Elsevier

World Neurosurgery

Volume 121, January 2019, Pages e302-e321
World Neurosurgery

Original Article
Residual Cerebral Aneurysms After Microsurgical Clipping: A New Scale, an Agreement Study, and a Systematic Review of the Literature

https://doi.org/10.1016/j.wneu.2018.09.100Get rights and content

Highlights

  • Classifications of postclipping angiographic results lack standardization.

  • The interobserver reproducibility of classifications has rarely been studied.

  • A new 4-category scale is proposed.

  • The interobserver agreement became substantial when the scale was dichotomized.

Objective

The surgical repair of a cerebral aneurysm does not always lead to complete occlusion. A standardized repeatable method of reporting results of surgical clipping is desirable. Our purpose was to systematically review methods of classifying aneurysm remnants, provide a new scale with precise definitions of categories, and perform an agreement study to assess the variability in adjudicating remnants after aneurysm clipping.

Methods

A systematic review was performed to identify ways to report angiographic results of surgical clipping between 1963 and 2017. Postclipping angiographic results of 43 patients were also independently evaluated by 10 raters of various experience and backgrounds using a new 4-category scale. Agreement between responses were analyzed using κ statistics.

Results

The systematic review yielded 63 articles with 37 different nomenclatures using 2–6 categories. The reliability of judging the presence of an aneurysm remnant on catheter angiography was studied only twice, with only 2 raters each time, with contradictory results. Interobserver agreement using the new 4-category scale was moderate (κ = 0.52; 95% confidence interval, 0.43–0.62) for all observers, but improved to substantial (κ = 0.62; 95% confidence interval, 0.47–0.76) when results were dichotomized (grade 0/1 vs. 2/3).

Conclusions

Various classification schemes to evaluate angiographic results after surgical clipping exist in the literature, but they lack standardization. Adjudication using fewer, better defined categories may yield more reliable agreement.

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.

References (35)

  • M. Sindou et al.

    Aneurysmal remnants after microsurgical clipping: classification and results from a prospective angiographic study (in a consecutive series of 305 operated intracranial aneurysms)

    Acta Neurochir (Wien)

    (1998)
  • J. Raymond et al.

    Endovascular treatment of acutely ruptured and unruptured aneurysms of the basilar bifurcation

    J Neurosurg

    (1997)
  • D. Roy et al.

    Endovascular treatment of unruptured aneurysms

    Stroke

    (2001)
  • L. Thines et al.

    Postoperative assessment of clipped aneurysms with 64-slice computerized tomography angiography

    Neurosurgery

    (2010)
  • E. Uysal et al.

    Comparison of multislice computed tomography angiography and digital subtraction angiography in the detection of residual or recurrent aneurysm after surgical clipping with titanium clips

    Acta Neurochir (Wien)

    (2009)
  • E. Gerardin et al.

    Usefulness of multislice computerized tomographic angiography in the postoperative evaluation of patients with clipped aneurysms

    Acta Neurochir (Wien)

    (2010)
  • A. Bharatha et al.

    Comparison of computed tomography angiography with digital subtraction angiography in the assessment of clipped intracranial aneurysms

    J Comput Assist Tomogr

    (2010)
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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.

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