(1) Acute or subacute onset, mostly with fever.
(2) Signs and symptoms of brain parenchymal damage, such as impaired consciousness, mental and behavioral abnormalities, movement disorders, and convulsive seizures.
(3) Cerebrospinal fluid examination may show non-suppurative changes in more than 2/3 of children.
(4) Viral etiology examination: It is the weak point of diagnosis in China, and at present, there are still some difficulties in the viral etiology diagnosis of most cases in China.
(5) EEG examination: when the cerebral cortex is extensively and severely damaged, EEG shows extensive high-voltage delta waves, and combined with the diagnostic index, it has the significance of auxiliary diagnosis at this time. The diagnosis of viral encephalitis cannot be made solely on the basis of clinical manifestations and EEG, because the specificity of EEG positivity is low and etiological diagnosis cannot be made. The EEG can be normal in basal ganglia, brainstem, and cerebellar encephalitis.
(6) Other than other diagnoses.