Collateral Status, Reperfusion, and Cerebral Edema After Thrombectomy for Stroke

Excerpt

Endovascular thrombectomy has revolutionized the landscape for those with acute ischemic stroke. Patients’ functional outcomes can be dramatically improved by reperfusion of large vessel occlusion (LVO) in both the anterior and posterior circulations [1‐3]. However, a major concern that remains, despite these advances, is that despite successful recanalization of occluded vessels and apparent reperfusion of ischemic brain tissue, up to half of patients still do not regain functional independence. Several reasons for this discrepancy, termed futile recanalization or clinically ineffective reperfusion, have been proposed [4, 5]: one hypothesis is that patients with LVO can still experience severe brain edema and hemorrhagic complications (i.e., reperfusion injury), which threaten loss of life and secondary brain injury, thereby imperiling recovery [6]. Experimental data and some human studies have suggested that reperfusion could exacerbate brain edema, especially when it occurs late and/or in the setting of large ischemic volumes [7, 8]. However, early clinical data from thrombectomy trials and registries instead suggested that reperfusion reduces edema, measured using midline shift [9, 10]. Additionally, two recent mediation analyses have suggested that a substantial proportion of the improvement in outcome observed in studies of endovascular reperfusion is mediated by a reduction in brain edema and not just final infarct volume [11, 12]. …