A54-34 From Misdiagnosis to Multisystem Crisis: IVIG-Associated Stroke Unmasking Myasthenia Gravis Initially Treated as Guillain-Barré Syndrome

Abstract Background Acute neuromuscular respiratory failure poses a diagnostic and therapeutic challenge, particularly when overlapping autoimmune features initially mask the underlying diagnosis. Myasthenia Gravis , an antibody-mediated disorder affecting the neuromuscular junction, and Guillain-Barré Syndrome , a demyelinating polyneuropathy, can share early bulbar and respiratory manifestations. Intravenous immunoglobulin is a mainstay therapy for both conditions but carries rare thromboembolic risks. Early recognition of such complications and reassessment of the underlying diagnosis are key to improving outcomes. Case Presentation A 56-year-old woman with diabetes, COPD, obstructive sleep apnea, and hypertension presented with progressive dysphagia, hoarseness, and dyspnea. Initial evaluation suggested a pharyngo-cervical-brachial variant of GBS, and IVIG was initiated. Soon after receiving IVIG, she developed acute right-sided weakness and aphasia. Brain MRI revealed a small acute infarct in the posterior left frontal lobe, and MRA showed no large-vessel occlusion. Tenecteplase was administered, but over the next 48 hours, she deteriorated with respiratory failure requiring intubation.Repeat imaging demonstrated a new large right middle cerebral artery infarct with mass effect and petechial hemorrhagic transformation, attributed to IVIG-associated hyperviscosity and thrombosis. Serologic testing later revealed markedly elevated acetylcholine receptor binding and blocking antibodies, confirming myasthenia gravis. High-dose methylprednisolone (1 g daily × 5 days) and pyridostigmine were initiated. Despite immunotherapy, she remained ventilator dependent, necessitating tracheostomy and PEG tube placement. After 29 days, she was discharged to inpatient rehabilitation on a prednisone taper, pyridostigmine, and prophylactic trimethoprim-sulfamethoxazole. Patient was breathing on room comfortably via capped tracheostomy Discussion This case highlights how therapeutic interventions can unmask underlying disease. What appeared to be GBS at first ultimately proved to be antibody-mediated myasthenia gravis, uncovered after an IVIG-associated stroke. IVIG-associated ischemic stroke, though uncommon, reflects hyperviscosity and prothrombotic effects that warrant vigilance in patients with vascular comorbidities.ConclusionManaging neuromuscular respiratory failure requires keeping an open diagnostic mind and close attention to complications of therapy. This case exemplifies the delicate balance between benefit and risk in immunotherapy and reminds us that, in autoimmune disease, treatment can both help and uncover the diagnosis This abstract is funded by: None