Anti-MOG Associated Disease is an autoimmune disorder of the central nervous system responsible for inflammation in the brain, spinal cord and/or optic nerves. This condition impacts both adults and children but is more common in children.
What is Anti-MOG Associated Disease?
Myelin Oligodendrocyte Glycoprotein (MOG) is a protein on the surface of cells called oligodendrocytes, which are present throughout the central nervous system (including the brain, optic nerves and spinal cord). The function this protein plays in the nervous system is not well understood, but the oligodendrocyte is an important cell in the nervous system that produces myelin, a fatty coating that insulates nerve cells.
Recently, many children with unexplained inflammation in the central nervous system were found to have antibodies in their blood that targeted the MOG protein in the central nervous system. Antibodies are a protein produced by immune cells that are important to the immune system’s response to infections. In this instance, the antibodies indicate that the immune system has become confused and has started to target the MOG protein.
What are the different types of Anti-MOG Associated Disease?
MOG antibodies have been detected in children and adults with inflammation in different parts of the nervous system. Some of the common presentations associated with MOG antibodies include:
- Optic neuritis: inflammation in the nerves connected to the eye
- Transverse myelitis: inflammation in the spinal cord (sometimes this can mimic acute flaccid myelitis)
- Acute disseminated encephalomyelitis (ADEM): A disorder associated with confusion or a decreased level of alertness, with inflammation that is typically in portions of the brain called the white matter (which is where most of the myelin is located in the brain)
What are the signs and symptoms of Anti-MOG Associated Disease?
The signs and symptoms of anti-MOG associated disease are based on which part of the nervous system is affected. Children presenting with ADEM or autoimmune encephalitis may have confusion, a decreased level of alertness, seizures, behavioral changes, numbness, weakness or difficulty walking. With optic neuritis, children will have vision changes and pain around the eyes. Transverse myelitis can cause changes in strength, sensation, walking and bowel/bladder function.
How is Anti-MOG Associated Disease diagnosed?
Children presenting with neurologic deficits consistent with anti-MOG associated disease will undergo a physical exam and a variety of tests that will include an MRI of the brain, spinal cord and optic nerves. Additionally, a lumbar puncture is often performed to obtain a cerebrospinal fluid sample. Blood testing will be done to look for the anti-MOG antibody. If the antibody is found in the blood, your doctors may consider checking for this antibody again in the future to see if the level of the antibody changes over time.
While some children with MOG antibodies may only have one episode, many children will experience inflammation within other areas of the nervous system. For example, if a child experienced optic neuritis and was found to have MOG antibodies, in the future they may develop inflammation in the spinal cord at a later time. The relative risk of future events in children with these antibodies is still being determined.
How is Anti-MOG Associated Disease treated?
The first phase of treatment for children with anti-MOG associated disease involves reducing the inflammation in the nervous system. To accomplish this, anti-inflammatory therapies are used. Commonly used therapies include high doses of steroids, plasmapheresis (PLEX), and/or intravenous immunoglobulin (IVIG). Steroids work by reducing the number of inflammatory cells in the brain. They can be administered by IV or orally. Most children do not have side effects but some may experience mood changes, appetite changes, difficulty sleeping or irritability. Rarely, patients can experience infection or bone abnormalities.
PLEX is a therapy that requires special IV access and a portable machine that cleans the blood of inflammatory proteins. A patient’s blood is circulated through the machine and proteins such as antibodies are removed. A therapy session takes about 90 minutes and is usually well tolerated. A patient usually receives five to seven treatments to complete a PLEX course.
IVIG in an infusible therapy that has been used extensively in pediatrics. IVIG is a collection of antibodies collected from blood donors and pooled together. When infused into patients the antibodies are thought to cause a reduction or blocking of the patient’s abnormal immune response.
After completing this treatment, patients often require rehabilitation and symptom management. This can include physical therapy, occupational therapy, speech/language therapy, swallow therapy and management of bladder dysfunction. Rarely, patients may experience neuropathic pain that requires treatment. In addition to evaluation by a neuropsychologist for cognitive, emotional and/or behavioral problems, patients may also require psychosocial support or therapy to manage the impacts of inflammation in the brain.
In children who have further episodes of inflammation in the nervous system, a therapy to suppress the immune system and prevent further inflammation may be needed. As anti-MOG associated disease is newly recognized, there is not a generally agreed upon treatment that best controls the inflammation associated with the disease. Commonly used medications include rituximab (which targets cells that produce antibodies), IVIG (which can be given monthly to prevent inflammation), mycophenolate or azathioprine (both of these are drugs used to prevent rejection of organ transplant and are commonly used in other autoimmune disorders). In the future, clinical trials to determine the best treatments for patients with MOG disorders are likely to provide insight into which treatments best control recurrent inflammation.