Basal temporal lobe epilepsy: SEEG electroclinical characteristics.

Area of Science:

• Neuroscience
• Epileptology
• Clinical Neurology

Background:

• Temporal lobe epilepsy (TLE) is the most common focal drug-resistant epilepsy.
• Seizures originating from basal temporal regions (BTR) are not well understood.
• Stereo electroencephalography (SEEG) is a key tool for localizing seizure origins.

Purpose of the Study:

• To describe the ictal networks and clinical features of seizures involving the basal temporal regions (BTR).
• To identify the most epileptogenic structures within the BTR.
• To evaluate the outcomes of surgical treatment for BTR epilepsy.

Main Methods:

• Utilized SEEG in 24 patients with BTR sampling.
• Quantitatively analyzed seizures using the epileptogenicity index (EI).
• Focused on patients with maximal epileptogenicity in BTR, analyzing ictal networks, semiology, and post-surgical outcomes.

Main Results:

• Rhinal cortex, parahippocampal cortex, and posterior fusiform gyrus were most epileptogenic (mean EI: 0.57-0.54).
• Three ictal network organizations identified: anterior (23%), posterior (30%), and global (47%).
• Naming deficits were more common with left BTR involvement; automatic speech with right BTR.

Conclusions:

• Basal-temporal lobe epilepsy is a distinct entity within the TLE spectrum.
• Resective surgery can achieve good seizure freedom rates (72%) in selected patients.
• Adequate preoperative language assessment is crucial for safe surgical outcomes.