Myasthenia gravis is typically an acquired autoimmune disorder in which
antibodies are directed at structural components of the neuromuscular junction, most commonly the
nicotinic acetylcholine receptor. The clinical manifestations of skeletal muscle weakness are broad. Patients most often report fatigable
muscle weakness. The eyelid levators and extraocular muscles are most commonly affected, resulting in symptoms of ptosis and
diplopia. Symptoms may be confined to the eyes (ocular myasthenia) or reflect bulbar, limb, or respiratory muscle weakness (generalized myasthenia). The diagnosis is based on a characteristic history and the finding of fatigable
muscle weakness on examination, and may be supported by diagnostic tests such as finding elevated titers of
acetylcholine receptor or muscle-specific
receptor tyrosine kinase (
MuSK)
antibodies, a positive
Tensilon test, a decremental response on slow repetitive nerve stimulation, and abnormal jitter on single fiber electromyography. This article presents a series of pearls to aid in the clinical and laboratory diagnosis of
myasthenia gravis, emphasizing key historical features, common and characteristic findings on examination, and potential pitfalls in the use of ancillary diagnostic studies.