Improved outcomes in pediatric epilepsy surgery: the UCLA experience, 1986-2008

Impact of epilepsy surgery on developmental trajectories of children under 3 years of age

AIM

To investigate the developmental effects of epilepsy surgery in young children.

METHOD

This study retrospectively reviewed 315 consecutive children under 3 years of age, and ultimately included 89 children (48 males, 41 females) with pre- and postsurgery developmental evaluations.

RESULTS

The mean general quotient before surgery was 46.7 (SD 24.7). Before surgery, the general quotient decreased in 77.6% of patients, while after surgery it increased in 55.1%. Furthermore, 70% of those 20 patients whose presurgical general quotient decreased by more than 10 points experienced positive changes. General quotient scores decreased in 15 out of the 22 patients classified in the normal/marginal presurgical category. Children who underwent surgery before the age of 12 months had a median gain in general quotient score by 7.6. Short-term general quotient scores were highly correlated with long-term scores (r = 0.909, p < 0.001).

INTERPRETATION

Surgical intervention was more inclined to positively impact developmental trajectories within a short postsurgical period, particularly among those affected by severe epileptic activity. However, in children with relatively typical development, certain developmental setbacks may arise. Postsurgical short-term developmental outcomes could predict longer-term outcomes.

Simultaneous 18F-FDG PET/MRI predicting favourable surgical outcome in refractory epilepsy patients

OBJECTIVES

To evaluate the (1) successful surgery proportion in patients with clear structural lesions on MRI and single abnormality on 18F-fluorodeoxyglucose positron emission tomography/Magnetic resonance imaging (18F-FDG PET/MRI); (2) predictive value of 18F-FDG PET/MRI for postsurgical outcome in refractory epilepsy patients.

METHODS

A retrospective study was conducted on 123 patients diagnosed with refractory epilepsy who underwent presurgical evaluation involving 18F-FDG PET/MRI and were followed for one-year post-surgery. Two neuroradiologists interpreted the PET/MRI images using visual analysis and an asymmetry index based on the standard uptake value. The Engel classification was used to assess surgical outcomes one-year post-surgery. Prognostic factors predicting post-surgical seizure outcomes were explored using univariate and binary logistic regression.

RESULTS

Definitely single lesion abnormality was observed in 35.0% (43/123) of the patients on the MRI portion of PET/MRI. The proportion increased to 74.0% (91/123) when 18 F-FDG PET portion was added. About 75% (69/91) of patients displaying a clear-cut lesion on 18 F-FDG PET/MRI were classified as Engel Class I one-year post-surgery. The proportion of Engel Class I patients was not significantly different when comparing MRI-single lesion patients with MRI-negative, PET-single lesion patients one year after surgery (81.4% vs. 70.0%, P = 0.24). Binary logistic regression analysis revealed that the detection of a clear single lesion on 18 F-FDG PET/MRI was a strong positive predictor of a favorable surgical outcome (OR 3.518, 95% CI 1.363-9.077, p = 0.009).

CONCLUSION

Single lesion detected on 18 F-FDG PET/MRI is useful to predict good surgical outcome for refractory epilepsy patients; Those patients should be considered as candidates for surgery.

Epilepsy surgery for children with epileptic spasms: A systematic review and meta-analysis with focus on predictors and outcomes

