Pearls• Cerebral air emboli (CAE) are scattered, small, distally located, and characteristically of low density on CT scan. • CAE should be considered as a stroke etiology in appropriate cases.• Prevention is a key treatment strategy.

Introduction: Mechanical thrombectomy (MT) for the treatment of acute ischemic stroke (AIS) in patients with large vessel anterior circulation occlusion has become a standard of care. Our study examines the risk of hemorrhagic transformation (HT) in patients that also underwent emergent carotid stenting (approximately 10%) during MT which potentially requires immediate antiplatelet use to prevent stent thrombosis. Methods: A hospital based stroke registry was used for retrospective analysis of 225 consecutive cases of large vessel anterior circulation strokes. Parenchymal hematoma (PH - PH1 and PH2) type of HT on 24 hour CT or MRI was defined as primary outcome. The study cohort was divided into carotid stenting and non stenting group. Baseline clinical and demographic characteristics were compared with uni-variate analysis. Multivariate logistic regression model was used to identify demographic and clinical predictors of PH. Results: Seventeen patients (7.55%) required immediate carotid stenting. 2 patients (11.8%) in the stenting group had PH compared to 24 (11.9%) in the non-stenting group (p=0.98). Intravenous thrombolytic was given to 59.2% patients in non-stenting group compared to 64.7% in stenting group (p=0.82). 52.9% were immediately started on antiplatelet or anticoagulation (29.4% - eptifibatide, 5.9% aspirin + clopidogrel, 17.6% heparin) in stenting group. In non stenting group 5% patient were immediately started on antiplatelet or anticoagulation (1.5% - eptifibatide, 1% aspirin + clopidogrel, 2% heparin, 0.5% aspirin alone). None of the patients in either group who had been started on antiplatelet or anticoagulation had PH. Multivariate analysis remained insignificant with small sample size. Conclusion: In this small, single center study, emergent carotid stenting during mechanical thrombectomy for large vessel anterior circulation stroke did not increase the risk of hemorrhagic transformation despite the early use of antiplatelet or anticoagulant medication or prior administration of intravenous thrombolytics.