Myasthenia gravis also known as MG is a disease in the muscles causing weakness in the skeletal muscles used for movement in the body and breathing. It is an autoimmune disease that attacks its own body tissues. Myasthenia gravis interrupts the connection between the nerve and muscles leading to damage of the neuromuscular junction. MG can occur in any race, gender, and age but most commonly in women around the ages of 20 to 40. Men are usually affected at the age of 50 to 60. Also, most common in families with inherited autoimmune diseases. From the Latin and Greek words grave and muscle weakness myasthenia earned its named. The first case of MG was founded by Thomas Willis in 1672, but it wasn’t until 1960 when scientist studied that MG was caused by antibodies attacking acetylcholine (ACh) receptors in the body
The cause of myasthenia gravis is caused by the immune system producing antibodies that destroy the receptor sites for neurotransmitter for acetylcholine. Acetylcholine is used to produce muscle contraction without it be able to produce movement in the body. Eventually there would be a decrease the amount of functional ACh receptors to the motor end plates of skeletal muscles. A protein produced by the immune system called muscle specific tyrosine kinase used to bring ACh to the muscle cell has been linked to causing nerve to muscle miscommunication leading to muscle weakness. Doctors think another cause of MG is the thymus because high percentages of those affected have tumors in the thymus. The thymus which is part of the immune system is in the middle of the chest just below the breastbone. When affected the thymus is presented large with clusters of immune cells called thymomas which sometimes can be cancerous. People can also contract myasthenia gravis from using a medicine call Penicillamine used to treat rheumatoid arthritis, other chronic autoimmune disorder, and Wilson’s disease Having a family history of myasthenia gravis can also increase the chances of developing the autoimmune disease.
The signs and symptoms that are seen with myasthenia gravis is muscle weakness that worsens with repeated activity and improve with rest that comes and goes. The symptoms and degree of weakness varies from person to person. Weakness and easily fatigue is the first most noticeable symptom because it starts to affect with daily activities. The neck and face are most often affected first. The muscles used in holding up the head become weak making the head feel like a bowling ball. People may start to feel that their eyes becoming weaker causing double vision, inability to focus on objects, and ptosis drooping of the eyelids. Swallowing and chewing is a little more difficult causing the risk of aspiration. Friends might notice a difference of facial expressions such as lack of smiling or laughter. Muscles used for speaking can be affected sounding as if you are talking with a stuffed nose. As the disease progresses the muscles in the limb become affected muscles start to contract causing stiffness. Unsteady gait can be noticed if the legs are affected. Not often but death can be a result of myasthenia gravis from the inability to produce movement of respiratory muscles.
Blood test are the most common and reliable laboratory tests used in detecting myasthenia gravis. Blood analysis detect a certain amount of abnormal myasthenic antibodies that is present in the blood, blocking the receptor sites for acetylcholine. Different types of antibodies like Anti–acetylcholine receptor antibody(AChR), Anti-agrin antibody, Anti-MuSK antibody, and Anti–striated muscle antibody is found in people with myasthenia gravis. If only the eyes muscles are being affected high levels of antibodies will not be present in the blood. Also nerve test is conducted with electrical recordings to show, if nerve impulse is being disrupted when blood results come back negative with ocular MG. Thyroid function test is also used to rule out any thyroid disorders associated with myasthenia gravis. Diagnosing myasthenia gravis can be prolonged because of the inconsistent of symptoms. For older individuals a chest CT is best used to rule out thymomas or an enlargement of the thymus. MRI’s are mostly used in detecting MG in the brain and eyes. Pulmonary function test is used to determine lung capacity due to decrease respirations caused myasthenic crisis. Edrophonium test detects ocular muscle weakness from MG by injecting edrophonium chloride into the body to reduce muscle weakness for a short amount of time. It prevents the breakdown of acetylcholine to increase its levels so communication between nerve and muscle is produce.
Myasthenia gravis is mistakenly diagnosed with in people who already experience mild to moderate weakness and restricted use of certain muscles. Diseases that cause muscle weakness like multiple sclerosis, Guillain-Barre syndrome, trigeminal neuralgia, and muscular dystrophy have common signs and symptoms like facial and eye lid drooping, increase weakness, unsteady gait, difficulty swallowing and chewing, and changes in speech. People with thyroid issues can be misdiagnosed because Identifying myasthenia gravis can be delayed because the symptoms may not always be present. Speaking to the doctor about any changes in health can be the best way to detect myasthenia gravis early.
There is no cure for myasthenia gravis, but treatments are used to decrease symptoms to improve quality of life. Treatments used for myasthenia gravis are medication like pyridostigmine an immunotherapeutic/Anticholinesterase agent, intravenous immunoglobulin, and prednisone. Surgeries like thymectomy which the removal of the thymus gland. This is only removed if the person has a tumor on the thymus gland. It helps reduce muscle weakness and the need to use immunosuppressant medications. Removing the antibodies from the blood is a procedure called plasmapheresis. This is only used on patients with severe cases of myasthenia gravis who do not respond to other treatments. Most people just decide to go the natural route taking care of themselves like eating healthy, improving diet, exercising, and managing stress.
The prognosis of myasthenia gravis is good. Treatments are improving muscle weakness and decreasing fatigue. Most people with myasthenia gravis are living normal lives and long lives. A lot of people go into remission temporally or permanently depending on how the treatment is working for them. Patients who have gone with removing their thymus have longer remission periods since eliminating the problem. People with severe cases of myasthenia gravis develop respiratory depression requiring immediate medical attention.