Myasthenia gravis

Myasthenia gravis (MG) is a chronic neuromuscular disease that may start slowly or suddenly. If you notice muscle weakness in any part of your body, you can trust your Aurora Health Care doctor to work with you to find treatment that controls your symptoms.

What is myasthenia gravis?

Myasthenia gravis is a disease that causes weakness in the voluntary muscles – muscles over which you have conscious control. Voluntary muscles are used for every movement you make and every time you stop moving.

The muscle weakness is caused by the autoimmune system, which produces abnormal antibodies that keep messages from your brain from reaching your muscles. Normally, a chemical called acetylcholine carries messages from your nerves to your muscles. But the antibodies block your muscles from picking up the message and that leads to the muscles not working well.

Myasthenia gravis & the thymus gland

Researchers believe that the thymus gland has a connection to myasthenia gravis. The thymus controls your immune system during childhood. For most people, the thymus grows bigger until puberty and then slowly gets smaller until it’s replaced by fat.

Many people who have MG either have a large thymus or develop tumors in the thymus (thymomas). Although thymomas are usually benign, they sometimes become cancerous. Doctors consider having either a large thymus or a thymoma to be a sign that you might have myasthenia gravis.

Myasthenia gravis symptoms

Everybody who has MG has different myasthenia gravis symptoms. Some patterns of symptoms are:

• Symptoms that affect the eyes and face.
• Focal symptoms which affect only one part of the body, such as just the left arm.
• Generalized myasthenia gravis, which affects the whole body including the eyes and face.

You may have symptoms that match one of those descriptions or you may have another set of symptoms. Some of the most common myasthenia gravis symptoms are:

• Blurred or double vision (diplopia)
• Changes in facial expressions
• Difficulty swallowing
• Drooping of one or both eyelids (ptosis)
• Impaired speech (dysarthria)
• Shortness of breath
• Weakness in the arms, hands, fingers, legs, and neck
• Weakness of the eye muscles (ocular myasthenia)

The muscle weakness caused by myasthenia gravis gets worse when you’re active and gets better when you rest. This is different than muscle weakness caused by other diseases and conditions.

A myasthenic crisis is a life-threatening event where a person has so much trouble breathing that they need a ventilator. Dial 911 or seek emergency treatment if you have extreme trouble breathing.

Triggers for myasthenia gravis symptoms

People who have symptoms of myasthenia gravis may notice there are things that trigger them to have worse symptoms. Known triggers for MG symptoms are:

• Certain medications
• Emotional stress
• Illness such as a virus
• Pregnancy and postpartum period
• Surgery
• Warm weather
• Worsening of another chronic illness

Myasthenia gravis risk factors

There are no known risk factors for myasthenia gravis. It’s not contagious or inherited, and it infects people of all racial and ethnic groups.

Statistics show that women younger than 40 and men older than 60 are more likely to develop the disease.

Myasthenia gravis diagnosis & testing

Symptoms of myasthenia gravis may be similar to symptoms of stroke, brain tumors and other neuromuscular diseases. To confirm a diagnosis of myasthenia gravis, your doctor needs to exclude other possible diseases. Researchers are still trying to find a test that will prove that a person has MG.

To reach a diagnosis, your doctor will start with a physical exam and ask about your symptoms and medical history. They’ll also perform a neurological exam that tests your sense of touch, coordination, eye movements, and muscle strength and tone.

Blood tests may be performed to check for several types of antibodies. Your doctor may also recommend tests like these:

• Computed tomography (CT) of the chest: Checks for a thymoma or enlarged thymus.
• Electromyography (EMG): Electromyography tests for problems in communication between nerves and muscles. It’s the most sensitive myasthenia gravis test.
• MRI of brain and eye orbit: Looks for growths unrelated to MG that may be causing eye symptoms.
• Repetitive nerve stimulation: Assesses muscle responses by stimulating nerves repeatedly with electricity.

Myasthenia gravis treatment options

Myasthenia gravis is a chronic illness that has many treatments designed to address symptoms and improve quality of life. Researchers continue to search for better treatments and our doctors have access to clinical trials that may be right for you.

Removing the thymus gland through surgery is one option. Research shows that it improves symptoms and may result in symptoms going away (remission).

There are several myasthenia gravis medication options for treatment. Cholinesterase inhibitors cause the effects of acetylcholine to last longer and increase the chances of messages getting through to your muscles. Corticosteroid and immunosuppressant drugs may relieve MG symptoms. Your health care team will check with you about any side effects and change treatments as needed.

Myasthenia gravis treatments with blood products

A blood plasma exchange may be suggested if you have a sudden worsening of symptoms or need to have surgery. An apheresis machine is used to filter the plasma from your blood and replace it with donated plasma. This procedure replaces abnormal antibodies with normal ones.

Intravenous immune globulin (IVIG) infusion may also be considered. Immunoglobulins (antibodies) are separated from donated plasma from thousands of people and injected into the bloodstream of the person who has MG. The addition of normal antibodies improves muscle strength.

Both myasthenia gravis treatments with blood products take several hours to complete and are usually provided as outpatient procedures.