Autoimmune Encephalitis (patient information)
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| Autoimmune encephalitis Patient information |
|---|
| Overview |
| Symptoms |
| Causes |
| Who is at highest risk? |
| Diagnosis |
| When to seek urgent medical care? |
| Treatment options |
| Finding medical care |
| Prevention |
| Outlook |
| Possible complications |
| Sources |
Overview
Autoimmune encephalitis is an illness in which your immune system, the body's defense against infection, mistakenly attacks your brain. This causes inflammation and can change your memory, behavior, speech, movement, and awareness.[1]
It is a type of encephalitis. Anti-NMDA receptor encephalitis is one form, but other forms also exist. Your doctor may identify a type by testing for antibodies, which are proteins made by the immune system.[2]
Autoimmune encephalitis can be serious and needs prompt medical care. Treatment can help, but recovery may take time. You cannot pass autoimmune encephalitis to someone else by normal contact.[3]
What are the symptoms of autoimmune encephalitis?
You or your family may notice changes over days or weeks, such as:
- Trouble remembering recent events, following a conversation, or thinking clearly.
- New confusion, strong anxiety, unusual beliefs, or behavior that is very different from usual.
- Seeing or hearing things that other people do not.
- Seizures, which may cause jerking, staring, or loss of awareness.
- Trouble speaking or speaking much less than usual.
- Unwanted movements, poor sleep, or unusual drowsiness.
Symptoms vary between people and between types of the illness.[1]
If your child is affected, you may notice a sudden change in behavior, loss of speech or other skills, unusual movements, or seizures. A headache or fever can occur before symptoms, but these are not always present.[4]
What causes autoimmune encephalitis?
Your immune system normally protects you from germs. In autoimmune encephalitis, parts of this system target the brain by mistake. Some forms involve antibodies against proteins on brain cells. Doctors do not always find a known antibody, so a negative antibody test does not settle the diagnosis on its own.[2]
Sometimes the illness follows herpes simplex encephalitis, an infection of the brain. Some cases are linked to a tumor or to certain cancer treatments that affect the immune system. In many people, no clear trigger is found. A tumor is an abnormal growth; it is not always cancer.[5]
Who is at highest risk?
You can develop autoimmune encephalitis at any age. Risk varies by type. Certain tumors, previous herpes simplex encephalitis, and some medicines are linked to the illness. Many affected people have no obvious trigger.[1]
Diagnosis
Your doctor will ask how your symptoms began and examine your memory, speech, movement, and alertness. A relative or friend may help describe changes you have not noticed.[6]
You may need:
- Blood tests to check for antibodies and other possible causes.
- A lumbar puncture, or spinal tap: a needle in your lower back collects a small sample of the fluid around your brain and spinal cord. Tests look for inflammation, infection, and antibodies.
- An MRI scan: this takes detailed pictures of your brain.
- An EEG: small sensors on your scalp record brain activity and may detect seizures.[6]
An MRI or routine spinal fluid result can be normal. Your doctor considers the results together with your symptoms and checks for other causes, including infection. There is no single test that diagnoses every form of autoimmune encephalitis.[2]
You may also have scans to look for a related tumor. The tests depend on your age, symptoms, and antibody results. Being offered these tests does not mean a tumor has already been found.[5]
When to seek urgent medical care?
Call your local emergency number or seek emergency care immediately if you or someone else develops:
- New severe confusion, a sudden major change in behavior, or difficulty waking.
- Loss of consciousness or trouble breathing.
- A severe headache with fever and a stiff neck.
These symptoms can have several causes and need urgent assessment.[7]
Also get emergency help for a first seizure, a seizure lasting five minutes or longer, a seizure lasting longer than the person's usual pattern, or repeated seizures without full recovery between them.[8]
If you are helping someone during a seizure, protect them from nearby dangers, cushion their head, and time the seizure. After the jerking stops, turn them onto their side. Do not put anything in their mouth or give food or drink until they have fully recovered. Stay with them. Follow an existing seizure care plan if you know how to do so.[8]
Treatment options
Treatment usually begins in hospital. If you are very unwell, you may need intensive care. When the medical evidence strongly supports autoimmune encephalitis, your team may start treatment before all antibody results return. They will also check urgently for infection and may give antiviral medicine while tests are pending.[9]
Treatment to calm the immune system may include:
- Corticosteroids: medicines that reduce inflammation.
- Intravenous immunoglobulin, or IVIG: a treatment given through a vein to help control the immune response.
- Plasma exchange: a procedure that removes harmful substances, including antibodies, from the liquid part of your blood.
