Myasthenia Gravis Presenting as Persistent Unilateral Ptosis with Facial Droop

Abstract

Background: Myasthenia gravis (MG) is an autoimmune neuromuscular disorder that is classically characterized by fluctuating weakness and fatigability of the ocular, bulbar, limb, or respiratory muscles. Over half of patients with MG will initially experience isolated ocular symptoms in one or both eyes. Most patients report that ocular symptoms are mild or undetectable upon awakening, and worsen throughout the day or with tasks such as driving. We describe an unusual case of MG presenting with an acute onset of persistent unilateral ptosis and ipsilateral facial droop without diurnal variation or other fluctuation in severity.

Case report: A 58-year-old man presented to the Emergency Department with a 3-day history of persistent, unilateral ptosis with facial droop, concerning for stroke. However, magnetic resonance imaging of the head found no evidence of stroke or any other central etiology. Routine laboratory testing was unremarkable. Neurology was consulted and they recommended sending acetylcholine receptor antibody tests. At the patient's subsequent neurology clinic visit, these tests were found to be abnormal. Electromyography was also done at this visit, confirming the diagnosis of MG. The patient subsequently underwent thymectomy and immunosuppressive therapy, with great improvement in his symptoms. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: MG may present as unilateral ptosis or facial drooping without the hallmark characteristic of fluctuating muscle weakness. Early diagnosis and subsequent treatment of MG improves long-term prognosis and remission rates. Emergency physicians should consider myasthenia gravis in cases of unilateral ocular symptoms after ruling out emergent central etiologies.

Keywords: facial weakness; myasthenia gravis; ptosis; stroke.