Understanding myasthenia gravis

Myasthenia gravis is a disorder of the immune system. It affects voluntary muscles — the muscles you control.

What is myasthenia gravis?

Myasthenia gravis is an autoimmune disease, meaning your immune system mistakenly attacks your body. In this condition, the immune system disrupts messages between your nerves and voluntary muscles.

Normally, nerve signals travel down nerves to meet muscle fibers in spots called neuromuscular junctions. The nerves send a chemical across the junctions to muscle fibers. Receptors on the fibers receive the chemical and tell the muscles to contract.

With myasthenia gravis, the immune system blocks or damages the receptors. The muscles receive fewer signals, cannot fully contract, and weaken. The weakness worsens with activity and gets better with rest.

Who gets myasthenia gravis?

Myasthenia gravis is relatively rare, affecting 36,000 to 60,000 Americans, according to the National Institutes of Health. This diagnosis has become more common in recent years, possibly because doctors are identifying it earlier. New treatments are also helping patients live longer.

Most patients can have a normal life expectancy. There is no cure, but with the right treatment, people can often control symptoms and lead active lives. Sometimes symptoms vanish temporarily or permanently.

Risk factors include:

Gender: Women are more likely to develop myasthenia gravis.

Age: Women who develop the disease are typically younger than 40. Men are typically older than 60.

Related disorders: People who have had one autoimmune disease, such as rheumatoid arthritis, are at greater risk of developing another, such as myasthenia gravis.

What causes myasthenia gravis?

Scientists don’t know exactly what causes myasthenia gravis. Many factors may come into play, including genetic changes. A virus or bacteria might trigger the condition.

Types of myasthenia gravis

• Generalized: Weakness in the torso, arms and legs.
• Ocular: Weakness in the eye muscles.
• Congenital: Present at or shortly after birth.
• Transient neonatal: Develops in infants whose mothers had the disease but vanishes within a few weeks.

Symptoms of myasthenia gravis

Myasthenia gravis affects voluntary muscles in the face, eyes, arms and legs. Symptoms, which may be similar to those of other conditions, can include:

• Drooping eyelids, blurry vision or double vision
• Muscle weakness in the face, neck, arms, hands, fingers or legs
• Problems chewing, swallowing, talking or smiling
• Shortness of breath or difficulty coughing or breathing deeply
• Tiring easily, especially in arm or leg muscles
• Limited facial expressions

Diagnosing myasthenia gravis

Myasthenia gravis can be difficult to diagnose because muscle weakness can be a sign of other conditions. Our specialists have the experience and skills to make an accurate diagnosis and rule out other conditions.

Treatments for myasthenia gravis

Your care team will work with you to develop a treatment plan to help you live well with myasthenia gravis. Your options may include medication, surgery or treatments to boost your immune system.

Support services

As part of your treatment at OHSU, you will meet with our team of social workers who can:

• Connect you with resources, such as finding in-home help.
• Answer questions and counsel you and your family.
• Help with financial questions or applications for Medicare or disability benefits.

Clinical trials and research

We offer access to clinical trials to test promising new treatments. For instance, OHSU researchers contributed to studies of the safety and effectiveness of eculizumab, which won approval from the U.S. Food and Drug Administration in 2017. It was the first FDA-approved medication for myasthenia gravis since the 1950s.

Learn more

• Myasthenia Gravis, U.S. National Library of Medicine
• Myasthenia Gravis, National Organization for Rare Disorders
• Myasthenia Gravis, U.S. Department of Health and Human Services