Autoimmune Encephalitis
Imagine waking up one day and feeling like your brain is on fire. You can’t remember who you are, where you are, or what you are doing. You see and hear things that are not there, and you act in ways that are not normal for you. You may even have seizures or lose consciousness. This is what some people experience when they have autoimmune encephalitis, a rare but serious condition where the body’s own immune system attacks the brain cells, causing inflammation and damage.
Here, we will tell you more about this condition and how it affects the brain. We will also tell you how it is diagnosed, how it is treated, and what are the possible complications. We hope this post will help you learn more about this condition and provide you with some useful resources.
What is encephalitis?
Encephalitis is a term that means swelling or inflammation of the brain tissue. It can affect the whole brain or only certain parts of it. Encephalitis can cause various neurological problems, such as headache, fever, confusion, seizures, and coma. Encephalitis can be life-threatening and requires prompt diagnosis and treatment.
Types of encephalitis:
There are two main types of encephalitis: infectious and autoimmune.
Infectious encephalitis:
This type of encephalitis is caused by a virus, bacterium, fungus, parasite, or other microorganism that infects the brain directly or spreads from another part of the body. Some of the common causes of infectious encephalitis are herpes simplex virus (HSV), West Nile virus, rabies virus, measles virus, and tick-borne encephalitis virus.
Autoimmune encephalitis:
This type of encephalitis is caused by the body’s own immune system attacking the brain cells, either by mistake or in response to a tumor, infection, or vaccine. Some of the common causes of autoimmune encephalitis are anti-NMDA receptor encephalitis, anti-LGI1 encephalitis, anti-CASPR2 encephalitis, and Rasmussen encephalitis.
Anti-NMDA receptor encephalitis is a type of autoimmune encephalitis that is caused by antibodies that target the NMDA receptors in the brain. These receptors are involved in learning, memory, and synaptic plasticity. The antibodies disrupt the normal function of the receptors and cause inflammation and damage to the brain. The symptoms of anti-NMDA receptor encephalitis include fever, headache, fatigue, psychosis, seizures, and cognitive impairment.
The condition can affect both children and adults but is more common in young women. It can be associated with tumors, especially ovarian teratomas, or infections, such as herpes simplex virus. The diagnosis is confirmed by detecting the antibodies in the blood or cerebrospinal fluid. The treatment consists of immunotherapy and tumor removal if present. The prognosis is variable, but most patients recover with treatment, although some may have residual neurological or psychiatric problems.
Anti-LGI1 encephalitis is a type of autoimmune encephalitis that is caused by antibodies that target the LGI1 protein in the brain. This protein is involved in regulating the communication between neurons, especially in the temporal lobe. The antibodies interfere with the function of the protein and cause inflammation and damage to the brain. The symptoms of anti-LGI1 encephalitis include cognitive impairment, memory loss, seizures, sleep disturbances, and psychiatric disorders.
The condition mainly affects middle-aged and older men. It is rarely associated with tumors but may be triggered by infections, vaccines, or drugs. The diagnosis is confirmed by detecting the antibodies in the blood or cerebrospinal fluid. The treatment consists of immunotherapy and seizure control. The prognosis is generally favorable, but some patients may have relapses or persistent neurological or psychiatric problems.
Anti-CASPR2 encephalitis is a type of autoimmune encephalitis that is caused by antibodies that target the CASPR2 protein in the brain and peripheral nervous system. This protein is involved in forming the voltage-gated potassium channel complex, which regulates the electrical activity of neurons. The antibodies disrupt the function of the protein and cause inflammation and damage to the brain and nerves. The symptoms of anti-CASPR2 encephalitis include cognitive impairment, memory loss, seizures, movement disorders, autonomic dysfunction, and peripheral nerve hyperexcitability.
The condition mainly affects older men. It is often associated with tumors, especially those of the lungs, thymus, or testes. This is called paraneoplastic syndrome, and it accounts for about 10-15% of cases. The diagnosis is confirmed by detecting the antibodies in the blood or cerebrospinal fluid. The treatment consists of immunotherapy, tumor removal if present, and symptomatic management. The prognosis is variable, but some patients may have a good outcome with treatment, while others may have severe or fatal complications.
