Myasthenia gravis (MG) is a rare neuromuscular disorder that causes weakness in the muscles that your body uses to move. This happens when the connection between nerve cells and muscles is disrupted. This disorder prevents the occurrence of severe muscle contractions and causes muscle weakness. In this article, we introduce the symptoms, causes, diagnosis and treatment of myasthenia gravis.
Statistics of patients with myasthenia gravis
The disease is the most common primary neuromuscular disorder, according to the Myasthenia Gravis Foundation. This disease is relatively rare; In the United States, it affects 14 to 20 out of every 100,000 people. Although the disease can affect people of any age, it is more common in women under 40 and in men over 60.
In Iran, there are no accurate statistics on patients with myasthenia gravis. منتها Research In 2017, the number of patients with this disease in Tehran is 134 out of every 100,000 people. also, Another study It shows that the number of patients with this disease in different regions of Iran is between 5.3 to 74 people per 100,000 people. However, researchers in this study have noted that depending on the race and ethnicity, the disease has different prevalence; For example, it is very rare in Turkmen tribes.
Symptoms of myasthenia gravis
The main symptom of this disease is weakness in the muscles under your control. In this condition, lack of muscle contraction occurs normally; Because they can not respond to nervous breakdowns. Without proper transmission of the blow, the connection between the nerve and the muscle is blocked and weakness is created. MG weakness usually gets worse with more activity and improves with rest.
Other symptoms of myasthenia gravis may include:
- Facial paralysis;
- Drooping eyelids;
- Roughness of voice;
- Dual vision (diplopia);
- Difficulty speaking;
- Difficulty swallowing or chewing;
- Difficulty breathing due to muscle weakness;
- Difficulty walking up stairs or lifting objects.
Not everyone experiences all of these symptoms. Muscle weakness may change from day to day. The severity of the symptoms usually increases over time if left untreated.
Cause of myasthenia gravis
Myasthenia gravis is a neuromuscular disorder that is usually caused by an autoimmune problem. Autoimmune disorders occur when the body’s immune system mistakenly attacks healthy tissue. Under these conditions, antibodies, which are proteins that usually attack harmful foreign substances in the body, attack the neuromuscular junction. Damage to the neuromuscular membrane reduces the effect of the neurotransmitter acetylcholine. Acetylcholine is a vital substance for communication between nerve cells and muscles. Finally, reducing the effect of this transporter leads to muscle weakness.
The exact cause of this autoimmune reaction is unknown to scientists. According to the Muscular Dystrophy Association, one theory is that certain viral or bacterial proteins may cause the body to attack acetylcholine.
Complications of myasthenia gravis
One of the most dangerous possible side effects of MG is myasthenia gravis. This includes life-threatening muscle weakness that can include respiratory problems. Talk to your doctor about these side effects. If you have trouble breathing or swallowing, go to the emergency room as soon as possible. People with MG are at higher risk for other autoimmune disorders such as lupus and rheumatoid arthritis.
How is myasthenia gravis diagnosed?
The doctor will perform a thorough physical examination and also review the history of symptoms. He or she may also have a neurological test. Myasthenia gravis diagnostic tests include the following:
- Check muscle tone;
- Assess muscle weakness;
- Examine your refluxes and reactions;
- Sensory testing in different areas of your body;
- Make sure your eyes are moving properly;
- Testing motor functions مانند (such as touching a finger to the nose).
Other tests that can help your doctor diagnose this condition include:
- Frequent nerve stimulation test;
- Blood tests for MG-related antibodies;
- Chest imaging using CT scan or MRI.
- Edrophonium test: In this test, a medicine called Tensilon (or placebo) is given intravenously and you are asked to perform muscle movements under a doctor’s supervision.
Treatment of myasthenia gravis
There is no cure for MG. The goal of treatment is to manage symptoms and control the activity of the immune system.
Corticosteroids and immunosuppressants can be used to suppress the immune system. These drugs help minimize the abnormal immune response that occurs in MG. In addition, cholinesterase inhibitors, such as pyridostigmine (Mestinon), can be used to increase nerve-muscle communication.
2. Removal of thymus gland
Removal of the thymus gland, which is part of the immune system, may be appropriate for many patients with myasthenia gravis. Patients usually experience less muscle weakness when the thymus is removed. According to the American Myasthenia Gravis Foundation, between 10 and 15 percent of people with MG have tumors in their thymus. Even if these tumors are benign, they can be removed because they may become cancerous.
3. Plasma exchange (plasmapheresis)
Plasmapheresis is a type of treatment by changing the patient’s blood plasma. This process removes harmful antibodies from the blood, which may improve muscle strength. Plasmapheresis is a short-term treatment. The body continues to produce harmful antibodies and weakness may recur. Plasma exchange is useful before surgery or during severe weakness.
4. Intravenous immunoglobulin
Intravenous immunoglobulin (IVIG) is a blood product made from donors. This method is used to treat autoimmune myasthenia gravis. Although IVIG does not work well, it does affect the production and function of antibodies.
5. changing life style
Here are some things you can do to help reduce the symptoms of MG:
- Get enough rest to help reduce muscle weakness;
- Avoid exposure to stress and heat, as both can make symptoms worse;
- If binoculars bother you, talk to your doctor about whether you should use eyeliner.
These treatments cannot cure myasthenia gravis. However, you will usually notice an improvement in your symptoms. Tell your doctor about any medications or supplements you are taking. Some medications may make the symptoms of MG worse. Talk to your doctor before taking any new medicine to make sure it is safe.