Myasthenia gravis is an autoimmune disorder that disrupts communication between nerve cells and muscles. It can cause muscle weakness and other symptoms depending on the affected areas.
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, more than 70,000 people in the United States have received a diagnosis of myasthenia gravis.
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.
Muscles typically fail to contract if they can’t respond to nerve impulses. When communication between nerve and muscle is blocked, weakness results. The degree of weakness can change daily, and symptom severity typically increases over time if left untreated.
Weakness associated with MG usually gets worse with activity and improves with rest.
People with MG may experience different symptoms affecting different parts of the body, such as:
Eyes
When affecting the eyes, MG can cause:
- drooping eyelids (ptosis)
- blurry or double vision (diplopia)
- issues with eye and eyelid movement
Face
MG can affect your control of your facial muscles. This can cause:
- facial paralysis
- changes in your facial expressions
- difficulties chewing
Throat
When MG affects the muscles of the throat, you may experience:
- difficulty speaking (dysarthria)
- issues with swallowing
- difficulty swallowing or chewing
- hoarse voice
- neck weakness, which can make it difficult to hold up your head
Chest
When MG affects the muscles of the chest area, you may experience
- shortness of breath
- difficulty breathing
- weakness in the diaphragm and chest muscles
This can lead to myasthenic crisis and respiratory failure.
A myasthenic crisis is life threatening and requires emergency medical treatment.
Arms and legs
MG can also affect muscles in your arms and legs, which may cause:
- fatigue
- weakness in your fingers, hands, and arms
- overall weakness in your legs
- problems walking up stairs or lifting objects
MG may be triggered by a combination of irregular antibodies or problems with the thymus gland, according to the Muscular Dystrophy Association (MDA).
The causes and risk factors can include:
An autoimmune reaction
Autoimmune disorders occur when your immune system mistakenly targets healthy tissue. In MG, these antibodies, which usually target harmful substances in the body, instead damage nerve cells.
The antibodies block or attack acetylcholine receptors, which makes muscles unable to respond to acetylcholine and contract. This results in muscle weakness.
The exact cause of this autoimmune reaction is unclear. The MDA suggests specific viral or bacterial proteins may prompt the body to target acetylcholine.
A family history of autoimmune diseases may increase your risk of developing an autoimmune disorder like MG.
Thymus gland irregularities
The thymus gland typically grows until puberty and controls healthy immune functions throughout your life. After puberty, the gland shrinks in size.
In
Developing benign or cancerous thymus gland tumors is also possible, which may interfere with crucial immune cell production. The enlarged thymus gland also produces antibodies that block acetylcholine.
About 75% of people with MG have thymus gland irregularities (thymic hyperplasia), and another 15% 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
While MG may develop at any age, the
About 10-15% of MG cases develop in childhood.
It’s also possible for newborn babies to have a temporary condition called neonatal myasthenia. This occurs when the mother has MG and passes the antibodies to a fetus. However, neonatal myasthenia is different from MG. It is temporary, lasting about
A doctor typically performs a complete physical exam and takes 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
- seeing how your eyes move
- testing sensation in different areas of your body
- testing motor functions, like touching your finger to your nose
Other tests that can help diagnose the condition include:
You may want to talk with a doctor if you have 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 have MG, you may go into remission, or a period where your symptoms may get better or go away. However, since remission may be temporary, it’s important to keep track of your symptoms and talk with a doctor if they return.
There is currently no cure for MG. Treatment involves managing symptoms and controlling the activity of your immune system. Treatment options can include:
Medication
Medications can help reduce muscle weakness or prevent progression of the disease. These can include:
- corticosteroids and immunosuppressants can help suppress the body’s irregular immune response
- cholinesterase inhibitors, such as pyridostigmine (Mestinon), can help increase communication between nerves and muscles
- monoclonal antibodies, such as eculizumab (Soliris), which can help prevent acetylcholine antibodies from damaging the neuromuscular junction in adults who test positive for the anti-acetylcholine receptor (AchR) antibody
Thymus gland removal
Doctors may recommend removing the thymus gland (thymectomy) in many people with MG. Doctors also recommend surgery to remove thymus gland tumors, even benign ones, as they may become cancerous.
Once the thymus is removed, patients typically show less muscle weakness. Research from 2017 also shows that thymectomy and prednisone may be more effective than taking prednisone alone.
Plasma exchange
Plasmapheresis, or plasma exchange, is a procedure that 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 an infusion of antibodies from healthy donors. It helps treat MG temporarily by binding to and removing antibodies that cause myasthenia gravis. Like plasmapheresis, the benefits are temporary. Doctors typically recommend it for severe MG symptoms.
Lifestyle changes
Some things you can do at home may help alleviate symptoms of MG include:
- Get plenty of rest to help minimize muscle weakness.
- If you’re bothered by double vision, talk with a doctor about wearing an eye patch.
- Avoid stress and heat exposure since both can worsen symptoms.
- If a doctor recommends it, regular low impact exercise may help strengthen your muscles.
You may also go into remission, during which treatment is not necessary.
Some medications and supplements can make MG symptoms worse. Before taking any new medication, check with a doctor or pharmacist to ensure it does not interact with your other medications.
Left untreated, MG may lead to complications. These can include:
Myasthenic crisis
One of the most dangerous potential complications of MG is a myasthenic crisis. An estimated
During a myasthenic crisis, you may experience severe muscle weakness that leads to respiratory failure.
You can talk with a doctor about your risk. You may need emergency medical attention if you have trouble breathing or swallowing.
Additional autoimmune disorders
MG may increase your risk of developing other autoimmune disorders, such as lupus and rheumatoid arthritis. A doctor will likely recommend regular blood testing to help detect these conditions so you can seek early treatment.
What is the life expectancy of a person with myasthenia gravis?
The life expectancy of a person with MG is
What happens to a person with myasthenia gravis?
A person with MG may experience muscle weakness in some areas of the body. Symptoms, such as double vision or fatigue, can depend on the area of the body affected.
What are the symptoms of myasthenia gravis in the eyes?
When it affects the eyes, MG can cause double vision, blurred vision, and drooping eyelids.
Is myasthenia gravis a form of MS?
While both MG and MS can affect muscle control, they are separate diseases. They both have an autoimmune component, but the specific cause is different.
Learn more about the differences and similarities between MG and MS.
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.
Early and proper treatment can help limit disease progression and improve quality of life.