Resection of piriform cortex predicts seizure freedom in temporal lobe epilepsy

Area of Science:

• Neurosurgery
• Epileptology
• Surgical Oncology

Background:

• Transsylvian selective amygdalo-hippocampectomy (tsSAHE) is a standard surgical treatment for drug-resistant mesial temporal lobe epilepsy (mTLE).
• While tsSAHE achieves seizure freedom in approximately 70% of patients, a significant portion experience persistent seizures post-operatively.
• Variations in the extent of resection of target anatomical structures may contribute to differing surgical outcomes.

Purpose of the Study:

• To investigate the correlation between the resected proportions of the hippocampus, amygdala, and temporal piriform cortex and the postoperative seizure outcome in patients undergoing tsSAHE.
• To identify specific target volumes crucial for achieving seizure freedom following tsSAHE for mTLE.

Main Methods:

• A retrospective analysis of 82 patients with mTLE who underwent tsSAHE between 2012 and 2017.
• Volumetric assessment of resected proportions of the hippocampus, amygdala, and temporal piriform cortex.
• Stratification of patients into favorable (International League Against Epilepsy (ILAE) class 1) and unfavorable (ILAE class 2-6) seizure outcome groups.

Main Results:

• Patients achieving favorable seizure outcomes demonstrated significantly larger resected proportions of the temporal piriform cortex compared to those with unfavorable outcomes (median 51% vs. 13%, P = 0.0001).
• No significant differences in the resected proportions of the hippocampus (81% vs. 80%, P = 0.7) or amygdala (100% vs. 100%, P = 0.7) were observed between the favorable and unfavorable seizure outcome groups.

Conclusions:

• The extent of temporal piriform cortex resection is a critical factor influencing seizure freedom after tsSAHE.
• These findings highlight the temporal piriform cortex as a key target volume for optimizing surgical success in tsSAHE for mTLE.