Preoperative predictors of seizure outcomes after epilepsy surgery for mesial temporal sclerosis: A systematic review
Clinical Snapshot
PICO Framework
| P — Population | Adults with mesial temporal lobe epilepsy due to hippocampal sclerosis undergoing surgical resection |
| I — Intervention | Preoperative clinical, neuroimaging, EEG, and neuropsychological assessment factors |
| C — Comparator | Various preoperative predictor variables compared for prognostic value |
| O — Outcomes | Postoperative seizure freedom (Engel I/ILAE 1) following epilepsy surgery |
Bottom Line
This systematic review of 24 studies confirms that multimodal concordance—combining MRI-visible hippocampal sclerosis, unilateral seizure onset on EEG, and concordant PET hypometabolism—is the strongest preoperative predictor of seizure freedom following MTLE surgery. Anterior temporal lobectomy achieves approximately 70% seizure freedom at 1-2 years when patients demonstrate this concordance pattern. Bilateral EEG or PET abnormalities consistently predict poorer outcomes, while structural measures like hippocampal volumes show limited prognostic value. For Australian epilepsy centres, these findings reinforce the importance of comprehensive presurgical evaluation and support current Medicare-funded assessment protocols. The evidence strongly supports using multimodal concordance as a key criterion for surgical candidacy, potentially improving patient selection and surgical outcomes in drug-resistant temporal lobe epilepsy.
Key Findings
P Value: Not applicable for systematic review
Effect Size: Seizure freedom rates 50-75% across studies, ~70% for anterior temporal lobectomy
Primary Outcome: Seizure freedom (Engel I/ILAE 1) following epilepsy surgery
Nnt Or Sensitivity: Multimodal concordance (MRI-visible HS + unilateral EEG + concordant PET) strongest predictor of seizure freedom
Confidence Interval: Not reported
Clinical Application
Highly feasible - multimodal assessment (MRI, EEG, PET) standard in Australian epilepsy surgery programs Directly applicable to Australian practice. Medicare covers presurgical evaluation including MRI, EEG monitoring, and PET scanning. Findings support current RANZCP and Epilepsy Society of Australia guidelines for comprehensive presurgical assessment Adults with drug-resistant MTLE-HS being considered for epilepsy surgery in Australian comprehensive epilepsy centres
Abstract
Mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS) is a leading cause of drug-resistant epilepsy. Surgical resection, particularly anterior temporal lobectomy (ATL), achieves high rates of seizure freedom, but outcomes vary. Identifying reliable preoperative predictors may optimize patient selection and surgical success. To systematically evaluate preoperative clinical, neuroimaging, and neuropsychological factors associated with postoperative seizure outcomes in MTLE. A systematic review was conducted according to PRISMA 2020 guidelines. PubMed, Scopus, and Web of Science were searched for cohort studies (2010-2025) reporting predictors of seizure freedom after MTLE-HS surgery. Eligible studies assessed one or more preoperative factors (clinical, EEG, imaging, neuropsychological) in relation to postoperative outcomes. Data were extracted for qualitative synthesis, and methodological quality was assessed with the Newcastle-Ottawa Scale (NOS). From 615 records, 24 studies were included, encompassing patients treated with ATL, selective amygdalohippocampectomy (SAHE), or stereotactic laser ablation. Seizure freedom rates (Engel I/ILAE 1) ranged from 50% to 75%, with ATL achieving ~ 70% at 1-2 years. Multimodal concordance-MRI-visible HS, unilateral seizure onset on EEG, and concordant PET hypometabolism-was the strongest predictor of seizure freedom. Bilateral EEG/PET abnormalities consistently predicted poorer outcomes, whereas structural measures, such as hippocampal subfield volumes and HS subtypes, showed little prognostic value. Multimodal presurgical concordance is a robust predictor of favorable outcomes in MTLE-HS surgery, whereas bilateral or discordant findings indicate a higher risk of failure. Comprehensive presurgical evaluation remains essential to optimize surgical decision-making.
References
- 1.Correa-Molina, N., Cordoba-Gallego, M. F., Rivas-Montalvo, M. K., Monroy-Santos, S., Martinez-Micolta, P., Mayor-Romero, L. C., Aguirre-Patiño, J. S., & Reyes, J. S. (2026). Preoperative predictors of seizure outcomes after epilepsy surgery for mesial temporal sclerosis: A systematic review. Neurosurgical Review. https://doi.org/10.1111/epi.18076
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