Risk of aneurysm recurrence in patients with clipped cerebral aneurysms: results of long-term follow-up angiography.

BACKGROUND AND PURPOSE

With many patients living long after microsurgical aneurysm clipping for subarachnoid hemorrhage (SAH) and with the evolution of intravascular procedures as less invasive alternatives, knowledge of the long-term results of clipping is becoming important.

METHODS

Of 412 patients who underwent clipping of ruptured or unruptured cerebral aneurysms at our institution between 1976 and 1994 and who survived >3 years after surgery, 225 patients who were in good general condition and younger than 80 years were offered follow-up angiography to detect newly formed aneurysms. Of the 225, 80 patients (35.6%) agreed to undergo angiography. In addition, 32 patients underwent angiography for new medical indications other than SAH. Therefore, 112 patients underwent angiography, representing a total of 140 clipped aneurysms.

RESULTS

The mean interval from surgery was 9.3 years for all patients and 9.0 years for the clipped aneurysms (range 3 to 21 years). Four aneurysm regrowths were detected of the 140 (2.9%) clipped aneurysms, representing 3 of 125 completely clipped aneurysms, 1 of 14 incompletely clipped aneurysms, and 0 of 1 aneurysm not studied with postoperative angiography. De novo aneurysms were detected in 9 of 112 (8.0%) patients. The annual rate of de novo aneurysm formation was 0.89%.

CONCLUSIONS

This study shows that the annual rate of de novo aneurysm formation is relatively high (0.89%) and that the cumulative risk becomes significant after 9 years. In consideration of the fatality rate of SAH, follow-up angiography may be indicated for patients with clipped aneurysms 9 to 10 years after surgery.