D.06 Insular involvement in intractable epilepsy: results of invasive EEG data

Abstract

Background: Exploration of the insular cortex is now commonly considered in patients with refractory epilepsy requiring invasive EEG investigations. The safety and yield of routine insular exploration is uncertain. Methods: All patients (pediatric and adult) who had invasive EEG (iEEG) with insular depth electrode placement, either through SEEG or open implantation, were reviewed. Ictal insular involvement was characterized as primary, secondary or not involved. Results of insular resections were recorded. Results: A total of 173 patients had iEEG of which 26 included insular electrodes (SEEG-18, Open - 8). No complications of placement were identified. Insular involvement was seen in 20 (76%) patients. Primary ictal involvement was identified in 9 (33 %) patients, while secondary spread was noted in 11 (42 %) patients. Six patients went on to have resections including the insular cortex of which 5 patients achieved good seizure control (Engle class I/II). Conclusions: Insular depth electrode placement is a safe and effective adjunct to invasive EEG investigations. Ictal involvement of the insular cortex was commonly identified in our series leading to inclusion of the insula in cortical resections with good seizure control, which may not have been considered without iEEG evidence.