Shop the MDA store for your limited edition 75th anniversary merchandise

Myasthenia Gravis (MG)

Signs and Symptoms

Myasthenia gravis (MG) causes fatigable muscle weakness of the body’s voluntary muscles (those that people can move at will). It does not damage the musculature of the heart or the gastrointestinal tract.

MG can affect any of the body’s voluntary muscles, but it has a predilection for the muscles that control movement of the eyes and eyelids, causing ocular weakness. Consequently, a partial paralysis of eye movements (ophthalmoparesis), double vision (diplopia), and droopy eyelids (ptosis) are usually among the first symptoms of MG. More than 50% of patients present with ocular symptoms of ptosis and/or diplopia. Of those who present with ocular manifestations, about half will develop generalized disease within two years.

In generalized MG, weakness can also be seen in the muscles of the face, neck, arms and legs of varying severity and involvement. It may become difficult to lift the arms over the head, rise from a sitting position, walk long distances, climb stairs, or grip heavy objects.

Weakness and fatigue in the neck and jaw can be seen in MG. This bulbar weakness — named for the nerves that originate from the bulblike part of the brainstem — can cause difficulty with talking (dysarthria), chewing, swallowing (dysphagia), and holding up the head. About 15% of patients present with bulbar symptoms. Bulbar weakness tends to give speech a slurred, nasal quality. It also can lead to frequent choking spells and make eating unpleasant and tiresome.

Limb weakness alone is highly uncommon and can be seen in only 5% of MG patients. In some rare cases, weakness may spread to muscles in the chest that control breathing.

Disease course

Weakness and fatigue in MG tend to fluctuate from day to day, and even during a single day. People with the disease are often strongest in the morning after a full night’s sleep and weakest in the evening. Exercise may also affect the weakness and fatigue experienced by those living with MG.

Over a longer term, the symptoms of MG usually progress, reaching maximum or near-maximum severity within one to three years of onset in most people. In about 15% of people, the disease remains ocular, but in most it becomes oculobulbar or generalized.

Remission, a resolution of most or all symptoms, occurs in about 80-85% of people with MG on medical therapy. 10-15% are felt to be refractory and do not respond to the traditional medications. The new targeted therapies and many drugs in the pipeline will play a role in the treatment of refractory and newly diagnosed MG patients. Compared to adult-onset MG, juvenile MG tends to progress more slowly and has a higher incidence of remission. Historically, many children given diagnoses of juvenile MG turned out to have a congenital myasthenic syndrome.

Additional reading

Last reviewed June 2025 by Neelam Goyal, MD.

Looking for more information, support or ways to get involved?

Find MDA
in your Community