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7 Facts About Myasthenia Gravis You Should Know

Updated on January 23, 2024

Myasthenia gravis is a neuromuscular disorder that affects how your nerves and muscles communicate. Myasthenia gravis can cause muscle weakness and limit your ability to complete daily activities, especially as the day goes on. If you or a loved one is living with myasthenia gravis, continue reading to learn seven things you should know about this condition.

1. Myasthenia Gravis Is an Autoimmune Condition

Myasthenia gravis is caused by an autoimmune condition where the body’s immune system mistakenly attacks healthy cells. When your immune system is working properly, special immune proteins called antibodies recognize and attack foreign invaders in your body, like bacteria or viruses.

When you have myasthenia gravis, abnormal antibodies start to inappropriately attack and destroy acetylcholine receptors (AChRs) on muscle cells. These receptors are found at the neuromuscular junction where nerve endings and muscle fibers meet.

Acetylcholine is a neurotransmitter released by motor nerve cells that tells your muscles to contract. When the immune system attacks the receptors for acetylcholine, there are less AChRs on the muscle cells for the nerves to communicate with. This results in muscle weakness.

While most people with myasthenia gravis (85 percent) have antibodies that target AChRs, a portion of people have other antibodies. Some antibodies target muscle-specific kinase (MuSK), which blocks signals in the neuromuscular junction. A smaller portion of people have neither AChR nor MuSK antibodies — this is known as seronegative myasthenia gravis.

2. Myasthenia Gravis Is a Rare Disease

Myasthenia gravis affects between 14 and 40 people per 100,000 people in the United States, making it a rare disease. Myasthenia gravis can occur in people of all ages, genders, races, and ethnic groups. Some groups are more likely to be diagnosed with myasthenia gravis, including:

  • Women younger than 40 years old
  • Men older than 60 years old
  • African American women

3. Thymus Gland Problems Are Common With Myasthenia Gravis

Many people with myasthenia gravis have problems with their thymus, a gland found in the upper chest above your heart. Your thymus is part of your lymphatic system and makes the white blood cells that help your immune system fight infections.

Research shows the thymus gland of some people with myasthenia gravis may deliver incorrect instructions to developing white blood cells. This may create abnormal antibodies that attack AChRs.

About two-thirds of people with myasthenia gravis have a thymus gland that’s larger than normal. Some of these people may develop a tumor in their thymus gland called a thymoma. Usually, thymomas are harmless, but they can sometimes be cancerous.

4. Myasthenia Gravis Symptoms Usually Worsen Over Time

The first symptoms of myasthenia gravis may start suddenly and get worse over time. Myasthenia gravis affects the muscles you control — known as voluntary muscles or skeletal muscles. These muscle groups attach to your bones to allow you to move. The heart and digestive tract muscles usually continue to function normally.

The symptoms of myasthenia gravis depend on which muscles are affected. Symptoms can come and go and can range from mild to severe.

Symptoms affecting eye muscles are often the first symptoms people with myasthenia gravis notice. These symptoms may include:

  • Double vision
  • Blurry vision
  • Drooping eyelids

When myasthenia gravis only affects your eyes, it’s known as ocular myasthenia. However, within two years of diagnosis, about 80 percent of people with ocular myasthenia develop symptoms of myasthenia gravis in other areas. Generalized myasthenia gravis may cause muscle weakness in other parts of your body, such as your:

  • Arms, hands, and fingers
  • Legs
  • Neck
  • Throat
  • Face

Muscle weakness in the above muscle groups can cause difficulty performing daily activities, including:

  • Walking
  • Eating
  • Making facial expressions
  • Lifting objects
  • Speaking
  • Swallowing
  • Getting up from a chair
  • Climbing stairs

For most people with myasthenia gravis, muscle weakness worsens with activity and gets better after resting.

5. Myasthenia Gravis Symptoms Can Be Life-Threatening in Rare Cases

If myasthenia gravis causes muscle weakness in the muscles that control breathing, it can be life-threatening. This is called a myasthenic crisis, and it’s a medical emergency. About 1 in 5 people with myasthenia gravis experience a myasthenic crisis at least once in their lifetime.

