After gamma knife surgery, there are side effects such as induced normal tissue edema and induced tissue cancer, as follows: 1. Induced normal tissue edema: Although gamma knife surgery is relatively minimally invasive, but after all, it is also to kill part of the cells, so there are many times some normal tissues around the tumor tissue will produce edema, necrosis and other conditions, which may induce headaches, dizziness and other adverse feelings. 2. Induced Tissue cancer: sometimes the cancer of tumor is caused by radiation irradiation. Although gamma knife surgery is a kind of artificially created rays with strict limitation, some patients may induce malignant disease of tumor, which is also unfavorable to patients. Therefore, it is important to improve the preoperative examination to clarify the specific situation, so that the surgery can be better.