Rasmussen encephalitis is a rare inflammatory neurological disease that affects only one hemisphere of the brain. It is characterized by chronic inflammation of the brain, with infiltration of immune cells that cause damage to the brain cells. The cause of the inflammation is unknown, but it may be related to genetic or environmental factors or infections. The symptoms of Rasmussen encephalitis include frequent and severe seizures, loss of motor skills and speech, weakness on one side of the body, and cognitive decline.
The condition mostly affects children under the age of 10, but can also affect adolescents and adults. The diagnosis is based on the clinical signs and symptoms, and the brain imaging findings. The treatment consists of anti-epileptic drugs, immunosuppressive drugs, or surgery to remove or disconnect the affected hemisphere. The prognosis is poor, as most patients are left with permanent neurological deficits, and some may die from the disease.
Seronegative Autoimmune Encephalitis
Seronegative autoimmune encephalitis is a type of autoimmune encephalitis that does not have any detectable antibodies in the blood or cerebrospinal fluid that are known to cause brain inflammation. Autoimmune encephalitis is a condition where the immune system mistakenly attacks the brain cells, causing various neurological and psychiatric symptoms. Seronegative autoimmune encephalitis is a subgroup of autoimmune encephalitis that is defined after excluding other causes of encephalitis, such as infections, tumors, or metabolic disorders.
The causes and mechanisms of seronegative autoimmune encephalitis are not fully understood, but some possible factors are genetic predisposition, environmental triggers, hidden antibodies, or non-antibody immune responses. The diagnosis of seronegative autoimmune encephalitis is based on the clinical signs and symptoms, the brain imaging findings, and the response to immunotherapy. The treatment of seronegative autoimmune encephalitis consists of immunosuppressive drugs, supportive care, and tumor removal if present. The prognosis of seronegative autoimmune encephalitis is variable, but some patients may have a good outcome with treatment, while others may have severe or fatal complications
Definition of autoimmune encephalitis:
An autoimmune encephalitis is a group of disorders that occur when the immune system produces antibodies that target specific proteins on the surface or inside of the brain cells, causing inflammation and damage. These antibodies are called autoantibodies, and they can interfere with the normal functioning of the brain, leading to various neurological and psychiatric symptoms. ²³
Signs and symptoms of autoimmune encephalitis:
The signs and symptoms of autoimmune encephalitis vary depending on the type of autoantibody, the area of the brain affected, and the severity of the condition. Some of the common signs and symptoms are:
– Changes in personality, mood, behavior, or cognition, such as memory loss, confusion, hallucinations, delusions, paranoia, or psychosis.
– Seizures, which can be focal or generalized, and may be difficult to control with medications.
– Movement disorders, such as tremors, dystonia, myoclonus, ataxia, or chorea.
– Sleep disturbances, such as insomnia, hypersomnia, or abnormal sleep movements.
– Autonomic dysfunction, such as sweating, flushing, heart rate changes, blood pressure changes, or urinary or bowel problems.
– Speech or language problems, such as aphasia, dysarthria, or mutism.
– Sensory or motor problems, such as numbness, tingling, weakness, or paralysis.
– Vision problems, such as blurred vision, double vision, or loss of vision.
Causes and risk factors of autoimmune encephalitis:
The exact causes and risk factors of autoimmune encephalitis are not fully understood, but some possible factors are:
– Genetic predisposition, which may make some people more susceptible to developing autoantibodies or having faulty immune regulation.
– Environmental triggers, such as infections, vaccines, drugs, or toxins, which may activate or mimic the autoantigens and trigger an immune response.
– Tumors, especially those of the ovaries, testes, lungs, or thymus, which may express the autoantigens and induce an immune reaction. This is called paraneoplastic syndrome, and it accounts for about 10-15% of autoimmune encephalitis cases.
Diagnosis of autoimmune encephalitis:
The diagnosis of autoimmune encephalitis is based on the clinical signs and symptoms, the medical history, the physical examination, and the laboratory tests. Some of the tests that may be done to confirm the diagnosis and identify the type of autoantibody are:
– Blood tests, to check for the presence of autoantibodies, inflammation markers, and tumor markers.
