The diagnosis of encephalitis cannot rely solely on auxiliary examinations; it must depend on the patient's medical history, clinical manifestations, and corresponding physical examination. If a patient presents with fever, headache, nausea, vomiting, and signs of nuchal rigidity upon examination, the possibility of encephalitis should be considered. Additionally, severe cases of encephalitis may exhibit seizures, cognitive changes, and personality alterations. Auxiliary examinations mainly include three types: the first type is imaging studies, primarily brain MRI, which can clearly identify the specific areas of the brain affected and determine which brain lobe is damaged. The second important examination is an electroencephalogram (EEG), which can detect diffuse slow waves, especially a significant presence of delta waves, highly indicative of encephalitis. The third important auxiliary examination is lumbar puncture for cerebrospinal fluid analysis; an increase in white blood cells and protein in the cerebrospinal fluid also suggests inflammation within the skull. Therefore, the main auxiliary examinations for encephalitis include MRI, EEG, and lumbar puncture.