Functional outcome after recanalization for acute pure M1 occlusion of the middle cerebral artery as assessed by collateral CTA flow

Objective: Collateral flow is important for ischemic brain tissue after an acute occlusion of the cerebral artery. The purpose of this study was to evaluate baseline collateral flow, on CT angiography (CTA), as a predictor of functional outcome in patients who had endovascular recanalization, after acute pure first segment (M1) occlusion of the middle cerebral artery (MCA).

Methods: Thirty patients with acute pure M1 occlusion treated by endovascular recanalization, who were ineligible for intravenous thrombolysis or resistant to intravenous thrombolysis, were reviewed. The relationship between baseline collateral flow, on CTA, and functional outcome, was analyzed. In addition, other factors affecting clinical outcome were assessed.

Results: The mean NIHSS score on admission was 16.87±4.86 (7-24). The mean time interval between onset of stroke symptoms and recanalization was 324.37±68.38 (210-463) min. Successful recanalization (TICI 2b-3) was achieved in 18 patients (60%). Twenty-seven of 30 patients improved their NIHSS score (mean 8.4); NIHSS score 8.9±5.4 (median 10, range 0-16) at seven days. Two patients had aggravated symptoms and one patient had no change on the NIHSS score. At 90 days after recanalization, a modified Rankin Scale (mRS) of ≤3 was achieved in 15 patients (50%) and a mRS of ≤2 was achieved in nine patients (30%). Symptomatic intra-cerebral hemorrhage occurred in two patients (6.7%). Multivariate regression analysis showed an initial NIHSS score (p=0.004), grade of baseline collateral flow on CTA (p=0.025), presence of diabetes mellitus (p=0.037), and TICI scale (p=0.049) were factors associated with an improved NIHSS. For the mRS at 90 days, only the grade of the baseline collateral flow on CTA was associated with a good functional outcome (p=0.013).

Conclusions: The results of this study suggest that the grade of baseline collateral flow, on CTA, is an independent predictor of functional outcome for endovascular recanalization of acute pure M1 occlusion of the middle cerebral artery.