What Is Encephalitis, and How Do You Treat It?
Key takeaways:
The cause of encephalitis is often unknown. In some cases an infection causes it, but it can also be autoimmune.
Encephalitis is serious and can be deadly. People who survive can have long-term neurological effects.
Early diagnosis and treatment are important in improving outcomes. Rehabilitation can also be useful in the recovery process.
Our brain is the command center for our body. So there can be serious consequences when there’s inflammation in the brain. This is what happens in encephalitis. Research shows that many people have not heard of encephalitis. But it’s more common than more familiar conditions like meningitis and multiple sclerosis. In 2019 alone, experts estimate there were over 1.4 million new cases of encephalitis worldwide.
What does encephalitis do to the brain?
If you have encephalitis, your brain tissue becomes irritated and inflamed. Because of this, the brain cells that send signals (neurons) may not work like they normally do. This can lead to changes in alertness and behavior, or even seizures.
Encephalitis is different from meningitis. In meningitis, there’s inflammation of the lining around the brain and spinal cord. Encephalitis is inflammation of the brain itself. But the two conditions can happen together. Depending on the cause, encephalitis may involve only certain parts of the brain.
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What causes encephalitis?
About 60% of encephalitis cases don’t have an identified cause. In cases with a known cause, it’s usually due to a virus or an autoimmune encephalitis.
Viral encephalitis
Many viruses can cause encephalitis. When a virus enters your body, it can reach the central nervous system and travel to the brain. The most common viral causes of encephalitis in the U.S. are:
Herpes simplex virus (causes herpes and cold sores)
Varicella-zoster virus (causes chickenpox and shingles)
Epstein-Barr virus (the “mono” or mononucleosis virus)
West Nile virus (mosquitoes transmit it)
Zika virus (mosquitoes can transmit it)
Enteroviruses (can cause hand, foot, and mouth disease and acute flaccid myelitis)
Measles (more common in unvaccinated people)
Rabies virus
Influenza virus
Autoimmune encephalitis
Autoimmune encephalitis can happen if your immune system begins to attack proteins in your brain by mistake. This can happen after certain infections, but many times the cause is unknown. It may also be associated with certain tumors. These include:
Ovarian teratoma (a type of tumor in the ovary)
Lymphoma (cancer of the lymph system)
Thymoma (cancer of the thymus gland)
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A certain class of cancer treatments can lead to autoimmune encephalitis. But this is rare. Immune checkpoint inhibitors — like nivolumab or ipilimumab — can trigger inflammation in the brain.
Other causes
There are other types of infections that may cause encephalitis in rare cases. This is much more likely in someone whose immune system is not functioning well. Some examples include:
Bacterial infections: Mycoplasma pneumoniae often causes respiratory disease and can cause encephalitis. It’s more common in kids.
Fungal infections: Cryptococcus and Coccidioides are two fungi that can cause infections. These are more likely to cause meningitis than encephalitis.
Amoeba: Naegleria fowleri is a parasite that can cause encephalitis. This type of infection is more common after swimming or diving in freshwater.
What are the symptoms of encephalitis?
Most of the time, symptoms of encephalitis develop quickly. They can evolve within days or sometimes weeks. Common symptoms include:
Confusion
Drowsiness or lethargy
Fever
Mood or psychiatric changes
Forgetfulness
Weakness and movement problems
Seizures
How do you diagnose encephalitis?
If you have symptoms of encephalitis, your provider may use different tests to help make the diagnosis. A lumbar puncture, or spinal tap, is an important test for diagnosing encephalitis. For this test a healthcare provider inserts a needle into the low back and takes a sample of cerebrospinal fluid (CSF). This is the fluid that surrounds the brain and spinal cord. They can analyze this fluid to identify any viruses or antibodies causing the inflammation.
An MRI is the best imaging test to show inflammation in different parts of the brain. A CT scan of the brain isn’t as good at showing inflammation, but it can still be helpful as part of the workup. If there’s a concern about seizures, you may also need an electroencephalogram (EEG). This test measures the electrical activity of the brain and can detect seizures.
How do you treat encephalitis?
The treatment for encephalitis depends on the cause. People with encephalitis are usually hospitalized for testing and initial treatment. Treatment may include:
Antiviral medications can treat some viral infections. Acyclovir is an antiviral that can treat HSV encephalitis.
Steroid medications, like methylprednisolone, are common treatment options. They may be more useful in treating autoimmune causes rather than viral causes.
Intravenous immunoglobulin (IVIG) is a treatment that helps to suppress the immune system. IVIG is a common treatment for autoimmune encephalitis.
Supportive care treatments help keep you safe while your body tries to recover. This can include IV fluids or medication for pain, fever, and seizures.
How serious is encephalitis?
Encephalitis is a serious condition that requires prompt diagnosis and early treatment. Those most at risk for death and severe illness are:
Infants and young children
Older adults
People with a weakened immune system
Issues of encephalitis can be severe and deadly. These can include:
Brain swelling
Respiratory failure
Aspiration pneumonia
Low platelet count
The risk of death from encephalitis can be as high as 40% in some parts of the world. For those who survive the illness, there’s also a risk of long-lasting effects.
How long does it take to recover from encephalitis?
The time it takes to fully recover from encephalitis can vary from weeks to months. Some people with autoimmune encephalitis even have a relapse. Even though most people survive encephalitis, many are left with long-term effects. And these residual issues can range from mild to severe. Some issues may not be obvious and may only appear on further testing.
Long-lasting effects of encephalitis may include:
Fatigue
Mood disturbance
Trouble with focus and attention
Seizures
Memory
Impaired hearing or vision
Physical, cognitive, and behavioral therapy are important parts of rehabilitation and may improve outcomes.
The bottom line
Encephalitis is a serious condition that causes inflammation in the brain. In many cases, it’s hard to know the exact cause. But sometimes an infection triggers it. Regardless of the cause, early diagnosis and treatment are important for recovery. Most people who have encephalitis survive with treatment. But many have ongoing impairments. Early and ongoing rehabilitation can help to restore normal function.
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References
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