Treatment of unruptured cerebral aneurysms by embolization with guglielmi detachable coils: case-fatality, morbidity, and effectiveness in preventing bleeding--a systematic review of the literature

Abstract

Objective: Guglielmi detachable coils (GDCs) increasingly are being used to treat unruptured cerebral aneurysms (UCAs). We systematically reviewed the literature to assess the case-fatality and permanent morbidity rates of GDC embolization of UCAs and the postembolization bleeding rate.

Methods: Through a MEDLINE search of the English, Italian, and French literature from January 1990 through December 2002, we retrieved studies on GDC embolization of aneurysms and extracted data on UCAs. Inclusion criteria were: 1) attempted GDC embolization of at least five consecutive patients with UCAs, 2) reported percentage of at least either case-fatality or permanent morbidity rate or crude data allowing an independent calculation. When data on UCAs could not be characterized with certainty among data on other, different lesions, the study was rejected.

Results: We included 30 studies. One thousand three hundred seventy-nine patients were available for the calculation of the case-fatality rate, 794 for the permanent morbidity rate, and 703 for the bleeding rate. The case-fatality rate was 0.6% (95% confidence interval, 0.2-1%), the permanent morbidity rate was 7% (95% confidence interval, 5.3-8.7%), and the bleeding rate was 0.9% per year (95% confidence interval, 0.41-1.4%). Only incompletely coiled UCAs of 10 mm or more accounted for the bleeding events. Morbidity decreased from 8.6% to 4.5% (P < 0.05) when the midyear of study (average calendar year of treatment) was 1995 or later.

Conclusion: GDC embolization of UCAs is relatively safe, and the outcome is progressively improving. Partial embolization of UCAs of 10 mm or more is unlikely to provide an acceptable protection. Most of the source publications suffer from methodological weaknesses. Prospective studies with longer follow-up periods are needed to definitively assess the effectiveness of GDCs on UCAs.