Sphenoid wing meningioma
5138392
166921428
2007-10-25T05:30:12Z
Jayvdb
101140
/* References */ link to [[American Journal of the Medical Sciences]], [[WP:AJ]] collaboration project of the week
A '''sphenoid wing meningioma''' is a [[benign]] [[brain tumor]] located near the [[sphenoid bone]].
==Meningioma==
A [[meningioma]] is a benign brain tumor. It originates from the [[dura mater]], the tissue enwrapping the brain and [[spinal cord]]. Meningiomas are much more common in females, and are more common after 50 years of age. Of all cranial meningiomas, about 20% of them are in the sphenoid wing. In some cases, deletions involving [[chromosome 22]] are involved.
==Diagnosis==
Sphenoid wing meningiomas are diagnosed by the combination of suggestive [[symptoms]] from the history and physical and [[neuroimaging]] by [[magnetic resonance imaging]] (MRI) or [[computer averaged tomography]] (CT). Tumors growing in the inner wing ([[clinoidal]]) most often cause direct damage to the [[optic nerve]] leading especially to a decrease in [[visual acuity]], progressive loss of color vision, defects in the field of vision (especially [[cecocentral]]), and an afferent [[pupil]]lary defect. If the tumor continues to grow and push on the optic nerve, all vision will be lost in that eye as the nerve atrophies. [[Proptosis]], or [[anterior]] displacement of the eye, and [[palpebral]] swelling may also occur when the tumor impinges on the [[cavernous sinus]] by blocking [[venous]] return and leading to congestion. Damage to cranial nerves in the cavernous sinus leads to [[diplopia]]. [[Cranial nerve]] VI is often the first affected, leading to diplopia with lateral gaze. If cranial nerve V-1 is damaged, the patient will have pain and altered sensation over the front and top of the head. [[Horner’s syndrome]] may occur if nearby sympathetic fibers are involved.
==Classification==
Tumors found in the external third of the sphenoid are of two types: [[en-plaque]] and [[globoid]] meningiomas. En plaque meningiomas characteristically lead to slowly increasing proptosis with the eye angled downward. Much of this is due to reactive orbital [[hyperostosis]]. With invasion of the tumor into the orbit, diplopia is common. Patients with globoid meningiomas often present only with signs of increased intracranial pressure. This leads to various other symptoms including [[headache]] and a swollen [[optic disc]]. The differential diagnosis for sphenoid wing meningioma includes other types of tumors such as [[optic nerve sheathe meningioma]], [[cranial osteosarcoma]], [[metastases]], and also [[sarcoidosis]]. Following the physical exam, the diagnosis is confirmed with neuro-imaging. Either a head CT or MRI with contrast such as gadolinium is useful, as meningiomas often show homogenous enhancement. Angiography looking for signs like stretched [[arteries]] may 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 meningomas 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. Fortunately, 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 5 to over 20 years, though most suffered unilateral [[blindness]] as well as paresis of extraocular movements.
==Recurrence==
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 by Medial Sphenoid Meningioma--"Radical" Surgery and Recurrence. ''Acta Neurochirurgica''. 103(3-4):87-91, 1990.
*Miller, N, V Biousse, N Newman, and J. Kerrison, eds. Walsh and Hoyt’s Clinical Neuro-Ophthalmology, 6th ed, vol. 2. Philadelphia: Lippincott Williams & Wilkins, 2005.
*Newman, S. Meningiomas: A Quest for the Optimum Therapy. ''Journal of Neurosurgery''. 80(2):191-4, Feb 1994.
*Park, J and P Black. Biology and Clinical Features of Meningioma. UpToDate, online, April 7, 2006.
*Park, J and P Black. Treatment of meningioma. UpToDate, online, April 7, 2006.
*Schmidek, H. Meningiomas and Their Surgical Management. Philadelphia: W.B. Saunders Company, 1991.
*Thomas, D, ed. Stereotactic and Image Directed Surgery of Brain Tumors. New York: Churchill Livingstone, 1993.
*Villavicencio A, P Black, D Shrieve, M Fallon, E Alexander and J Loeffler. Linac Radiosurgery for Skull Base Meningiomas. ''[[Acta Neurochirurgica]]''. 143(11):1141-52, Nov 2001.
*Wilson, WB. Meningiomas of the Anterior Visual System. ''[[Survey of Ophthalmology]]''. 26(3):109-27, Nov-Dec 1981.
[[Category:Medical terms]]
[[Category:Neurology]]