Background: Delineation of the epileptogenic zone (EZ) is crucial during resective surgery in patients with epilepsy. In recent years, high-frequency oscillations, including fast ripples and ripples, have been considered promising biomarkers of the EZ. The objective of this study was to perform a systematic review and meta-analysis to evaluate the diagnostic accuracy of fast ripples and ripples in identifying EZs.
Methods: The PubMed, Embase, and Cochrane databases were searched systematically. The review process followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A bivariate mixed-effects regression approach was used to obtain summary estimates of the sensitivity and specificity of fast ripples and ripples.
Results: Thirteen studies were included in this review (12 for fast ripples and eight for ripples). Fast ripples had a pooled sensitivity of 0.80 (95% confidence interval [CI], 0.62-0.91), a specificity of 0.72 (95% CI, 0.55-0.85), and a summary area under the curve of 0.82 (95% CI, 0.79-0.86). The threshold effect was detected for ripples, and the summary area under the curve was 0.75 (95% CI, 0.71-0.79), with a sensitivity of 0.38 (95% CI, 0.18-0.64) and specificity of 0.90 (95% CI, 0.70-0.97).
Conclusions: Fast ripples are a biomarker of the EZ with moderate diagnostic accuracy; in contrast, ripples are not as effective.
Keywords: Epilepsy; Epileptogenic zone; Fast ripples; High-frequency oscillations; Meta-analysis; Ripples.
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