Cerebral Venous Thrombosis, Seasonal Trends, and Climatic Influence: A Region-SpecificStudy

Ann Indian Acad Neurol. 2020 Jul-Aug;23(4):522-527. doi: 10.4103/aian.AIAN_409_19. Epub 2019 Jul 11.

Abstract

Background and purpose: Studies looking at seasonal variation on cerebral venous thrombosis (CVT) are few with conflicting conclusions. In this region-specific study, we looked for climatic influence and seasonal trends on the incidence of CVT.

Methods: Imaging proven adult CVT cases treated over a period of 18 years from a specific geographical location with similar seasons and climatic conditions were studied. Metrological parameters prepared using 30 years of data was used. Quantum geographical information system (QGIS software) and SPSS v 22 were used for patient plotting and analysis.

Results: Total of 970 cases were studied. The incidence was significantly higher in summer 411 (42.3%) compared with autumn 317 (32.7%) and winter 242 (25.05); P = 0.038. This trend was consistent across all the 18 years in time series analysis. Mean age was 33.5 years (range 18-88 years). A significant majority 673 (69.4%) were below 40 years of age; P = 0.012. Females constituted 394 (40.6%) of cases. Postpartum CVT cases constituted 237 (30%). Interaction analysis showed younger age (<40 years) were more vulnerable for CVT in summer; P = 0.009. There was no seasonal influence on postpartum CVT. Apart for a weak positive correlation between rain fall (r = 0.18, P < 0.01); humidity and cloud cover was not influencing the incidence.

Conclusions: Higher ambient temperatures were consistently associated with higher incidence of CVT. This is the largest region-specific study on CVT in the world. These results may be applicable to other regions with similar climatic conditions.

Keywords: Ambient temperatures; cerebral venous thrombosis; climate; epidemiology; incidence; season.