Abstract WP251: Neuroimaging features of cerebral air embolism: a matched case-control study

Introduction: Cerebral air embolism (CAE) is a rare but treatable cause of ischemic stroke. Prompt diagnosis is critical to expedite appropriate treatment. We aimed to better define the imaging features of CAE by comparing MRI features in patients with confirmed CAE to those in cardioembolic stroke due to atrial fibrillation (AF). Methods: In a retrospective, matched case-control study, CAE cases from 2012-2023 were matched 1:2 by presenting NIHSS to control patients who had stroke due to AF and were not treated with thrombolytics or thrombectomy. MRIs were reviewed by a neuroradiologist blinded to group. The primary outcome was presence of pre-specified neuroimaging features on MRI, which included number of infarctions, diffusion restriction pattern, location, and laterality. Results: Fourteen patients with stroke due to CAE (median age 61, 64% female, median NIHSS 12) and 28 controls with stroke due to AF (median age 81, 43% female, median NIHSS 12) were included. The predominant infarct topography in CAE patients was gyriform in 86%, punctate in 7%, and wedge-shaped in 7%, whereas in patients with stroke due to AF the predominant infarct topography was wedge-shaped in 71%, punctate in 18%, and gyriform in 11% (p<0.001). CAE patients more often presented with multiple (93% versus 50%, p=0.007) and bilateral infarctions (79% versus 43%, p=0.048). Cortical borderzone involvement was more frequent in patients with CAE compared to those with AF (86% versus 25%, p<0.001). There was no difference in vascular territory distribution of infarctions between groups. The presence of both predominantly gyriform infarction topography and cortical borderzone involvement had a 76.6% sensitivity and 96.4% specificity for CAE. Conclusions and Relevance: In this matched case-control study, we found that CAE cause characteristic gyriform infarction patterns on MRI that are distinct from typical cardioembolic stroke. In addition, cortical borderzone predilection and multifocal infarctions were substantially more frequent in CAE. This constellation of findings, in the appropriate clinical context, should strongly suggest CAE as the mechanism of neurologic injury, and may facilitate timely identification of this uncommon but critical diagnosis.