Abstract
We studied 33 patients with subarachnoid hemorrhage of unknown etiology despite from repeated angiography last 18 years. The incidence was 4.9% among the aneurysmal subarachnoid hemorrhage. Male predominance revealed (male : female=1 : 0.89) and mean age was 51.2 years which showed slightly younger than the patients with aneurysmal subarachnoid hemorrhage. Ten of 21 patients obtained CT examination showed perimesencephalic hemorrhage. In these patients, one patient showed normal pressure hydrocephalus, however, 2 out of 4 patients who had subarachnoid hemorrhage in not only basal cistern but also Sylvian cistern showed normal pressure hydrocephalus. 23 patients had good prognosis and returned previous activity. No patients showed re-bleeding. One patient died of hypertensive intracerebral hemorrhage, one died of malignancy and 3 died of repiratory failure or cardiac failure.
These results show that the subarachnoid hemorrhage especialy localized in peri-mesencephalic cistern is a distinct pathology from aneurysmal subarachnoid hemorrhage.
