Case Report: Recurrent sinus arrest induced by repeated vomiting.

Neuromyelitis optica spectrum disorder (NMOSD) can affect autonomic centers in the dorsal medulla, but presentation with recurrent sinus arrest is extremely rare. We report a 71-year-old woman with 10 days of persistent hiccups and vomiting who developed repeated syncopal episodes. ECG monitoring revealed vomiting-induced bradycardia progressing to sinus arrest, and Holter monitoring showed nocturnal sinus pauses up to 40.6 s. Routine cardiac and neurological evaluations were unremarkable, but serum anti-aquaporin-4 antibodies were markedly elevated, and brain MRI demonstrated a dorsal medullary lesion, confirming NMOSD with area postrema involvement. The patient was treated with intravenous immunoglobulin and high-dose methylprednisolone, resulting in complete resolution of vomiting and normalization of sinus node function. A temporary pacemaker was required acutely, and a permanent pacemaker was implanted before discharge. She remained stable on rituximab without relapse. This case underscores that severe vomiting-triggered sinus arrest may be an autonomic manifestation of NMOSD and is reversible with timely immunotherapy.