Tolga D. Dittrich, MD
Endovascular treatment (EVT) is a fundamental component of acute therapy for ischemic stroke due to large vessel occlusion. Although the clinical decision for or against EVT is individual and multifactorial, it is mainly based on radiological parameters, especially the ischemic core’s visualization on neuroimaging. In their review, Goyal et al. address the practical difficulties in attributing image-defined core significance to EVT.
Clinically, the term “core” is commonly used as a synonym for infarcted brain tissue that can no longer be saved. However, the concept of a homogeneous infarction core is increasingly being challenged. The reality seems to be much more complicated, since the susceptibility of different cell and tissue types is variable, and, depending on the speed of reperfusion, there may be no, partial, or complete necrosis of the core area.
The prevailing uncertainty in determining poorly perfused brain tissue’s viability status by current imaging techniques is especially relevant in the late time window (i.e., 6-24 hours after the onset of symptoms). The landmark trials for EVT in the late time window (i.e., DAWN, DEFUSE-3) excluded patients with large image-defined cores (>50 ml and >70 ml, respectively) on the premise of less potentially salvageable brain tissue.
Ongoing randomized controlled trials (TENSION, SELECT-2, TESLA) investigate whether patients presenting in the late time window with large image-defined cores may also benefit from EVT. These trials may help further to clarify the connection between core extent and clinical outcome.
