Myasthenia gravis (MG) is a neuromuscular disorder that causes weakness in the skeletal muscles, which are the muscles your body uses for movement.
MG happens when communication between nerve cells and muscles becomes impaired. This impairment prevents crucial muscle contractions from occurring, causing muscle weakness.
According to the Myasthenia Gravis Foundation of America, MG is the most common primary disorder of neuromuscular transmission.
MG is considered a relatively rare condition that affects about 20 out of every 100,000 people in the United States. However, it’s also underdiagnosed, so the prevalence could be higher.
Learn more about the symptoms and causes of MG and what treatment options are available for this neuromuscular disorder.
The main symptom of MG is weakness in the voluntary skeletal muscles, which are muscles under your control.
The failure of muscles to contract usually happens because they can’t respond to nerve impulses. Without proper transmission of the impulse, the communication between nerve and muscle is blocked and weakness results.
Weakness associated with MG usually gets worse with more activity and improves with rest. Symptoms of MG may present via
MG can cause dropping of the eyelids, as well as double or blurry vision. You may also experience overall weakness in your eye muscles.
In addition to facial paralysis, MG may lead to changes in your facial expressions.
When MG affects the muscles of the throat, you may experience:
- trouble talking
- difficulty breathing
- difficulty swallowing or chewing
- hoarse voice
- weakness in your neck, making it difficult to hold your head up
When MG affects the muscles of the chest area, you may experience severe and potentially life threatening symptoms:
- respiratory failure, caused by weakness in the diaphragm and chest muscles that may lead to myasthenic crisis and is considered an emergency
Arms and legs
MG can also affect the muscles in your arms and legs, leading to the following symptoms:
- weakness in your fingers, hands, and arms
- overall weakness in your legs
- problems walking up stairs or lifting objects
Not everyone will have every symptom, and the degree of muscle weakness can change from day to day. The severity of the symptoms typically increases over time if left untreated.
While the exact cause of autoimmune diseases like MG is unknown, MG may be triggered by a combination of irregular antibodies or problems with the thymus gland, according to the Muscular Dystrophy Association (MDA).
Risks for developing MG may also increase with age.
Antibodies and MG
Autoimmune disorders occur when your immune system mistakenly attacks healthy tissue. In MG, antibodies, which are proteins that usually attack foreign, harmful substances in the body, attack nerve cells.
Damage to the neuromuscular membrane
The exact cause of this autoimmune reaction is unclear to scientists. The MDA suggests that certain viral or bacterial proteins may prompt the body to attack acetylcholine.
Having a family history of autoimmune diseases may also increase your risk of developing an autoimmune disorder like MG.
Thymus gland irregularities
Your thymus gland naturally grows until puberty and is responsible for controlling healthy immune functions throughout your entire life. After puberty, the gland shrinks in size.
In people with MG, the thymus gland stays large, according to the
It’s also possible to develop benign or cancerous tumors of the thymus gland, which may interfere with important immune cell production, like T-cells. The enlarged thymus gland also produces antibodies that block acetylcholine.
According to the MDA, about 75 percent of people with MG have thymus gland irregularities (thymic hyperplasia )and another 15 percent have tumors.
As a result, the thymus gland may give your immune system incorrect instructions, which researchers believe may lead to immune cell destruction that causes MG.
Age plays a role
While MG may develop at any age, it’s most common in people over the
About 10 to 15 percent of MG cases develop in childhood, but most children achieve remission.
It’s also possible for newborn babies to have a temporary condition called neonatal myasthenia. This occurs when the mother has MG and passes on the antibodies to a fetus. However, neonatal myasthenia is temporary, lasting about
Your doctor will perform a complete physical exam, as well as take a detailed history of your symptoms. They’ll also do a neurological exam.
This may consist of:
- checking your reflexes
- looking for muscle weakness
- checking for muscle tone
- making sure your eyes move properly
- testing sensation in different areas of your body
- testing motor functions, like touching your finger to your nose
Other tests that can help your doctor diagnose the condition include:
Contact your doctor if you have any unusual symptoms affecting your eyes, face, throat, or overall body movements. You should be especially aware of possible MG symptoms if you’re an older adult with a personal or family history of autoimmune disorders.
If you’ve already been diagnosed and treated for MG, you may go into remission at some point. However, since remission may only be temporary, it’s important to keep track of your symptoms and talk with your doctor if they return.
There is currently no cure for MG. The goal of treatment is to manage symptoms and control the activity of your immune system. Talk with your doctor about the following options.
Corticosteroids and immunosuppressants can be used to suppress the immune system. These medications help minimize the irregular immune response that occurs in MG.
Additionally, cholinesterase inhibitors, such as pyridostigmine (Mestinon), can be used to increase communication between nerves and muscles.
Thymus gland removal
Removal of the thymus gland (thymectomy), which is part of the immune system, may be appropriate for many patients with MG. Tumors, even those that are benign, are always removed because they may become cancerous.
Once the thymus is removed, patients typically show less muscle weakness. Research from 2017 also shows that thymectomy results may be more effective in those who also take prednisone.
Plasmapheresis is also known as a plasma exchange. This process removes harmful antibodies from the blood, which may result in an improvement in muscle strength.
Plasmapheresis is a short-term treatment. The body continues to produce harmful antibodies, and weakness may recur. Plasma exchange is helpful before surgery or during times of extreme MG weakness.
Intravenous immune globulin
Intravenous immune globulin (IVIG) is a blood product that comes from donors. It’s used to treat autoimmune MG. Although it’s not entirely known how IVIG works, it affects the creation and function of antibodies.
There are some things you can do at home to help alleviate symptoms of MG:
- Get plenty of rest to help minimize muscle weakness.
- If you’re bothered by double vision, talk with your doctor about whether you should wear an eye patch.
- Avoid stress and heat exposure, since both can worsen symptoms.
These treatments cannot cure MG. However, you’ll typically see improvements in your symptoms. It’s also possible to go into remission, during which treatment is not necessary.
Tell your doctor about any medications or supplements you take. Some drugs can make MG symptoms worse. Before taking any new medication, check with your doctor to ensure it’s safe.
Left untreated, MG may lead to complications. Talk with your doctor about your personal risk.
One of the most dangerous potential complications of MG is a myasthenic crisis. It’s estimated that
During a myasthenic crisis, you may experience severe muscle weakness that leads to respiratory failure, according to the
Talk with your doctor about your risks. If you start to have trouble breathing or swallowing, call 911 or go to your local emergency room immediately.
Additional autoimmune disorders
Having MG may place you at a higher risk of developing other autoimmune disorders, such as lupus and rheumatoid arthritis. Your doctor will likely recommend regular blood testing to help detect these conditions so you can seek early treatment.
The long-term outlook for MG depends on a lot of factors. Some people will only have mild symptoms, while others may have more severe ones. Remission is also possible.
Talk with your doctor about what you can do to minimize the severity of your MG. Early and proper treatment can help limit disease progression and improve your overall quality of life.