Very Late-Onset Generalized Myasthenia Gravis Presenting With Worsening Frailty

Very late-onset myasthenia gravis, defined as disease onset after 75 years of age, is a rare but increasingly recognized clinical entity due to population aging and improved access to diagnostics. We report the case of a woman who was in her 80s and presented with progressive fatigability, bulbar symptoms, and functional decline, initially misattributed to normal aging and degenerative conditions. Clinical examination revealed fluctuating ptosis and proximal muscle weakness, and bedside ice pack testing supported a diagnosis of myasthenia gravis (MG). Serological testing confirmed elevated acetylcholine receptor antibodies. She responded well to a combination of pyridostigmine, low-dose corticosteroids, and mycophenolate mofetil, with improvement tracked via the Quantitative Myasthenia Gravis (QMG) score. This case illustrates the diagnostic challenges of MG in older adults and emphasizes the importance of recognizing reversible causes of frailty. It also highlights the geriatric principle of aligning care with what matters most to the individual, preserving function, independence, and identity.