Myasthenia Gravis

Myasthenia gravis is an autoimmune condition that causes skeletal muscle weakness. These are the muscles that connect to your bones and help you move. Myasthenia gravis usually targets the muscles in your eyes, face, neck, arms and legs. It can affect your ability to:

• Move your eyes or blink.
• Keep your eyes open.
• Make facial expressions.
• Chew, swallow and talk.
• Raise your arms up and lift objects.
• Walk upstairs or get up from a chair.

Muscle weakness gets worse after physical activity and improves after rest. Symptoms usually happen quickly.

Myasthenia gravis is a chronic (long-lasting) neuromuscular condition (it affects the junction between your nerves and muscles). There isn’t a cure, but effective treatment can help you manage your symptoms and function well.

What are the types of myasthenia gravis?

The types of myasthenia gravis include:

• Autoimmune myasthenia: It’s an autoimmune condition where the cause isn’t well understood but the likely cause is the production of certain types of antibodies (immune system proteins). This is the most common type.
• Neonatal myasthenia: A fetus gets certain antibodies from the birthing parent who has myasthenia gravis. An infant may have a weak cry or sucking reflex at birth. These temporary symptoms usually go away after three months.
• Congenital myasthenia: It isn’t an autoimmune condition, and a genetic change causes this type.

There are two subtypes of autoimmune myasthenia:

• Ocular: The muscles that move your eyes and eyelids weaken. Your eyelids may droop, or you may not be able to keep your eyes open. Some people have double vision. Eye weakness is often the first sign of myasthenia. Ocular myasthenia gravis may evolve into the generalized form for nearly half of all people diagnosed with this type.
• Generalized: Muscle weakness affects your eye muscles and others in your face, neck, arms, legs and throat. You may find it difficult to speak or swallow, lift your arms over your head, stand up from a seated position, walk long distances and climb stairs.

How common is myasthenia gravis?

Myasthenia gravis affects about 20 out of every 100,000 people around the world. The actual number may be higher, as some people with mild cases may not know they have the condition. In the United States, there are approximately 60,000 people affected by myasthenia gravis at any given time.