[Statistical patterns in the distribution of spontaneous subarachnoid hemorrhages].

A study of 788 cases of spontaneous subarachnoidal hemorrhages, which were observed in some neurological clinics during the past 5 years, permitted an analysis of the statistical data concerning the distribution and outcomes of this form of strokes depending upon the age of the patient and etiology. Among the observed population, individuals of a young and middle age prevailed (78% of the patients were younger than 60 years). The role of separate etiological factors is different in different age groups in individuals under 40, subarachnoidal hemorrhages are mainly produced by a rupture of cerebral vascular aneurysms; in the age group of 40--59 years by arterial hypertension, while in the elderly by atherosclerosis in combination with arterial hypertension. The outcomes of subarachnoidal hemorrhages in general are more favourable in the older age groups. However, in hemorrhages of an aneurysmal etiology the lethality amounts to 21%, and is especially high in repeated strokes. In the group of patients with hemorrhages of an aneurysmal etiology the highest lethality was recorded in a localization of the aneurysm in the anterior communicating artery and anterior cerebral artery.