Incidence of Postoperative Cerebral Aneurysm Clip Slippage: Review of a Consecutive Case Series of 115 Clipped Aneurysms

Objective: Although delayed postoperative clip slippage has been reported in previous case reports and case series, its true incidence with high rate of follow-up imaging has not been reported. We attempted to determine the incidence of clip slippage in a cohort of consecutive aneurysm clippings. Methods: We performed a retrospective review of a prospectively maintained database of 115 consecutive saccular aneurysm clippings at a single institution. Postoperative imaging was reviewed for clip slippage within 24 hours and at 3–12 months. Eighty-six aneurysms (75.8%) were exclusively clipped with Sugitaclip (Mizuho Medical, Tokyo, Japan) Titanium II clips, 16 aneurysms were exclusively clipped with Yaşargil (Aesculap, Center Valley, PA) titanium clips (13.9%), 5 aneurysms were only clipped with Sugita aneurysm clips (4.3%), and 3 aneurysms were only clipped with Peter Lazic (Peter Lazic Microsurgical Innovations, Tuttlingen, Germany) clips (2.6%). Results: In this cohort, 94.7% of clipped aneurysms had follow-up imaging within 24 hours, and 51.3% had delayed follow-up imaging within 3–12 months. We identified 3 cases of clip slippage in 115 consecutive aneurysm clippings, resulting in an incidence of 2.6%. The average cumulative closing force of clips per aneurysm across the study was 2.32 N, and the median number of clips placed was 1. Two of the 3 cases of clip slippage had a closing force <2.32 N and only placement of a single clip. Conclusions: Because our series showed a 2.6% incidence of clip slippage, clipped aneurysms should be monitored with early and delayed vascular follow-up imaging. Lower cumulative clip closing force, single clip placement, and oversized clip blade length may be risk factors for postoperative aneurysmal clip slippage.