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.

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.

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 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.

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.

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.

Autoimmune encephalitis diagnosis involves a review of your symptoms, a physical exam and several tests. It's important to get an accurate diagnosis because autoimmune encephalitis, also known as AE, can be mistaken for other diseases.

Experts have created autoimmune encephalitis criteria to help healthcare professionals diagnose people with AE. Healthcare professionals look for patterns of symptoms that signal AE. They also test for signs that antibodies are attacking receptors in the brain to cause AE.

Tests also help rule out other possible causes of your symptoms, such as infections or other autoimmune conditions.

Sometimes people are incorrectly diagnosed with autoimmune encephalitis. It's important for healthcare professionals to consider all potential conditions when making a diagnosis.

Lab tests

Testing for autoimmune encephalitis includes checking for antibodies. AE is caused by antibodies in the brain that attack proteins and receptors in the brain and cause symptoms.

Some tests may be done on your blood. Other tests are done on the fluid that surrounds your brain and spinal cord, known as cerebrospinal fluid. Cerebrospinal fluid is removed using a procedure known as a lumbar puncture. During the procedure, a healthcare professional numbs the lower back and uses a hollow needle to remove cerebrospinal fluid for testing.

Brain imaging

Your healthcare professional also may recommend an MRI of your brain. MRIs can look for signs of autoimmune encephalitis or rule out other causes of your symptoms.

Other imaging tests may look for signs of cancer that may have triggered AE.

EEG

An electroencephalogram, also known as an EEG, tests the electrical activity in your brain. It may show seizure activity and may help your healthcare professional diagnose AE. An EEG also can help rule out other conditions.

Autoimmune encephalitis treatment focuses on the immune system, which is mistakenly attacking brain cells. If a tumor is causing autoimmune encephalitis, the first step is to diagnose and treat the tumor.

Medicines

Immunotherapy works by reducing the immune system's activity and improving inflammation.

Two types of immunotherapy are given through an IV in a vein in the arm. Most people get this therapy in a hospital. Medicines include:

• Methylprednisolone (Solu-Medrol). This high-dose steroid is given daily for 3 to 7 days.
• Immunoglobulin (IVIg). This medicine may be given daily for 2 to 5 days.

Other treatment options include:

• Oral corticosteroids. With this medicine, you start with a larger dose and then slowly lower the dose over weeks to months, known as tapering.
• Plasma exchange. This therapy gets rid of antibodies that are causing the immune system to attack brain cells. During plasma exchange, the liquid part of your blood is removed and separated from your blood cells. The blood cells are put back into your body and your body makes more plasma.

If your symptoms respond to immunotherapy, the medicine doses are slowly lowered over time, known as tapering. You may take an oral corticosteroid at a lower dose for several weeks. Or you may get monthly doses of methylprednisolone or immunoglobulin through an IV for several months.

If your symptoms aren't improving, your healthcare professional also may recommend the medicines rituximab (Rituxan, Truxima, others), cyclophosphamide or tocilizumab (Actemra, Tofidence, Tyenne). These medicines can improve symptoms and help lower the chances of AE coming back.

Most people recover with treatment. The earlier you receive treatment, the more quickly you may recover. Early treatment also lowers the chances of having lasting symptoms due to AE or having another bout of autoimmune encephalitis.

Therapies

You may need treatment for complications, such as epilepsy, sleep conditions and trouble with movements. You also may need rehabilitation if AE affected your memory, thinking skills or speech. Occupational and speech therapists, along with mental health professionals and other specialists, can help in your recovery.

If cancer triggered autoimmune encephalitis, you're treated for the cancer and monitored to check if the cancer comes back. Sometimes people with other symptoms related to AE need to get regular care from specialists.

The long-term outlook can vary from person to person. Full recovery may take months or years. Many people continue to have symptoms related to thinking and behavior for longer than a year. But treatment continues to improve symptoms for 18 months to two years.

Some people fully recover while others may have lasting symptoms that are mild or more serious. Getting treated early helps improve your long-term outlook.

People who have recovered from certain types of autoimmune encephalitis, such as anti-NMDA receptor encephalitis and anti-LGI1 encephalitis, are at risk of symptoms coming back. Sometimes symptoms return after several years.

Autoimmune encephalitis can cause serious symptoms that need emergency medical care. Your healthcare team includes specialists, including doctors who specialize in the brain and nervous system, known as neurologists.

If your symptoms aren't as serious, you might start by seeing your regular healthcare professional. Your healthcare professional may refer you to a neurologist or another specialist. Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fasting before having a specific test. Make a list of:

• Your symptoms, including any that seem unrelated to the reason for your appointment.
• Key personal information, including major stresses, recent life changes and family medical history.
• All medicines, vitamins or other supplements you take, including the doses.
• Questions to ask your healthcare professional.

Take a family member or friend along, if possible, to help you remember the information you're given.

For autoimmune encephalitis, some basic questions to ask include:

• What's likely causing my symptoms?
• Other than the most likely cause, what are other possible causes for my symptoms?
• What tests do I need?
• Is my condition likely short term or lasting?
• What's the best course of action?
• What are the alternatives to the primary approach you're suggesting?
• I have these other health conditions. How can I best manage them together?
• Are there restrictions I need to follow?
• Should I see a specialist?
• Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, such as:

• When did your symptoms begin?
• Do your symptoms occur all the time or off and on?
• How bad are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?