| Criteria | Description |
1 | Positive diagnosis of influenza | Influenza infection is surely present |
2 | Clinical manifestations | Neuropsychiatric symptoms appear for the first time during the recovery from influenza or 2 to 3 weeks after the onset of influenza: personality changes, seizures, delirium, hallucinations, gibberish, limb weakness or dyskinesia, etc. |
3 | Laboratory | CSF cell number increased, lymphocyte hyperplasia, protein can be slightly increased or normal |
4 | Brain imaging | The EEG may show diffuse slow electrical activity |
5 | Best treatment practice | Intravenous immunoglobulin (IVIG) (e.g., 400 mg/kg daily for 5 days); intravenous methylprednisolone; plasma exchange |