Rates and predictors of seizure outcome after corpus callosotomy for drug-resistant epilepsy: a meta-analysis

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OBJECTIVE

Corpus callosotomy is a palliative surgery for drug-resistant epilepsy that reduces the severity and frequency of generalized seizures by disconnecting the two cerebral hemispheres. Unlike with resection, seizure outcomes remain poorly understood. The authors systematically reviewed the literature and performed a meta-analysis to investigate rates and predictors of complete seizure freedom and freedom from drop attacks after corpus callosotomy.

METHODS

PubMed, Web of Science, and Scopus were queried for primary studies examining seizure outcomes after corpus callosotomy published over 30 years. Rates of complete seizure freedom or drop attack freedom were recorded. Variables showing a potential relationship to seizure outcome on preliminary analysis were subjected to formal meta-analysis.

RESULTS

The authors identified 1742 eligible patients from 58 included studies. Overall, the rates of complete seizure freedom and drop attack freedom after corpus callosotomy were 18.8% and 55.3%, respectively. Complete seizure freedom was significantly predicted by the presence of infantile spasms (OR 3.86, 95% CI 1.13–13.23), normal MRI findings (OR 4.63, 95% CI 1.75–12.25), and shorter epilepsy duration (OR 2.57, 95% CI 1.23–5.38). Freedom from drop attacks was predicted by complete over partial callosotomy (OR 2.90, 95% CI 1.07–7.83) and idiopathic over known epilepsy etiology (OR 2.84, 95% CI 1.35–5.99).

CONCLUSIONS

The authors report the first systematic review and meta-analysis of seizure outcomes in both adults and children after corpus callosotomy for epilepsy. Approximately one-half of patients become free from drop attacks, and one-fifth achieve complete seizure freedom after surgery. Some predictors of favorable outcome differ from those in resective epilepsy surgery.

ABBREVIATIONS EEG = electroencephalography; PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-analyses.

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Article Information

Correspondence Alvin Y. Chan: University of California, Irvine, CA. alvinyhchan@gmail.com.

INCLUDE WHEN CITING Published online June 1, 2018; DOI: 10.3171/2017.12.JNS172331.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

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Figures

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    Flow chart summarizing the manuscript selection process.

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    Postoperative seizure outcome rates across all studies by publication date. Z-statistics and p values for Fisher transformation tests are provided. A: Percent of patients with complete seizure freedom per study over time (Z = 1.384; p = 0.166). B: Percent of patients with drop attack freedom per study over time (Z = 0.051; p = 0.959).

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    Meta-analyses examining factors associated with seizure freedom (p values for heterogeneity tests are provided). A: Complete over partial corpus callosotomy (p = 0.90, I2 = 0%, χ2 = 2.83). B: Normal over abnormal MRI findings (p = 0.47, I2 = 0%, χ2 = 3.53). C: Lateralized over nonlateralized EEG findings (p = 0.78, I2 = 0%, χ2 = 3.20). D: Epilepsy duration < 15 years over ≥ 15 years (p = 0.61, I2 = 0%, χ2 = 8.17). E: Presence over absence of infantile spasms (p = 0.043, I2 = 0%, χ2 = 2.75). Significant predictors of complete seizure freedom (p < 0.05) after meta-analysis include normal MRI (B), shorter epilepsy duration (D), and the presence of infantile spasms (E). M-H = Mantel-Haenszel. Figure is available in color online only.

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    Meta-analyses examining factors associated with freedom from drop attacks (p values for heterogeneity tests are provided). A: Complete over partial corpus callosotomy (p = 0.23, I2 = 27%, χ2 = 6.81). B: Idiopathic over known epilepsy etiology (p = 0.91, I2 = 0%, χ2 = 4.09). Both complete callosotomy (A) and idiopathic epilepsy etiology (B) significantly predict drop attack freedom after meta-analysis (p < 0.05). Figure is available in color online only.

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