Introduction Leptomeningeal arteries are recruited in the acute phase of an ischemic stroke and their role is to increase brain perfusion to the hypoperfused area via retrograde flow.

Aim of Study To investigate the effects of leptomeningeal collaterals on Computed Tomography Perfusion (CTP) values and their correlation with patient outcomes.

Methods 158 patients with anterior circulation stroke who underwent mechanical thrombectomy were included in the study. Using the Tan classification, which rates collateral circulation on a 4-point scale (0–3), we examined the collateral grade score of the patients on Computed Tomography Angiography (CTA). We correlated the collateral recruitment with core and penumbra volumes, as well as the potential recuperation ratio (PRR) and mismatch ratio on CTP. We also correlated them with the rate of functional independence 3 months after stroke (mRS) and mortality.

Results The incidence of atrial fibrillation, diabetes mellitus, and anticoagulant use were similar across all patients; however, the incidence of arterial hypertension varied (p=0.022). Higher Tan scores were associated with lower core volumes (p=<0.001), higher PRR (p =<0.001), and mismatch ratios (p=<0.001). Tan scores did not correlate with penumbra volumes (p=0.122) or successful recanalization (p =0.383). Higher Tan scores were associated with a decreased mortality rate (p=<0.001) and better mRS scores in stroke patients (p=<0.001).

Conclusion Leptomeningeal arteries are an important compensatory mechanism in the event of an acute ischemic stroke. There is a strong correlation between the arteries’ visibility and CTP values, as well as improved functional outcomes in acute ischemic stroke patients.