The clinical utility of intraoperative electrocorticography in pediatric epilepsy surgical strategy and planning

Abstract

OBJECTIVEIn this study, the authors aimed to determine 1) whether the use of intraoperative electrocorticography (ECoG) affects outcomes and complication rates of children undergoing resective epilepsy surgery; 2) which patient- and epilepsy-related variables might influence ECoG-based surgical strategy; and 3) what the predictors of epilepsy surgery outcomes are.METHODSOver a period of 12 years, data were collected on pediatric patients who underwent tailored brain resections in the Motol Epilepsy Center. In patients in whom an abnormal ECoG pattern (e.g., spiking, suppression burst, or recruiting rhythm) was not observed beyond presurgically planned resection margins, the authors did not modify the surgical plan (group A). In those with significant abnormal ECoG findings beyond resection margins, the authors either did (group B) or did not (group C) modify the surgical plan, depending on the proximity of the eloquent cortex or potential extent of resection. Using Fisher’s exact test and the chi-square test, the 3 groups were compared in relation to epilepsy surgery outcomes and complication rate. Next, multivariate models were constructed to identify variables associated with each of the groups and with epilepsy surgery outcomes.RESULTSPatients in group C achieved significantly lower rates of seizure freedom compared to groups A (OR 30.3, p < 0.001) and B (OR 35.2, p < 0.001); groups A and B did not significantly differ (p = 0.78). Patients in whom the surgical plan was modified suffered from more frequent complications (B vs A+C, OR 3.8, p = 0.01), but these were mostly minor (duration < 3 months; B vs A+C, p = 0.008). In all cases, tissue samples from extended resections were positive for the presence of the original pathology. Patients with intended modification of the surgical plan (groups B+C) suffered more often from daily seizures, had a higher age at first seizure, had intellectual disability, and were regarded as MR-negative (p < 0.001). Unfavorable surgical outcome (Engel class II–IV) was associated with focal cortical dysplasia, incomplete resection based on MRI and/or ECoG findings, negative MRI finding, and inability to modify the surgical plan when indicated.CONCLUSIONSIntraoperative ECoG serves as a reliable tool to guide resection and may inform the prognosis for seizure freedom in pediatric patients undergoing epilepsy surgery. ECoG-based modification of the surgical plan is associated with a higher rate of minor complications. Children in whom ECoG-based modification of the surgical plan is indicated but not feasible achieve significantly worse surgical outcomes.

A spiking neural network (SNN) for detecting high frequency oscillations (HFOs) in the intraoperative ECoG

“…2 Department of Neurosurgery, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland. 3 University Children's Hospital, University of Zurich, 8032 Zurich, Switzerland. 4 Klinisches Neurozentrum Zürich, University Hospital Zurich, University of Zurich, 8006 Zurich, Switzerland.…”

“…The efficacy of epilepsy surgery requires the complete resection of the epileptogenic brain tissue 2 . Intraoperative electrocorticography (ECoG) can be performed during surgery to optimize the delineation of the epileptogenic zone (EZ) against healthy brain tissue by taking into account interictal spike patterns [3][4][5][6] . This so called "tailoring" may guide surgical decisions, but the value of interictal spikes as an epilepsy biomarker in this context is under debate 7 .…”

Neural Fragility of the Intracranial EEG Network Decreases after Surgical Resection of the Epileptogenic Zone

“…A biomarker that leverages interictal data and specific to the EZ would significantly advance surgical approaches for focal epilepsy. 30,31 In this study, we evaluate neural fragility as a correlate of surgical outcome using pre and post resection iEEG interictal recordings of the same subjects. We hypothesize that neural fragility of the brain network will decrease in cases of successful surgical resection.…”

An electronic neuromorphic system for real-time detection of High Frequency Oscillations (HFOs) in intracranial EEG

“…Selected patients with focal epilepsy can achieve seizure freedom if the epileptogenic zone (EZ), which is the brain area generating the seizures, is correctly identified and surgically removed in its entirety. Presurgical and intraoperative measurement of iEEG signals is often needed to identify the EZ precisely [18][19][20][21] . High Frequency Oscillations (HFOs) have been proposed as a new biomarker in iEEG to delineate the EZ 16,17,[22][23][24][25][26] While HFOs have been historically divided into "ripples" (80-250 Hz) and "fast ripples" (FR, 250-500 Hz), detection of their co-occurrence was shown to enable the optimal prediction of postsurgical seizure freedom 22 .…”