To conduct a systematic review of the literature regarding rates and predictors of favorable seizure outcome after resective surgery for epileptic spasms (ES) in pediatric patients. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards were followed. We searched PubMed, EMBASE, and Cochrane CENTRAL for articles published on the prevalence or incidence of epileptic spasm since 1985. Abstract, full-text review, and data extraction were conducted by two independent reviewers. Meta-analysis was performed to assess overall seizure freedom rate. Subject-level analysis was performed on a subset of studies to identify prognostic indicators. A total of 21 retrospective studies (n = 531) were included. Meta-analysis of all studies demonstrated a pooled seizure freedom rate of 68.8%. Subject-level analysis on 18 studies (n = 360) demonstrated a significant association between duration of spasms and recurrence of spasms after surgery, with an estimated increased risk of 7% per additional year of spasms prior to operation. Patients who underwent resective surgery that was not a hemispherectomy (i.e., lobectomy, lesionectomy, etc.) had an increased recurrence risk of 57% compared to patients who had undergone hemispherectomy. Resective surgery results in seizure freedom for the majority of pediatric patients with epileptic spasms. Patients who undergo hemispherectomy have lower risk of recurrence than patients who undergo other types of surgical resection. Increased duration of spasms prior to surgery is associated with increased recurrence risk after surgery. PLAIN LANGUAGE SUMMARY: Children with epileptic spasms (ES) that do not respond to medications may benefit from surgical treatment. Our study reviewed existing research to understand how effective surgery is in treating ES in children and what factors predict better outcomes. Researchers followed strict guidelines to search for and analyze studies published since 1985, finding 21 studies with a total of 531 patients. They found that, on average, nearly 70% of children became seizure-free after surgery. Further individual analysis of 360 patients showed that longer duration of spasms before surgery increased the risk of spasms returning by 7% per year. Additionally, children who had less extensive surgeries, such as removal of only a specific part of the brain, had a 57% higher risk of seizure recurrence compared to those who had a hemispherectomy, which removed or disconnected half of the brain. Overall, the study concludes that surgery can often stop seizures, especially when more extensive surgery is performed and when the surgery is done sooner rather than later.

National 22-year epilepsy surgery landscape shows increasing open and minimally invasive pediatric epilepsy surgery

OBJECTIVES

A surgical "treatment gap" in pediatric epilepsy persists despite the demonstrated safety and effectiveness of surgery. For this reason, the national surgical landscape should be investigated such that an updated assessment may more appropriately guide health care efforts.

METHODS

In our retrospective cross-sectional observational study, the National Inpatient Sample (NIS) database was queried for individuals 0 to <18 years of age who had an International Classification of Diseases (ICD) code for drug-resistant epilepsy (DRE). This cohort was then split into a medical group and a surgical group. The former was defined by ICD codes for -DRE without an accompanying surgical code, and the latter was defined by DRE and one of the following epilepsy surgeries: any open surgery; laser interstitial thermal therapy (LITT); vagus nerve stimulation; or responsive neurostimulation (RNS) from 1998 to 2020. Demographic variables of age, gender, race, insurance type, hospital charge, and hospital characteristics were analyzed between surgical options. Continuous variables were analyzed with weight-adjusted quantile regression analysis, and categorical variables were analyzed by weight-adjusted counts with percentages and compared with weight-adjusted chi-square test results.

RESULTS

These data indicate an increase in epilepsy surgeries over a 22-year period, primarily due to a statistically significant increase in open surgery and a non-significant increase in minimally invasive techniques, such as LITT and RNS. There are significant differences in age, race, gender, insurance type, median household income, Elixhauser index, hospital setting, and size between the medical and surgical groups, as well as the procedure performed.

SIGNIFICANCE

An increase in open surgery and minimally invasive surgeries (LITT and RNS) account for the overall rise in pediatric epilepsy surgery over the last 22 years. A positive inflection point in open surgery is seen in 2005. Socioeconomic disparities exist between medical and surgical groups. Patient and hospital sociodemographics show significant differences between the procedure performed. Further efforts are required to close the surgical "treatment gap."

