Abstracts

Rationale:
Evidence from EEG-fMRI studies suggests that the piriform cortex is a common area of the brain that is activated during focal epileptic discharges. Surgery to remove the temporal lobe outweighs continued medical therapy in patients with temporal lobe epilepsy (TLE), and now recent evidence suggests that more extensive removal of the piriform cortex during an anterior temporal lobectomy (ATL) is a determining factor in whether patients with temporal lobe epilepsy (TLE) become seizure free. We aimed to replicate this study with a large cohort of TLE patients at our centre, who underwent a standard ATL with follow up times taken at 2 and 10 years.
Method:
There were 110 participants eligible for this study, with 85 and 29 of those having complete data at 2 years and 10 years, respectively. Participants were labelled as ‘seizure free’ if they had had no seizures after surgery, not including post-surgical ‘neighbourhood seizures’. Patients with continuing auras and no seizures were labelled as being seizure free. The frontal and temporal parts of the piriform cortex were manually segmented in a systematic way on both preoperative and postoperative T1 weighted MR images, using anatomical landmarks as guides. Segmentation was completed in the coronal plane, in slices up-sampled to 0.4x0.4mm in-plane, with a 1.2mm slice thickness. Groupwise comparisons were made between the ‘seizure free’ and ‘non-seizure free’ groups, based on pre-surgical factors and the percentage loss of piriform cortex in each patient.
Results:
There were no significant differences in the pre-surgical factors between the two groups, at both 2 and 10 years. There were no significant differences between the two groups in the percentage of piriform cortex resected. In the 10 year follow up group, there was a trend toward a greater proportion of the temporal piriform cortex resected and a non-seizure-free outcome (p=0.10), and similarly for the total piriform cortex resected (p=0.06).
Conclusion:
This replication study found no statistically significant differences between the ‘seizure free’ and ‘non-seizure free’ groups, when comparing both pre-surgical factors and the percentage of piriform resected during surgery. With this new evidence conflicting with current knowledge, there is room for additional studies to further elucidate the relationship between the piriform cortex and seizure freedom after ATL.
Funding:
:There was no funding provided to support this research.