Questions On Autoimmune Epilepsy
Guest Article by Lily Wong-Kisiel, MD
Epilepsy is a brain disorder where there is increased likelihood to generate spontaneous seizures. The information about your child’s seizures, such as age when seizures began, the appearance of your child’s seizures, family history, and your child’s other medical history, directs the tests your neurologist may order. Sometimes these tests include imaging scans of the brain, EEG, blood and urine studies to investigate the possible causes of epilepsy. Etiology, or cause, of epilepsy is diverse and is classified into three broad categories according to the 2010 International League Against Epilepsy Commission on Classification and Terminology 2005-2009: (1) genetic, (2) structural/metabolic and (3) unknown cause. However, even with extensive laboratory testing, nearly half of those with childhood onset epilepsy may have no identifiable cause.
Autoimmune epilepsy is still a rare, but increasingly recognized cause of epilepsy, which might have been previously thought to be of unknown cause. This article explains the basic concepts of autoimmune disorder, features of autoimmune epilepsy, how it is diagnosed, and treatments for autoimmune epilepsy.
What is the immune system and what are the types of immune disorders?
Your immune system protects the body from infections and foreign substances that invade the body and cause disease. White blood cells, or leukocytes, are the cells involved and they are produced or stored in lymph nodes, thymus, spleen, and bone marrow. The leukocytes circulate through the body in blood vessels and in smaller channels of “lymphatic vessels” and monitor for viruses, bacteria, or foreign substances that may cause a problem. Antibodies are proteins produced by the immune system and are used in the coordinated attack of infections or foreign substances.
Problems with the immune system can be categorized into 4 groups: (1) cancers of the immune system, (2) immunodeficiency disorders, (3) hypersensitivity disorders, and (4) autoimmune disorders. Cancers of the immune system occur when cells of the immune system grow out of control, such as lymphomas and leukemia. Immunodeficiency disorders happen when components of the immune system are lacking or not present. Hypersensitivity disorders, such as allergies, occur when the immune system overreacts to substances from the outside environment.
In contrast to hypersensitivity disorders, autoimmune disorders are groups of diseases in which the immune system attacks the body’s healthy organs and tissues, as if they are foreign. Instead of useful antibodies that attack infections or harmful foreign substances, the immune system may produce antibodies directed at normal body tissue (auto-antibodies) causing problems with normal function. Examples of autoimmune disorders include rheumatoid arthritis, in which the immune system sees normal joints of the knee, hand, and foot as foreign. In systemic lupus erythematosus, normal muscle, join, kidney and other organs including the nervous system are injured by the immune system.
What are the features of autoimmune epilepsy in children?
Autoimmune epilepsy is a group of disorders where the malfunctioning immune system causes recurrent seizures, difficulty in thinking, emotions, or other brain functions. Autoimmune epilepsy should be distinguished from seizures that happen in other autoimmune disorders where the immune system attacks multiple different body organs and not limited to the nervous system. An example is system lupus erythematosus.
Autoimmune epilepsy can be considered when no cause for seizures can be identified in a child. Children with autoimmune epilepsy may have persistent unexplained fevers, rash, or illness before seizures and other neurologic symptoms. In a previously normal child, there may be increasing problems with memory and learning (encephalopathy) before the onset of seizures. Seizures are typically difficult to control and poorly responsive to antiepileptic medications. Seizures may be generated from different regions or hemispheres of the brain and change over time. Prolonged seizures or status epilepticus may occur repeatedly. Patients may have issues with ongoing irritability or personality change, sleep issues, or involuntary movements in the face and extremities not due to seizures. Steroid, which is often prescribed for common respiratory illness in children, may reveal an unsuspected improvement in seizures.
Specifically, in Rasmussen’s encephalitis, patients progress with focal seizures at escalating frequency and repeated imaging of the brain show hemispheric atrophy and increasing weakness in the contralateral arm or leg. In limbic encephalitis, memory and personality change is prominent with ongoing temporal lobe seizures. Although these are called “encephalitis,” neither Rasmussen’s encephalitis or limbic encephalitis are due to infections. The specific features of autoimmune epilepsy often correlate with the type of auto-antibody found in individual patients. For example, children with auto-antibody to voltage-gated potassium channel have unexplained encephalopathy and present with status epilepsy. Auto-antibodies to NMDA-receptor are seen in children with increasing irritability and personal change before appearance of involuntary movements, particularly around the mouth and in the face. These involuntary movements are not seizures. Other autoimmune epilepsies in children are being increasing described.
What tests can be done to support autoimmune epilepsy?
The suspicion for autoimmune epilepsy relies on careful exclusion of other causes of epilepsy. Tests should include screening for underlying toxin or metabolic conditions. Children should be evaluated for underlying brain infections such as encephalitis, meningitis, or abscess. High resolution 3-tesla MRI brain is used to rule out subtle malformation of brain development. Blood and urine tests may detect genetic or metabolic conditions. Careful history regarding your child’s seizures and additional EEG monitoring may identify a particular epilepsy syndrome, which may respond better to change in antiepileptic medication or other treatments. A psychologist maybe asked to document verbal skills, processing speed, and other tasks to detect subtle differences in developmental skills.
Auto-antibodies can be detected from the blood or from cerebrospinal fluid (CSF). CSF is normal fluid which bathes the brain and continuous with the fluid that surrounds the spinal cord in the back. A lumbar puncture is a safe procedure where a needle is inserted your child’s lower back to draw out the cerebrospinal fluid. The testing of auto-antibodies would include a group or panel of auto-antibodies. Because auto-antibodies are sometimes seen in adults with cancer, additional tests maybe performed to look for hidden tumors even in children. These tests may include blood and urine tests and imaging of the body.
What are the treatments for autoimmune epilepsy?
In addition to using antiepileptic medications to control seizures, immunotherapy is used to treat autoimmune epilepsy. Intravenous immunoglobulin (IVIG) is a blood product of pooled antibodies collected from healthy volunteers. IVIG can block and remove damaging auto-antibodies. Intravenous steroid is used in high doses. IVIG or high dose intravenous steroid is given in repeatedly, usually every week for about 6 weeks. If there is a good result, then time interval between IVIG or intravenous steroid is gradually increased (every other week followed by every 3 weeks). Plasma exchange requires a machine to draw blood, filters and removes the harmful auto-antibodies before returning the blood back to the body. Plasma exchange is usually used if IVIG and intravenous steroid are not helpful. Other immunosuppressing medications used in transplant patients are sometimes used.
In summary, autoimmune epilepsy is a rare, but important cause of difficult to control seizures and other changes in brain function in children and teenagers. Autoimmune epilepsy can be considered when there is no identifiable cause despite other thorough investigations. Detecting auto-antibodies in the blood or cerebral spinal fluid, may lead to an early diagnosis and using immunotherapy may lead to earlier recovery and improved outcome.
by Lily Wong-Kisiel, MD
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