The acute phase symptoms of patients with radiation encephalopathy are dominated by acute cranial hypertension manifestations: headache and dizziness. In severe cases, there is nausea, vomiting, and optic papillary edema. Early clinical manifestations are mostly seen in the more typical drowsiness syndrome, learning, memory loss, and some patients can show symptoms of mental abnormalities such as irritability and involuntary crying; late stage patients mainly have radiation brain necrosis and severe neurological dysfunction: patients with frontal and temporal lobe damage can show timing and disorientation, and even dementia and seizures; brainstem damage can have symptoms of cranial nerve and pyramidal bundle damage, such as diplopia, Brainstem injury can have symptoms of cranial nerve and pyramidal tract damage, such as diplopia, choking, positive Binskins sign, etc.; cerebellar damage leads to ataxia (unstable gait, swaying limbs, delayed reaction and poor accuracy in movement) and abnormal muscle tone. Damage to functional areas of the brain can cause corresponding neurological deficits, such as hemiparesis, aphasia, and dyscognition. According to the time of occurrence of different symptoms, radiation brain injury can be divided into three phases: acute phase, early late-response phase (early late-response phase) and late late-response phase (late late-response phase). 1. Acute phase: It occurs several days or weeks after the start of radiotherapy and manifests itself as changes in mental status and mental state, including headache, nausea, vomiting, intracranial hypertension and impaired consciousness. It is generally considered to be reversible. 2. Early and late onset phase: It occurs 1 to 6 months after irradiation and may present with transient demyelination. Patients may show symptoms such as increased excitability, loss of appetite, dizziness, drowsiness, loss of learning memory, irritability and fatigue, and even an exacerbation of tumor-related symptoms and signs. The above symptoms and signs are mostly recoverable. 3. Late late-onset stage: This stage is irreversible damage. It appears 6 months to several years after irradiation, causing obvious damage to capillary endothelial cells and oligodendrocytes; the lesions are severe or even fatal, including brain atrophy, cerebral leukomalacia, necrosis, endocrine dysfunction, reduced cognitive ability and dementia. Focal radionecrosis manifests as alterations in motor, sensory, language, and receptive abilities, seizures, and elevated cranial pressure. Diffuse white matter damage manifests as anything from mild lethargy to memory loss, personality changes, ataxia, and eventually dementia or death.