Authors: Yuhei Urakami

Abstract

Background

Cardiac arrest is a common emergency department (ED) presentation, but brainstem infarction as the underlying cause is exceptionally rare and often overlooked. Basilar artery occlusion (BAO) can result in sudden dizziness, nausea, dysarthria, diplopia, cranial nerve palsies, respiratory failure, and coma. These signs are frequently missed, as patients typically present unresponsive, making clinical assessment challenging before imaging. Although rare, BAO is potentially reversible if recognized and treated promptly. We report a case of cardiac arrest due to BAO where early suspicion and rapid imaging led to successful reperfusion and survival.

Case Presentation

A 63-year-old man—previously independent, with a history of hypertension, diabetes, dyslipidemia, and prior lacunar infarction—collapsed suddenly at work, moments after complaining of nausea. Paramedics found him deeply comatose (GCS 3). During transport, he developed bradypnea, hypotension, and bradycardia, progressing to pulseless electrical activity shortly after arrival to the ED. The patient was intubated immediately, and return of spontaneous circulation (ROSC) was achieved after a single cycle of advanced life support with 1 mg epinephrine. Initial arterial blood gas revealed profound hypercapnic acidosis (pH 6.99, PaCO₂ 103 mm Hg). Point-of-care ultrasound showed preserved cardiac function.

Non-contrast head CT showed no hemorrhage. Contrast-enhanced CT from head to torso ruled out aortic dissection, pulmonary embolism, and other major causes. CT angiography revealed basilar artery occlusion. Mechanical thrombectomy was initiated within 3 hours of first medical contact, achieving near-complete reperfusion in a single pass. Spontaneous breathing resumed immediately. Brain MRI performed the following day revealed infarctions extending from the pons to the medulla, involving bilateral Anterior Inferior Cerebellar Artery (AICA) and Posterior Inferior Cerebellar Artery (PICA) territories.

The patient was extubated on day 5. At the time of transfer, he was able to follow commands despite mild residual impaired consciousness (GCS E4V3M6), with quadriparesis and central vocal cord paresis. 

Conclusion

When faced with unexplained cardiac arrest—particularly with non-shockable rhythms and no evident cardiopulmonary or hemorrhagic etiology—emergency physicians must consider brainstem infarction as a potentially reversible cause. Basilar artery occlusion should be part of the differential diagnosis, especially when prodromal symptoms such as nausea or altered consciousness precede arrest, or when severe hypercapnia is present. Early recognition through appropriate imaging—especially head-and-neck CT angiography—can enable timely reperfusion, offering a chance for survival and neurological recovery. Delayed diagnosis may result in missed opportunities for intervention.

Keywords: Resuscitation, Basilar Artery Occlusion