Robot-assisted insular stereoelectroencephalography in pediatric drug-resistant epilepsy: accuracy and diagnostic value.

Background: Insular epilepsy is a well-known cause of drug-resistant epilepsy (DRE) in the pediatric population. It can be a source of surgical epilepsy treatment failures when not ruled out pre-operatively. Non-invasive methods often provide limited information about its existence, being the invasive methods necessary to diagnose it in the vast majority of cases. The most used is stereoelectroencephalography (SEEG). We report a series of DRE pediatric patients in which insular SEEG was performed to rule out insular epilepsy.

Method: We performed a retrospective review of pediatric DRE patients operated on SEEG including insular electrodes between April 2016 and September 2022. We described the different trajectories used (orthogonal or oblique) and surgical techniques. After implantation, we assessed electrodes' precision using three measures: entry point location error (EPLE), target point location error (TPLE), and target deviation (TD). We also reported complications that occurred with this technique as well as the diagnostic information provided.

Results: Overall, 32 DRE patients were operated on SEEG including insular electrodes. Four hundred one electrodes were implanted, 148 (39.91%) of whom were directed to the insula. One hundred twelve followed an orthogonal trajectory, and 36 were oblique. The mean EPLE was 1.45 mm, TPLE was 1.88 mm and TD was 0.71 mm. Three patients suffered from frontal hematoma, two of them diagnosed on post-operative MRI and one who required surgery, with no sequelae. One patient suffered from meningitis treated with antibiotics with no permanent sequelae. Nine patients (28.13%) had the insula included in the epileptogenic zone.

Conclusions: Insular epilepsy has to be ruled out in DRE patients when little suspicion is obtained after non-invasive testing. This is especially important in the pediatric population, in which seizure semiology is more difficult to characterize and failures to control epilepsy have devastating consequences in neurocognitive development and scholarship. Given its relative low rate of relevant complications and potential benefits, we should consider widening the inclusion criteria for insular SEEG monitoring.