Acute Obstructive Hydrocephalus: An Unexpected Cause of Cardiac Arrest

Emergency physicians are well-versed in managing cardiac arrests, including the diagnostic and therapeutic steps after return of spontaneous circulation. Neurologic emergencies are a common cause of out-of-hospital cardiac arrest and must remain high in the differential diagnosis, as such cases often require specific interventions that may deviate from more common care pathways. Performing a noncontrast head computed tomography (NCHCT) scan after cardiac arrest has been found to change management, although the optimal timing of this imaging is unclear.

This is the case of a young, pregnant woman who presented to the emergency department after cardiac arrest with return of spontaneous circulation in the prehospital setting. She was found to have acute obstructive hydrocephalus on NCHCT, which was later confirmed to be due to a previously undiagnosed colloid cyst of the third ventricle. This acute obstruction resulted in myocardial stunning and, ultimately, cardiac arrest. Although outcomes are often dismal when the cause of arrest is secondary to neurologic catastrophe, this patient survived with completely intact neurologic function. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although acute obstructive hydrocephalus due to a colloid cyst adjacent to the third ventricle is a rare condition, it is a potentially reversible neurologic cause of out-of-hospital cardiac arrest. However, positive outcomes depend on obtaining the diagnosis rapidly with neurologic imaging and advocating for neurosurgical intervention. This case supports the recommendation that emergency physicians should strongly consider post-cardiac arrest neurologic imaging when another cause is not immediately obvious.