[Operative neurosurgery: personal view and historical backgrounds. (5) Meningioma]

Abstract

The author reports his experience of 410 surgeries of meningiomas on 365 cases during the last 13.5 years, including 51 surgeries on recurrent meningiomas and 8 surgeries with the change of initial approach on the same meningiomas. In the surgical management of meningiomas, following comments are to be emphasized: Appropriate approach and interruption of blood supply are of cardinal importance in surgical management of meningiomas. For the latter purpose, preoperative embolization of feeding arteries is recommended especially in deep seated and large meningiomas more than 3 cm in diameter for carrying out their surgical extirpation fast and radically. Olfactory groove meningiomas, planum sphenoidal meningiomas, tuberculum sellae meningiomas and sphenoid ridge meningiomas are managed with pterional approach. The latter two meningiomas may necessitate selective extradural anterior clinoidectomy SEAC. For the management of large midline meningiomas, combination with interhemispheric approach is necessary to manage pial supply appropriately for the preservation of circulation of the anterior cerebral artery ACA. Extension of the former two meningiomas to the other side can be managed with falcal incision and/or drilling out of the crista galli without performing a bifrontal approach. Reduction of exophthalmos due to sphenoid ridge meningiomas infiltrating Periorbita and extraocular muscles is hardly to be expected even after subtotal removal and extensive decompression of the orbita at the superior and lateral walls in combination with SEAC. Accidental compromise of the lenticulostriate arteries arising from M1 portion embraced by tumor nodules should be managed with oxycellulose and fibrin glue at first without their bipolar coagulation, as resulting infarction in the territory causes persistent hemiparesis. Meningiomas in the cavernous sinus should be observed as long as possible in case of no growth, as they remain the same in their size and extension mostly for a long time. In case of growth, stereotactic radiosurgery is the first choice and at last would come surgical intervention at the cost of quality of life QOL. Appropriate approaches for meningiomas arising from the incisura tentorii would be either the amygdalohippocampectomy AHE approach namely transSylvian transsulcus circularis approach for their anterior localization or the supracerebellar transtentorial SCTT approach for the posterior localization in the sitting position. In the latter following structures are to be preserved with great care: A. parietooccipitalis, trochlear nerve, Vena Rosenthal and the superior cerebellar artery which could have considerable supply to the tumor. Meningiomas of the falcotentorial junction are managed also with this approach but may necessitate combination of the suboccipital transtentorial approach large upper clivus meningiomas can be removed more effectively by paramedian or lateral suboccipital craniotomy via SCTT approach in the sitting position rather than the subtemporal transpetrosal approach. Clean and wider operative fields in the former approach are emphasized. Special mention is made to transvertebralis (dural) ring approach TVRA for the foramen magnum or lower clivus meningiomas, in which the vertebral artery can be mobilized without performing more extensive far lateral approach. Difficulties of management of recurrent parasagittal meningiomas with the location corresponding to the gyrus paracentralis plus supplementary motor area are to be emphasized. Role of the venous sinus reconstruction is discussed. Difficulties of management of recurrent meningiomas represented by atypical or anaplastic meningiomas WHO grade II or III which can not be managed only by surgical removal is discussed by presenting some example cases. Biological activity of meningiomas in different location can be quite different in multiple recurrent meningiomas. Meningiomas intractable to irradiation and/or chemotherapy are another challenging topic, being beyond the scope of this paper.