Diagnosis

To diagnose your condition, your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor may conduct several tests, including:

Neurological examination

Your doctor may check your neurological health by testing your:

  • Reflexes
  • Muscle strength
  • Muscle tone
  • Senses of touch and sight
  • Coordination
  • Balance

The key sign that points to the possibility of myasthenia gravis is muscle weakness that improves with rest. Tests to help confirm the diagnosis may include:

Edrophonium test

Injection of the chemical edrophonium chloride (Tensilon) may result in a sudden, although temporary, improvement in your muscle strength. This is an indication that you may 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 may conduct an ice pack test. In this test, a doctor places 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. Doctors may conduct this test instead of the edrophonium test.

Blood analysis

A blood test may 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 many times to see if its ability to send signals worsens with fatigue.

Single-fiber electromyography (EMG)

Electromyography (EMG) 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.

Imaging scans

Your doctor may order a CT scan or an MRI to check if there's a tumor or other abnormality in your thymus.

Pulmonary function tests

Your doctor may perform pulmonary function tests to evaluate whether your condition is affecting your breathing.

Treatment

Doctors use a variety of treatments, alone or in combination, to relieve symptoms of myasthenia gravis.

Medications

  • Cholinesterase inhibitors. Medications such as pyridostigmine (Mestinon) enhance communication between nerves and muscles. These medications don't cure the underlying condition, but they may improve muscle contraction and muscle strength.

    Possible side effects may include gastrointestinal upset, 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 may also prescribe other medications that alter your immune system, such as azathioprine (Imuran), mycophenolate mofetil (CellCept), cyclosporine (Sandimmune, Neoral), methotrexate (Trexall) or tacrolimus (Prograf).

    Side effects of immunosuppressants can be serious and may include nausea, vomiting, gastrointestinal upset, increased risk of infection, liver damage and kidney damage.

Intravenous therapy

  • 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 beneficial effects usually last only a few weeks.

    After repeated treatments, it may be difficult for doctors to gain access to your vein. They may need to implant a long, flexible tube (catheter) into your chest to conduct the procedure.

    Other risks associated with plasmapheresis include a drop in blood pressure, bleeding, heart rhythm problems or muscle cramps. Some people may also 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.

    IVIg has a lower risk of side effects than do plasmapheresis and immune-suppressing therapy. However, it may take about a week to start working, and the benefits usually last no more than three to six weeks.

    Side effects, which usually are mild, may include chills, dizziness, headaches and fluid retention.

  • Monoclonal antibody. Rituximab (Rituxan) is an intravenous medication that is used in some cases of myasthenia gravis. This drug depletes certain white blood cells, altering the immune system and improving myasthenia gravis.

    Rituximab is usually given in infusions at an infusion center or done in a hospital on an outpatient basis. Repeat infusions are often done over a few weeks. Occasionally the infusions are repeated months later.

Surgery

About 15 percent of the people with myasthenia gravis have a tumor in their thymus gland, a gland under the breastbone that is involved with the immune system. If you have a tumor, called a thymoma, doctors will conduct surgery to remove your thymus gland (thymectomy).

If you don't have a tumor in the thymus gland, surgery to remove the thymus gland may improve your myasthenia gravis symptoms. It may eliminate your symptoms, and you may be able to stop taking medications for your condition. However, you may not notice the benefits of a thymectomy for several years, if at all.

A thymectomy may be performed as an open surgery or as a minimally invasive surgery.

In an open surgery, your surgeon splits the central breast bone (sternum) to open your chest and remove your thymus gland.

Surgeons may perform minimally invasive surgery to remove the thymus gland, which uses smaller incisions. Minimally invasive thymectomy may include:

  • Video-assisted thymectomy. In one form of this surgery, surgeons make a small incision in your neck and use a long thin camera (video endoscope) and small instruments to visualize and remove the thymus gland through your neck.

    Alternatively, surgeons may make a few small incisions in the side of your chest. Doctors use a video scope and small instruments to conduct the procedure and remove the thymus gland through these incisions.

  • Robot-assisted thymectomy. In a robot-assisted thymectomy, surgeons make several small incisions in the side of your chest. Surgeons conduct the procedure to remove the thymus gland using a robotic system, which includes a camera arm and mechanical arms.

Benefits of these procedures may include less blood loss, less pain, lower mortality rates and shorter hospital stays compared with open surgery.

