[An epidemiological study of stroke in a geriatric community--with special reference meteorological factors]

The incidence of cerebrovascular event during a period of 3 years in the geriatric society in Japan was examined along with the alternating pattern of cerebrovascular accidents in relation to aging and seasonal factors. The population of Tsuwano town was approximately 7000. The percentage of aged people over 65-year-old reached 23.1% in the 1990 national census. All cerebrovascular accident patients in our hospital and two outpatients clinic in this city were registered during the period from April, 1990 to March, 1993. The number of patients in the period was 95 cases, of which 19 were classified as transient ischemic attack (TIA), 30 as cerebral thrombosis, 16 as cerebral embolism, 10 as cerebral hemorrhage, 7 as subarachnoid hemorrhage, and 13 as unclassified cerebral infarction. The frequency of each type except TIA was 39.5% cerebral thrombosis, 21.1% cerebral embolism, 13.2% cerebral hemorrhage, and 9.2% subarachnoid hemorrhage. In all cases, hypertension was observed in 62.1%, and past history of cerebrovascular accident was observed in 29.5%. The cerebral embolism group was older than the other groups and one-half of this group had atrial fibrillation. Peak incidence differed by type of illness, TIA and cerebral embolism occurred uniformly throughout the year, but subarachnoid hemorrhage and cerebral thrombosis in the spring. The relationship of cerebrovascular accident to crisis, especially potentiation by cerebral thrombosis was evaluated in light of climatic factors.