myasthenia

/ˌmaɪəsˈθiːniə/
noun
  1. A medical condition characterized by muscle weakness and fatigue, often due to a problem with nerve signals to the muscles.
    • The patient's myasthenia made it difficult for her to lift her arms above her head.
    • Treatment for myasthenia often includes medications that improve nerve-muscle communication.
    • Doctors diagnosed myasthenia after noticing the man's eyelids drooping by the end of the day.