The usual medical text infers that the diagnosis of myasthenia gravis is, as a rule, not difficult. In suspected cases the use of the therapeutic test as devised by Viets and Schwab1 will usually leave no doubt as to the diagnosis. Similarly, the aggravation of the myasthenia by the administration of quinine or its derivatives is reported to make certain the diagnosis.2
The present case is reported because the diagnosis was unsuspected for a period of seven years, the main complaint being one not usually found in myasthenia gravis.
REPORT OF CASE
A white woman aged 58 was first seen June 20, 1949. The presenting complaint was "palpitation" of seven years' duration; secondarily the patient complained of weakness and fatigue.The family history was noncontributory; both parents had died of "heart disease," the father at 87 years of age and the mother at 79. Two siblings were