THE FAR LATERAL APPROACH FOR VENTRALLY PLACED FORAMEN MAGNUM AND UPPER CERVICAL-SPINE TUMORS

Tumours of the foramen magnum region present a considerable surgical challenge. Their location combined with the close anatomical relation to sensitive and important vascular and nervous structures can make total removal difficult and sometimes impossible. Posterior and posteriolateral approaches, despite their simplicity, offer poor exposure and require retraction or rotation of the spinomedullary junction. Anteriolateral extrapharyngeal approaches are restrictive when a spacious superior exposure is necessary, while the vascular structures hidden by the tumours themselves appear only at the end of a rather tedious resection. The direct anterior transoral route, although effective for midline lesions, can be restrictive for laterally placed or broad-based tumours. A true lateral exposure provides an attractive alternative, the only anatomical obstacles being the horizontal part of the vertebral artery and the occipital condyle with its articulation with the lateral atlantal mass. A lateral approach was used in 15 patients with ventrally located tumours of the craniocervical junction, resulting in 12 total and three subtotal removals. In no case has there been inadequate tumour exposure and there were no complications of instability, CSF leak or infection directly related to the operation. Important advantanges of the approach include: excellent exposure of the ventral spinomedullary junction, early and safe exposure of vascular structures, preservation of stability, minimal risk of infection, elimination of the need for neuraxis retraction and simplicity of instruments and technique.