Is early thrombectomy of proximal middle cerebral artery occlusion to salvage internal capsule associated with improved clinical outcomes?

Background: Eloquence of tissue rather than infarct volume is a better predictor of outcomes following proximal middle cerebral artery (MCA) occlusion. The aim of this study was to determine the impact of white matter tract involvement, specifically the internal capsule (IC), following occlusion of non-collateralized lenticulostriate arteries (LSAs) on functional outcomes.

Methods: A retrospective observational single-center study of patients with proximal MCA occlusions in the period from 2015 to 2020 who were treated with mechanical thrombectomy and had post-interventional diffusion-weighted imaging was conducted. Patients were distributed based on the presence or absence of IC infarction (IC+ vs. IC-) at the level supplied by the MCA LSAs. Multivariate logistic or linear regression analysis was used to evaluate factors associated with the development of IC infarction.

Results: Of 368 patients with proximal MCA occlusion, 200 (55%) developed IC+ infarction. On univariate analysis, patients with IC+ infarction had higher baseline NIHSS (National Institute of Health Stroke Scale), lower ASPECTS (Alberta Stroke Program Early CT Score), lower collateral score, and were less likely to have partial reperfusion of LSA prior to thrombectomy. On multivariate analysis, those with higher baseline NIHSS, low ASPECTS, lack of successful reperfusion (TICI2b, 2c, 3), poor collateral circulation, and/or lack of partial perfusion of LSA prior to thrombectomy were likely to develop IC+ infarction. After adjusting for confounders, patients with IC+ infarction were less likely to experience early neurological improvement, more likely to develop hemorrhagic transformation of putamen, and had larger infarct volume. However, no significant correlation between IC+ infarction with poor 3-month functional outcome was observed.

Conclusion: Delayed recovery is possible despite IC+ infarction and hemorrhagic transformation of lenticulostriate territory. Larger studies are needed to confirm these findings.