Myasthenia gravis

What is myasthenia gravis?

Myasthenia gravis (MG) is a disorder that causes weakening in specific muscles.

These consist of:

The term "ocular myasthenia gravis" is used by doctors when MG only affects the muscles in the eyelids and around the eyes.

This kind is seen in about 50% of MG patients.

• Jaw muscles 

• Leg or arm muscles

• Breathing-supporting muscles

Antibodies, which the immune system typically produces, aid in preventing infection. However, in those who have MG, the immune system unintentionally produces certain antibodies that target the connections between muscles and neurons.

What are the symptoms of MG?

The main symptom is muscle weakness. It can come and go, and is often worse later in the day. It can cause:

• Droopy eyelids

• Blurry vision or double vision

• Trouble chewing food

• Trouble swallowing

• Trouble talking

• Head that feels heavy or drops forward

• Breathing difficulty

• Weakness

What tests do I need?

• Blood tests to look for certain antibodies (Acetylcholine Receptor antibody, Anti-MuSK antibody etc.).

• Electrical tests of nerves and muscles:

  • Repetitive Nerve Stimulation test from affected muscles

• Imaging tests, such as CT or MRI scans

  • CT/MRI of Chest to look for thymus gland (part of the immune system) tumor or hyperplasia

  • CT scan or MRI of the head to rule out mimickers

How is MG treated?

Treatments include:

• Pyridostigmine for muscle weakness

• Immunomodulators like prednisone and azathioprine.

• Fast-acting immune system treatments, such as:

  • IV immunoglobulin (IVIg)

  • Plasma exchange

• Surgery to remove the thymus gland

• If MG attacks the muscles that help with breathing, they are usually treated in the intensive care unit (ICU)

• Children with MG can take some of the same medicines as adults. Surgery to remove the thymus gland is safe for children and often works well

What if somebody wants to get pregnant?

• Talk to your doctor or nurse before you start trying to have a baby. Pregnancy can make MG worse.

Special note:

It is especially important to get the flu shot every year and the pneumonia vaccine at least 1 time.

Some medicines can make MG worse so If you get a prescription for a new medicine, consult your doctor.