[Lateral approach to the anterior foramen magnum tumor: report of two cases].

A procedure for lateral approach to the ventral portion of the foramen magnum and the upper cervical canal is described. The patient was placed in the lateral position and a curvilinear skin incision was made from the retoroauricular area down to the lateral neck across the sternocleidomastoid muscle, and underlying muscle layers were divided. A suboccipital hemicraniotomy and hemilaminectomies were performed with an air drill. Because the medulla and the cervical cord are displaced posteriorly by the tumor, there is no need to retract those structures and all the tumors can be removed under direct vision. This procedure was applied on the two patients with ventrally situated foramen magnum tumors; a neurenteric cyst and neurofibroma, and both of the tumors were successfully removed under direct vision. Major advantages of this approach are that there is no need for retraction of the spinal cord, and there is excellent exposure of an anteriorly located tumor, no postoperative cervical spine instability, no risk for CSF leak and infection, which effects are often found after the anterior approach. The procedure, like the posterior approach, is relatively simple.