Misdiagnosis of myasthenia gravis.

Patients with myasthenia gravis (MG) are too often misdiagnosed as having another disorder. Three patients are presented who were thought to have amyotrophic lateral sclerosis, velopharyngeal incompetence, and no diagnosis of MG, but actually each had myasthenia gravis. Their histories illustrate how the diagnosis of myasthenia gravis can be easily missed.There is no typical case of myasthenia gravis but, rather, this entity remains a clinical diagnosis that relies on a well-taken history, adequate examination, and appropriate interpretation of laboratory tests. To miss the diagnosis of myasthenia gravis is to cause the patient social, psychological, medical, and economic suffering.