What is myasthenia gravis?
Myasthenia gravis is a relatively rare autoimmune neuromuscular disease that leads to fluctuations in muscle weakness and fatigue. Muscle weakness happens due to the passage of antibodies that prevent acetylcholine receptors at the postsynaptic neuromuscular junction, inhibiting the excitatory effects of the neurotransmitter acetylcholine on nicotinic receptors at the neuromuscular junctions.
Myasthenia gravis means “severe muscle weakness,” but most cases are mild and life expectancy is normal.
The muscles around the eyes are affected first, causing the eyelids to shrink. Patients have double vision, weak arms, and legs, and difficulty chewing, swallowing, speaking, and breathing. Involuntary muscles, such as the heart muscle, are not affected.
Causes of myasthenia gravis
Your body’s own immune system damages muscle receptors and causes myasthenia gravis. Among myasthenia gravis, your immune system produces antibodies that conflict with the receptors. This interference damages the connection between the chemical and the receptors that travel from the nerve endings. This connection is essential for your muscles to function properly. Without it, the muscles will weaken.
The thymus, which is part of the immune system, is abnormal in most cases of MG. Few people with MG have benign tumors of the thymus gland termed thymomas. Doctors do not fully explain the connection between the thymus gland and MG.
Risk factors for myasthenia gravis
Risk factors for myasthenia gravis are most common in:
- Women less than 40 years old
- Men over 60 years old
- People with a family story of systemic lupus erythematosus
Symptoms of myasthenia gravis
The symptoms of myasthenia gravis (MG) vary widely. In some, only the eye muscles are affected, while in others, it affects many muscles, including those that control breathing.
The most common symptoms of myasthenia gravis are:
- Visual problems, including drooping eyelids (ptosis) and second vision (diplopia)
- Muscle weakness and fatigue may vary quickly in strength over days or even hours and worsen as muscles are practiced (early fatigue)
- Facial muscle engagement causing a mask-like appearance; a smile may resemble more like a snarl
- Trouble swallowing or pronouncing words
- The weakness of the neck or limbs
The symptoms of myasthenia gravis may look like other diseases. Always see your doctor for a diagnosis.
Diagnosis of myasthenia gravis
Your healthcare provider can diagnose myasthenia gravis based on your symptoms and some tests. During the physical exam, your healthcare provider will ask about your medical history and symptoms.
An easy way to diagnose myasthenia gravis is to evaluate how you respond to certain medications. Muscle weakness dramatically improves for a time when you are given an anticholinesterase drug. If it responds to the toxin, it supports the diagnosis of myasthenia gravis.
Other tests that may be done include:
- Entire medical history and physical examination, including the history of any other autoimmune diseases.
- Electrodiagnostic tests (EMG/NCS): Our neuromuscular neurologists evaluate the function of muscles and nerves using a machine that measures electrical signals in individual muscles and nerves. Learn more about electromyography. The use of single fiber EMG is particularly useful in myasthenia gravis, which can detect the disease even when other tests are negative or involuntary.
- Laboratory tests: Tests may be conducted to look for antibodies in the blood that are linked with myasthenia gravis.
- Imaging studies: Testing may involve CT scan or magnetic resonance imaging (MRI) of the chest seeing for tumors that are sometimes seen in patients with myasthenia gravis.
Treatment for myasthenia gravis
There are several treatments to strengthen the muscles of people with MG. For most people with angina, treatment will work well. In some people, MG can be relieved for a time and the muscle weakness can go away completely. In rare cases, people go into remission or get better without treatment.
The purpose of treatment is to improve muscle function and limit swallowing and breathing problems. Most people with this condition can improve their muscle strength and lead a normal or normal life. In more severe cases, help is needed to breathe and eat.
Treatment for MG may include:
- Cholinesterase inhibitors: These are the medications that are commonly used to treat MG, but they are very helpful in milder forms of the condition. These drugs work by preventing the breakdown of acetylcholine, thus increasing the capacity for muscle contraction. The most commonly prescribed form of this medication is pyridostigmine (Mestinon).
- Immunosuppressants: Corticosteroids and other drugs such as cyclosporine and azathioprine can help MG patients by suppressing the activity of the immune system. These treatments are usually for sicker patients. Although they are often very effective, these medications can cause serious side effects. The patient should consult with their physician regarding the potential value of these drugs in the treatment of MG.
- Thymectomy: It is the surgical removal of the thymus gland, which is rare in most people with MG. This surgery is done for those with MG with tumors, as well as for those without tumors. This surgery improves symptoms in most MG patients.
Different therapies sometimes used to treat MG when weakness is very serious include:
- Plasmapheresis: It is a method of conversion of blood plasma. It “filters” the blood of acetylcholine receptor antibodies by rearranging the patient’s plasma with donor plasma. Plasmapheresis is a life-saving device in the treatment of MG; However, it is costly, time-consuming, and can be linked with side effects such as low blood pressure, infections, and blood clots.
- Immunoglobulin. It is a blood product that helps to decrease the immune system’s intervention on the nervous system. It is applied intravenously (IV).
Myasthenia gravis cannot be prevented. However, a person can take steps to stop the swelling of symptoms or stop problems from developing.
These involve careful hygiene to stop infections and immediate treatment if they do occur.
It is also advisable to avoid severe temperatures and overeat. Effective stress management also reduces the frequency and severity of symptoms.
While complications of myasthenia gravis are treatable, few can be life-threatening.
Complications may include the following:
- Myasthenic crisis is a life-threatening disease that affects breathing and requires immediate treatment for the person to breathe on their own.
- Thymus tumors, which usually are not cancerous, occur in up to 15 percent of people with myasthenia gravis.
- People with myasthenia gravis are more likely to have an overactive or dysfunctional thyroid and autoimmune conditions, such as rheumatoid arthritis or lupus.
When to contact the doctor
Contact your doctor if you have a problem:
- Using your arms or hands
- Holding up your head
Departments to consult for this condition
- Department of Neurology