Seizure Control Outcomes following Resection of Cortical Dysplasia in Patients with DEPDC5 Variants: A Systematic Review and Individual Patient Data Analysis

There is insufficient evidence regarding the efficacy of epilepsy surgery in patients with pharmacoresistant focal epilepsy and coexistent DEPDC5 (dishevelled EGL-10 and pleckstrin domain-containing protein 5) pathogenic (P), likely pathogenic (LP), or variance of unknown significance (VUS) variants. To conduct a systematic review on the literature regarding the use and efficacy of epilepsy surgery as an intervention for patients with DEPDC5 variants who have pharmacoresistant epilepsy. A systematic review of the current literature published regarding the outcomes of epilepsy surgery for patients with DEPDC5 variants was conducted. Demographics and individual patient data were recorded and analyzed. Subsequent statistical analysis was performed to assess significance of the findings. A total of eight articles comprising 44 DEPDC5 patients with genetic variants undergoing surgery were included in this study. The articles primarily originated in high-income countries (5/8, 62.5%). The average age of the subjects was 10.06 ± 9.41 years old at the time of study. The most common form of epilepsy surgery was focal resection (38/44, 86.4%). Thirty-seven of the 40 patients (37/40, 92.5%) with reported seizure frequency results had improvement. Twenty-nine out of 38 patients (29/38, 78.4%) undergoing focal resection achieved Engel Score I postoperatively, and two out of four patients achieved International League Against Epilepsy I (50%). Epilepsy surgery is effective in patients with pharmacoresistant focal epilepsy and coexistent DEPDC5 P, LP, or VUS variants.

Pediatric epilepsy surgery from 2000 to 2018: Changes in referral and surgical volumes, patient characteristics, genetic testing, and postsurgical outcomes

OBJECTIVE

Neurosurgery is a safe and effective form of treatment for select children with drug-resistant epilepsy. Still, there is concern that it remains underutilized, and that seizure freedom rates have not improved over time. We investigated referral and surgical practices, patient characteristics, and postoperative outcomes over the past two decades.

METHODS

We performed a retrospective cohort study of children referred for epilepsy surgery at a tertiary center between 2000 and 2018. We extracted information from medical records and analyzed temporal trends using regression analyses.

RESULTS

A total of 1443 children were evaluated for surgery. Of these, 859 (402 females) underwent surgical resection or disconnection at a median age of 8.5 years (interquartile range [IQR] = 4.6-13.4). Excluding palliative procedures, 67% of patients were seizure-free and 15% were on no antiseizure medication (ASM) at 1-year follow-up. There was an annual increase in the number of referrals (7%, 95% confidence interval [CI] = 5.3-8.6; p < .001) and surgeries (4% [95% CI = 2.9-5.6], p < .001) over time. Duration of epilepsy and total number of different ASMs trialed from epilepsy onset to surgery were, however, unchanged, and continued to exceed guidelines. Seizure freedom rates were also unchanged overall but showed improvement (odds ratio [OR] 1.09, 95% CI = 1.01-1.18; p = .027) after adjustment for an observed increase in complex cases. Children who underwent surgery more recently were more likely to be off ASMs postoperatively (OR 1.04, 95% CI = 1.01-1.08; p = .013). There was a 17% annual increase (95% CI = 8.4-28.4, p < .001) in children identified to have a genetic cause of epilepsy, which was associated with poor outcome.

SIGNIFICANCE

Children with drug-resistant epilepsy continue to be put forward for surgery late, despite national and international guidelines urging prompt referral. Seizure freedom rates have improved over the past decades, but only after adjustment for a concurrent increase in complex cases. Finally, genetic testing in epilepsy surgery patients has expanded considerably over time and shows promise in identifying patients in whom surgery is less likely to be successful.

Multivariate analysis of seizure outcomes after resective surgery for focal epilepsy: a single-center study on 833 patients

The predictors of seizure outcomes after resective surgery for focal epilepsy, for an update on the features of good and poor outcomes, are investigated. A retrospective study of patients with focal epilepsy undergoing resective surgery from March 2011 to April 2019 was performed. There were 3 groups according to the seizure outcomes: seizure freedom, seizure improvement, and no improvement. Predictors of seizure outcomes were identified by multivariate logistic regression analysis. Of all 833 patients, 561 (67.3%) patients remained seizure-free at the last follow-up, 203 (24.4%) patients had seizure improvement, and 69 (8.3%) had no improvement. The mean follow-up duration was 5.2 years (range: 2.7 to 9.6). Predictors of better outcomes included epilepsy duration < 5 years, localized discharge, no. of antiepileptic drugs at surgery < 3, and temporal lobe resection. However, predictors of worse outcomes included intracranial hemorrhage in infancy, interictal abnormal discharge, intracranial electrode monitoring, and acute postoperative seizure. Our study suggests that resective surgery for focal epilepsy has satisfactory outcomes. Short epilepsy duration, localized discharge, and temporal lobe resection are positive predictors of seizure freedom. Patients with these predictors are intensively recommended for surgery.

