Ventilator Dependence in an Octogenarian: A Diagnostic Challenge Unveiling Myasthenia Gravis

Introduction: Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterized by fluctuating skeletal muscle weakness. Elderly-onset MG often presents with subtle, atypical symptoms and typically lacks thymic involvement. The overlap of late-onset MG with age-related frailty and comorbidities delays diagnosis and increases the risk of myasthenic crisis, with recent studies identifying advanced age, comorbidities, and late-onset MG as key predictors of extubation and weaning failure.


Description: An 88-year-old woman with a history of cervical spondylosis, post recent C5–C7 discectomy, was initially admitted following cardiac arrest secondary to respiratory failure from suspected aspiration pneumonia. After 14 days of failed extubation trials, she underwent tracheostomy and was discharged to a long-term acute facility for persistent ventilator dependency. She returned one month later with fluctuating mental status, and progressive bulbar and proximal muscle weakness. Serologic testing revealed markedly elevated acetylcholine receptor antibodies: modulating at 97% inhibition (normal < 32%), blocking at 87% inhibition (normal < 15%), and binding at 147.96 nmol/L (normal < 0.30 nmol/L). Imaging ruled out thymoma, and paraneoplastic workup was deferred due to advanced age and family wishes. She was initially treated with IVIG and pyridostigmine without improvement but responded dramatically to plasmapheresis with successful ventilator weaning. A subsequent relapse required a second IVIG course, but given her advanced age and multiple comorbidities, hospice care was considered.


Discussion: Myasthenia gravis (MG) is rare in octogenarians and often misattributed to ICU-related conditions like critical illness neuropathy, postoperative weakness, neurovascular events, or frailty. In this case, persistent ventilator dependence and bulbar symptoms prompted further evaluation, with serologies and a strong response to IVIG and plasmapheresis confirming the diagnosis. Given thymic involution and surgical risk with age, thymectomy is generally not recommended in elderly patients without thymoma. This case highlights the importance of maintaining a broad differential, as early recognition and timely treatment of MG in elderly patients are essential for reversing respiratory failure and improving outcomes