Meningioma accounts for 15% of intracranial tumors, mostly in adults, but less common in the elderly and children, most of them are solitary and only 1-2% are multiple. Most meningiomas are found in the parsagittal sinus, the convex surface of the brain and the pars falcae, followed by the pterygoid crest, saddle node, olfactory groove, pontocerebellar horn and cerebellar vermis. The shape of meningioma is related to the growth site, most of them are spherical or hemispherical, and a few are flat. Benign meningioma grows slowly and has a long course, so that the surrounding neural tissue can have sufficient time to adapt to the development of the tumor, and the tumor often grows very large without serious clinical symptoms. Especially meningiomas growing in non-functional areas can remain undetected for a lifetime, until it is clear at autopsy after death. The clinical symptoms caused by meningiomas are determined by their location. Meningiomas near the central sulcus of the brain often cause epilepsy and incomplete hemiparesis of the contralateral limb; meningiomas in the frontal lobe and anterior cranial fossa can cause psychiatric symptoms; meningiomas in the medial pterygoid crest and saddle node can cause visual acuity loss or visual field defects; meningiomas in the pontocerebellar horn of the cerebellum can cause V-VIII cranial nerve damage and cerebellar damage. Symptoms. 3.When the tumor is large, it can affect the local blood flow or obstruct the cerebrospinal fluid circulation and absorption, which can lead to cranial hypertension, mainly manifesting as headache and visual impairment, and in advanced stage, it can lead to double blindness. Gamma knife treatment of meningioma 1, the indications for gamma knife treatment: 1) diameter within 30mm 2) meningioma residual after surgery or postoperative recurrence 3) tumor located in high-risk areas such as brainstem, saddle or adhesions with large blood vessels 4) patients of advanced age, poor health and can not tolerate surgery 5) patients who are afraid of surgery and do not want to operate. 2. Efficacy evaluation: 1) Classical surgery is still the first choice for meningioma treatment. However, for deep meningiomas or tumors with adhesions to nerves, blood vessels or brainstem, surgery is difficult to achieve complete resection, and gamma knife treatment can be considered as the first choice. Even if all tumors are fully resected, there is still recurrence after surgery. The 5-year recurrence rate can reach 10-20%, and the 15-year recurrence rate reaches 30-40%; 2) The effective sign of gamma knife treatment of meningioma is the cessation of tumor growth or tumor volume reduction. Gamma knife efficiency of 90% or more, its 5-year recurrence rate after treatment is lower than the recurrence rate of surgery (less than 10%); 3) gamma knife for post-surgical residual or post-operative recurrence of meningioma has a particularly important significance. According to statistics, it can save nearly 90% of patients from reoperation, especially meningiomas located near the brainstem and cranial nerves; 4) brain edema induced by radiotherapy is the most common complication after gamma knife treatment of meningioma, most occurring 1-6 months after treatment, and edema of larger meningiomas can be up to 8-12 months.