Number of epilepsy surgeries has decreased despite an increase in pre-surgical evaluations at a tertiary pediatric epilepsy center in Ontario

OBJECTIVE

A recent U.S. study reported that the number of epilepsy surgeries has remained stable or declined in recent years despite an increase in pre-surgical evaluation. This study aimed to evaluate trends in pre-surgical evaluation and epilepsy surgery from 2001 to 2019 and to determine whether these trends have changed in the later period (2014-2019) compared to earlier period (2001-2013).

METHODS

This study evaluated trends in pre-surgical evaluation and epilepsy surgery at a tertiary pediatric epilepsy center. Children with drug resistant epilepsy who were evaluated for surgery were included. Clinical data, reasons for not undergoing surgery, and surgical characteristics of surgery patients were collected. Overall trends and trends in later period compared to earlier period for pre-surgical evaluation and epilepsy surgery were assessed.

RESULTS

There were 1151 children who were evaluated for epilepsy surgery and 546 underwent surgery. There was an upward trend in pre-surgical evaluation in the earlier period (rate ratio [RR]=1.04 (95%CI:1.02-1.07), p<0.001) and the trajectory of presurgical evaluation in the later period was not significantly different to the earlier period (RR=1.00 [95%CI:0.95-1.06], p = 0.88). Among the reasons for not undergoing surgery, failure to localize the seizures occurred more frequently in later period than earlier period (22.6% vs. 17.1% respectively, p = 0.024). For number of surgeries, there was an upward trend between 2001 and 2013 (RR=1.08 [95%CI:1.05-1.11], p<0.001), and a decreasing trend in the later period compared to earlier period (RR=0.91 [95%CI:0.84-0.99], p = 0.029).

CONCLUSION

Despite an increasing trend in pre-surgical evaluation, there was a decreasing trend in the number of epilepsy surgery in the later period as there was a larger proportion of patients in whom the seizures could not be localized. Trends in presurgical evaluation and epilepsy surgery will continue to evolve with introduction of technologies such as stereo-EEG and minimally invasive laser therapy.

Trajectory of Health-Related Quality of Life After Pediatric Epilepsy Surgery

Importance

Health-related quality of life (HRQOL) is regarded as a key outcome for evaluating treatment efficacy. However, it is uncertain how HRQOL evolves after epilepsy surgery compared with medical therapy, such as whether it continues to improve over time, improves and then remains stable, or deteriorates after a period of time.

Objective

To assess trajectory of HRQOL over 2 years in children with drug-resistant epilepsy (DRE) treated with surgery compared with medical therapy.

Design, Setting, and Participants

Prospective cohort study assessing HRQOL longitudinally over 2 years. Participants were children recruited from 8 epilepsy centers in Canada from 2014 to 2019 with suspected DRE aged 4 to 18 years who were evaluated for surgery. Data were analyzed from May 2014 to December 2021.

Exposures

Epilepsy surgery or medical therapy.

Main Outcomes and Measures

HRQOL was measured using the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE)-55. HRQOL and seizure frequency were assessed at baseline, 6-month, 1-year, and 2-year follow-ups. Clinical, parent, and family characteristics were assessed at baseline. A linear mixed model was used to evaluate HRQOL over time, adjusting for baseline clinical, parent, and family characteristics.

