Indications: 1. Meningiomas located at the base of the skull or deep in the brain. 2.The maximum diameter of the tumor is less than 30mm, and meningioma in the convex surface of the brain and parsagittal sinus should preferably be less than 25mm. 3.Meningioma in the saddle area without obvious visual field impairment. 4.Multiple meningiomas, but there should be no obvious cranial hypertension. 5.Meningioma with residual or recurrence after surgery. 5.Patients of advanced age, who cannot tolerate surgery. 6.Patients with combined heart, liver, lung and kidney, hematological system diseases or diabetes mellitus, who are not suitable for surgery. 7.Patients who refuse craniotomy. Efficacy: Because of the tough texture of meningioma, it is generally believed that gamma knife treatment of meningioma is mainly to control the further growth and enlargement of the tumor, but with the prolongation of observation time after treatment, cases of tumor shrinkage or even disappearance are not uncommon. Some literature reports, benign meningioma gamma knife treatment after 5 years tumor growth control rate of 91% to 97%, atypical meningioma growth control rate of 68%, malignant meningioma growth control rate is 0%. It can be seen that the efficacy of Gamma Knife is really good for benign meningioma, followed by atypical meningioma, and the worst for malignant meningioma. Observation of efficacy: The observation of efficacy after gamma knife treatment of meningioma has two main aspects. One is to observe how the patient’s symptoms change. After treatment, the patient’s symptoms are better, stable, or worse. If the symptoms improve or stable means more satisfactory, if the symptoms worsen, then we should promptly image review to find the cause of symptom aggravation, in order to give targeted treatment. Second, regular imaging follow-up observation. After gamma knife treatment, MRI review is done every 6 months, requiring plain scan plus enhancement scan. Focus on observing the tumor volume changes, enhancement effect changes and whether there is edema around the tumor. Generally, within a long enough observation time, tumor volume reduction, no change or tumor center enhancement effect can be judged as effective; if the tumor volume increases, it is generally regarded as ineffective; if the tumor volume reduction or no change, and the perineural edema appears less obvious, edema disappears after treatment is still considered effective, but the appearance of edema should be judged as a side effect. If severe cerebral edema occurs and the effect of treatment such as dehydration is not good and has to be transferred to surgical treatment, it should be judged as ineffective. Now the clinical occurrence of severe cerebral edema is very rare, generally edema symptomatic treatment (intermittent repeated dehydration plus hormone) can be reduced or disappear. The observation after gamma knife treatment of meningioma is a long-term process, the patient’s symptoms are slow to reduce, mostly maintain the level before treatment or improve. If the tumor shrinks, the images can be reviewed annually after two years.