Abstract
Based on clinical experience, many neurosurgeons have the vague impression that patients with subarach-noid hemorrhage tend to be admitted in clusters. The present investigation was undertaken to ascertain whether or not this is true for datd collected at Showa-Inan Hospital in the southern part of Nagano Prefecture. Judging from a study of 632 cases out 835 whose onset of stroke was identified, from 1972 to 1991, it appeared that clustering was evident because multiple onsets within a day were observed (on 27 occasions, 2 cases in a day; on 4 occasions, 3 cases in a day; on 57 occasion, 2 patients in a day or a couple of days : on 10 occasions, 3 patients on the same day or within the next 2 days; on 3 occasions, 4 patients in a day or within 2 or 3 days). 40.5% of all cases were admitted within the first 3 days, and 55.1% were clustered within 6 days, instead of the average of one case in 11 days. On the other hand, the present investigation showed clearly that significant differences between clustered and solitary attack groups in terms of sex, age, location of the aneurysm involved, barometric pressure and tendency for barometric changes before the onset of subarachnoid hemorrhage, could not be recognized.
