Stent-unsheathed effect predicts acute distal middle cerebral artery atherosclerotic disease-related occlusion.

Background: The differentiation of intracranial atherosclerosis (ICAS) and embolism is important.

Objective: In cases of ICAS, we observe a phenomenon that we call the "post-stent-deployment effect"; that is, all major branches are clearly visible beyond the occlusion segment when the stent is deployed at the site of occlusion. Our objective is to evaluates whether this post-stent-deployment effect can be used to differentiate ICAS from embolism in the distal M1 segment occlusion.

Methods: We conduct a retrospective study which reviewed consecutive patients with acute distal M1 segment and in whom recanalization was achieved by endovascular treatment. The post-stent-deployment effect was assessed in these patients. The sensitivity, specificity, positive predictive values (PPV), and accuracy of the post-stent-deployment effect for prediction of ICAS were assessed.

Results: From January 2015 to July 2018, a total of 80 patients were evaluated. The post-stent-deployment effect was more frequently observed in patients with ICAS than in those with embolism (100% vs 15.0%, P < .001). For identifying ICAS in distal M1 segment, the sensitivity, specificity, PPV, and accuracy of the post-stent-deployment effect were 100%, 85.0%, 69.0%, and 88.7%, respectively.

Conclusion: Our study finds that the sensitivity and accuracy of the post-stent-deployment effect in predicting distal M1 segment ICAS occlusion in patients with acute symptoms was high, and it may be useful in identifying ICAS lesion.