Results

There were 111 surgical and 154 medical patients (mean [SD] age at baseline was 11.0 [4.1] years; 118 [45%] were female). At baseline, HRQOL was similar among surgical and medical patients. HRQOL of surgical patients was 3.0 (95% CI, -0.7 to 6.8) points higher at 6-month, 4.9 (95% CI, 0.7 to 9.1) points higher at 1-year, and 5.1 (95% CI, 0.7 to 9.5) points higher at 2-year follow-ups compared with medical patients. Surgical patients experienced greater improvements in social functioning relative to medical patients, but not for cognitive, emotional, and physical functioning. At 2-year follow-up, 72% of surgical patients were seizure-free, compared with 33% of medical patients. Seizure-free patients reported higher HRQOL than those who were not.

Conclusions and Relevance

This study provided evidence on the association between epilepsy surgery and children's HRQOL, with improvement in HRQOL occurring within the first year and remaining stable 2 years after surgery. By demonstrating that surgery improved seizure freedom and HRQOL, which has downstream effects such as better educational attainment, reduced health care resource utilization, and health care cost, these findings suggest that the high costs of surgery are justified, and that improved access to epilepsy surgery is necessary.

Surgery for pediatric drug resistant epilepsy: a narrative review of its history, surgical implications, and treatment strategies

BACKGROUND AND OBJECTIVE

Drug-resistant epilepsy (DRE), also known as medically refractory epilepsy, is a disorder of high prevalence and negatively impacts a patients quality of life, neurodevelopment, and life expectancy. Pediatric epilepsy surgery has been conducted since the late 1800s, and randomized controlled trials have demonstrated the marked effectiveness of surgery on seizure reduction and the potential for cure. Despite the strong evidence for pediatric epilepsy surgery, there is also strong evidence describing its underutilization. The objective of this narrative review is to describe the history, strength, and limitations in the evidence of surgery for pediatric drug resistant epilepsy.

METHODS

This narrative review was conducted utilizing standard search engines to include the relevant articles on the topic of surgery for drug resistant epilepsy in children, with main keywords including surgery in pediatric epilepsy and drug-refractory epilepsy.

KEY CONTENT AND FINDINGS

The first components describe the historical perspective of pediatric epilepsy surgery and the evidence that highlight the strengths and limitations of epilepsy surgery. We then highlight the importance of presurgical referral and evaluation, followed by a section detailing the surgical options for children with DRE. Lastly, we provide a perspective on the future of pediatric epilepsy surgery.

CONCLUSIONS

Evidence supports the role for surgery in pediatric medically refractory epilepsy in seizure frequency reduction, improved curative rates, and improvements in neurodevelopment and quality of life.

Clinical profile and outcomes of epilepsy surgery in children from a tertiary epilepsy care center in India

INTRODUCTION

The present study aims to describe epilepsy surgery outcomes in the pediatric population from a tertiary center in India.

METHODOLOGY

Children less than 18 years who underwent epilepsy surgery between June 2015 and December 2019 for whom at least a 1-year follow-up was available, were retrospectively evaluated for clinical presentation, radiology, surgical intervention, and seizure outcomes.

OBSERVATIONS

Out of a total of 355 epilepsy surgeries performed, 242 were in the pediatric group (140 males, 80 females). The mean age at surgery was 9.4 years ±4.8 years (range 4 months-18 years). The mean duration of epilepsy was 5.64 years ±3.91 (range 2 months-17 years). 126 patients experienced daily seizures, 45 weekly and 39 reported monthly seizures. Six had refractory status epilepticus. All the patients were on multiple anti-epileptic drugs (AEDs): the mean number of AEDs was 3.27 ± 0.98 (range 2-7 AEDs). Focal seizure was the most common seizure type seen in 72.27% of children (159/220). The most frequent etiology was focal cortical dysplasia (70), followed by bilateral parieto-temporo-occipital gliosis (48). All the patients underwent standard pre-surgical evaluation. Eleven patients needed stage 2 evaluation (intracranial EEG). The different surgeries performed were electrocorticography (ECOG) and navigation-guided resection (65), anterior temporal lobectomy and hippocampectomy (ATLAH) (48), functional hemispherotomy (39), callosotomy (28), disconnection surgeries (16), and multilobar resection (12). Twelve patients underwent more than one surgery. The patients were followed up between a minimum of 12 months and a maximum of 66 months (median 32 months; IQR 20 months). Engel class 1 outcome was observed in 81.38% in definitive surgeries. Outcomes of temporal lobe (TL) surgeries (92.3%) were better compared to hemispheric (87.17%) and extratemporal lobe (ETL) surgeries (75.32%). We encountered unexpected transient motor deficits in 2 patients and culture-proven meningitis in 8 patients. Post-surgery drug freedom (P-value 0.003) was the most important factor for better developmental, cognitive and behavioral outcomes.

