Relationship between Spontaneous Cerebral Hemorrhage and Climatic Factor

ABSTRACT

The author investigated whether there were clear seasonal variations in the incidence of both spontaneous intracerebral hemorrhages(SICH) and subarachnoid hemorrhage(SSAH), and which climatic factor affected on the occurrence rate. From January 1988 to December 1994, 787 patients with SICHs and 556 patients with SSAHs were admitted to our hospital. The author compared the occurrence rate of spontaneous cerebral hemorrhages and the meteorological data on each date, such as daily temperatures(average, maximu, and minimum), temperature change(intradiurnal and daily), precipitation, average wind speed, average relative humidity, duration of sunshine, mean sea level barometric pressure, daily barometric pressure difference and wind-chilling effect. There was a clear seasonal variation in the occurrence rate of SICHs. It was high in early spring(February, March, and April) and early winter(October and December)(P<0.05). In SSAHs, there was no statistically significant differences in the occurrence rate, however. Daily temperatures(average, maximum, and minimum) and mean sea-level barometric pressure were the important climatic factors influencing the occurrence rate of SICHs(P<0.05). The lower daily temperatures(average, maximum, and minimum ), and the higher mean sea-level barometric pressure, the more SICHs occurred. In SSAHs, daily average temperature and intradiurnal temperature affected on the occurrence rate(P<0.05), however, there was no climatic factors with a statistically significant correlation. These results suggested that SSAHs differed from SICHs in its pathogenic mechanism. In any events, the dry(high barometric pressure) and cold(low temperature) weather might be a risk factor for the hypertensive patients. To reduce or prevent SICHs, such a hypertensive patient should not go out in dry and cold weather.