Your doctor will determine which treatment may be most appropriate for you based on several factors, including:

  • Your age
  • Severity of your condition
  • Location of muscles affected
  • Other existing medical conditions

Lifestyle and home remedies

Supplementing your medical care with these approaches may 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. Small meals eaten several times a day may be easier to handle. 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 may need support, such as next to the bathtub or next to steps. Keep your floors clean, and move any loose rugs out of areas where you may walk. Outside your home, keep paths, sidewalks and driveways cleared of leaves, snow and other potential debris that could cause you to stumble.
  • Use electric appliances and power tools. You may lose energy quickly when conducting tasks. Try using an electric toothbrush, electric can openers and other electrical tools to perform tasks when possible.
  • Wear an eye patch. Consider wearing an eye patch if you have double vision, as this can help relieve the problem. Try wearing the eye patch while you 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 to coincide with the time at which you have the most energy. Also, try to reduce extra walking in your house when working on projects, as it may reduce your energy.

Coping and support

For people with myasthenia gravis and their family members, coping with the disease may be difficult.

If you have myasthenia gravis, find ways to relax. Stress may worsen your condition.

Also, ask for help with tasks if you need it. Your family and friends may be able to assist you with tasks that are difficult.

If you're a family member of someone with myasthenia gravis, try to be understanding of your loved one's emotions as he or she adjusts to the condition. Read about myasthenia gravis and learn about what your family member is experiencing.

You and your family members may benefit from participating in a support group. A support group may offer a place for you to meet people who understand what you and your family members are going through.

Preparing for your appointment

You're likely to start by first seeing your family doctor or a general practitioner. You'll likely be referred to a doctor trained in nervous system conditions (neurologist) for further evaluation.

Because there's often a lot to talk about at your appointment, it's a good idea to be well-prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

To make the most of your appointment, take steps to prepare yourself, including:

  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Bring a list of all medications, vitamins or supplements that you're taking.
  • Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions ahead of time will help you make the most of your time together. List your questions from most important to least important in case time runs out. For myasthenia gravis, some basic questions to ask your doctor include:

  • What is likely causing my symptoms?
  • Other than the most likely cause, what are other possible causes for my symptoms?
  • What kinds of tests do I need?
  • What is the most appropriate course of action?
  • What are the alternatives to the primary approach that you're suggesting?
  • I have these other health conditions. How can I best manage them together?
  • Are there any restrictions that I need to follow?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

  • When did you first begin experiencing symptoms?
  • 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?

Myasthenia gravis care at Mayo Clinic

Aug. 02, 2017
References
  1. Kliegman RM, et al. Disorders of neuromuscular transmission and of motor neurons. In: Nelson Textbook of Pediatrics. 20th ed. Philadelphia, Pa.: Elsevier; 2016. http://www.clinicalkey.com. Accessed Jan. 15, 2016.
  2. Myasthenia gravis fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm. Accessed Jan. 15, 2016.
  3. Ferri FF. Myasthenia gravis. In: Ferri's Clinical Advisor 2016. Philadelphia, Pa.: Mosby Elsevier; 2016. https://www.clinicalkey.com. Accessed Jan. 15, 2016.
  4. Myasthenia gravis. Office of Women's Health. U.S. Department of Health and Human Services. http://www.womenshealth.gov/publications/our-publications/fact-sheet/myasthenia-gravis.html. Accessed Jan. 15, 2016.
  5. Bird SJ. Clinical manifestations of myasthenia gravis. http://www.uptodate.com/home. Accessed Jan. 18, 2016.
  6. Myasthenia gravis. Merck Manual Professional Version. http://www.merckmanuals.com/professional/neurologic-disorders/peripheral-nervous-system-and-motor-unit-disorders/myasthenia-gravis. Accessed Jan. 15, 2016.
  7. Allan WC. Pathogenesis of myasthenia gravis. http://www.uptodate.com/home. Accessed Jan. 18, 2016.
  8. Gilhus NE, et al. Myasthenia gravis: Subgroup classification and therapeutic strategies. The Lancet Neurology. 2015;14:1023.
  9. Avidan N, et al. Genetic basis of myasthenia gravis: A comprehensive review. Journal of Autoimmunity. 2014;52:145.
  10. Bird SJ. Treatment of myasthenia gravis. http://www.uptodate.com/home. Accessed Jan. 18, 2016.
  11. Bird SJ. Diagnosis of myasthenia gravis. http://www.uptodate.com/home. Accessed Jan. 18, 2016.
  12. Neurological diagnostic tests and procedures. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/misc/diagnostic_tests.htm. Accessed Jan. 18, 2016.
  13. Rowse PG, et al. Minimally invasive thymectomy: The Mayo Clinic experience. Annals of Cardiothoracic Surgery. 2015;4:519.
  14. Ye B, et al. Surgical techniques for early stage thymoma: Video-assisted thoracoscopic thymectomy versus transsternal thymectomy. Journals of Thoracic and Cardiovascular Surgery. 2014;147:1599.
  15. Barbara Woodward Lips Patient Education Center. Myasthenia gravis: A guide for patients. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2003.
  16. Riggin ER. EPSi. Mayo Clinic, Rochester, Minn. Jan. 19, 2016.
  17. Crum BA (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 5, 2016.