MOG antibody demyelination

This information from Great Ormond Street Hospital (GOSH) explains about Myelin Oligodendrocyte Glycoprotein (MOG) antibodies and the symptoms and treatment of MOG antibody associated demyelination.

Antibodies are proteins that circulate in the blood stream. They are part of the body’s immune (defence) system and are produced by a certain type of white blood cell (B cell lymphocyte) to help attack and destroy viruses and bacteria and protect us from infection.

Bacteria, viruses and other germs have proteins on their surfaces called antigens. The immune system is programmed to recognise these antigens as being ’foreign‘ and in turn the B cell lymphocytes produce lots of antibodies which attach to the infecting germs to destroy them.

Sometimes the immune system becomes mis-programmed and will produce antibodies against brain protein. This can sometimes be in response to a simple infection especially in children.

Myelin Oligodendrocyte Glycoprotein (MOG) is a glycoprotein which is part of normal myelin and is found on the surface of the myelin sheath of nerve cells. Myelin is a fatty protein that insulates and protects the nerve and helps maintain the speed of transmission of messages from the brain to the rest of the body.

Antibodies to MOG cause the myelin sheath to fall off, this is known as demyelination. Demyelination means that messages cannot pass along the nerve effectively and these messages may slow down or stop completely. This in turn can cause neurological (brain and nervous system) symptoms.

Symptoms of MOG antibody demyelination can be variable from person to person and can range from mild to severe depending on which parts of the brain are affected. Some children may initially present with acute disseminated encephalomyelitis (ADEM) which is an inflammatory condition that mainly affects the brain and others may have signs of optic neuritis or transverse myelitis.

Optic neuritis is demyelination of the optic nerve and can affect one or both eyes. Symptoms can include:

• pain on moving eye
• blurred vision
• loss of colour vision
• in rare cases, complete loss of vision

• back pain
• weakness of both legs
• bowel/bladder problems
• arm weakness (if higher up the spinal cord)

For many children that have a MOG antibody demyelination episode, it will be a one off and they have no further attack of symptoms (relapse). However, some children may be at risk of further relapses. These relapses could happen either months or even years apart and therefore it can be difficult to predict.

Due to the symptoms of MOG antibody demyelination being similar to other demyelinating conditions, a diagnosis at a specialist paediatric neurology centre is usually advised. A specialist blood sample will identify if the MOG antibody is present and therefore the cause of the demyelination.

Your child may need other investigations completed, such as a MRI scan to look at your child’s brain and spine in more detail to see where the inflammation has occurred, an eye assessment (ophthalmology) to check the optic nerve and a lumbar puncture to look at the cerebrospinal fluid that surrounds the brain and spinal cord. Any investigations that your child needs will be fully explained to you and consent taken if necessary.

Intravenous steroid treatment is often used to treat the acute symptoms of demyelination to try to reduce the inflammation that has occurred. This will usually be given at high dose for three to five days via a cannula into a vein. Your child may then start an oral course of steroid tablets and you will be given a plan of how to reduce these gradually.

Children usually respond very well to steroid treatment during this acute phase. Steroids have both short and long term side effects so your child will not usually stay on them for a long time. These side effects will be discussed with you in more detail at the time. Steroids do not change your child’s risk of a relapse.

In rare cases, if high dose steroids do not improve your child’s symptoms, other treatment may need to be considered, such as intravenous immunoglobulins (IVIGs) or plasma exchange. Both these treatments will be explained in full detail if needed.

For many children, after an initial attack, it can be difficult to predict if further attacks will happen so it is not always beneficial to start a long term treatment. If a child continues to have relapses, then maintenance treatment may be required to prevent further relapses. Medicines that may be used include azathioprine, mycophenolate mofetil or in some cases rituximab. These types of medicine are used to control your child’s immune system and to damp down inflammation. Any medication started would be discussed in full detail if needed.

The discovery of MOG antibody is still fairly recent and therefore there is still much to be learnt about it. Research continues to be ongoing and experts are learning more about MOG antibodies all the time. The aim of current research is to see if predicting relapses and disease severity can guide our treatment decisions with the ultimate goal to improve the health of the children with these Useful numbers and links antibody driven demyelinating conditions.