What is myasthenia gravis?
Myasthenia gravis (MG) is a rare autoimmune condition that causes muscle weakness. It happens when the immune system interferes with signals between nerves and muscles. MG only affects the muscles you can voluntarily control, like the ones in your arms, legs, or eyelids. It also commonly affects the muscles used for breathing, swallowing, and eye movements.
MG is also closely linked to conditions of the thymus gland, a small organ in the chest that plays a role in the immune system. Some people with MG have changes in the thymus, including thymic hyperplasia or a thymic tumor called a thymoma.
At Penn Medicine, a coordinated team works together to diagnose and treat these conditions. Our Myasthenia Gravis and Thymoma Program is one of the few in the nation that coordinates all your care in one place, giving you access to experts in every field from neurology to thoracic surgery.
How these conditions may affect you
While muscle weakness is the main sign of MG, the condition is often linked to changes in your thymus gland.
The muscle weakness caused by MG can come and go. You might notice that you feel stronger after you rest but get weaker again after you use your muscles. These signs usually peak within the first two years of the condition.
Common symptoms include:
- Drooping eyelids or double vision
- Changes in speech
- Difficulty swallowing or chewing
- Weakness in the arms and legs
- Trouble holding up your head
- Loss of facial expression
A thymoma is a slow-growing tumor on the thymus gland, located in the center of your chest behind the breastbone. While these growths usually stay in the thymus, some can be more aggressive and grow toward your heart or lungs. Because they grow so slowly, you might not notice anything for years. Many people only find out they have a thymoma during an exam for a different illness.
Common symptoms include:
- Shortness of breath
- Difficulty swallowing
- Chest pain or pressure
- A persistent cough
- Hoarseness
- Muscle weakness
Thymic hyperplasia happens when your thymus gland becomes inflamed. This is a benign (non-cancerous) condition. It’s often linked to other health issues like thyroid problems or MG.
Common symptoms include:
- Shortness of breath
- Difficulty swallowing
- Chest discomfort
- Cough
- Decreased appetite
- Unintended weight loss
Tests used to confirm a diagnosis
Diagnosis begins with a careful review of symptoms and a physical exam. Specialized blood testing helps confirm MG and evaluate the thymus gland. Imaging tests are used to look for thymic abnormalities. In most cases, imaging provides enough information, and a biopsy isn’t needed unless the mass is large or unclear.
Treating myasthenia gravis and thymoma
To improve the muscle weakness caused by myasthenia gravis, your care team will recommend medicines to suppress the immune system. In addition to pills, there are emergency treatments available for people who are short of breath or are having trouble swallowing. These include intravenous gamma globulin (IVIG) and plasma pheresis.
Thymic hyperplasia by itself doesn't require any treatment, but associated conditions like hyperthyroidism may. In people with MG and thymic hyperplasia, your provider may recommend surgery to remove the thymus gland.
Thymoma is most often treated with surgery to remove the tumor. Additional therapies may be recommended if the tumor has spread beyond the thymus.
Advanced radiation therapy
When radiation therapy is part of treatment, Penn Medicine offers highly precise options. Proton therapy, available at select Penn Medicine locations in Pennsylvania and New Jersey, targets tumors while limiting radiation exposure to nearby organs like the heart and lungs.
The center uses advanced pencil beam scanning technology, which allows radiation to be delivered with exceptional accuracy. This approach may reduce side effects during treatment and long after therapy is complete. We also have clinical trials for people who aren’t responding to conventional treatments.
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