Late-Onset Autoimmune Myasthenia Gravis: A Diagnosis Not to Be Overlooked in the Elderly

Autoimmune myasthenia gravis is a rare neuromuscular disorder of autoimmune origin, characterized by fluctuating muscle weakness. Although it classically occurs in young adults, late onset in the elderly is possible, often with atypical presentations that may delay diagnosis. We report the case of an 81-year-old female patient who initially consulted us with fluctuating right ptosis, in the absence of other neurological signs. Biological workup revealed the presence of anti-acetylcholine receptor (anti-AChR) antibodies, confirming the diagnosis of autoimmune myasthenia gravis. Thoracic imaging revealed no thymoma. Anticholinesterase therapy was initiated with partial improvement, followed by clinical progression two years later to bulbar involvement (dysarthria, swallowing disorders). Management involved the administration of intravenous immunoglobulins, with a favorable clinical response. Corticosteroid therapy was then introduced, together with azathioprine immunosuppressive therapy, stabilizing the course. This case illustrates the importance of considering the diagnosis of myasthenia gravis, even at an advanced age, in the face of fluctuating or unusual signs. It also highlights the diagnostic and therapeutic challenges specific to the geriatric population, particularly in relation to comorbidities, adverse drug reactions, and the need for multidisciplinary follow-up. Early recognition and treatment of the disease can significantly improve prognosis and quality of life.