Prevention of rebleeding after operation for subarachnoid hemorrhage of unknown cause.

This study is presented to promote prophylactic operation to prevent rebleeding after subarachnoid hemorrhage (SAH) of unknown cause. Twenty-two cases of nontraumatic SAH of unknown cause of a total of 254 cases of SAH treated during a 5-year period (1980-1984) were available for this study. A follow-up study (4 to 61 months after treatment; median, 43 months) revealed a 4.5% mortality rate. Four patients chosen from among the 22 SAH cases underwent prophylactic operation. The decision to operate was based on repeated angiography showing regional cerebral vasospasm corresponding to a limited hyperdense area on the computed tomographic scan at the time of the onset of SAH. Microsurgery revealed a minute protrusion (less than 2 mm in diameter) or thinning of the arterial wall with old hematoma of the surrounding brain in all 4 cases, and treatment required only coating of the abnormal site. All 4 patients are now fully recovered. Frequently, abnormal changes of such cerebral arteries as the anterior communicating artery, the internal carotid artery (C-1 and C-2), and the middle cerebral artery (M-1) may occur. Therefore, the authors emphasize the necessity of surgical treatment for specific cases of SAH with an unknown cause.