Autoimmune encephalitis

Overview

Autoimmune encephalitis (en-sef-uh-LIE-tis) is a group of conditions that causes swelling in the brain. This happens because the immune system mistakenly attacks brain cells. Autoimmune encephalitis symptoms can vary but may include memory loss, changes in thinking, changes in behavior and seizures.

Autoimmune encephalitis is different from encephalitis caused by viral or bacterial infections, known as infectious encephalitis. Infectious encephalitis isn't caused by an immune reaction, and it's treated with different medicines. Research has found that the number of people with autoimmune encephalitis is comparable to the number of people with infectious encephalitis.

Experts don't know what causes autoimmune encephalitis, also known as AE. For some people, AE is triggered by certain cancers or infections. Autoimmune encephalitis also may be triggered by medicines. People with an autoimmune disease or a family history of autoimmune disease may be more likely to get AE. Healthcare professionals use several tests to diagnose autoimmune encephalitis.

Without treatment, autoimmune encephalitis can cause serious complications, including death. But treatments can lead to recovery. Many people with AE make a full recovery, but some can have lasting symptoms.

Symptoms

Autoimmune encephalitis symptoms can vary from person to person. But symptoms can occur in a pattern that is predictable depending on the type of autoimmune encephalitis. Many people have a headache, fever and other symptoms of an infection followed by:

• Psychiatric symptoms that may include anxiety, panic attacks, changes in behavior, agitation, hallucinations, delusions and trouble organizing thoughts.
• Trouble with memory.
• Trouble with language, such as talking less or repeating words or phrases.
• Movements that are not voluntary.
• Seizures.
• Changes in consciousness.
• Less sleep at the beginning of the disease followed by excess sleep during recovery.

Sometimes AE causes serious seizures that need emergency care, known as status epilepticus. These seizures last more than five minutes or occur one after another while the person is not conscious.

Autoimmune encephalitis symptoms can get worse over time. This disease course is known as progressive. Symptoms also might alternate between getting better and getting worse. This course is known as relapsing-remitting. These are similar to the disease courses people experience with multiple sclerosis.

When to see a doctor

Get emergency medical care if you or someone you're with has serious symptoms of AE. This includes having seizures that last more than five minutes or that happen one after another with a loss of consciousness. Also seek emergency medical care for high fevers or trouble breathing.

See your healthcare professional right away if you have any other symptoms of autoimmune encephalitis. AE can become serious quickly if not treated.

Causes

Autoimmune encephalitis causes are not known. Autoimmune encephalitis, also known as AE, happens when the immune system mistakenly attacks heathy brain cells.

Antibodies are part of the immune system. They help protect the body from viruses, bacteria and other substances that can cause illnesses. But in autoimmune encephalitis, the antibodies target and attack certain receptors in the brain. This leads to swelling in the brain, also known as inflammation, and other symptoms.

AE may be triggered by:

• Certain cancers. When this happens, it's known as paraneoplastic AE.
• Infections, such as from the herpes simplex virus.
• Certain medicines, such as monoclonal antibodies and medicines to suppress the immune system after a transplant.

Autoimmune encephalitis is more likely to occur in people who have an autoimmune disease or who have a strong family history of autoimmune disease.

Types

There are several different types of AE. Each type of autoimmune encephalitis is caused by the immune system attacking different receptors in the brain. Some of the types and causes include:

• Anti-NMDA-receptor autoimmune encephalitis. This is the most common type of AE. In this type, antibodies attack the NMDA receptor in the brain. It often affects young women and children and can cause seizures, facial movements, psychosis and other symptoms.
• Anti-GABA-B receptor encephalitis. This type of AE is related to a tumor, often small-cell lung cancer. This type of AE can cause seizures, confusion and memory loss. The average age of diagnosis of this type is 60.
• Anti-GABA-A receptor encephalitis. People with this type of AE are usually diagnosed around age 40, but children also can have this type of AE. This type of AE can cause seizures, movement disorders, and changes in thinking and behavior.
• Anti-AMPA receptor encephalitis. This type of AE usually affects women and can cause confusion and memory loss. The average age of diagnosis is age 62.
• Anti-LGI1 limbic encephalitis. This type of autoimmune encephalitis tends to affect men. It can cause memory loss, confusion and seizures. The average age of diagnosis is age 60.
• Anti-CASPR2 associated encephalitis. People with this type of AE often have symptoms that include confusion, memory loss, trouble with sleep, nerve pain and other symptoms. This type also can cause a rare disease known as Morvan syndrome. Morvan syndrome can cause hallucinations, memory loss, changes in blood pressure and painful cramps. Men are more likely to have this type of AE. The average age of diagnosis is 60.
• Anti-IgLON5 disease. People who have this type of AE have sleep symptoms that include behaviors and movements after falling asleep. The average age of diagnosis is 64.

Risk factors

Risk factors for autoimmune encephalitis, also known as AE, include:

• Having had AE in the past, especially if it wasn't treated.
• Having had herpes simplex virus encephalitis.
• Taking monoclonal antibodies or medicines to suppress the immune system after a transplant.
• Having a tumor, especially small-cell lung cancer.

Researchers are studying whether certain genes may be related to autoimmune encephalitis.

Complications

Serious autoimmune encephalitis, also known as AE, can lead to complications such as:

• Seizures that need emergency care, known as status epilepticus. The immune system's attack on the brain during AE can lead to seizures and a condition called autoimmune epilepsy. Sometimes the seizures may last more than five minutes or occur one after another. The person isn't conscious in between the seizures. These serious seizures are known as status epilepticus.
• Not enough air entering the lungs, known as respiratory failure. People with respiratory failure may need treatment with a machine that helps them breathe, known as mechanical ventilation.
• Trouble with heart rate and blood pressure. AE can affect heart rate, blood pressure, digestion and urination. These are known as autonomic functions.
• Fevers. People with AE may have high fevers.

Another possible complication is that the condition may come back after recovery. This is known as a relapse. A relapse is more likely in people who had anti-LGI1 limbic encephalitis or anti-CASPR2 associated encephalitis.

Prevention

Autoimmune encephalitis, also known as AE, can't always be prevented. But getting cancer screenings can help your healthcare professional find tumors and treat them early. This could prevent autoimmune encephalitis that is triggered by cancers. Talk with your healthcare professional about your cancer risk and if cancer screening is recommended.