Diagnosis of Myasthenia Gravis

Abstract

Myasthenia gravis (MG) diagnosis is primarily clinically based. By the end of the clinical evaluation, clinicians have a sense as to whether presenting symptoms and elicited signs are weakly or strongly supportive of MG. Diagnostic tests can reaffirm the clinicians' impression. Edrophonium testing is rarely used but helpful in cases of measurable ptosis. Decremental response on slow-frequency repetitive nerve stimulation has a modest diagnostic yield in ocular MG but is helpful in generalized MG cases. The most sensitive test is single-fiber electromyography. In this article, the authors review the diagnostic testing approach of practicing clinicians for suspected MG cases.

Keywords: Acetylcholine receptor–binding autoantibodies; Agrin; Edrophonium test; Low-density lipoprotein receptor–related protein 4 (LRP4); Muscle-specific tyrosine kinase (MuSK); Myasthenia gravis; Repetitive nerve stimulation; Single-fiber electromyography.