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An electromyography may be used to diagnose myasthenia gravis.

An electromyography may be used to diagnose myasthenia gravis.
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Myasthenia gravis

2-minute read

Myasthenia gravis is a rare disease. Its main symptom is muscle weakness. Myasthenia gravis can’t be cured but treatments are available to help manage the symptoms.

What is myasthenia gravis?

Myasthenia gravis is a disease of the neuromuscular system. It is caused by a breakdown in communication between your nerves and muscles.

The name of the disease comes from the Greek ‘myasthenia’, meaning muscle weakness, and the Latin ‘gravis’, meaning severe.

Causes of myasthenia gravis

Myasthenia gravis is an autoimmune disease. This means it is caused by your body’s immune system.

People with myasthenia gravis are more likely than others to have relatives with other autoimmune diseases, such as Graves' disease, rheumatoid arthritis and lupus.

Babies can also get a form of myasthenia gravis from their mothers. This is usually temporary.

It is not really understood why some people get autoimmune diseases and not others.

Myasthenia gravis symptoms

Myasthenia gravis often begins in your eye muscles or elsewhere on your face. It can make it hard to control your eye and eyelid movements, and to talk, chew and swallow.

The symptoms can appear suddenly or take weeks to develop. They might come and go.

Some people find:

  • it hard to walk normally
  • their arms, hands, fingers, legs or neck are weak
  • the expression on their face changes
  • they feel short of breath
  • they have trouble swallowing

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

Most people with myasthenia gravis say that the muscle weakness is often worse when they are active and improves after they rest.

The disease can affect the muscles that control breathing in some people.

Myasthenic crisis is a medical emergency that develops when the breathing control muscles are severely weakened. It is usually triggered by an infection, emotional stress, or a bad reaction to medication.

Myasthenia gravis diagnosis

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

  • a blood test
  • electromyography (a test that measures muscle function)
  • injection of the drug Tensilon 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 your upper chest)

Myasthenia gravis treatment

Myasthenia gravis is one of the most treatable neuromuscular disorders. Common treatments include:

  • medicines to improve muscle strength or inhibit the immune system
  • treatment to filter the blood through a machine
  • surgery to remove the thymus gland

Often, a combination of treatments are used.

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Last reviewed: January 2018

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