Meningiomas are benign brain tumors that begin growing in the dura mater, the fibrous membrane that envelops the brain and spinal cord. They are generally very slow growing tumors and usually are not symptomatic until they become quite large. The standard treatment for meningiomas is surgical resection. Gamma knife radiosurgery is an alternative to surgery in the treatment of meningiomas. The treatment is successful over 90% of the time.