Learn all about autoimmune encephalitis. The major role of our immune system is to recognize and get rid of infection. But sometimes some components of the immune system, called antibodies, may instead react with proteins in our own body causing an autoimmune disease. When this reaction is against proteins in the brain it is called Autoimmune Encephalitis.
The term “autoimmune encephalitis” appears in the medical literature in the 1970’s and 1980’s, the first specific AE antibody was identified in 2005 when Dr. Joseph Dalmua described the anti-NMDA-receptor encephalitis type. The field of AE has expanded rapidly since then. Now there are more than fifteen known types of AE, including auto-antibodies directed against NMDA, LGI1, CASPR2, VGKC-complex antibodies, AMPA, and GABA.
About 70% of patients have prodromal symptoms consisting of headache, fever, nausea, vomiting, diarrhoea, or upper respiratory-tract symptoms. The exact cause in majority of the patients with Autoimmune Encephalitis is not clear.
Autoimmune encephalitis is associated with systemic autoimmune disorders, CNS autoimmune disorders and paraneoplastic syndromes. Pathogenesis is likely to be mediated by antibodies (Abs) to CNS proteins. The Abs are directed against membrane receptors and ion channel-associated proteins that are expressed on the surface of neurons in the CNS, such as N-methyl D-aspartate receptors and leucine-rich, glioma inactivated protein and contactin-associated protein like, that are associated with voltage-gated potassium channels.
Encephalitis is usually a viral illness, which means that antibiotics are not used to treat viral infections. However, some antiviral drugs have been used to treat HSV infections, and some doctors may attempt to use antiviral drugs on other acute viral infections. No antiviral drugs to date are used to treat arboviral infections. Treatment includes first-line steroids, intravenous immunoglobulins (IVIG), and plasma exchange, and second-line Rituximab and Cyclophosphamide, followed in many cases by steroid-sparing agents in the long-term.
What is Autoimmune Encephalitis?
Autoimmune encephalitis (or autoimmune encephalopathy) is a diverse group of neuro-psychiatric disorders recognized recently, presenting acutely or subacutely with alteration of consciousness, cognitive decline, seizure, abnormal movements. Encephalitis is an inflammation (swelling) of the brain. Encephalitis is usually caused by a virus, but other things (including bacteria) can also cause it. Infection with many different viruses can lead to encephalitis. So how contagious the infection is depends on which virus caused it. Viruses like West Nile are only transmitted through the bite of infected insects; it’s not possible to catch them from other people. But viruses like EBV are passed from person to person.
Anti-NMDA Receptor Encephalitis
N-Methyl D-aspartate receptor (NMDAR) Ab encephalitis is the most common Ab-mediated autoimmune encephalopathy. It was first described in 2005 as a paraneoplastic syndrome associated with ovarian teratomas in young women and the antigenic target was determined in 2007, associated with antibodies against NR1 or NR2 subunits of the NMDA receptor. Irani et al. in 2010 presented NMDAR Ab encephalitis in a predominantly non-paraneoplastic disorder of both sexes. NMDA receptor is a protein in the brain that helps control the electrical activity of nerves and therefore antibodies against these receptors are likely to have an important role in directly causing the disease.
Autoimmune Encephalitis Symptoms
Symptoms associated with autoimmune encephalitis can include:
- Weakness or numbness of part of the body
- Loss of balance
- slowed or blurred speech or loss of ability to speak
- Involuntary movements
- distorted vision
- Cognitive impairment
- Memory disturbance
- decreased level of consciousness – to the point of unresponsiveness, catatonia or coma
- Seizures (either self-evident or smaller seizures that show up on an eeg reading)
- Partial or complete loss of appetite for long periods
- Food and drink tasting inedible or triggering nausea
- Excessive eating without feeling sated
- Inability to sleep
- Loss of inhibition
- Rapid, pressured, or involuntary speech
- Hallucinations (visual or auditory) and delirium
- Paranoid thoughts
- Severe anxiety
Autoimmune Encephalitis Treatment
Autoimmune Encephalitis is treated with immunotherapy. Immunotherapy slows down the over excited immune system. By slowing down the immune system it slows down and attempts to stop the attack that is occurring. Initially, high dose steroids are used to slow down the immune system and bring down the inflammation in the brain in a broad way.
Immunotherapy treatment is the combination of treatments that include first-line therapies: steroids, IVIG, plasma exchange (plasmapheresis) and second -line therapies: Rituxamab (Rituxan) and cyclophosphamide (Cytoxan), followed in many cases by steroid-sparing agents such as cellcept or azathioprine in the long-term. The fact that patients who receive second line immunotherapies have fewer relapses, is leading many physicians to use rituximab initially as a first line treatment. Anticonvulsants like lorazepam (Ativan) can be given for seizure control. Steroids have not been established as being effective although they may still be used in some cases. Diuretics may be used to lower intracranial pressure in individuals who have encephalitis and increased intracranial pressure.