title: Cerebral Venous Sinus Thrombosis May Follow a Seasonal Pattern.
abstract: BACKGROUND
  Several studies have demonstrated seasonal and temporal variations in the incidence of arterial stroke; however, for cerebral venous sinus thrombosis (CVST), such study seems lacking. The main aim of this study was to investigate whether there is any seasonal variation for CVST, and association between CVST occurrence and temperature.
  
  
  METHODS
  This retrospective study was conducted from January 2004 to July 2015 in 2 referral centers for the patients with cerebrovascular disorders. One hundred and sixty-six consecutive patients with a hospital admission or discharge diagnosis of definite CVST were included. The incidence of CVST was compared between high-temperature and low-temperature months.
  
  
  RESULTS
  The mean age of patients was 36.71 ± 12.44 and 130 (78.31%) subjects were female. The highest frequency of CVST was seen in 3 months of July to September (1.69/month per year); and the lowest frequency of CVST was seen from December to April (.83/month per year). Additionally, there was a significant correlation between the mean average of temperature in each month and the frequency of CVST occurrence (r = .60, P = .03). Moreover, we found a cluster of patients, mostly females, in whom CVST occurred in cold months and accompanied visible cerebral infarct with higher occurrence of seizure, focal neurological deficit, and loss of consciousness.
  
  
  CONCLUSIONS
  It seems that the incidence of CVST increases in high-temperature months of the year and dehydration and ensuing consequences may play an important role in such augmentation; however, the visible cerebral infarct is again more observed in low-temperature months.
authors: Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors: Golshan
authors: G
authors: Salehi
authors: Iranian Center of Neurological Research, Imam Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors: Payam
authors: P
authors: Sarraf
authors: Iranian Center of Neurological Research, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: f-fatehi@tums.ac.ir.
authors: Farzad
authors: F
authors: Fatehi
mesh_terms: D000328:Adult; D003392:Cranial Sinuses / Q000000981:diagnostic imaging; D003681:Dehydration / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D012851:Sinus Thrombosis, Intracranial / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D013696:Temperature; D013997:Time Factors; D055815:Young Adult
keywords: Association; Iran; cerebral venous sinus thrombosis; incidence; season; stroke; temperature