Introduction: The parahippocampal gyrus (PHG), along with other medial temporal structures, plays a key role in the epileptogenic pathway of mesial temporal lobe epilepsy (MTLE). Although the PHG is not typically targeted for seizure control, it is often collaterally ablated due to its proximity to other targets. This study evaluates whether variations in PHG ablation volume correlate with seizure outcomes.
Methods: Seizure outcomes and imaging were retrospectively analyzed in MTLE patients who underwent stereotactic laser amygdalohippocampotomy (SLAH) from 2018 to 2024. The PHG, though not originally targeted, was ablated collaterally. PHG and contrast-enhancing ablation volumes were segmented using BrainLab software. Volumetric differences were assessed against seizure outcomes (Engel Class I-II vs. III-IV) at 6-12. Statistical analyses included the Mann-Whitney U Test for PHG ablation means and Spearman’s correlation for associations with seizure outcomes.
Results: Twelve patients (mean age 37 ± 16 years), including three with mesial temporal sclerosis, underwent SLAH, with a mean follow-up of 35 months. At 6-12 months, five patients achieved Engel Class I-II outcomes, while seven were Class III-IV. The mean PHG ablation volume was 0.43 ± 0.38 cm³. Class I-II patients had a mean ablation volume of 4.86 cm² versus 7.00 cm² for Class III-IV (p = 0.38), with ablation percentages of 5.89% and 8.33% (p = 0.37). No differences in age, gender, epilepsy duration, or seizure frequency were found.
Conclusion : In this MTLE cohort, PHG ablation volume showed no significant association with Engel outcomes at 6-12 months. Although Class I-II patients had slightly lower PHG ablation volumes, this difference was not statistically significant. Larger studies are needed to clarify anatomical predictors of seizure outcomes in MTLE.
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