Mayo Autoimmune Encephalitis Panel
The Mayo autoimmune encephalitis panel is a set of tests that can help diagnose autoimmune encephalitis, a condition where the immune system attacks the brain and causes inflammation. Autoimmune encephalitis can have various causes and symptoms, and it can be life-threatening if not treated promptly. The Mayo Panel includes comprehensive evaluations, targeted antibody testing, and complementary assays to pinpoint the cause and facilitate personalized therapy selection.
The panel can be done using serum or spinal fluid specimens, depending on the clinical situation. The panel evaluates 20 antibodies that are known to be associated with autoimmune encephalitis, such as anti-NMDA receptor, anti-LGI1, anti-CASPR2, and anti-CRMP-5 antibodies. The panel also directs a focused search for cancer, which can be a trigger or a complication of autoimmune encephalitis. The panel is part of an evolving approach to testing for autoimmune neurological disorders using phenotype-specific evaluations.
– Cerebrospinal fluid (CSF) analysis, to check for the presence of autoantibodies, inflammation markers, and infection markers. CSF is the fluid that surrounds the brain and spinal cord, and it can be obtained by a lumbar puncture or a spinal tap.
– Brain imaging, such as magnetic resonance imaging (MRI) or computed tomography (CT) scan, to check for the presence of brain inflammation, lesions, or tumors. MRI is more sensitive than CT scans, and it can also show the specific areas of the brain that are affected.
– Electroencephalogram (EEG), to check for the presence of abnormal brain activity, such as seizures or encephalopathy. EEG is a test that measures the electrical activity of the brain using electrodes attached to the scalp.
– Other tests, such as neuropsychological tests, nerve conduction studies, electromyography, or evoked potentials, to check for the presence of cognitive, sensory, or motor impairments.
Treatment of encephalitis:
The treatment of encephalitis depends on the cause, the type, and the severity of the condition. The main goals of the treatment are to reduce inflammation, treat the infection or the tumor, prevent the complications, and support the recovery. The treatment may include the following:
– Medications, such as antiviral drugs, antibiotics, antifungal drugs, or antiparasitic drugs, to treat the infection that caused the encephalitis. These drugs are usually given intravenously or orally, depending on the type of infection and the response to the treatment.
– Immunotherapy, such as corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, or monoclonal antibodies, suppresses the immune system and reduces the production of autoantibodies that cause encephalitis. These drugs are usually given intravenously, and they may have side effects such as infections, bleeding, or allergic reactions.
– Chemotherapy, radiotherapy, or surgery, to treat the tumor that caused the encephalitis. These treatments are usually done by specialists, and they may have side effects such as hair loss, nausea, vomiting, or nerve damage.
– Supportive care, such as oxygen therapy, ventilation, fluid management, pain relief, fever control, nutrition, or physiotherapy, to help the patient recover and prevent complications such as seizures, brain edema, organ failure, or infections. These treatments are usually done by nurses, doctors, or therapists, and they may require hospitalization or intensive care.
Complications of encephalitis:
Encephalitis can cause serious and potentially life-threatening complications, such as:
– Brain damage, which can result in permanent neurological or psychiatric problems, such as memory loss, cognitive impairment, personality changes, mood disorders, psychosis, epilepsy, movement disorders, speech disorders, vision disorders, or sensory disorders.
– Coma, which is a state of unconsciousness where the patient cannot be awakened or respond to stimuli. Coma can last for hours, days, weeks, or months, and it can lead to death or permanent disability.
– Death, which can occur due to the severity of the brain inflammation, the failure of the vital organs, the complications of the treatment, or the underlying cause of the encephalitis. The mortality rate of encephalitis varies depending on the type, the cause, and the treatment, but it can range from 5% to 40%.
References
(1) Encephalitis – Symptoms and causes – Mayo Clinic.
(2) Autoimmune encephalitis – Wikipedia.
(3) Encephalitis | Johns Hopkins Medicine.
(4) Autoimmune Encephalitis: Brain & Spinal Inflammation | HSS.