Abstracts

Rationale: Localization of the epileptogenic zone (EZ) is the crux of safe and effective epilepsy surgery.  Stereoelectroencephalography (SEEG) and subdural recordings (SDE) are both useful methods for localizing the EZ, however, many institutions use SEEG and SDE for the same indications and there is ongoing debate about which method is superior.  Existing meta-analyses suggest that SEEG is associated with fewer complications than SDE, but it remains unknown how these approaches compare with regard to postoperative seizure freedom.  To directly evaluate this question, we performed a meta-analysis of the available literature to determine the relative efficacy of SEEG and SDE with regard to rates of resective epilepsy surgery and postoperative seizure freedom.  Methods: A literature search was performed in compliance with PRISMA guidelines to include both adult and pediatric SEEG and SDE articles. Relevant articles were identified from 3 electronic databases (Medline, Embase, Cochrane Central) from their inception to January 2018.  Articles were included only if SEEG and SDE implantation methods were clearly defined.  We excluded articles that only considered patients who underwent resection as rate of post-implantation resection surgery was one of our primary outcomes of interest.  The quality of methodology and bias risk were assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies. Results: Of 11,462 articles screened, 69 articles met our inclusion criteria and were subjected to meta-analysis (see Figure).  These articles reported rates of resective epilepsy surgery and ultimate seizure freedom after SEEG in 33 articles (2,271 patients) and SDE in 35 articles (2,229 patients).  The mean rate of subsequent resective epilepsy surgery for implanted patients was 82.2% (std dev 13.1 [95% CI: 77.8 to 86.8]) for SEEG and 81.5% for SDE (std dev 14.7 [95% CI 76.7 to 86.3]).  The mean rate of postoperative seizure freedom was higher for SEEG (64.2% +/- 16.9 [95% CI 57.4-71.0]) than for SDE (57.5% +/- 14.2 [95% CI 52.1 - 62.9]), but did not reach statistical significance.  Conclusions: Our meta-analysis reveals that SEEG and SDE lead to similar rates of post-implantation resective epilepsy surgery and post-resection seizure freedom.  While there is a trend toward higher rates of seizure freedom in patients who undergo SEEG compared to SDE, this finding did not reach statistical significance.  Furthermore, our findings should be considered in conjunction with other meta-analyses that suggest differences in the safety profile of SEEG and SDE.  Funding: Not applicable