Postoperative seizure and memory outcome of temporal lobe epilepsy with hippocampal sclerosis: A systematic review

We conducted a systematic review and meta-analysis to evaluate postoperative seizure and memory outcomes of temporal lobe epilepsy with different hippocampal sclerosis (HS) subtypes classified by International League Against Epilepsy (ILAE) Consensus Guidelines in 2013. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MOOSE (Meta-Analysis of Observational Studies in Epidemiology) guidelines, we searched PubMed, Embase, Web of Science, and Cochrane Library from January 1, 2013 to August 6, 2023. Observational studies reporting seizure and memory outcomes among different HS subtypes were included. We used the Newcastle-Ottawa scale to assess the risk of bias and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to grade the quality of evidence. Seizure freedom and improved outcome (Engel 1 or ILAE class 1-2) ≥1 year after surgery were defined as the primary and secondary seizure outcome. A random-effects meta-analysis by DerSimonian and Laird method was performed to obtain pooled risk ratio (RRs) with 95% confidence interval (CIs). The memory impairment was narratively reviewed because of various evaluation tools. Fifteen cohort studies with 2485 patients were eligible for the meta-analysis of seizure outcome. Six cohorts with detailed information on postoperative memory outcome were included. The pooled RRs of seizure freedom, with moderate to substantial heterogeneity, were .98 (95% CI = .84-1.15) between HS type 2 and type 1, 1.11 (95% CI = .82-1.52) between type 3 and type 1, and .80 (95% CI = .62-1.03) between the no-HS and HS groups. No significant difference of improved outcome was found between different subtypes (p > .05). The quality of evidence was deemed to be low to very low according to GRADE. The long-term seizure outcome (≥5 years after surgery) and memory impairment remained controversial.