Seasonal and Diurnal Variations of Aneurysmal Subarachnoid Hemorrhage

The seasonal and diurnal variations in the incidence of hypertension, cerebrovascular accident, coronary heart disease were well documented, but the relation between season and daytime on the onset of aneurysmal subarachnoid hemorrhage (ASAH) was a subject of controversy. In the present study we aimed to evaluate the role of season of year and diurnal changes on the onset of ASAH. The time was categorized into two intervals of daytime and night time. Also patients were evaluated in two age groups of ≥ 60 and under 60. There were 107 files of patients with definite diagnosis of ASAH. The main common symptom was headache (88.8%). 52.2% of patients were referred to the hospital in day time and 45.8% were in night time, and the difference was not statistically significant. Moreover, the frequency of ASAH in winter and falls was about 51.4% and that of summer and spring was 45.6% and the difference was not significant. Seasonal frequency in patients with or without hypertension, cigarette smoking or both was not also statistically different. seasonal and diurnal variation didn’t show considerable effect on the onset of ASAH in our study. Even this effect was not observed in hypertensive patients. However, we need other researches on a larger sample of patients considering the influence of hypertension in relation to season and daytime in the onset of ASAH. Acta Medica Iranica, 44(5): 341-344; 2006 © 2006 Tehran University of Medical Sciences. All rights reserved.