During a myasthenic crisis, the muscles that control your breathing become too weak to bring enough air in and out of your lungs to meet your body’s needs. If this occurs, you may need a machine called a continuous positive airway pressure (CPAP) machine or a ventilator to help you breathe.

A myasthenic crisis usually doesn’t happen suddenly. You may notice worsening symptoms that let you know a myasthenic crisis is coming on, such as:

  • Shortness of breath
  • Sleep apnea
  • Increased difficulty swallowing
  • Increased muscle weakness

If you notice any of these developing, reach out to your doctor or care team right away.

6. Diagnosis Is Often Delayed

Myasthenia gravis has symptoms similar to those of other medical conditions, such as brain tumors, multiple sclerosis, or a stroke. This can delay the diagnosis of myasthenia gravis for months or years.

Your doctor will perform a physical exam and conduct neurological tests to test the health of your nerves. Neurological tests will check the following:

  • Reflexes
  • Muscle strength and tone
  • Coordination and balance
  • Vision
  • Sense of touch

Other tests your doctor may order to confirm a diagnosis of myasthenia gravis may include:

  • Blood tests — People with myasthenia gravis may have abnormal antibodies that target AChRs.
  • Ice pack test — People with myasthenia gravis may notice improvement in a drooping eyelid after applying an ice pack for two minutes.
  • Repetitive nerve stimulation — This test studies how well nerves communicate with muscles.
  • Electromyography (EMG) — This test measures how well the brain communicates with muscles.
  • Imaging tests — A CT scan or MRI test can check for problems with the thymus gland.

7. There Are Several Effective Treatments for Myasthenia Gravis

While there currently isn’t a cure for myasthenia gravis, your neurologist can help you manage your symptoms with the right treatment plan. Your treatment will depend on the severity of your myasthenia gravis, your age, and any other health conditions you might have. You can use one treatment or a combination of therapies.

Medications

There are different types of medications available to treat myasthenia gravis.

Acetylcholinesterase inhibitors can help improve symptoms of muscle weakness by blocking the protein that breaks down acetylcholine. This means there’s more acetylcholine available to communicate with your muscles. Examples of acetylcholinesterase inhibitors include:

Immunosuppressive drugs can help improve myasthenia gravis symptoms by reducing the amount of abnormal antibodies your immune system makes. This means fewer AChRs are destroyed, and your nerves and muscles can communicate more efficiently. Examples of immunosuppressive drugs include:

Biologic drugs target different parts of your immune system that are overactive. They work by blocking the production of abnormal antibodies. As a result, this helps reduce inflammation in the neuromuscular junction. Some biologics also help get rid of the antibodies that target AChRs. Examples of biologic drugs for myasthenia gravis include:

Intravenous Therapy

Intravenous therapies may be used to help improve severe myasthenia gravis symptoms before surgery or if other treatments don’t work. Examples of intravenous therapy include:

  • Plasmapheresis — A plasma-exchange procedure where abnormal antibodies are filtered out of your blood plasma
  • Intravenous immunoglobulin (IVIG) — A treatment that delivers a concentrated injection of antibodies to alter your immune system

Surgery

Your doctor may recommend surgery to remove your thymus gland, called a thymectomy. This procedure may improve your long-term outlook with myasthenia gravis. It may take one or two years to see the benefit of this treatment.

Find Your Team

On MGteam — the social network for people living with myasthenia gravis and their loved ones — members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Do you have questions about myasthenia gravis? What would you tell someone who was newly diagnosed? Share your experience in the comments below, or start a conversation by posting on your Activities page.

    Updated on January 23, 2024
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    Luc Jasmin, M.D., Ph.D., FRCS (C), FACS is a board-certified neurosurgery specialist. Learn more about him here.
    Emily Wagner, M.S. holds a Master of Science in biomedical sciences with a focus in pharmacology. She is passionate about immunology, cancer biology, and molecular biology. Learn more about her here.

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