Acute encephalopathy associated with influenza A virus infection.

Twenty-one patients aged 4-78 years with influenza A virus-associated acute encephalopathy were studied. Influenza A virus could be detected only in a cerebrospinal fluid (CSF) specimen obtained from 1 of 18 patients, despite the use of a highly sensitive polymerase chain reaction assay. Six patients experienced influenzal encephalopathy during the course of respiratory illness. Five of these patients had hypoprothrombinemia and 4 had increased serum creatinine levels, indicating hepatic and/or renal dysfunction. Fourteen patients experienced postinfluenzal encephalopathy