be used to supplement evaluation of vascular involvement and to determine whether embolization would be helpful if surgery is being considered. Treatment Meningiomas have been divided into three types based on their patterns of growth. Histological factors that increase the grade include a high number of mitotic figures, necrosis and local invasion. Treatment of sphenoid wing meningiomas often depends on the location and size of the tumor. Gamma knife radiation and microscopic surgery are common options. Their encapsulated, slow growth makes meningiomas good targets for radiosurgery. In one series, less than one-third of clinoidal meningiomas could be completely resected without unacceptable risk of damaging of blood vessels (especially the carotid artery) or cranial nerves, risks that are lower with radiosurgery. If surgery is done and the entire tumor cannot be removed, then external beam radiation helps reduce recurrence of the growth. In fact, surgery followed by radiation at recurrence provided excellent tumor control in cases where gross-total resection cannot be achieved. Most all meningiomas grow very slowly and almost never metastasize to other parts of the body. In part because of its slow growth, if a tumor is asymptomatic and found only by imaging, the best course is often observation with serial clinical exams and imaging. Possible indications for intervention would be a rapid increase in growth or involvement of cranial nerves. Untreated, one small series showed survival rates ranging from five to over twenty years, though most had unilateral blindness as well as paresis of extraocular movements. Prognosis Higher grade tumors have been shown to correspond with higher recurrences. Depending on the grade and extent of resection, from less than 1 in 10 to over two-thirds of tumors will recur after surgical excision. Follow-up clinical exams, as well as neuroimaging, can aid in detecting recurrences. As many meningiomas have receptors for progesterone, progesterone blockers are being investigated. Two other drugs that are being studied for use are hydroxyurea and interferon alpha-2b. References Al-Mefty, O, ed. Meningiomas. New York: Raven Press, 1991. Bonnal J, A Thibaut, J Brotchi, and J Born. Invading Meningiomas of the Sphenoid Ridge. Journal of Neurosurgery. 53(5):587-99, Nov 1980. Kearns, T and H Wagener. Ophthalmologic Diagnosis of Meningiomas of the Sphenoidal Ridge. American Journal of the Medical Sciences, 226(2):221-8, Aug 1953. Khoromi, S and S. Zachariah. Meningioma, Sphenoid Wing. Emedicine, available online: http://www.emedicine.com/oph/topic670.htm, April 5, 2006. Kleinpeter G and F Bock. Invasion of the Cavernous Sinus