Your team may use one treatment or combine treatments.[10]
If you do not improve enough, you may need medicines such as rituximab or cyclophosphamide. These reduce parts of the immune response. The choice depends on your type of illness, other health problems, and response to treatment.[5]
If a related tumor is found, treating or removing it may be part of your care. You may also need medicines for seizures, sleep, or severe agitation, and help with breathing, fluids, or feeding.[10]
If your child has anti-NMDA receptor encephalitis, treatment and follow-up will be chosen for their age, symptoms, and recovery. Some children need stronger medicines or longer treatment.[11]
As you recover, you may need help with walking, speech, memory, mood, or daily tasks. Ask about physical therapy, occupational therapy, speech therapy, and support for thinking and memory. Follow your prescribed plan and discuss medicine changes with your care team.[12]
Where to find medical care for autoimmune encephalitis?
For urgent symptoms, go to an emergency department. Ongoing care is usually led by a neurologist, a doctor who treats the brain and nerves. A specialist in immune-related brain illness may also be involved. Children should be assessed by a children's neurology team.[9]
For information and family support, you can visit Encephalitis International. Ask your treating team about local rehabilitation, psychological support, and patient groups.[13]
Prevention
There is no proven way to prevent every case of autoimmune encephalitis. After treatment, your follow-up plan can help your team recognize problems early. Keep appointments and report new or returning symptoms. Some people need ongoing immune treatment to reduce the chance of another episode, but this is not needed for everyone.[12]
Ask your team about tumor follow-up, vaccines, and ways to reduce infection risk while taking medicines that suppress your immune system.[5]
What to expect (Outlook/Prognosis)?
Many people improve with treatment, but your recovery depends on the type and severity of your illness. Some people recover fully; others have lasting difficulties. Improvement may continue over months or years. The illness can sometimes return after recovery; this is called a relapse.[6]
You may feel much more tired than before. Try short activities followed by rest, and increase activity gradually with advice from your team. Ask for a plan for returning to school or work, and discuss when driving and other activities are safe.[13]
If your child has ongoing memory, attention, or behavior changes, the school may need to provide extra support during recovery.[4]
Possible complications
Without treatment, autoimmune encephalitis can cause lasting brain injury or death. Serious complications may include:
- Long or repeated seizures.
- Breathing problems that need a breathing machine.
- Dangerous changes in heart rate or blood pressure.
- Loss of consciousness.[9]
Other problems can include ongoing seizures, memory or thinking difficulties, mood or behavior changes, poor sleep, and long-lasting tiredness. These problems may need follow-up care and rehabilitation.[12]
Treatment can also cause side effects, including a higher risk of infection with some medicines. Your team may arrange blood tests and other checks to reduce these risks.[5]
Sources
- ↑ 1.0 1.1 1.2 Mayo Clinic Staff. Autoimmune encephalitis: Symptoms and causes. Mayo Clinic. December 13, 2024. Accessed October 31, 2026.
- ↑ 2.0 2.1 2.2 Graus F, Titulaer MJ, Balu R, et al. A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol. 2016;15(4):391–404. doi:10.1016/S1474-4422(15)00401-9. PMID:26906964.
- ↑ NHS. Encephalitis. Accessed October 31, 2026.
- ↑ 4.0 4.1 Great Ormond Street Hospital for Children NHS Foundation Trust. Autoimmune encephalitis. Patient and family information. Accessed October 31, 2026.
- ↑ 5.0 5.1 5.2 5.3 5.4 Hahn C, Budhram A, Alikhani K, et al. Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults. Can J Neurol Sci. 2024;51(6):734–754. doi:10.1017/cjn.2024.16. PMID:38312020.
- ↑ 6.0 6.1 6.2 Mayo Clinic Staff. Autoimmune encephalitis: Diagnosis and treatment. Mayo Clinic. December 13, 2024. Accessed October 31, 2026.
- ↑ NHS. Encephalitis: Symptoms. Accessed October 31, 2026.
- ↑ 8.0 8.1 NHS. What to do if someone has a seizure (fit). Accessed October 31, 2026.
- ↑ 9.0 9.1 9.2 Michael BD, et al. Management of suspected infectious and autoimmune encephalitis in adults – National Guidelines from the United Kingdom Joint Societies. J Infect. Published online October 2026:106873. doi:10.1016/j.jinf.2026.106873. PMID:42863638.
- ↑ 10.0 10.1 NHS. Encephalitis: Treatment. Accessed October 31, 2026.
- ↑ Nosadini M, Thomas T, Eyre M, et al. International Consensus Recommendations for the Treatment of Pediatric NMDAR Antibody Encephalitis. Neurol Neuroimmunol Neuroinflamm. 2021;8(5):e1052. doi:10.1212/NXI.0000000000001052. PMID:34301820.
- ↑ 12.0 12.1 12.2 Abboud H, Probasco J, Irani SR, et al.; Autoimmune Encephalitis Alliance Clinicians Network. Autoimmune encephalitis: proposed recommendations for symptomatic and long-term management. J Neurol Neurosurg Psychiatry. 2021;92(8):897–907. doi:10.1136/jnnp-2020-325302. PMID:33649021.
- ↑ 13.0 13.1 Encephalitis International. Guidelines for recovery. Accessed October 31, 2026.