Myasthenia gravis

Diagnosis usually starts with a neurological exam. The doctor checks muscle strength and tone, coordination, sense of touch and eye movements. A blood test looks for antibodies against the acetylcholine receptor (AChR) or a protein called MuSK. For a drooping eyelid, a quick ice pack test may be added. The edrophonium test uses a medicine that briefly relieves weakness in people with MG.

Nerve and muscle tests help too. In repetitive nerve stimulation, small electrical pulses are sent through a nerve again and again to see how the muscle responds. Single-fiber electromyography (EMG) is considered the most sensitive test for MG. It can help find mild MG when other tests are normal. A CT or MRI scan of the chest looks for a large thymus or a thymus tumor (thymoma). Breathing tests (lung function tests) measure how well a person is breathing.

Diagnosis can take time. Weakness is common in many conditions, so MG can be hard to spot when it is mild or limited to a few muscles. When MG starts in the eye muscles only, doctors keep watching for spread. Some people later develop wider weakness, most often within the first two years.

There is no known cure, but most people with MG live to an average life expectancy. Pyridostigmine helps signals pass from nerve to muscle. Steroids and other medicines that calm the immune system can lower harmful antibodies, but they can cause serious side effects and need careful monitoring.

Newer targeted medicines act on one part of the immune attack. Generalized MG means weakness beyond the eye muscles. In the United States, three medicines that block part of the immune system called complement are approved for generalized MG in people with AChR antibodies: ravulizumab and zilucoplan for adults, and eculizumab for adults and children aged 6 and older. Medicines that block a receptor called FcRn lower antibody levels. One of them, nipocalimab, was approved in 2025 for generalized MG in people aged 12 and older with AChR or MuSK antibodies.

Surgery to remove the thymus, called thymectomy, can reduce weakness and the need for immune medicines in some people. When weakness is severe, plasma exchange or intravenous immunoglobulin (IVIG) can help remove or lower harmful antibodies, but the effect usually lasts only weeks or months.

An autologous stem cell transplant uses strong chemotherapy to clear out much of the immune system, then gives back the person’s own stored blood-forming cells. For MG, it has been used only in a small number of people whose severe disease did not respond to many treatments, and doctors do not widely consider it. In a Canadian study of 21 such people treated from 2001 to 2022, 16 of the 18 who could be assessed became free of MG symptoms, or nearly so, without MG treatment and stayed that way through follow-up. But two people died from transplant complications within 100 days, and two more died years later from causes that may or may not have been linked to the transplant. The researchers wrote that this risk may be high in medically complex patients and that new studies, planned in advance, are needed.

Most people with MG live to an average life expectancy, according to the U.S. National Institute of Neurological Disorders and Stroke (NINDS). Some go into remission for a while or for good. People whose weakness starts only in the eye muscles may later develop weakness in other muscles, so they are watched over time.

The biggest danger is a myasthenic crisis, the breathing emergency described above. NINDS estimates that 15 to 20% of people with MG have at least one crisis. Up to half of them cannot point to a trigger. A crisis is an emergency, and it is treated in the hospital. In a large study of U.S. hospital stays from 2000 to 2005, about 96 in 100 people admitted in crisis survived their stay. Among people with MG in the hospital, older age and breathing failure raised the risk of death.

In older adults, other illnesses often matter more than MG itself. A study followed more than 6,000 U.S. Medicare patients aged 65 and older who were newly diagnosed with MG. They died at higher rates than similar people without MG. Once the researchers took other health problems into account, survival was about the same.