Acute and subacute neurovascular impact of cryptogenic air emboli.

Background: Cerebral air embolism is a rare cause of acute ischemic stroke that is becoming increasingly well-described in the literature. However, the mechanism and severity of this type of injury can vary, with ischemia typically emerging early in the course of care. To the best of our knowledge, delayed ischemia in this setting has not yet been described.

Case Description: A stroke code was called for an unresponsive, hospitalized, 75-year-old man. A computerized tomography (CT) scan of the head revealed air within the right greater than left hemispheric cortical veins with loss of sulcation, concerning for developing ischemia, and CT angiography revealed absent opacification of the distal cortical vessels in the right anterior cerebral artery and middle cerebral artery territories. Magnetic resonance imaging (MRI) of the brain was obtained 5.75 h after the patient's last known well-showed small areas of subtle cortical diffusion restriction. Follow-up CT head within 24 h showed near-complete resolution of the air emboli after treatment with 100% fraction of inspired oxygen on mechanical ventilation. Subsequent MRI, performed 4 days after the initial event, showed extensive cortical diffusion restriction and cerebral edema crossing vascular territories.

Conclusion: This case highlights that cerebral air emboli can cause delayed ischemia that may not be appreciated on initial imaging. As such, affected patients may require intensive neurocritical care management, close neurologic monitoring, and repeat imaging irrespective of initial radiographic findings.