Decompensating esophoria as the presenting feature of myasthenia gravis

Myasthenia gravis is a disease in which antibodies directed at nicotinic acetylcholine receptors are produced, leading to a deficiency of acetylcholine receptors at the neuromuscular junction. This results in impairment of muscular excitation, which appears clinically as fatigable muscle weakness. Weakness of the extraocular muscles occurs in nearly 90% of all myasthenics at disease onset, with ptosis being the most common presenting feature. Myasthenia gravis affecting one or a combination of the extraocular muscles without ptosis is less common; however, cases such as bilateral internuclear ophthalmoplegia without ptosis have been described in the literature. The authors present a case in which decompensating esophoria was the presenting feature of myasthenia gravis.