What is myasthenia gravis?

Myasthenia gravis is a rare disease of the neuromuscular system, caused by a breakdown in communication between the nerves and muscles. This leads to muscle weakness during activity, which can improve after a period of rest.

Myasthenia gravis can’t be cured, but treatments are available to help manage your symptoms.

What are the symptoms of myasthenia gravis?

The symptoms of myasthenia gravis often begin in your eye muscles or elsewhere on your face. It can become hard to control your eye and eyelid movements, and to talk, chew and swallow.

Your symptoms can appear suddenly or take weeks to develop. They might also come and go. They may include:

• drooping of one or both eyelids
• blurred or double vision
• unsteady walking
• weak arms, hands, fingers, legs, and neck
• a change in facial expression
• shortness of breath
• trouble swallowing and/or impaired speech

The muscle weakness is usually worse when you’re active and improves after you rest.

If you notice any of these symptoms, you should see your doctor.

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What causes myasthenia gravis?

Myasthenia gravis is an autoimmune disease. This means it is caused by your body’s immune system mistakenly attacking healthy tissue at the junction (meeting) between nerves and muscles. This causes problems in the signals that your nerves send to your muscles.

Males and females from all ethnic groups can get myasthenia gravis, but it is most common in females under age 40 and males over age 60. If you have myasthenia gravis, you and your family are more likely to develop other autoimmune diseases, such as Graves' disease, rheumatoid arthritis and lupus.

Babies can get a form of myasthenia gravis from their mothers, but this is usually temporary.

It is not understood why some people get autoimmune diseases while others do not.

How will I be diagnosed with myasthenia gravis?

Your doctor will talk to you about your symptoms and examine you. You might also have some tests to confirm a diagnosis, such as:

• a blood test for the antibodies that are typically seen in myasthenia gravis (AChR antibodies)
• ice test — the doctor examines you for improved eyelid droop after covering the eye for a minute or two with a cold pack
• nerve conduction tests and electromyography (a test that measures muscle function)
• injection of the drug edrophonium to see its effect on muscle strength
• imaging such as a chest x-ray, a CT scan or an MRI, to look for abnormalities in the thymus gland (a small gland in the upper chest)

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What treatment will I need for myasthenia gravis?

Myasthenia gravis is one of the most treatable neuromuscular disorders.

Common treatments include:

• medicines to improve muscle strength or help balance your immune system
• treatment filter your blood through a machine which removes the antibodies that cause myasthenia gravis
• surgery to remove your thymus gland, where your body produces the antibodies that attack your muscles

Often, a combination of treatments is used.

What is a myasthenic crisis?

Myasthenic crisis is a medical emergency that develops when the muscles that control your breathing are severely weakened. A crisis is usually triggered by an infection, emotional stress, or a bad reaction to medicine. You may need treatment with a ventilator in hospital.

If you or someone else is having trouble breathing, call triple-zero (000) and ask for an ambulance.