What are the Symptoms of Myasthenia Gravis?

Reviewed by: HU Medical Review Board | Last reviewed: August 2020

Myasthenia gravis (MG) is a condition that causes muscle weakness. This weakness tends to get worse the longer the muscles are used and gets better after the muscles are rested. It is caused by a breakdown in how the nerves and muscles communicate. While there is no cure for MG, there are many treatments to help control the symptoms.1,2

It can be hard to diagnose MG because the symptoms may appear suddenly and then go away after rest. The degree of muscle weakness can be very different from person to person and may disappear for days, weeks, or months. However, the muscle weakness tends to get worse over time, with the worst symptoms appearing within a few years of the first symptoms.2-4

The muscles most often affected are those that you can control, which are also called voluntary muscles. This includes muscles that control eyes, facial expressions, chewing, talking, swallowing, and sometimes, breathing.1-3

The most common symptoms of myasthenia gravis include:1-3

  • Weakness of the eye muscles that leads to blurred or double vision
  • Drooping of 1 or both eyelids
  • Changes in facial expressions
  • Trouble swallowing or chewing
  • Trouble speaking
  • Weakness in the arms, hands, fingers, or legs
  • Shortness of breath

Eye muscles

More than half of people with myasthenia gravis have problems with their eyes first. The most common eye symptoms include:1,2

  • Drooping of 1 or both eyelids. This is also called ptosis.
  • Double vision or blurred vision. This is also called diplopia.
Examples of ptosis or drooping eyelids in one eye or both eyes.
Different types of diplopia or double vision in myasthenia gravis.

Both symptoms may get better after closing the eyes to rest the muscles. If the person’s muscle weakness remains only in the eyes, doctors call it ocular myasthenia gravis. More than half of those who have eye symptoms first go on to develop muscle weakness in other parts of the body.4

Face, throat, and neck muscles

It is not very common for the muscles of the face or throat to be affected first, but it does happen in some people with MG. For about half of people with MG, muscle weakness begins in the eyes and later spreads to other parts of the body.

The most common problems people with MG have with the muscles in their face and neck are:1-3

  • Jaw muscles that feel tired while eating a meal
  • Trouble swallowing or choking easily
  • Talking in a lower or softer tone than normal, or sounding like they have a stuffy nose
  • Changes to facial expressions such as a smile begins to look like a snarl
  • Head feels heavy or drops forward, especially toward the end of the day

Arm, hand, finger, and leg muscles

Myasthenia gravis can make limb muscles weak. This can make it harder to pick up and hold onto objects or make it harder to walk. It can be hard to open the fingers or lift a foot. Arm weakness is more common than leg weakness.1-3

Trouble breathing

The most serious symptom of MG is a myasthenic crisis. A myasthenic crisis occurs when a person with myasthenia gravis has so much trouble breathing that they need an oxygen mask or to be put on a ventilator. This is not a common symptom, but it does happen to about 1 in 5 people with MG.1,2

Symptoms change over time

Many doctors believe there are 3 stages to myasthenia gravis:1-3

  • The first phase in which symptoms change the most and become the most severe over 5 to 7 years.
  • The second phase in which symptoms are stable and consistent. Infections and stress may make symptoms worse.
  • The third phase in which remission may occur whether the person is taking medicine to control their symptoms or has stopped taking medicine entirely.

While treatments may help improve the symptoms of MG, many find living with a chronic condition to be unpredictable, as well as physically and emotionally challenging.

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