Autoimmune encephalitis is inflammation of the brain caused by the immune system mistakenly attacking healthy brain tissue. It can develop over days to weeks and often produces a confusing mix of psychiatric symptoms, memory problems, seizures and movement changes — which is why it is sometimes mistaken at first for a psychiatric illness, a rapidly-progressive dementia, or a viral infection.
The single most important message about autoimmune encephalitis is this: it is treatable, and the earlier treatment starts, the better the recovery. Many people — particularly with the most common antibody types — improve substantially or recover with prompt immunotherapy.
What is autoimmune encephalitis?
In autoimmune encephalitis, antibodies or immune cells target proteins in the brain. The conditions are grouped by the antibody involved and — crucially — by whether that antibody attacks a protein on the surface of brain cells or inside them:
🎯 Cell-surface antibodies
For example NMDA receptor, LGI1, CASPR2, GABA-B — these are the most treatable, because the antibody itself drives the disease and can be cleared with immunotherapy.
🔬 Intracellular / paraneoplastic antibodies
For example anti-Hu, anti-Yo, anti-Ma2, high-titre GAD65 — often linked to an underlying cancer; treatment then includes finding and treating the tumour.
Symptoms and red flags
The pattern depends on the antibody:
🧠 Anti-NMDA receptor encephalitis
Often in younger adults and children: psychiatric or behavioural change, agitation or psychosis, followed by seizures, a movement disorder, autonomic instability and reduced consciousness. In young women it can be associated with an ovarian teratoma.
💭 LGI1 encephalitis
Usually older adults: short-term memory loss, confusion, and very brief, frequent faciobrachial dystonic seizures (jerks of the face and arm). A low blood sodium level is common.
⚡ CASPR2
Memory and behaviour change, nerve hyperexcitability (cramps, twitching), pain and disturbed sleep.
🌀 GABA-B and others
Prominent seizures; sometimes linked to lung cancer.
When to act fast: any previously-well person with subacute (days-to-weeks) memory loss, new psychiatric symptoms, unexplained seizures, or a new movement disorder should be assessed urgently. Time-to-treatment is the single largest factor in long-term outcome.
How autoimmune encephalitis is diagnosed
🧪 Antibody testing in blood and spinal fluid
Testing both is important, as some antibodies are detected in only one.
💧 Lumbar puncture (CSF)
Cerebrospinal fluid (CSF) often shows inflammation and helps exclude infection.
🧲 MRI of the brain
MRI (magnetic resonance imaging) may show inflammation in the inner temporal lobes (limbic encephalitis), or may be normal.
📈 EEG
The EEG (electroencephalogram) detects seizure activity and characteristic patterns (such as “extreme delta brush” in NMDAR encephalitis).
🔍 A search for an underlying tumour
CT, MRI or PET, and pelvic imaging where relevant — because treating an associated cancer is part of treating the encephalitis.
Treatment
First-line immunotherapy
Treatment usually begins quickly, often before every test result is back, and includes high-dose corticosteroids, intravenous immunoglobulin (IVIG), and/or plasma exchange (PLEX). If a tumour is found, removing it is an essential part of treatment.
Second-line treatment
If the response is incomplete, rituximab and/or cyclophosphamide are added. For difficult cases, newer options such as tocilizumab and bortezomib are used in specialist centres.
Reassuring: with prompt first-line treatment — and second-line therapy when needed — many people with cell-surface antibody encephalitis, especially NMDAR, make a substantial recovery, although it can take months.
Outlook
Recovery is often gradual, measured in months rather than days, and rehabilitation plays an important role. Relapses can occur, so ongoing neurology follow-up is part of care. The outlook is generally best when treatment starts early and any associated tumour is treated.
Autoimmune encephalitis care at East Neurology
Dr Tal Koren provides subspecialty neuroimmunology assessment for suspected and confirmed autoimmune encephalitis at East Neurology in Bondi Junction, coordinating antibody testing, imaging, treatment and follow-up alongside Dr Ron Granot and the wider team. Suspected acute encephalitis is a medical emergency and should be managed in hospital; the practice provides diagnosis, second opinions and ongoing care.
Frequently asked questions
Is autoimmune encephalitis the same as a brain infection?
No — the symptoms can overlap, but autoimmune encephalitis is caused by the immune system, not a germ. The two are told apart with spinal fluid tests, antibody testing and MRI, and treatment is different.
Can it be mistaken for a psychiatric illness?
Yes, especially early NMDA receptor encephalitis. A new psychiatric presentation with seizures, a movement disorder, or rapid change in a previously-well person should prompt testing for autoimmune encephalitis.
Will I fully recover?
Many people recover well, particularly with the common cell-surface antibodies and early treatment, though recovery often takes months. Outcomes vary with the antibody type and how quickly treatment begins.
Related reading
- Neuroimmunology — overview of conditions and team
- EEG (brain-wave) testing
- Multiple sclerosis
- Dr Tal Koren — Consultant Neurologist (Neuroimmunology)
External resources
- Encephalitis International — information and support
This page is general information about autoimmune encephalitis and is not personal medical advice. Suspected acute encephalitis needs urgent hospital assessment.
Book an appointment
To arrange a consultation about autoimmune encephalitis with Dr Tal Koren, ask your GP or specialist for a referral, then get in touch. Suspected acute encephalitis needs urgent hospital assessment.
Or call 02 9388 0615. East Neurology is a private practice; we do not bulk bill (including DVA cardholders) — Medicare claims are processed for you on the day.