Cerebral vein and dural sinus thrombosis in adults in Isfahan, Iran: frequency and seasonal variation

Objective - To estimate the frequency of cerebral vein and dural sinus thrombosis (CVST) and its seasonal variation. Methods - A clinic-based prospective case-register study was conducted from 2001 to 2004. Hundred and twenty-two consecutive definite CVST patients (26 men and 96 women) treated in two major neurological centres of Isfahan, Iran, were included in the study. Part of examination included an assessment of CVST including conventional angiography and/or magnetic resonance imaging and self-reported medical history. Population data were obtained from the 1996 Iran Census. The mean (standard deviation) age of participants was 35.5 (11.9) years. Results - The annual frequency (95% confidence interval) of CVST was 12.3 (10.1, 14.5) per million in a population of 2,472,751, with higher rate in women than in men [19.9 (15.5, 23.9) women and 5.1 (3.2, 7.1) men] and with increasing age in women (up to 50 years), but not in men. The female/male ratio was 3.9 (2.5-6.0). The monthly frequency of CVST ranged from 0.6 per million (0.1, 1.1) in August to 2.1 (1.2, 3.0) in September. The seasonal CVST rate ranged from 2.2 per million (1.3, 3.2) in summer to 4.3 (3.1, 5.7) in autumn. The differences were statistically significant either for the months or season (P < 0.05). Conclusion - The findings of this study show the CVST frequency in adults. More women than men are present with CVST and its frequency increased during autumn.