Myasthenia Gravis

Myasthenia gravis, or MG, is a type of autoimmune disease. It stops nerve signals that normally travel to certain muscles. This causes the muscles to become weak. The muscles tend to get weaker in periods of activity and get stronger after periods of rest. There is no cure for MG, but long-term remission is possible. Remission is a period of time with no symptoms. MG can affect people of any age or ethnic group, but it’s more common in people in their 20s, 60s, and 70s.

Causes

MG is caused by a problem in a person’s immune system. In a person with MG, their body’s immune system makes abnormal kinds of disease-fighting proteins called antibodies. The abnormal antibodies attack the links between nerves and muscles. These links are called neuromuscular junctions. The nerves then can’t get signals to the muscles they control. As a result, the muscles don’t work properly.

Symptoms

The main symptom of MG is muscle weakness. The muscle weakness can range from mild to severe. Depending on which muscles are affected, MG may cause:

  • Trouble speaking, chewing, and swallowing
  • Weakness in the neck, arms, and legs
  • Shortness of breath, especially along with swallowing, speech, or neck weakness
  • Tiredness
  • Droopy eyelids
  • Weak eye movements, which can cause double vision

Diagnosis

The health care provider will ask about your health history and symptoms. He or she will check your muscle strength and examine your vision, chewing, and swallowing.

You may also have certain tests. These include blood tests, imaging tests, and nerve and muscle tests. The blood tests help check for certain cells or antibodies in the blood. An imaging test called Magnetic Resonance Imaging, or MRI, uses magnets and radio waves to take pictures of your body and look for problems.

A nerve conduction velocity, or NCV, test helps to check nerve and muscle function. Small round disc electrodes are attached to wires and put on the skin over certain nerves and the muscles they control. A brief electrical current is sent to the nerves. The test shows how long it takes for the muscles to act on the nerve signal.

An electromyogram, or EMG, test may be done to check nerve and muscle function. Small needle electrodes are placed into muscles in the arms or legs. The test shows the electrical activity of the muscles when they are active and when they are at rest. This is often done at the same time as the NCV test.

Lastly, you may have an edrophonium test. This is to help check muscle strength. Medication is injected into a vein. In a person with MG, the medication will cause a brief increase in muscle strength. For instance, his or her eyelids may be less droopy for a short time.

Treatments

If your tests confirm that you have MG, you and your health care provider can talk about the treatment options that are right for you. These may include medications, blood therapies, or surgery.

Medications can help improve muscle weakness. Some treat the problems at the neuromuscular junction. Others help stop the immune system from making abnormal antibodies.

You may also be given special blood products that help fight the body’s abnormal immune response. These treatments are called plasma exchange and high-dose IVIG. These are mainly used when a severe attack of MG occurs and you need to be in the hospital.

Or, you may have surgery to remove the thymus gland. In a person with MG, the thymus gland is more likely to be enlarged or abnormal. In some cases, removing the gland may help symptoms go away.

What to Do

If you have MG, try to keep up a daily exercise program as advised by your health care provider and physical therapist. They will teach you the best exercises to help strengthen your muscles. Expect daily changes in your energy levels. Plan your daily activities around the times when you feel more energetic. And take your medication exactly as directed. Do not start new medications without checking with your health care provider. Make sure to have regular follow-up visits to your health care provider.

Go to the emergency room or call 911 if you have severe breathing or swallowing problems.

What We Have Learned

  1. Myasthenia gravis is a type of autoimmune disorder. True or False?
    The answer is True. MG stops nerve signals from traveling to certain muscles. This causes the muscles to become weak.
  2. Tiredness and fatigue are symptoms of MG. True or False?
    The answer is True. Tiredness and droopy eyes, as well as weakness in the neck, arms, and legs are all symptoms of MG.
  3. Daily changes in your energy levels are normal, and you should plan activities around that. True or False?
    The answer is True. Keeping up a daily exercise program is important, so plan your activities for when you are feeling good.