SURGERY FOR TUMORS OF THE FOURTH VENTRICLE: THE CHARACTERISTICS OF ACCESSES AND THE ROLE OF ENDOSCOPIC TECHNIQUES

Abstract

The use of current accesses to the tumors of the fourth ventricle, which fill and compress from the outside its cavity, was assessed in 28 patients. Original associated endomicrosurgical techniques were used. Two groups and five topographic types of fourth ventricle tumors are identified. Basic accesses — telovelar and supracerebellar — eliminate the necessity of dissecting the vermis cerebelli. The key endoscopic technique is to provide a simultaneous survey of the lower and upper poles of a tumor during its removal. The technique of trochlear removal of metastatic nodes from the fourth ventricle is shown. The benefits of endoscopic techniques are to early examine the vulnerable vascular and neural structures blocked by a tumor at the access step; to reduce the volume of an access itself and the traction of cerebellar and truncal structures; to completely survey the Sylvian aqueduct without additionally displacing or dissecting the vermis cerebelli; to maintain optical sharpness within sight of differently remote microstructures. Overall, incorporation of the endoscopic method realizes the principle of mini-invasive neurosurgery.