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Meningiomas are a diverse set of tumors arising from the meninges, the membranous layers surrounding the central nervous system. They arise from the arachnoid "cap" cells of the arachnoid villi in the meninges. These tumors usually are benign in nature; however, a small percentage are malignant. Many meningiomas are asymptomatic, producing no symptoms throughout a person's life, and if discovered, require no treatment other than periodic observation. Typically, symptomatic meningiomas are treated with either radiosurgery or conventional surgery. Historical evidence of meningiomas has been found going back hundreds of years, with some successful surgeries for their removal beginning in the 1800s. ==Signs and symptoms== (詳細はautopsy without having caused symptoms. Larger tumors may cause symptoms, depending on the size and location. *Focal seizures may be caused by meningiomas that overlie the cerebrum. *Progressive spastic weakness in legs and incontinence may be caused by tumors that overlie the parasagittal frontoparietal region. *Sylvian tumors may cause myriad motor, sensory, aphasic, and seizure symptoms, depending on the location. *Increased intracranial pressure eventually occurs, but is less frequent than in gliomas. *Diplopia (Double vision) or uneven pupil size may be symptoms if related pressure causes a third and/or sixth nerve palsy. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Meningioma」の詳細全文を読む スポンサード リンク
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