Alena Jahodová, Barbora Beňová, Martin Kudr, Petr Ježdík, Radek Janča, Anežka Bělohlávková, Petr Liby, Róbert Leško, Michal Tichý, Pavel Čelakovský and Pavel Kršek
Resective epilepsy surgery is an established treatment method for children with focal intractable epilepsy, but the use of this method introduces the risk of postsurgical motor deficits. Electrical stimulation mapping (ESM), used to define motor areas and pathways, frequently fails in children. The authors developed and tested a novel ESM protocol in children of all age categories.
The ESM protocol utilizes high-frequency electric cortical stimulation combined with continuous intraoperative motor-evoked potential (MEP) monitoring. The relationships between stimulation current intensity and selected presurgical and surgery-associated variables were analyzed in 66 children (aged 7 months to 18 years) undergoing 70 resective epilepsy surgeries in proximity to the motor cortex or corticospinal tracts.
ESM elicited MEP responses in all children. Stimulation current intensity was associated with patient age at surgery and date of surgery (F value = 6.81, p < 0.001). Increase in stimulation current intensity predicted postsurgical motor deficits (F value = 44.5, p < 0.001) without effects on patient postsurgical seizure freedom (p > 0.05).
The proposed ESM paradigm developed in our center represents a reliable method for preventing and predicting postsurgical motor deficits in all age groups of children. This novel ESM protocol may increase the safety and possibly also the completeness of epilepsy surgery. It could be adopted in pediatric epilepsy surgery centers.
Robert Lesko, Barbora Benova, Petr Jezdik, Petr Liby, Alena Jahodova, Martin Kudr, Michal Tichy, Josef Zamecnik and Pavel Krsek
In 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.
Over 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.
Patients 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.
Intraoperative 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.