Myasthenia Gravis

What is Myasthenia Gravis?

What is myasthenia gravis? Myasthenia gravis, sometimes called MG, is a chronic (long-lasting) disease that causes weakness in your voluntary muscles. The voluntary muscles are the ones that you can control. They include the muscles you use for: Eye and eyelid movement Facial expressions Chewing Talking Swallowing Breathing Moving your arms and legs You can also have weakness in other muscles. This weakness gets worse with activity, and better with rest. Myasthenia gravis is a type of autoimmune disease. In autoimmune diseases, your immune system attacks the healthy cells of your organs and tissues by mistake. What causes myasthenia gravis? Myasthenia gravis is caused by an error in how nerve signals are sent to muscles. These signals get blocked at the nerve-muscle junction. This junction is the place where the nerve endings connect with the muscles they control. Normally, this is how the signals work: The signals travel down a nerve that controls movement in the muscle The nerve endings release a substance called acetylcholine Acetylcholine binds to the muscle tissue at the nerve-muscle junction This causes the muscle to contract (move) But in someone with myasthenia gravis, the body's own immune system makes antibodies that block the binding of acetylcholine to the muscle. This makes the muscles weaker. The thymus gland, which is part of your immune system, may play a role in myasthenia gravis. Normally, your thymus gland is active and growing when you are a child. It makes white blood cells to fight infections. At puberty, it starts getting smaller and is replaced by fat. It is usually small by the time you are an adult. But in many adults with myasthenia gravis, the thymus gland stays large. And some people with myasthenia gravis can get thymomas, which are tumors of the thymus. The are usually benign (not cancer), but they can sometimes become cancerous. Who is more likely to develop myasthenia gravis? Although myasthenia gravis can affect people of any age, it is most common in young adult women (under age 40) and older men (over age 60). It is usually not inherited (passed down in families). Myasthenia gravis normally does not affect infants. But if you are pregnant and have myasthenia gravis it's possible to pass the antibodies to your fetus. The baby can then be born with neonatal myasthenia. This condition is usually temporary, and the symptoms typically go away within two to three months after birth. What are the symptoms of myasthenia gravis? The symptoms of myasthenia gravis will depend on which muscles are affected. The symptoms often include: Weakness of the eye muscles Drooping of one or both eyelids Blurred or double vision Changes in facial expressions Trouble swallowing Shortness of breath Speech problems Weakness in the arms, hands, fingers, legs, and neck Different people have different levels of muscle weakness. And the weakness can vary from day to day. Some days it might be mild, and other days it might be worse. Physical activity often makes the muscle weakness worse. Some people with myasthenia gravis can get severe weakness that affects the muscles that control breathing. This is called a myasthenic crisis, and it is a life-threatening emergency. How is myasthenia gravis diagnosed? There are many other conditions that can cause muscle weakness, so myasthenia gravis can be hard to diagnose. To find out if you have myasthenia gravis, your health care provider: Will ask about your medical history and symptoms Will do a physical exam, including a neurological exam Will likely order tests for myasthenia gravis, including: Blood tests Imaging tests Electromyography (EMG) and nerve conduction studies What are the treatments for myasthenia gravis? There is no cure for myasthenia gravis, but treatments that can improve muscle weakness and help with symptoms. They include: Anticholinesterase medicines, which can improve nerve-to-muscle messages and make muscles stronger. Immunosuppressive medicines, which are

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