Introduction: It has been increasingly recognized that the insular cortex plays an important role in fronto-temporal epilepsy (FTE) in children. The insula however cannot properly by monitored with conventional subdural grids, and open surgical resection of the insula is technically difficult and often associated with significant morbidity. Stereotactically-placed insular depth electrodes allow direct and comprehensive monitoring of this region, and can easily be replaced with a laser applicator for minimally-invasive treatment via thermo-ablation.
Methods: We used CPT billing records dating from January 2010 to the present day to identify all the cases of depth electrode insertion performed at Dell Children's Medical Center (Austin, TX). Electronic medical records were then reviewed to specifically identify insular depth electrodes.
Results: Of the 104 depth electrodes placed in 80 patients, 45 of these were inserted into the insular cortex. In more than half of these cases, insular involvement prompted thermoablation or surgical resection of some portion of the insula. There were no serious adverse effects or complications associated with the placement of insular depth electrodes. Insular depth electrodes were utilized in cases with subtle cortical thickening as well as MEG dipole clustering within the insular cortex. They were also used in many cases of FTE where seizures recurred after an initial surgical resection.
Conclusions: Given the low morbidity and comprehensive coverage attainable with two posteriorly placed depth electrodes, it is worth considering whether insular depth electrodes should be part of the standard presurgical evaulation in every pediatric patient with partial, non-lesional, fronto-temporal epilepsy.
Patient Care: Redefine the standard presurgical work-up for partial, non-lesional FTE
Learning Objectives: 1) Consider the various possible indications for insular depth electrode placement.
2) Consider the role of thermoablation for insular-lobe epilepsy.
References: 1) Nguyen DK et al. Revisiting the role of the insula in refractory partial epilepsy. Epilepsia 2008.
2) Ryvlin P et al. Nocturnal hypermotor seizures suggesting frontal lobe epilepsy can arise in the insula. Epilepsia 2006