CONCLUSION

Epilepsy surgeries are safe and seizure outcomes are excellent in properly selected cases with thorough presurgical evaluation. Early referral to a tertiary epilepsy center is needed for timely intervention.

The role of neurosurgery in the management of tuberous sclerosis complex–associated epilepsy: a systematic review

OBJECTIVE

Tuberous sclerosis complex (TSC) is an autosomal dominant, multisystem neurocutaneous disorder associated with cortical tubers, brain lesions seen in nearly all patients with TSC, which are frequently epileptogenic. Seizures are often the earliest clinical manifestation of TSC, leading to epilepsy in over 70% of patients. Medical management with antiepileptic drugs constitutes early therapy, but over 50% develop medically refractory epilepsy, necessitating surgical evaluation and treatment. The objective of this study was to summarize the literature and report seizure outcomes following surgical treatment for TSC-associated epilepsy.

METHODS

A systematic literature review was performed in accordance with the PRISMA guidelines. The PubMed and Embase databases were searched for journal articles reporting seizure outcomes following epilepsy surgery in TSC patients. Included studies were placed into one of two groups based on the surgical technique used. Excellent and worthwhile seizure reductions were defined for each group as outcomes and extracted from each study.

RESULTS

A total of 46 studies were included. Forty of these studies reported seizure outcomes following any combination of resection, disconnection, and ablation on a collective 1157 patients. Excellent and worthwhile seizure reductions were achieved in 59% (683/1157) and 85% (450/528) of patients, respectively. Six of these studies reported seizure outcomes following treatment with neuromodulation. Excellent and worthwhile seizure reductions were achieved in 34% (24/70) and 76% (53/70) of patients, respectively.

CONCLUSIONS

Surgery effectively controls seizures in select patients with TSC-associated epilepsy, but outcomes vary. Further understanding of TSC-associated epilepsy, improving localization strategies, and emerging surgical techniques represent promising avenues for improving surgical outcomes.

Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion

BACKGROUND

Hemispherectomy and its modern variants are effective surgical treatments for medically intractable unihemispheric epilepsy. Although some complications such as posthemispherectomy hydrocephalus are well documented, midline brain shift (MLBS) after hemispheric surgery has only been described anecdotally and never formally studied.

OBJECTIVE

To assess the natural history and clinical relevance of MLBS and determine whether cerebrospinal fluid (CSF) shunting of the ipsilateral surgical cavity exacerbates MLBS posthemispheric surgery.

METHODS

A retrospective review of consecutive pediatric patients who underwent hemispheric surgery for intractable epilepsy and at least 6 months of follow-up at UCLA between 1994 and 2018 was performed. Patients were grouped by MLBS severity, shunt placement, valve type, and valve opening pressure (VOP). MLBS was evaluated using the paired samples t-test and analysis of covariance adjusting for follow-up time and baseline postoperative MLBS.

RESULTS

Seventy patients were analyzed, of which 23 (33%) required CSF shunt placement in the ipsilateral surgical cavity for posthemispherectomy hydrocephalus. MLBS increased between first and last follow-up for nonshunted (5.3 ± 4.9-9.7 ± 6.6 mm, P < .001) and shunted (6.6 ± 3.5-16.3 ± 9.4 mm, P < .001) patients. MLBS progression was greater in shunted patients (P = .001). Shunts with higher VOPs did not increase MLBS relative to nonshunted patients (P = .834), whereas MLBS increased with lower VOPs (P = .001). Severe MLBS was associated with debilitating headaches (P = .048).

