What Is Myasthenia Gravis?
Myasthenia gravis is a chronic condition that causes muscles to tire and weaken easily. For example, if you have myasthenia gravis, you may notice that during a meal, your jaw muscles become tired and weak, making you less able to chew food. After you have rested for a little while, the muscles may become strong again, allowing you to resume eating.
This waxing-and-waning weakness of muscles, worsening with use and improving with rest, is a hallmark of this disease. There typically are periods when you may notice more symptoms (called an exacerbation) and periods when symptoms decrease or disappear (remission).
Myasthenia gravis that affects multiple muscle groups throughout the body is called generalized myasthenia gravis. Commonly affected muscles can make it hard for you to chew, swallow, smile, shrug, lift your arms, grip objects, stand up, or climb stairs. Weakness in the muscles that control eye movement can cause double vision or drooping eyelids. When the muscles needed for breathing are affected, you may have a myasthenic crisis, which is a life-threatening situation.
Though anyone can get myasthenia gravis, those most likely to do so are women between ages 20 and 40 or men between ages 50 and 70. If a woman with myasthenia gravis gives birth, the baby may have some temporary, and potentially life-threatening, muscle weakness (neonatal myasthenia) because of antibodies that have transferred from the mother's bloodstream. Typically, during the baby's first weeks of life, the antibodies are cleared from the baby's circulation and the baby develops normal muscle tone and strength.
Myasthenia Gravis Symptoms
The disease most commonly affects muscles that control eye and eyelid movement, so the first symptoms you notice may be eyelid drooping or blurred or doubled vision. Most will go on to have weakness in other muscle groups in one or two years.
General symptoms of myasthenia gravis include:
- Weakness in your eye muscles
- Drooping eyelids
- Double vision
- Blurred vision
- Changes in your facial expressions
- Trouble swallowing
- Shortness of breath
- Problems speaking
- Problems walking and lifting things
- Trouble holding up your head
If the muscles you use to breathe get weak enough that you can’t control them, it’s called a myasthenic crisis. This is a medical emergency that may require a ventilator to help you breathe. Around 15% to 20% of people with myasthenia gravis have at least one myasthenic crisis. They can be caused by an infection, stress, surgery, or a reaction to medication.
Myasthenia Gravis Causes
Under normal conditions, nerves tell your muscles to move by sending a chemical message through a connection point called a receptor on the muscle. The chemical that carries this message is acetylcholine. When acetylcholine binds to the receptor, the muscle contracts. In myasthenia gravis, your immune system attacks these acetylcholine receptors on the muscle, which disrupts communication between the nerves and muscles.
Myasthenia gravis is considered to be an autoimmune disorder. In an autoimmune disease, some of the body's antibodies (special proteins in your body that are programmed to fight foreign invaders such as bacteria, viruses, or fungi) mistake a part of your own body as foreign, resulting in its destruction. In the case of myasthenia gravis, antibodies block, attack, or destroy the acetylcholine receptors needed for muscle contraction.
No one knows exactly what causes the body to begin producing the antibodies that destroy acetylcholine receptors. In some cases, the process seems to be related to the thymus gland, which helps produce antibodies.
About 15% of people with myasthenia gravis have a thymoma, or tumor of the thymus gland. Most thymomas are benign (not cancerous). Doctors often remove the thymus through a procedure called a thymectomy because this gland produces the antibodies that attack the communication between nerves and muscles. A thymectomy can also improve myasthenia gravis symptoms in some people even when no tumor is present.
Myasthenia Gravis Diagnosis
To see if you have myasthenia gravis, your doctor will start with a neurological exam. This includes a test of your:
- Reflexes
- Muscle strength
- Muscle tone
- Touch
- Sight
- Coordination
- Balance
- Fatigability (how soon your muscles weaken)
Then you’ll have tests to help look more closely at symptoms of myasthenia gravis. These include:
Medication test. Your doctor may give you a medication such as pyridostigmine (Mestinon) to see if it improves your muscle strength. If it does, that’s a sign you might have myasthenia gravis.
Ice pack test. If you have a drooping eyelid, your doctor may place an ice pack on it for a few minutes to see if the lower temperature helps lift it.
Blood test. Your doctor draws a small sample of blood and sends it to a lab to check for antibodies that affect how nerves and muscles communicate.
Repetitive nerve stimulation. Electrodes placed on your muscles send small electrical pulses to see how your nerves respond to repeated signals.
Single-fiber electromyography (EMG). A thin wire electrode goes into a muscle to measure how well signals travel between nerves and muscles at the neuromuscular junction.
Imaging. Your doctor may order a CT scan or MRI to look for an enlarged thymus or thymus tumor that may be adding to antibody production.
Pulmonary function tests. These tests measure how well your breathing muscles work to see if myasthenia gravis affects them.
Myasthenia Gravis Treatment and Home Remedies
Your treatment will depend on your age, how severe your symptoms are, and how fast the condition is getting worse. You might need one or several treatments together. Your doctor may recommend a medication such as:
- Cholinesterase inhibitors. These medications boost the communication between your nerves and your muscles. They can help strengthen muscles.
- Corticosteroids. Corticosteroids such as prednisone mute your immune system and slow the release of antibodies that could be helping block your nerve receptors.
- Immunosuppressants. Your doctor may add immunosuppressants to your corticosteroids to help reduce your immune system response.
- Neonatal Fc receptor blocker. It works by blocking the autoantibodies that cause myasthenia gravis and helps ease the symptoms.
- Complement inhibitors. These targeted therapies block part of your immune system called the complement pathway, which plays a key role in the autoimmune attack in myasthenia gravis.
If you’re dealing with a sudden worsening of symptoms or will soon have surgery or other therapies, your doctor may recommend intravenous (IV) therapy. Choices for this include:
- Plasmapheresis. This procedure filters your blood. It goes through a machine that removes certain antibodies. The effects are faster than other treatments, but they don't last long (about a month). This procedure is usually used in a crisis.
- Intravenous immunoglobulin (IVIg). This therapy injects new antibodies into your bloodstream. These antibodies alter your immune system response to help with symptoms. Results typically last about three to six weeks.
- Monoclonal antibodies. Your doctor will likely recommend this option only if other treatments haven’t worked. They can have serious side effects.
If your myasthenia gravis is due to a tumor on your thymus gland, you may need surgery to remove the whole gland (thymectomy). Even if you don’t have a tumor, taking your thymus out may help ease your symptoms. It may take years to see benefits from a thymectomy.
You may need open surgery to remove your thymus. A surgeon opens your breastbone to get to your thymus and take it out.
Another option that may work is minimally invasive surgery. There are two options:
- Video-assisted thymectomy. Surgeons make small cuts in your neck or chest and use a long, thin camera called an endoscope along with instruments to take out your thymus.
- Robot-assisted thymectomy. Surgeons make the same small cuts as video-assisted thymectomy and then use a robot with a camera and mechanical arms to remove your thymus.
Along with medical treatments, you can make lifestyle changes to help manage your myasthenia gravis symptoms, including:
- Save energy when you eat. If chewing is a struggle, eat at times when you have the most strength. You might find it easier to eat several small meals a day instead of longer, larger ones less often. Stick to soft foods, and take breaks between bites.
- Install safety aids. Put handrails anywhere you might need a helpful handle, like next to the toilet or near tables. Remove any tripping risks such as rugs or floor clutter.
- Let machines do the work. Switch to an electric toothbrush and can opener, or any other device that can save you strength.
- Wear an eye patch. It can help with double vision. Use one when you watch TV or read, and switch eyes from time to time.
- Plan ahead. Be smart with your strength. Do chores or errands when you feel best during the day.
