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Risk of recurrent subarachnoid hemorrhage after complete obliteration of cerebral aneurysms.

BACKGROUND AND PURPOSE
The neck clipping of cerebral aneurysms is a well-established treatment for subarachnoid hemorrhage (SAH) caused by aneurysmal rupture. However, it is still unclear how great a risk of recurrence patients with a successfully treated aneurysm carry over a long-term period.


METHODS
Of 425 patients with SAH surgically treated in Aizu Chuou Hospital from 1976 to 1994, 220 cases meeting the following criteria were studied: (1) all aneurysms detected by 3- or 4-vessel cerebral angiography were clipped, (2) complete obliteration of aneurysm(s) was confirmed by postoperative angiography, and (3) the patient survived >3 years. All patients were traced until January 1998 for recurrent SAH or death. The mean follow-up period was 9.9 (range, 3 to 21) years.


RESULTS
Six patients (2.7%) had recurrent SAH, each with an interval ranging from 3 to 17 years (mean, 11 years) since the original treatment. In addition, 2 patients were found to have regrowth of the originally operated aneurysms. The cumulative recurrence rate of SAH, calculated using the Kaplan-Meier method, was 2.2% at 10 years and 9. 0% at 20 years after the original treatment.


CONCLUSIONS
The recurrence rate was considerably higher than the previously reported risk of SAH in the normal population, and the rate increased with time. These data indicate that patients with ruptured cerebral aneurysms still carry higher risks for SAH in a long-term period, even after complete obliteration of the aneurysm, and that periodic examination to detect recurrent aneurysms may be indicated for such patients.