Chronic Recording Electrocorticography Guided Resective Epilepsy Surgery: Overview and Future Directions

Sensing, modeling, and neuromodulation technologies are profoundly advancing the practice of epilepsy surgery.  Chronically implanted neural monitoring technologies developed for seizure termination and seizure prediction have each been found to be useful in unintended applications, specifically for the planning of resective surgery.  We review and summarize the use of chronic monitoring in an unanticipated context in which it was found to be invaluable in the planning of surgery; this was observed in a pivotal study of a seizure detection and termination system.  Monitoring of patients chronically in their normal ambulatory setting, as facilitated by this technology, allows unperturbed assessment of patients while on outpatient medication regimens and without the time and space constraints imposed by cost and infection risk inherent in subacute inpatient invasive monitoring.  Five patients in the NeuroPace US pivotal trial underwent resective surgery which was subsequent to and enabled by chronic recordings from the implanted monitoring system.  These resective surgeries were independent from the primary intended function of the implanted neural monitoring device.  Chronic monitoring facilitated greater anatomical localization of the sources and allowed for a deeper understanding of the dynamic network behavior of interconnected seizure foci, thereby facilitating a substantially more sophisticated approach to resective surgery.  In the NeuroPace trial, monitoring and analysis of chronic unlimited recording electrocorticography (CURE) from chronically implanted subdural and depth electrodes facilitated planning of resective surgery that resulted in near or complete seizure freedom in 4 patients.  This series suggests that chronic recording of electrocorticographic signals is a therapeutic modality meritorious of further investigation.  Note: This was analysis and study was performed on patients previously enrolled in the NeuroPace® RNS® Ststem Pivotal trial: http://clinicaltrials.gov/show/NCT00572195