Women who develop the condition usually have their first symptoms in their 30's or 40's, but men who develop the condition usually display symptoms in their 60"s or 70's. Babies born to mothers who have myasthenia gravis may have symptoms for a short time after they are born, but they usually recover with minimal treatment. These babies need to be monitored for a week or two after birth to make sure they do not suffer respiratory failure.
A muscular disorder with progressive symptoms—but not always
In the other 6 out of 7 people who come down with myasthenia gravis, however, there can be regurgitation of recently swallowed food and liquids through the nose. Then there can be difficulty with swallowing, difficulties with speech, problems with the arms and legs, and difficulty breathing. Progression from facial symptoms to systematic symptoms usually takes about a year, and maximum disability usually occurs within three years.
A muscular disorder caused by an immune system gone amuck
The fundamental cause of myasthenia gravis is a misdirected attack by the immune system at the neuromuscular junction of the skeletal muscles. Nerve cells are not like electrical cables. They do not touch. Instead, they send neurotransmitters across tiny gaps to stimulate each other to send the signals that control muscle movement.
In myasthenia gravis, the immune system sends out B cells to attack the acetylcholine that nerve cells use to communicate with each other across these tiny gaps. Then the thymus may send out T-cells that attack the nerves themselves.
Why does the immune system attack the nerves that control the skeletal muscles? Scientists still don't know all the reasons why myasthenia gravis develops, but it often occurs with other conditions in which the immune system is overactive, such as hyperthyroidism, rheumatoid arthritis, and lupus. The same kinds of treatments offered for these autoimmune conditions are also offered in myasthenia gravis.
Myasthenia gravis treatments of the twentieth century
For most of the twentieth century, the main treatment for myasthenia gravis was steroid injections. Steroids such as Prednisone were given to stop the action of the immune system on the nerves.
Steroids were of some benefit in slowing down symptoms, but they also cause considerable side effects. Weight gain was universal. Skin became thinner. And since the objective of the treatment was to stop the immune system, infections became more frequent and harder to treat. Despite aggressive treatment, many people succumbed to the disease.
Myasthenia gravis treatments in the twenty-first century
Nowadays, most people who have myasthenia gravis are still treated with steroids, but there are options that allow treatment with a smaller dose. The immune modulating drug azathioprene (Imuran) takes six to twelve months to begin to work, but when it starts offering protection, it is then possible to use a smaller dosage of steroids.
Crisis situations can now be treated with plasmaphoresis, a process of clearing the B-cells and T-cells that are destroying nerve cells out of the bloodstream. This procedure can literally reverse the disease—but only for six to eight weeks, when the immune cells start to reappear. Still, this procedure can prevent the complications of the most severe manifestations of the disease requiring a feeding tube and catheter. If these kinds of treatments can be avoided, then the greatly increased risk of infections associated with these treatments can be avoided as well.
The downside of medications that control myasthenia gravis is that they remove the immune system as a line of defense against cancer. People who receive successful treatment for myasthenia gravis are at elevated risk for aggressive forms of cancer. Treatment with statin drugs for high cholesterol can aggravate symptoms, and the medications prescribe for this condition usually make oral contraceptives for birth control less effective.
Surgical care for myasthenia gravis
This neuromuscular condition is also sometimes treated with surgery. The B cells that destroy acetylcholine at the junctions between nerves to the muscles are made in the thymus, an immune gland in the middle of the chest. Surgically removing the thymus stops the production of the B cells.
Thymus removal is usually reserved for people who have generalized symptoms. It is not a treatment for people with the disease who just have drooping eyelids, for instance. (Sometimes the "droop" is corrected with plastic surgery.) This operation, known as a thymectomy, sometimes causes complete reversal of the disease, especially in patients who have not yet reached the age of 40. After seven to ten years, however, symptoms usually gradually return, since other kinds of immune cells also damage the nerves.
Home care for myasthenia gravis
People who have myasthenia gravis often can eat solid food but have trouble swallowing liquids. The fluid tends to come up through their noses. Liquids need to be thickened to avoid this kind of regurgitation. Hot liquids and highly spiced or acidic liquids have to be avoided. People who have myasthenia and their families and caretakers should also receive professional instruction on how to avoid aspiration, regurgitation of food or fluid into the lungs.
Is myasthenia gravis treatable?
Once fatal in 30 to 40 per cent of cases, myasthenia gravis is now considered a treatable neuromuscular condition. Over 95 per cent of people who have myasthenia gravis are stable with good medical and personal care. Because the symptoms of the disease sometimes get dramatically worse in just a few hours, however, a close relationship with the care provider and ready access to medical care are absolutely essential. It is especially important to be on the lookout for acute changes in symptoms during hot weather.
People who survive myasthenia gravis for three years usually do not get worse. With the best medical care, sometimes a completely normal life is possible. Usually a high quality of life is achieved.