Pediatric Cardiac Arrest Secondary to Guillain-Barré Syndrome-Induced Dysautonomia

<b>Background:</b> Guillain-Barré syndrome (GBS) is an acute immune-mediated polyneuropathy often associated with autonomic dysfunction. Although transient cardiovascular instability is common, severe dysautonomia leading to cardiac arrest is rarely documented in children. <b>Methods:</b> We report the case of an 11-year-old previously healthy boy who initially presented with acute ophthalmoplegia and rapidly progressed to quadriplegia and areflexia. He developed fluctuating blood pressure and bradycardia, culminating in cardiac arrest due to asystole at 24 h after admission, requiring 17 min of resuscitation. <b>Results:</b> Electrophysiological studies confirmed a demyelinating polyneuropathy. Although intravenous immunoglobulin (IVIG) was initiated 5 h after admission, clinical improvement was achieved only after subsequent plasmapheresis on day 20, with the recovery of autonomic function by day 35. He was extubated on day 45 and discharged on day 83 with a near-complete recovery after prolonged intensive care and rehabilitation. <b>Conclusion:</b> This case highlights the potential for rapid and life-threatening autonomic instability in pediatric GBS. Unlike typical cases, the patient progressed to cardiac arrest within 24 h despite IVIG, highlighting the need to consider plasmapheresis for non-responders. Continuous hemodynamic monitoring is essential to prevent fatal outcomes, even in patients with initially mild or atypical presentations.