Meningiomas make up about one-fifth of all primary intracranial tumors. Meningiomas are usually slow growing. Approximately a quarter of patients with meningioma present with epilepsy. In the remainder the effects of the pressure of the growing tumor (headache, vomiting, etc.) often become evident first.

Simply, meningiomas are tumors that arise from the leptomeninges (tissue that serves as the lining of the brain). They develop from cells of arachnoid granulations, and they can occur throughout the supratentorial and infratentorial compartment. They are generally benign tumors, and only rarely do they undergo malignant transformation.

http://meningioma1.blogspot.com/2011/03/meningioma.html

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