What does myasthenia mean?
Myasthenia is a chronic autoimmune disease in which the immune system interferes with communication between nerves and skeletal muscles. The resulting weakness commonly fluctuates during the day, worsens with repeated use, and improves after rest. Symptoms can include drooping eyelids, double vision, difficulty speaking or swallowing, and unusual fatigue. Because respiratory muscles may be affected, severe cases can develop into a myasthenia crisis requiring emergency treatment. Although often called myasthenia gravis, the condition has several clinical subtypes. In everyday speech, the word refers chiefly to the disorder involving antibodies against acetylcholine receptors or related proteins at the junction between nerves and muscles. Recognizing it matters because many symptoms can resemble those of other neurological or muscular conditions, making specialist diagnosis important.
nounA chronic autoimmune disorder in which antibodies disrupt the transmission of nerve impulses to muscles, causing fluctuating weakness that often worsens with activity and improves with rest.
- A chronic autoimmune disorder characterized by fluctuating muscle weakness caused by impaired transmission of signals from nerves to muscles.
"Fatigue and drooping eyelids are common early symptoms of myasthenia."
"Her vision doubled and her arms grew weak after a few minutes of use, symptoms that were eventually diagnosed as myasthenia."
"Rapid breathing and severe weakness can indicate a myasthenia crisis and require emergency medical treatment."
Rare; in clinical prose, the condition is normally discussed without a plural.
"The clinic specializes in difficult-to-diagnose myasthenias."
Myasthenia puts muscle power on an unpredictable schedule: it may fail briefly during conversation, then recover after a period of rest.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does myasthenia come from?
The word was formed in the 19th century from Greek roots meaning muscle and weakness. It combines mys, “muscle,” with astheneia, “weakness,” derived from a- and sthenos, “strength.” The same Greek elements appear in terms such as asthenia, myopathy, and myocyte, which respectively refer to general weakness, muscle disease, and muscle cells.
Related word forms
How myasthenia is actually used
The unqualified term is used medically for myasthenia gravis, although other recognized subtypes exist. The condition can affect skeletal muscles, including those controlling the eyes, face, swallowing, and breathing.
Easily confused with myasthenia
Myasthenia is specifically an autoimmune disorder of neuromuscular transmission, whereas myopathy is a broader term for diseases that damage or weaken muscle tissue.