Very Late-Onset Myasthenia Gravis in a Very Elderly Patient: Diagnostic Challenges and Importance of Early Recognition

Background: Myasthenia gravis is an autoimmune disorder of the neuromuscular junction characterized by fluctuating skeletal muscle weakness. Late-onset MG (onset ≥ 50 and <65 years) and very late-onset MG (VLOMG; onset ≥ 65 years) are increasingly recognized subgroups, and diagnosis in very elderly patients remains challenging because symptoms frequently overlap with age-related conditions and comorbidities. Case Presentation: An 88-year-old man with very late-onset myasthenia gravis (symptom onset at approximately age 85) was urgently referred because of a several-day history of rapidly worsening dysphagia and dysarthria, superimposed on fluctuating diplopia, dysphagia, dysarthria, and fatigable bulbar symptoms that had progressively worsened over the preceding three years. Initial diagnostic evaluation was challenging because of advanced age, previous lacunar infarctions, and multiple comorbidities, including pulmonary thromboembolism, chronic kidney disease, and permanent pacemaker implantation (which precluded brain MRI). Neurological examination and the characteristic fluctuation of symptoms raised suspicion of myasthenia gravis. Serological testing confirmed markedly elevated acetylcholine receptor antibodies, whereas MuSK antibodies were negative. Repetitive nerve stimulation was not performed given the high antibody titer and unambiguous clinical presentation. Thoracic computed tomography excluded thymoma. Treatment with pyridostigmine, azathioprine (maintenance dose kept lower than standard due to chronic kidney disease stage IIIB), and low-dose prednisone (selected due to age and comorbidity profile) resulted in early, patient-reported clinical improvement (approximately 60% in speech and swallowing) over eight weeks of follow-up; a validated severity scale (MG-ADL) showed a score of six (scoring range 0–24). Conclusions: Myasthenia gravis should remain an important differential diagnosis in very elderly patients presenting with fluctuating ocular and bulbar symptoms, even in the presence of multiple comorbidities that may obscure the diagnosis. In this patient, early recognition, antibody testing, and individualised initiation of therapy were followed by meaningful short-term improvement; a single case with eight weeks of follow-up cannot establish that such therapy prevents disease progression or myasthenic crisis, and longer follow-up and additional cases are needed.