Medical expert of the article
New publications
Influenza encephalitis
Last reviewed: 07.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Influenza encephalitis is caused by influenza viruses A1, A2, A3, B. It occurs as a complication of influenza. Acute non-inflammatory influenza encephalopathy is characterized by the development of seizures and coma on the same day or the next day after the onset of flu symptoms.
Symptoms influenza encephalitis.
Nervous system damage develops in all cases of influenza and is manifested by headache, pain when moving the eyeballs, muscle pain, adynamia, drowsiness or insomnia. All these symptoms are classified as general infectious and general cerebral in common influenza. However, in some cases, nervous system damage occurs in the form of influenza encephalitis, which develops more often at the end of the disease, even 1-2 weeks after it. In this case, the patient's health deteriorates again, the body temperature rises, general cerebral symptoms (headache, vomiting, dizziness), mild meningeal symptoms occur. Against this background, mild signs of focal brain damage appear. Peripheral nervous system damage is possible in the form of neuralgia of the trigeminal and greater occipital nerves, lumbosacral and cervical radiculitis, damage to the sympathetic ganglia.
In the acute period of influenza, severe damage to the nervous system in the form of hemorrhagic influenza encephalitis may develop. The disease begins apoplectiformly: with a high rise in body temperature, chills, impaired consciousness up to coma. Epileptic seizures often occur. Focal symptoms are distinguished by significant polymorphism. Traces of blood are found in the cerebrospinal fluid. The course of this form of influenza encephalitis is severe. A fatal outcome often occurs. After recovery, pronounced neurological disorders usually remain.
[ 8 ], [ 9 ], [ 10 ], [ 11 ], [ 12 ], [ 13 ], [ 14 ], [ 15 ]
Where does it hurt?
Diagnostics influenza encephalitis.
In the cerebrospinal fluid, a slight pleocytosis and a moderate increase in protein content are detected; cerebrospinal fluid pressure is elevated. Leukocytosis or leukopenia is determined in the blood.
What do need to examine?
What tests are needed?