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As several randomized trials have shown the overwhelming benefit of endovascular treatment (EVT) compared with medical management alone for acute ischemic stroke (AIS) due to large vessel occlusion (LVO),1 EVT has become an integral part of LVO treatment.2 For medium vessel occlusions (MeVOs)—that is, M2/3, A2/3, and P2/3 segment occlusions—the situation is less clear.
What we know and don’t know about MeVOs
We know that the natural history of M2 occlusions is poor. Despite the relatively distal occlusion site, only half of patients with M2 occlusions achieve a good functional outcome at 90 days.3 The clinical course of M3 occlusions and occlusions of the A2/3 and P2/3 segments is unknown, partly because vascular imaging was not routinely performed for AIS in the pre-EVT era, and even if it was, detecting MeVOs can be challenging, particularly for physicians with little imaging experience. Technically, imaging tools to detect MeVOs, such as perfusion imaging and multiphase CT angiography,4 have been available for many years, even before devices that render safe and responsible EVT in MeVOs possible. However, it is only recently that innovative postprocessing methods, such as time variant multiphase CT angiography color maps,5 which further facilitate MeVO detection for unexperienced readers, have become available. Since MeVO patients were underrepresented in previous EVT trials (the MulticenterRandomized Clinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) trialwas the only trial that included patients with M2 occlusions, and they constituted only 8% of the trial’s patient population),6 there is no clear guideline based EVT recommendation for MeVO strokes.2 7 We have …
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Correction notice Since the online publication of this article, the sentence 'For medium vessel occlusions (MeVOs)—that is, M2/, A2/3, and P2/3 segment occlusions—the situation is less clear' was updated to 'For medium vessel occlusions (MeVOs)—that is, M2/3, A2/3, and P2/3 segment occlusions—the situation is less clear'
Contributors MG: conceptualization and critical revision of the manuscript. JMO: drafting and critical revision of the manuscript and figures. BKM and MDH: critical revision of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial. or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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