Encephalitis is inflammation of the brain. There are several causes, including viral infection, autoimmune inflammation, bacterial infection, insect bites and others. When inflammation is caused by an infection in the brain, it’s known as infectious encephalitis. And when it’s caused by your own immune system attacking the brain, it’s known as autoimmune encephalitis. Sometimes there is no known cause.
The symptoms of encephalitis can range from mild to severe.
Mild symptoms include:
- Fever
- headache
- vomiting
- stiff neck
- lethargy (exhaustion)
Severe symptoms include:
- fever of 103°F (39.4°C) or higher
- confusion
- drowsiness
- hallucinations
- slower movements
- coma
- seizures
- irritability
- sensitivity to light
- unconsciousness
Infants and young children show different symptoms. Call a doctor immediately if your child is experiencing any of the following:
- vomiting
- bulging fontanel (soft spot in the scalp)
- constant crying
- body stiffness.
- poor appetite
What are the risk factors for encephalitis?
- older adults
- children under the age of 1
- people with weak immune systems
You may also have a higher risk of getting encephalitis if you live in an area where mosquitos or ticks are common. Mosquitos and ticks can carry viruses that cause encephalitis. You’re more likely to get encephalitis in the summer or fall when these insects are most active.
Causes Encephalitis?
In approximately half of patients, the exact cause of encephalitis is not known.
In those for whom a cause is identified, there are two main types of encephalitis:
- Infectious encephalitis. This condition occurs when a virus or other agent directly infects the brain. The infection may affect one area or be widespread. Viruses are the most common causes of infectious encephalitis, including some that can be passed by mosquitoes or ticks. Very rarely, encephalitis may be caused by bacteria, fungus or parasites.
- Autoimmune encephalitis. This condition occurs when your own immune cells mistakenly attack the brain or make antibodies targeting proteins and receptors in the brain. The exact reason why this happens is not completely understood. Sometimes the abnormal immune response can be triggered by benign or cancerous tumors, known as paraneoplastic and autoimmune encephalitis. Other types of autoimmune encephalitis such as acute disseminated encephalomyelitis (ADEM) can be triggered by infection in your body. This is known as post-infectious autoimmune encephalitis. In many instances, no definitive trigger for the abnormal immune response is identified.
Prevention
The best way to prevent viral encephalitis is to take precautions to avoid exposure to viruses that can cause the disease. Try to:
- Practice good hygiene. Wash hands frequently and thoroughly with soap and water, particularly after using the toilet and before and after meals.
- Don’t share utensils. Don’t share tableware and beverages.
- Teach your children good habits. Make sure they practice good hygiene and avoid sharing utensils at home and school.
- Get vaccinations. Keep your own and your children’s vaccinations current. Before traveling, talk to your health care provider about recommended vaccinations for different destinations.
Encephalitis is a rare yet serious disease that can be life-threatening. You should call your doctor immediately if you have symptoms of encephalitis.
How is encephalitis diagnosed?
Your doctor will first ask you about your symptoms. They may perform the following tests if encephalitis is suspected.
Spinal tap or lumbar puncture
In this procedure,your doctor will insert a needle into your lower back to collect a sample of spinal fluid. They will test the sample for signs of infection.
Brain imaging with CT scan or MRI
CT scan and MRI detect changes in brain structure. They can rule out other possible explanations for symptoms, such as a tumor or stroke. Certain viruses have a tendency to affect certain areas of the brain. Seeing what parts of your brain are affected can help determine what type of virus you have.
Electroencephalograph (EEG)
An EEG uses electrodes (small metal discs with wires) attached to the scalp to record brain activity. An EEG does not detect the virus that causes encephalitis, but certain patterns on the EEG may alert your neurologist to an infectious source of your symptoms. Encephalitis can lead to seizures and coma in later stages. That’s why the EEG is important in determining the areas of the brain that are affected and the types of brain waves that occur in each area.
Blood tests
A blood test can reveal signs of a viral infection. Blood tests are rarely performed alone. They usually help diagnose encephalitis along with other tests.
Brain biopsy
Your doctor will remove small samples of brain tissue to test for infection. This procedure is rarely performed because there’s a high risk of complications. It’s usually only done if doctors can’t determine the cause the brain swelling or if treatment isn’t working.
How is encephalitis treated??
Anti-viral medications can help treat herpes encephalitis. However, they aren’t effective in treating other forms of encephalitis. Instead, treatment often focuses on relieving symptoms. These treatments may include:
- rest
- pain killer.
- corticosteroids (to reduce brain inflammation)
- mechanical ventilation (to help with breathing)
- lukewarm sponge baths
- anticonvulsants (to prevent or stop seizures)
- sedatives (for restlessness, aggressiveness, and irritability)
- fluids (sometimes through an IV)
You may need to be hospitalized during treatment, especially with brain swelling and seizures.
Get immediate care if you are experiencing any of the more-severe symptoms associated with encephalitis. A severe headache, fever and change in consciousness require urgent care.
