Your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor might use several tests, including:
Your doctor may check your neurological health by testing:
- Muscle strength
- Muscle tone
- Senses of touch and sight
Tests to help confirm a diagnosis of myasthenia gravis might include:
Injection of the chemical edrophonium chloride that results in a sudden, temporary improvement in muscle strength might indicate that you have myasthenia gravis.
Edrophonium chloride blocks an enzyme that breaks down acetylcholine, the chemical that transmits signals from your nerve endings to your muscle receptor sites.
Ice pack test
If you have a droopy eyelid, your doctor might place a bag filled with ice on your eyelid. After two minutes, your doctor removes the bag and analyzes your droopy eyelid for signs of improvement.
A blood test might reveal the presence of abnormal antibodies that disrupt the receptor sites where nerve impulses signal your muscles to move.
Repetitive nerve stimulation
In this nerve conduction study, doctors attach electrodes to your skin over the muscles to be tested. Doctors send small pulses of electricity through the electrodes to measure the nerve's ability to send a signal to your muscle.
To diagnose myasthenia gravis, doctors will test the nerve repeatedly to see if its ability to send signals worsens with fatigue.
Single-fiber electromyography (EMG)
This test measures the electrical activity traveling between your brain and your muscle. It involves inserting a fine wire electrode through your skin and into a muscle to test a single muscle fiber.
Your doctor might order a CT scan or an MRI to check if there's a tumor or other abnormality in your thymus.
Pulmonary function tests
These tests evaluate whether your condition is affecting your breathing.
Various treatments, alone or in combination, can relieve symptoms of myasthenia gravis. Your treatment will depend on your age, how severe your disease is and how fast it's progressing.
Cholinesterase inhibitors. Medications such as pyridostigmine (Mestinon, Regonal) and neostigmine (Bloxiverz) enhance communication between nerves and muscles. These medications aren't a cure, but they can improve muscle contraction and muscle strength in some people.
Possible side effects include gastrointestinal upset, diarrhea, nausea, and excessive salivation and sweating.
- Corticosteroids. Corticosteroids such as prednisone inhibit the immune system, limiting antibody production. Prolonged use of corticosteroids, however, can lead to serious side effects, such as bone thinning, weight gain, diabetes and increased risk of some infections.
Immunosuppressants. Your doctor might also prescribe other medications that alter your immune system, such as azathioprine (Azasan,, Imuran) mycophenolate mofetil (Cellcept), cyclosporine (Sandimmune) methotrexate (Trexall) or tacrolimus (Astrograf XL, Prograf). These drugs, which can take months to work, might be used with corticosteroids.
Side effects of immunosuppressants, such as increased risk of infection and liver or kidney damage, can be serious.
The following therapies are usually used in the short term to treat a sudden worsening of symptoms or before surgery or other therapies.
Plasmapheresis (plaz-muh-fuh-REE-sis). This procedure uses a filtering process similar to dialysis. Your blood is routed through a machine that removes the antibodies that block transmission of signals from your nerve endings to your muscles' receptor sites. However, the good effects usually last only a few weeks, and repeated procedures can lead to difficulty accessing veins for the treatment.
Risks associated with plasmapheresis include a drop in blood pressure, bleeding, heart rhythm problems or muscle cramps. Some people develop an allergic reaction to the solutions used to replace the plasma.
Intravenous immunoglobulin (IVIg). This therapy provides your body with normal antibodies, which alters your immune system response. Benefits are usually seen in less than a week and can last three to six weeks.
Side effects, which usually are mild, can include chills, dizziness, headaches and fluid retention.
- Monoclonal antibody. Rituximab (Rituxan) and the more recently approved eculizumab (Soliris) are intravenous medications used in some cases of myasthenia gravis. These drugs are usually used for people who don't respond to other treatments. They can have serious side effects.
Some people with myasthenia gravis have a tumor in their thymus gland. If you have a tumor, called a thymoma, doctors will surgically remove your thymus gland (thymectomy).
Even if you don't have a tumor in the thymus gland, removing the gland might improve your myasthenia gravis symptoms. However, the benefits of thymectomy can take years to develop.
A thymectomy can be performed as an open surgery or as a minimally invasive surgery. In open surgery, your surgeon splits the central breastbone (sternum) to open your chest and remove your thymus gland.
Minimally invasive surgery to remove the thymus gland uses smaller incisions. It might also involve:
- Video-assisted thymectomy. In one form of this surgery, surgeons make a small incision in your neck or a few small incisions in the side of your chest. They then use a long, thin camera (video endoscope) and small instruments to see and remove the thymus gland.
- Robot-assisted thymectomy. In this form of thymectomy, surgeons make several small incisions in the side of your chest and remove the thymus gland using a robotic system, which includes a camera arm and mechanical arms.
These procedures might cause less blood loss, less pain, lower mortality rates and shorter hospital stays compared with open surgery.
Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.
Lifestyle and home remedies
To help you make the most of your energy and cope with the symptoms of myasthenia gravis:
- Adjust your eating routine. Try to eat when you have good muscle strength. Take your time chewing your food, and take a break between bites of food. You might find it easier to eat small meals several times a day. Also, try eating mainly soft foods and avoid foods that require more chewing, such as raw fruits or vegetables.
- Use safety precautions at home. Install grab bars or railings in places where you need support, such as next to the bathtub or next to steps. Keep your floors clean, and move area rugs. Outside your home, keep paths, sidewalks and driveways cleared of leaves, snow and other debris that could cause you to stumble.
- Use electric appliances and power tools. To help you maintain your energy, try using an electric toothbrush, electric can openers and other electrical tools to perform tasks.
- Wear an eye patch. If you have double vision, an eye patch can help relieve the problem. Try wearing one to write, read or watch television. Periodically switch the eye patch to the other eye to help reduce eyestrain.
- Plan. If you have chores, shopping or errands to do, plan the activity for when you have the most energy.
Coping and support
Coping with myasthenia gravis can be difficult for you and your loved ones. Stress can worsen your condition, so find ways to relax. Ask for help when you need it.
Learn all you can about your condition, and have your loved ones learn about it, as well. You all might benefit from a support group, where you can meet people who understand what you and your family members are going through.
Preparing for your appointment
You're likely to first see your family doctor or a general practitioner, who will then refer you to a doctor trained in nervous system conditions (neurologist) for further evaluation.
Here's information to help you get ready for your appointment.
What you can do
Take a friend or family member along to help you absorb the information you're given. Make a list of:
- Your symptoms and when they began
- All medications, vitamins or supplements you take, including doses
- Questions to ask your doctor
For myasthenia gravis, questions to ask your doctor include:
- What is likely causing my symptoms?
- What tests do I need?
- What course of action do you recommend?
- What are the alternatives to the approach you're suggesting?
- I have these other health conditions. How can I best manage them together?
- Are there restrictions I need to follow?
- Are there brochures or other printed materials I can have? What websites do you recommend?
Don't hesitate to ask other questions.
What to expect from your doctor
Be prepared to answer questions your doctor is likely to ask, such as:
- Have your symptoms been continuous or occasional?
- How severe are your symptoms?
- What, if anything, seems to improve your symptoms?
- What, if anything, appears to worsen your symptoms?