Anti-NMDA receptor encephalitis is a disease that happens when antibodies produced by the body’s immune system attack the NMDA receptors in the brain.
NMDA receptors are the proteins that manage the brain’s electrical impulses, and their function is essential for judgment, perception of reality, human interaction, memory encoding and retrieval, and management of unconscious activities (like breathing, swallowing, etc.), called autonomic functions.
why Antibodies are an important component of the body’s defense system?
All healthy people produce antibodies to fight viruses, bacteria, and tumors. Under normal circumstances, the body prevents the production of antibodies against its tissues. However, in some people, the body produces antibodies that attack its cells. In such cases, the patient is said to have an “auto-immune” disease.
In the case of anti-NMDA receptor antibody encephalitis, the body produces antibodies that attack NMDA receptors where they are found in greatest concentration: in the brain. However, you do not yet have a clear understanding of why these anti-NMDA receptor antibodies are created.
Anti-NMDA receptor encephalitis may be associated with a tumor – in such a case it would be called a “para (associated with) neo (new) plastic disease. If a tumor is found, it is usually a benign (non-cancerous) tumor of the ovary. The most common type of tumor is teratoma. However, unlike other types of tumors, this one could contain many different types of body tissue (including brain tissue!).
It is generally more likely to find a tumor in young women who become ill during their childbearing years, and less likely in people who are very young (0 to 10 years old) or older (over 50 years old). Anti-NMDA receptor antibody encephalitis affects women (80%) more than men (20%).
Tumors can also occur in men. In such cases, they are found usually in the testicles. Other types of tumors that have been associated with NMDA receptor encephalitis include lung cancer, thyroid gland tumors, breast cancer, colon cancer, and neuroblastomas.
What are the main symptoms?
- Flu-like symptoms
- Memory deficits, including short-term memory loss
- Sleeping troubles
- Speech disorders – the patient is no longer able to produce coherent language or may be completely unable to communicate
- Cognitive or behavioral disorders – confused thinking, hallucinations, delusional thoughts, disinhibited behavior
Epileptic seizures
Movement disorders, usually of the arms and legs, mouth and tongue, but can include whole body spasms. These types of movements are very common in anti-NMDA receptor encephalitis, and the patient is unable to control them. These movements are usually very violent and require the patient to be immobilized and sedated for their safety and that of their healthcare providers.
In contrast, the patient may also be unable to move and resemble a statue, maintaining the same position for hours or days (catatonia).
- Loss of consciousness – the patient may be semi-conscious or fall into a coma
- Autonomic dysfunction – erratic breathing, heart rate, and blood pressure; loss of bladder and bowel control
- Central hypoventilation – the patient may stop breathing and require a mechanical breathing machine
- Vision and/or hearing may also be affected.
What tests can diagnose anti-NMDA receptor antibody encephalitis?
To make a diagnosis of anti-NMDA receptor encephalitis, the presence of antibodies must be detected in the body fluids of the person whose symptoms correspond to anti-NMDA receptor encephalitis. Antibodies can be found in the blood or spinal fluid.
Tests using spinal fluid are more accurate than blood tests. Therefore, if blood tests are negative, it is recommended to test the spinal fluid before concluding that the patient does not have NMDA receptor antibody encephalitis.
Imaging is also an important component of the evaluation of a patient with suspected NMDA receptor encephalitis and should include studies examining the brain (MRI) and studies examining the body for the presence of an associated tumor.
What is the treatment for the disease?
Patients diagnosed with anti-NMDA receptor antibody encephalitis should be admitted to the hospital, where they can be observed and cared for by a team of doctors, nurses, and other healthcare professionals.
Although each patient’s disease, symptoms, and experience are different, the majority are treated with medications that reduce the levels of antibodies in the blood and spinal fluid. These medications include corticosteroids, intravenous immunoglobin, and plasmapheresis (PLEX).
Sometimes you need to use stronger drugs to eliminate the antibodies. The drugs most often used to treat NMDA receptor encephalitis are rituximab and cyclophosphamide 9.
Many other medications may also be needed for a variety of reasons, including those that manage blood pressure, stop seizures, relieve anxiety, improve sleep, and treat hallucinations or abnormal behaviors.
Patients may need to continue taking these medications even after they begin to recover from the illness.
What is the prognosis?
Now anti-NMDA receptor encephalitis happens to be a serious, life-threatening illness, but the majority of patients who are promptly diagnosed and treated recover well from the illness.
Recovery is usually slow and can take months or even years! The recovery process is often complicated by ups and downs, and fear of relapse or reoccurrence of symptoms. During this time, the patient must continue to be monitored by their doctor. Even when recovery is well established, it is very important to participate in routine medical examinations, including repeat imaging, to ensure that no tumors are found.
Conclusion
Unfortunately, not all people with anti-NMDA receptor encephalitis recover from the illness. It can be fatal, and most patients who die from it die from cardiac arrest (when the heart stops beating) or from complications associated with long hospital stays and the use of powerful drugs that weaken the immune system (which makes people more susceptible to serious infections).
Some patients also may never fully recover from the illness, and their loved ones may notice changes in their personality or other differences from their state before the illness began.
References
- National Institutes of Health(2023) Anti-NMDAR Encephalitis Available online at: https://www.ncbi.nlm.nih.gov/books/NBK551672/
- Cleveland Clinic(n.d) Adult-onset Anti-NMDA Receptor Encephalitis Available online at: https://my.clevelandclinic.org/departments/neurological/depts/multiple-sclerosis/ms-approaches/adult-onset-anti-nmda-receptor-encephalitis
