Etiologies and Risk Factors of Anterior and Posterior Circulation Strokes: A Comparison Study From South India

While anterior and posterior circulation strokes share most pathophysiological mechanisms, there is concern that significant differences may exist in some etiopathogenic factors. This study aims to compare the etiologies and risk factors of patients with anterior and posterior circulation strokes to ascertain if the operating mechanisms are any different and warrant different interventions.

A retrospective study compared the etiologies, risk factors, and stroke severity of 350 patients diagnosed with either anterior circulation infarcts (ACI) or posterior circulation infarcts (PCI) confirmed by magnetic resonance imaging. Stroke etiologies were classified according to the Trial of Organization 10172 in Acute Stroke Treatment (TOAST) criteria.

The sample included 254 patients (72.6%) with ACI and 96 patients (27.4%) with PCI. Patients with PCI had a lower mean NIHSS score on admission (6.05 versus 8.70, p<0.001) and a lower mRS score at discharge (1.91 versus 2.48, p=0.004). The most frequent etiology for both types of strokes was large-artery occlusion, occurring in 77.1% of patients with PCI and 61.4% of those with ACI. PCI patients showed a significantly higher proportion of diabetes mellitus (80.2% versus 68.1%, p=0.025) and hypertension (82.2% versus 67.3%, p=0.006) as compared to patients with ACI. Other risk factors and etiologies were similar across both ACI and PCI.  Conclusions: Our study of South Indian patients showed that the most critical etiology for ACI and PCI was large artery atherosclerosis (LAA), which was relatively more frequent in patients with PCI. Patients with ACI have more severe strokes compared to PCI. Hypertension and diabetes were the more commonly encountered risk factors for PCI than for ACI. Our results imply that mechanisms of stroke for patients with both ACI and PCI are mostly similar, and treatment should address this correlation rather than focus on other differences. Stricter control of diabetes and hypertension may be warranted for patients with PCI, considering the more significant role attributed to these risk factors in this stroke category.