Radiotherapy reactions in brain tissue can be divided into three stages according to the time of symptoms, as follows: 1. Acute stage: It occurs in radiotherapy or appears 6 weeks after radiotherapy, manifesting as transient edema around the tumor, which can lead to weakness, headache and sleepiness. Further aggravation of cerebral edema may lead to headache, nausea, vomiting and other symptoms. Mild dermatitis may appear in the irradiated field, and hair loss is common in the irradiated area. If the dose is high, permanent baldness may occur, in addition to otitis externa and otitis media; 2. Subacute phase: 6 weeks to 6 months after radiotherapy, transient neural demyelination lesions, symptoms such as headache, drowsiness and easy fatigue; 3. Late phase: sequelae are 6 months to several years after radiotherapy, altered mental status, neurocognitive impairment, memory loss, and most serious leading to radiation brain necrosis. Three years after radiotherapy is an important time period in which severe functional impairment, such as dementia, can occur. The sequelae of the middle ear include loss of hearing in the high-frequency portion and impairment of vestibular function.