Steven Vernino, M.D., Ph.D. Answers Questions On: Myasthenia Gravis
What are the symptoms of myasthenia gravis?
Myasthenia gravis (MG) is an autoimmune disorder in which the body produces antibodies that disrupt the communication between the nerve cells and the muscles, causing extreme muscle weakness and fatigue.
MG often causes droopiness of the eyelids and/or weakness of the face, as well as double vision, and symptoms tend to worsen as the day goes on. The condition can become so severe that it affects the muscles used to breathe, swallow, and speak.
Symptoms typically arise over a period of weeks and may worsen in the months following their onset.
The most prevalent autoimmune neuromuscular disorder, myasthenia gravis is believed to impact between 36,000 to 60,000 people in the U.S.
How is myasthenia gravis diagnosed?
Myasthenia gravis is diagnosed using a combination of physical examination, blood tests, and specialized electrodiagnostic testing.
This multipronged approach helps us ensure a correct diagnosis because the blood test – designed to detect the presence of the antibody that targets the acetylcholine receptors in the muscle cells – isn’t perfect.
Only 70 to 75 percent of people diagnosed with MG have that antibody. Of the patients who don’t have it, some instead have anti-MuSK antibodies, which target a protein called muscle-specific kinase that is essential for neuromuscular junction development. Another 15 to 20 percent of people with MG don’t have any detectable antibodies.
How is myasthenia gravis treated?
We treat myasthenia gravis by treating the symptoms and by trying to reduce the levels of the antibodies. There are three main MG treatments, and what we choose depends upon the patient and the severity of the condition.
One way to manage mild cases of MG is to treat the symptoms with a medication that helps to strengthen the connection between the nerve cells and the muscles.
In more severe cases, we may use drugs that reduce the production of the problematic antibodies. These drugs include steroids, immunosuppressants, and intravenous immunoglobulin (IVIG). Plasma exchange (a treatment to quickly remove the antibodies from the blood) is sometimes used, as well.
About 10% of patients with MG have a rare tumor of the thymus gland (thymoma), and other patients have swelling of the thymus (thymic hyperplasia). In some cases, our thoracic surgeons remove the thymus gland (thymectomy) using a minimally invasive, robotic surgery. Our group took part in a recently published international study that reveals that a thymectomy improves the outcomes in certain MG patients.
In many cases, we’re able to treat myasthenia gravis so effectively that patients are back to living relatively normal lives within a few months. Patients may need to take medications and they might require a little extra rest, but overall we’re able to manage most cases very successfully.
Are there risk factors for myasthenia gravis?
People who have thymoma are very likely to have myasthenia gravis – although only 10 to 15 percent of MG patients have a thymoma.
In addition, some people and families are genetically predisposed to developing autoimmune diseases such as myasthenia gravis, rheumatoid arthritis, lupus, and Crohn’s disease.