Abstract
Among the 611 cases of subarachnoid hemorrhage (SAH) experienced in our clinic during a period from April 1978 to June 1983, the etiology was not defined in 26 cases in spite of four vessel study which were performed more than twice.
The follow-up studies on such 26 cases were performed 5 to 67 months later from the onset by means of questionnaire. The follow-up study was completed 25 out of 26 cases and episodes of recurrent SAH was not recognized in any of the 25 cases.
Also follow-up cerebral angiography was done on 10 cases 8 to 44 months later in which SAH had been found on CT scan. And in only one case, an anterior cerebral artery aneurysm was found.
These results suggest that the prognosis of the cases with SAH of unknown etiology is very good when the diagnosis is made strictly. However, careful observation for more than a year including differential diagnosis follow-up angiography is strongly recommended in such cases, especially when CT scan obviously demonstrates SAH.
