title: Epidemiology of subarachnoid hemorrhage in the Yaeyama Islands, an isolated subtropical region of Japan most frequently affected by typhoons: a population-based study.
abstract: OBJECTIVE
  The present study analyzed epidemiological data for patients with subarachnoid hemorrhage (SAH) in a subtropical region of Japan that is the most frequently affected by typhoons.
  
  
  METHODS
  The medical records of hospitalized patients who had been diagnosed as having SAH at Okinawa Prefectural Yaeyama Hospital during a 13-year period were reviewed. Demographic and epidemiological data including date and time of onset and activity at onset and clinical data were collected. Meteorological data for typhoon's approaches to the Yaeyama Islands were obtained from the web-site of the Japan Meteorological Agency. In addition, patients who had developed SAH during a period of 3days before and after the closest approach of a typhoon (CAT) were examined.
  
  
  RESULTS
  A total of 94 patients were identified. A monthly peak in August, a weekly peak on Monday, and two daily peaks in the evening and morning were observed. The incidence of SAH during a period of 3days before and after the CAT was approximately twice as high as that on other days, and a statistically significant difference was found.
  
  
  CONCLUSIONS
  Periodic patterns of SAH onset revealed unusual monthly and circaseptan variations and the usual circadian variation. SAH onset was associated with typhoon's approaches.
authors.affiliation: Department of Neurosurgical Emergency, National Hospital Organization Kanmon Medical Center, Simonoseki, Yamaguchi, Japan. IZMHR@kanmon-mc2.hosp.go.jp
authors.forename: Akifumi
authors.initials: A
authors.lastname: Izumihara
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D055867:Cyclonic Storms; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011153:Population; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology*; D014887:Weather