What is Myasthenia Gravis?
Myasthenia gravis (pronounced My-as-theen-ee-a Grav-us) is a serious neurological disease caused when a person’s immune system is too active and makes antibodies that cause muscle weakness. Antibodies are proteins made by white blood cells and their primary role is to help the immune system recognize and fight bacteria and viruses. In myasthenia gravis, the antibodies affect the ability of nerve signals to trigger the muscles to contract, resulting in muscle weakness. Approximately 15% of patients with myasthenia gravis have weakness that is limited to the face and eye muscles, and 85% have more generalized weakness which can affect speech, swallowing, arm and leg muscles, as well as breathing muscles. The weakness often fluctuates, tending to be better after rest and worse with sustained physical activity. In some people, the weakness remains very mild but it can be disabling or even fatal by causing weakness of breathing muscles.
How is this condition diagnosed and by whom?
A neurologist plays a critical role in both the diagnosis and management of patients with myasthenia gravis. Many people may display symptoms for some time before a final diagnosis is made.
A diagnosis of myasthenia gravis can be confirmed by the presence of antibodies in the blood. There are different types of antibodies that the doctor may look for. The doctor may also evaluate the function of the thyroid gland, because problems with the thyroid can sometimes look like myasthenia and if a patient has myasthenia, than thyroid problems can make the myasthenia worse. Other important tests include electrical testing of the nerves and muscles. A highly specialized test called single fiber electromyography is another test that evaluates whether nerve signals are making muscle cells fire together, and is typically done when there is uncertainty if weakness is indeed related to a diagnosis of myasthenia gravis.
Is the thymus gland connected to an MG diagnosis?
If myasthenia gravis is confirmed, you doctor may order a CT scan of your chest to look at your thymus gland in your chest. The thymus gland is an important organ in the development of the immune system at a very young age, but stops working as you get older and enter the teenage years. A small percentage of patients with myasthenia may actually have a tumor to the thymus gland, which requires surgery. In some patients with myasthenia who have no tumor surgery to take out the thymus gland may be considered, with the idea that the thymus gland is overactive and removal may improve the myasthenia symptoms. The doctor may also order testing of your breathing to make sure the breathing muscles are strong.
What medications are used for treatment?
There are a number of medications used to treat myasthenia gravis, and it is important to recognize that myasthenia gravis is treatable. Medications such as pyridostigmine (Mestinon®) is used to help with weakness, it helps the nerve signals get to muscles better. Corticosteroids (e.g., prednisone) and immunosuppressant agents (e.g., Imuran®) may be used to suppress the abnormal action of the immune system that occurs in myasthenia gravis. Intravenous immunoglobulins (IVIg) and plasmapheresis, or plasma exchange, may be especially useful during severe myasthenia gravis weakness. IVIG affects the function or production of the abnormal antibodies and plasmapheresis is a procedure that removes the abnormal antibodies from the plasma of the blood. The best choice of treatment for each patient is determined by a neurologist according to the severity of the myasthenia gravis and other existing medical conditions.
If you suspect you have MG or have been diagnosed and would like a second opinion, you can make an appointment with Emory Neurology by calling 404-778-7777.