Generalized Myasthenia Gravis Identified During Evaluation for Streptococcal Pharyngitis: A Case Report

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction characterized by fluctuating skeletal muscle weakness that worsens with exertion and improves with rest.Ocular manifestations, including ptosis and diplopia, are common early features, but generalized disease may also involve bulbar, limb, axial, or respiratory muscles.Because symptoms may be intermittent or occur alongside common acute illnesses, first-contact clinicians must avoid prematurely attributing fatigue or malaise to a concurrent infection when focal fatigable weakness is present.We present a case of a 50-year-old woman with hypertension, obesity, postmenopausal bleeding, and 12 lb of unintentional weight loss over three months who presented to an outpatient clinic with upper respiratory symptoms and generalized fatigue.Rapid antigen testing was positive for group A Streptococcus, and antibiotic therapy with amoxicillin was initiated.During the same evaluation, she reported several weeks of progressive right eyelid drooping, intermittent diplopia, worsening fatigue later in the day, evening gait difficulty, and slurred speech that became more noticeable during prolonged conversations.Examination demonstrated right-sided ptosis, preserved pupillary responses, and ocular misalignment worsened by sustained upward gaze.The ice-pack test improved right margin reflex distance 1 from 1 mm to 4 mm after two minutes of cooling.Given the combination of ocular, bulbar, and limb fatigability, the presentation was classified as generalized myasthenia gravis, Myasthenia Gravis Foundation of America class IIb.Acetylcholine receptor binding antibody was elevated at 8.6 nmol/L, repetitive nerve stimulation demonstrated a 17% decrement in compound muscle action potential amplitude with 3-Hz stimulation of the right facial nerve recording from the nasalis, and chest computed tomography showed no thymoma.Pyridostigmine was initiated at 30 mg orally three times daily and later increased to 60 mg three times daily as tolerated, with improvement in ptosis and dysarthria at two-week follow-up.This case highlights the importance of recognizing generalized myasthenia gravis when fatigable ptosis, diplopia, dysarthria, and end-of-day weakness coexist with a common acute infection.Streptococcal pharyngitis explained the patient's upper respiratory symptoms but did not explain the pattern of fluctuating ocular and bulbar weakness.Bedside fatigability testing, careful differential diagnosis, medication review, and urgent neurology referral are essential because infection can precipitate clinical worsening and myasthenic crisis.