Difference between risk factors of anterior and posterior circulation strokes.

The cerebrovascular diseases rank first in frequency and importance among all the neurological diseases of adult life. It is important to understand the risk factors associated with stroke subtypes in order to improve primary and secondary preventative strategies. There is currently no information on the relationship of these stroke subtypes with cerebrovascular risk factors. Clinicians have tended to view strokes occurring in the anterior circulation (AC) and the posterior circulation (PC) as separate entities because the most common ischemic strokes occur in the AC, while strokes occurring in the PC are the most severe. Furthermore, AC and PC strokes have different underlying pathogenesis, natural histories and potential responsiveness to interventions such as anticoagulation and risk factors. We sought to explore differences between AC and PC strokes concerning their risk factors. In this prospective descriptive study, we evaluated 250 patients; 125 had AC involvement and 125 had PC. involvement, and were referred to Alzahra and Noor University Hospitals and private clinics between January 2000 and December 2004. Strokes in AC and PC were diagnosed by clinical and neuroimaging findings including brain CT Scanning and MRI. Pre-stroke cerebrovascular risk factors for each patient recorded from previous and present evaluations included hypertension, diabetes mellitus, hyperlipidemia and smoking. The average age of patients with AC stroke was 73 ± 19.15 and the average age of patients with PC stroke was 70 ± 19.7. Of 125 patients with AC stroke, 57 (45.6%) were male and 68 (54.4%) were female. Of 125 patients with PC stroke, 54 (43.2%) were male and 71 (56.8%) were female. The prevalence of hypertension as a major risk factor of stroke was higher in patients with PC stroke in comparison to patients with AC stroke (60 % vs. 40.8%) and the odds ratio for PC stroke was 2.8 (95% CI; 1.27 – 3.73). The prevalence of smoking in patients with PC stroke was higher than in those with AC stroke (32.8% vs. 15.2%) and this difference was statistically significant (P = 0.001). The prevalence of hypertension as a major risk factor of stroke was higher in patients with PC strokes. However, there was no increased prevalence of stroke associated with diabetes mellitus between AC and PC strokes. Our results also showed that hyperlipidemia was a risk factor for AC and PC strokes and the prevalence was equal in both types, while the prevalence of smoking in PC strokes was higher compared to AC strokes.