Preresection intraoperative electrocorticography (ECoG) abnormalities predict seizure‐onset zone and outcome in pediatric epilepsy surgery

Abstract

SUMMARYObjective: The predictive value of intraoperative electrocorticography (ECoG) in pediatric epilepsy surgery is unknown. In a population of children undergoing ECoG followed typically by invasive extraoperative monitoring (IEM) and resection, we aimed to determine the relationship between frequent ECoG abnormalities and the seizure onset zone and outcome after resection. Methods: We retrospectively identified 103 children with preresection ECoG of sufficient technical quality. ECoG records were scored based on electrode location and frequency, blinded to the seizure-onset zone and outcome. Electrographic seizure and spike locations were identified. Locations of seizures and spike populations were then compared to the location of seizure-onset zone defined by IEM using subdural electrodes and resection margin. Results: Electrographic seizures were identified in 11 (11%) of 103 patients. A spike population of one or more was noted in 79 (77%) of 103 patients. In 50 (63%) of 79 patients, spike populations correlated with seizure-onset zone location. The overall surgical outcome was good (ILAE 1 to 3) in 53 (52%) of 101 patients. Outcome was good in seven (78%) of nine patients when electrographic seizure location was resected. The best outcomes were obtained with resection of both the seizure-onset zone and ECoG abnormalities to include seizures and spike locations (22/33 good outcome, 67%, p = 0.008). There was a significantly better outcome in children with complete resection of ECoG-identified spike populations (14/26, 62% good outcome) compared to when none were resected (4/14, 29%, p = 0.043). Significance: Electrographic seizures and frequent spikes are frequently seen on preresection ECoG in children. The brain locations corresponding to these discharges are highly concordant with the seizure-onset zone; resection of these regions is correlated with good seizure outcome. Further research is needed to design interventions that increase the reliability of ECoG prediction of the epileptogenic zone and obviate the need for IEM.

Reproducibility of interictal spike propagation in children with refractory epilepsy

“…The relationship between spike and seizure networks has been controversial for decades . Previous studies have shown that complete excision of regions generating spike discharges (ie, irritative zone) is correlated with seizure‐free outcomes, whereas others find that complete irritative zone resection is neither necessary nor sufficient to ensure favorable outcomes . Network‐based analysis of spike propagation is relatively understudied compared to the standard clinical approach, which emphasizes the spatial localization of spike discharges rather than spike coactivation between brain regions .…”

Subdural grid and depth electrode monitoring in pediatric patients

“…Several epileptiform patterns may be recorded, including continuous or intermittent bursts of spike and wave and high‐frequency oscillations . Attenuation of beta activity or the presence of delta‐wave activity may indicate a higher likelihood of an epileptic focus that warrants electrode coverage .…”

Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings

“…However, evidence supporting this interpretation of spike activity is inconclusive (3). Resection of the spiking region has been associated with improved surgical outcomes (4, 5), though for many patients, persistent postoperative spiking is compatible with seizure freedom (6). Spikes are routinely observed in regions beyond the neurologist-defined seizure onset zone (SOZ), and the localization of spikes to the SOZ varies tremendously between patients and across time (7).…”