Evaluation and Treatment of Intradural Tumours Located Anterior to the Cervicomedullary Junction by a Lateral Suboccipital Approach

Tumours located anterior to the cervicomedullary junction have been most commonly approached via one of two routes: anterior/transoral or posterolateral. Each of these surgical corridors can pose potential pitfalls. To circumvent these problems, a lateral suboccipital approach in conjunction with an upper cervical hemilaminectomy has been used. Selecting an appropriate surgical corridor between the lower cranial nerves (IX through XII), the vertebral artery, and the posterior inferior cerebellar artery has allowed satisfactory tumour removal. A three-dimensional picture of tumour location and relationship to surrounding neural and vascular structures is obtained preoperatively from computed tomography and magnetic resonance. Arteriography is essential to determine the origin, course, and relation of each vertebral to the tumour as well as the contribution of each vertebral to the basilar. In instances of abnormalities in the posterior circulation, evaluation of the carotid contribution to the basilar is crucial. The advantages of this approach are several. First, a direct view of the anterior surface of the lower brainstem und upper cervical cord is obtained. Second, surgery is undertaken in a sterile field in which the dura can be closed watertight. Third, neither mastoidectomy nor transposition of the vertebral artery is required. The major difficulty is the necessity to operate through narrow surgical corridors bounded by the lower cranial nerves, vertebral and posterior inferior cerebellar arteries, and the lower medulla and upper cervical cord. These structures provide the major obstacles to dissection as well as the primary causes of morbidity.