In the current study, 40 patients with acute ischemic stroke were enrolled. This study aimed at evaluating the relationship between the state of the cerebral collateral blood vessels and the functional outcome of patients with acute ischemic stroke after thrombolytic therapy. Mean age of those patients was 58.55 ± 11.47 years and the majority of them were males. Also, HTN and DM were the most frequently reported risk factors (50% and 25%, respectively). These results were consistent a previously reported study by Yeo and colleagues that enrolled 209 patients with acute ischemic stroke. Mean age of patients was 64 years. Also, the most frequent risk factors were HTN (63.2%) and DM (29.2%) . Besides, Elessawi and colleagues studied 30 patients with acute stroke; 70% of them were males. Out of all patients, 56.6% had DM and 66.6% had HTN .
Regarding etiology of the stroke, in majority (70%) of patients, large-artery atherosclerosis was the etiology of stroke. Cardioembolic etiology was present in 6 (15%) patients. Undetermined aetiologies also, were present in another 6 (15%) patients. In contrast, Yeo and colleagues found that the most frequent etiology was cardioembolic causes (48%) followed by large-artery atherosclerosis (26%) . These discrepancies could be attributed to different population, sample size and selection bias.
Higher frequency of large-artery atherosclerosis in the current study could be explained by relatively high frequency of diabetic patients (25%). It was found that diabetic patients are susceptible to vessel insult. In patient with diabetes, the reduced elasticity of blood vessels and stenosis of the cerebral capillaries can impact adversely the establishment of collateral circulation, and aggravating clinical symptoms .
Functional outcome in the current study was assessed by modified Rankin Scale after 3 months from rtPA administration where 26 (65%) patients had good outcome and 14 (35%) patients had poor outcome. In line with the current study, Elessawi and colleagues showed that 60% of patients who received rtPA had good outcome with regard to mRS after 3 months .
Also, in agreement with the current study, a previous study by Yeo and colleagues recruited 200 patients with AIS. The authors found that good functional outcomes (mRS 0–2) at 3 months were achieved in 107 (53.5%) patients following rtPA . Also, the present results were consistent with those of Leonard and colleagues who demonstrated that early neurological improvement during the first 24 h after intravenous thrombolysis is always associated with better functional outcomes at 3 months by mRS in acute ischemic stroke patients .
Here, we found that both groups of patients either with poor or good functional outcome had insignificant differences with regard to baseline NIHSS (11.69 ± 3.69 versus 13.14 ± 3.01; p = 0.21). Also, we found that majority of patients had moderate stroke based on baseline NIHSS. This result was also reported by Yeo and colleagues .
In the current study, low NIHSS was a predictor for good functional outcome with odds ratio was 1.23. Also, Kazi and colleagues found that a lower baseline NIHSS score was independently predictive of a favorable outcome for patients with AAIS (OR 1.268, 95% CI 1.76–1.358) .
In the current study, intracranial collaterals were assessed by Miteff, Tan, and Maas method where majority of patients with good functional outcome had good collaterals either pre-rtPA or post-rtPA injection. With multivariate regression analysis, it was found that only baseline Miteff method can be used as predictors of good functional outcome with odds ratio was 3.30. Yeo and colleagues stated that Miteff methods had odds ratio 3.38 for prediction functional outcome in patients with AIS .
In line with the current study, it was found that only the Miteff grading system could determine good functional outcomes at 3 months. These results could be attributed to good collaterals in Sylvian fissure and the insular regions, main regions assessed by Miteff scoring system, improve perfusion which lead to better outcomes .
The modified Tan method is easily replicable across readers since it is a basic grading system. However, it was discovered that it was not a reliable predictor of a positive result. Similarly, the Maas system failed to predict good functional outcomes .
Also, in the current study, it was found that all patients with good functional outcome and only one patient with poor functional outcome had ASPECT score ≥ 8. We found that ASPECT score ≥ 8 was a predictor for good functional outcome with odds ratio was 4.56. It was found that ASPECT method had 100% sensitivity and 92.9% specificity for prediction of good functional outcome with overall accuracy was 97.6% and area under curve was 0.96. This was consistent with Esmael and colleagues who found that patients with ASPECTS ≤ 7 were significantly associated with about fourfold increased risk of poor outcomes (OR 3.95, 95% CI 2.09–11.38, and P < 0.01) .
The current study found that failure of intracranial collaterals was able to predict poor functional outcome based on Miteff, Maas and modified Tan methods. This finding is contrary to that of Yeo and colleagues who found that collateral failure was not associated with worse outcomes, this observation was postulated to the transient during the early critical period which have disappeared in the follow-up imaging .
The study had limitations; obtaining 2 CTA for all patients was a challenge for the cost and the hazards of radiation dose. Also, the small sample size of our study affected the ability to show some associations which could be found with larger sample size.