Myasthenia gravis

Myasthenia gravis is a long term (chronic) condition that causes muscle weakness and fatigue.

It's a rare condition that commonly affects the muscles that control the eyes and eyelids. It can also affect the face, speaking, chewing, swallowing and other parts of the body.

It can affect people at any age, but is most often found in women under 40 and men over 60.

There are other rarer types of myasthenia which you can read about on myaware.

If you drive, you must inform the DVLA that you have myasthenia gravis.

Symptoms of myasthenia gravis

The first symptoms of myasthenia gravis are often droopy eyelids or double vision. It usually affects the eyes first and may spread to other parts of the body. It can take weeks, months or years for symptoms to develop in other parts of the body.

The severity of the symptoms is different for each person. It's likely that your symptoms will tend to get worse when you're tired. The symptoms might improve after resting.

Symptoms can include:

Eyes

You might experience droopy eyelids affecting one or both eyes, and double vision.

In some people, only the eye muscles are affected (ocular myasthenia).

In most people, the symptoms will spread to affect other parts of the body over time.

Swallowing, speaking and breathing

You might experience:

  • slurred speech
  • difficulty swallowing
  • difficulty making facial expressions like smiling
  • problems with chewing
  • a change in your voice
  • choking or accidentally inhaling food which can cause chest infections
  • shortness of breath
Limbs and neck

The muscle weakness might spread to other parts of the body like your arms, legs and neck.

You might experience:

  • weakness in your arms, legs, neck or other parts of your body
  • difficulty holding your head up
  • aching muscles
  • problems with tasks like climbing stairs or washing your hair
Myasthenic crisis

Some people can experience severe breathing and swallowing difficulties, which require immediate hospital treatment. This is called a myasthenic crisis.

It's possible for patients to experience a myasthenic crisis before they know they have myasthenia gravis.

Urgent advice: Phone 999 for an ambulance if:

  • you're experiencing severe breathing or swallowing problems

You might need emergency hospital treatment.

You should avoid activities that could become dangerous if you experience sudden weakness, like swimming alone.

Diagnosing myasthenia gravis

It can be difficult to diagnose myasthenia gravis. Your doctor will ask about your medical history and symptoms.

You might need several tests to rule out other causes of your symptoms before you can be diagnosed with myasthenia gravis.

Blood test

A blood test will look for a high level of antibodies (made by your immune system) which might be causing myasthenia gravis.

You might be offered another blood test at a later date if your initial blood test is normal but you continue to experience worsening symptoms.

Electromyography

You might have electromyography (an EMG) to test your nerves and muscles.

During electromyography, you'll have small needles inserted into your muscles to measure their electric activity. These are usually inserted around your eyes, forehead or arms.

The test will measure the signals from the nerves to the muscles. If the test detects a disruption in the signals, this might be a sign of myasthenia gravis.

Scans

You might have a computerised tomography (CT) scan to check if the thymus gland in your chest is bigger than expected or has grown abnormally (a thymoma).

The thymus gland is part of your immune system. Problems with the thymus gland like inflammation (swelling), can be linked to myasthenia gravis.

An magnetic resonance imaging (MRI) scan might be used to check if your symptoms are being caused by an issue in your brain.

Treating myasthenia gravis

There are treatments available that can help reduce the affects of your symptoms.

If your symptoms get worse following certain triggers, you should try to avoid those triggers as much as possible.

Triggers might include:

  • stress
  • tiredness
  • infections
  • medicines
  • surgery

Treatment might include: 

Medicine

Pyridostigmine

Sometimes myasthenia gravis can be treated with pyridostigmine alone. It works by temporarily improving the nerve to muscle transmission to help muscle strength.

It can reduce muscle weakness and for some people this is the only medication they need to control the condition.

It's effects do not last long and it needs to be taken periodically throughout the day to give the best results.

Side effects can include stomach upset, diarrhoea and drooling.

Steroids

You might be advised to take steroid tablets like prednisolone if pyridostigmine isn't helping.

Steroid tablets work by reducing the activity of your immune system to stop it attacking the communication between your nerves and muscles.

It's likely you'll be advised to take the tablets every other day. You're likely to start at a low dose which will be built up quickly. This might gradually be reduced once your symptoms are under control. It's important that you do not stop your steroids suddenly, as this can make you very ill.

Using steroids long term can cause side effects including osteoporosis (weak bones), weight gain, infection and diabetes.

Read more about the side effects of steroids

Immunosuppressants

Immunosuppressants work by reducing the activity of your immune system. Your healthcare team might suggest taking immunosuppressants if:

  • steroids aren't controlling your symptoms
  • you need a high dose of steroids to control your symptoms

Commonly used immunosuppressants include azathioprine, mycophenolate mofetil and methotrexate.

You'll need to take the tablets every day and it can take at least 9 months to feel the full effect. You'll be advised to take steroids at first.

Immunosuppressants night cause side effects like:

  • loss of appetite and tiredness
  • feeling sick
  • increased risk of infections

You'll have regular blood tests to check the the medicine isn't causing any harm.

You might be able to stop taking immunosuppressants if they keep your symptoms under control over a few years.

Surgery

Your healthcare team might recommend surgery to remove the thymus gland (thymectomy).

Symptoms should improve within the first few months after surgery and can continue to improve for up to 2 years.

Surgery can reduce:

  • the dose of steroids
  • the need to take other immunosuppressants
  • the chances of needing to go to hospital because of worsening symptoms

Surgery might not help myasthenia symptoms in someone that has a thymoma. Your healthcare team might still recommend having your thymus gland removed because it can cause problems if it keeps growing.

Your thymectomy will usually be carried out through keyhole surgery. The thymus is removed using surgical instruments inserted through small cuts (incisions) in the chest.

Plasma exchange and IVIG

Plasma exchange and IVIG (intravenous immunoglobulin) can offer a quick improvement (within a few days) for people with myasthenia gravis who are particularly unwell or are having a myasthenic crisis.

Plasma exchange is an emergency treatment that removes antibodies from your own blood. This treatment is given in hospital and the benefits can last around 6 weeks.

IVIG treatment involves an injection of normal antibodies from donated blood to temporarily change the way your immune system works.

The two treatments are similar and your healthcare team will decide which is the best option for you. Although the benefits only last a few weeks, it can give time for the longer term treatments to take effect and help improve symptoms.

You might find that, during pregnancy or after having a baby, your myasthenia gravis worsens. If you're planning a pregnancy or become pregnant, you should speak to your healthcare team. Don't stop taking your medications without first speaking to your healthcare professional.

Last updated:
02 December 2022

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