Original ArticleResidual Cerebral Aneurysms After Microsurgical Clipping: A New Scale, an Agreement Study, and a Systematic Review of the Literature
Introduction
The goal of surgical aneurysm repair is to safely prevent aneurysm rupture or rebleeding, but angiographic results remain the most frequent way of judging treatment success in the short-term, particularly for unruptured aneurysms. Although clipping is reputed to be an effective and durable treatment, a systematic review has shown that angiographic results after clipping of unruptured aneurysms remain poorly documented.1 One problem that is apparent when reviewing the literature is a lack of standardization of terminology. Angiographic results are often reported in vague terms, such as complete or incomplete occlusions, or the presence of a remnant or not. Some classification systems have been proposed, but categories are almost always incompletely defined, and their reliability is almost never validated. Repeatable and standardized adjudications of aneurysm remnants are needed if we are to develop valid instruments to compare results of treatments or study the long-term clinical significance of residual aneurysms in terms of risk of growth or hemorrhage.
We aimed to systematically review definitions and classifications of postclipping aneurysm remnants, as well as reports of their reliability. We then studied the interobserver and intraobserver reliability of a new semi-quantitative scale that was designed to define aneurysm remnants more precisely.
Section snippets
Systematic Review
A detailed protocol for the search strategy was designed and implemented according to the PRISMA (Preferred Reported Items for Systematic Reviews and Meta-Analyses) statement.2 The electronic search was performed using Embase, CINAHL, EBM, Cochrane, and MEDLINE databases with no starting date specification, including publications in English and French up to July 2017 (Appendix A).
All articles including a classification of postclipping aneurysm remnants and all reports of the reliability of
Results
The search yielded 8668 titles; 5289 abstracts were reviewed; 245 full-text articles that mentioned postclipping aneurysm remnants were analyzed. After applying the predefined selection criteria, 174 studies were excluded, including 171 (70%) because no definition was provided for what was considered an aneurysm remnant (Figure 2), leaving 71 reports to review in detail (Appendix A).
Sixty-three articles (89%) were case series reporting the efficacy of surgical aneurysm clipping, using 37
Discussion
This systematic review shows that the definitions and classification schemes to evaluate postclipping angiographic results are so varied and nonstandardized that communication of results and comparisons between series is problematic.19 The reliability of classification systems of angiographic results has infrequently and insufficiently been assessed in the literature. Rectifying this shortcoming seems crucial to permit the conduct of proper meta-analysis and comparisons of the results of
Conclusions
There are a variety of nomenclatures and classification systems to evaluate angiographic results after surgical aneurysm clipping, but none has been validated as reliable, and none is widely used. A 4-category system can produce reliable results when analyzed in a dichotomous fashion.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.