpoint coagulation of the arterial stump under direct vision after debulking the tumor is desirable. When pinpoint hemostasis cannot be achieved, coagulation of the AMS including the bleeding artery to a depth of 1-2 mm is advisable. As central arteries run tortuously in the AMS, the direction of the coagulation should be inclined craniocaudally, although this may increase the risk of damaging the adjacent central vessels. Surgeons should be aware of the anatomical relationship between the AMS, the central vessels, and the tumor feeding arteries to perform safe detachment of the tumors in the ventral region.