CONCLUSION

Patients undergoing hemispheric surgery often develop postoperative MLBS, ie, exacerbated by CSF shunting of the ipsilateral surgical cavity, specifically when using lower VOP settings. MLBS exacerbation may be related to overshunting. Severe MLBS is associated with debilitating headaches.

Machine Learning Approaches for Imaging-Based Prognostication of the Outcome of Surgery for Mesial Temporal Lobe Epilepsy

Objectives

Around 30% of patients undergoing surgical resection for drug‐resistant mesial temporal lobe epilepsy (MTLE) do not obtain seizure freedom. Success of anterior temporal lobe resection (ATLR) critically depends on the careful selection of surgical candidates, aiming at optimizing seizure freedom while minimizing postoperative morbidity. Structural MRI and FDG‐PET neuroimaging are routinely used in presurgical assessment and guide the decision to proceed to surgery. In this study, we evaluate the potential of machine learning techniques applied to standard presurgical MRI and PET imaging features to provide enhanced prognostic value relative to current practice.

Methods

Eighty two patients with drug resistant MTLE were scanned with FDG‐PET pre‐surgery and T1‐weighted MRI pre‐ and postsurgery. From these images the following features of interest were derived: volume of temporal lobe (TL) hypometabolism, % of extratemporal hypometabolism, presence of contralateral TL hypometabolism, presence of hippocampal sclerosis, laterality of seizure onset volume of tissue resected and % of temporal lobe hypometabolism resected. These measures were used as predictor variables in logistic regression, support vector machines, random forests and artificial neural networks.

Results

In the study cohort, 24 of 82 (28.3%) who underwent an ATLR for drug‐resistant MTLE did not achieve Engel Class I (i.e., free of disabling seizures) outcome at a minimum of 2 years of postoperative follow‐up. We found that machine learning approaches were able to predict up to 73% of the 24 ATLR surgical patients who did not achieve a Class I outcome, at the expense of incorrect prediction for up to 31% of patients who did achieve a Class I outcome. Overall accuracies ranged from 70% to 80%, with an area under the receiver operating characteristic curve (AUC) of .75–.81. We additionally found that information regarding overall extent of both total and significantly hypometabolic tissue resected was crucial to predictive performance, with AUC dropping to .59–.62 using presurgical information alone. Incorporating the laterality of seizure onset and the choice of machine learning algorithm did not significantly change predictive performance.

Significance

Collectively, these results indicate that "acceptable" to "good" patient‐specific prognostication for drug‐resistant MTLE surgery is feasible with machine learning approaches utilizing commonly collected imaging modalities, but that information on the surgical resection region is critical for optimal prognostication.

Predictors of longitudinal seizure outcomes after epilepsy surgery in childhood

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Long term seizure outcome in children following epilepsy surgery is favorable.

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Histopathology is an independent determinant of long-term seizure outcome.

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Long-term seizure outcome remains stable in children with tumours and FCD type 2b, whereas seizure freedom declines with time in children with other types of FCD and cortical malformations.

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Children with moderate to severe developmental disability and younger age of seizure onset have higher seizure recurrence reflecting broader epileptic networks.

There is a paucity of data on longitudinal seizure outcome of children undergoing epilepsy surgery. All children (n = 132) who underwent resective epilepsy surgery from January 1998 to December 2015 were identified. Relevant clinical, neurophysiological, imaging, surgical and seizure outcome data were extracted. Multivariable logistic regression analysis and Kaplan-Meier survival with Cox proportional hazard modelling were performed. The mean age at surgery was 7.8 years (range 0.2–17.9). 71% were seizure-free at a mean follow up of 5.3 ± 2.7 years. Of those who were seizure-free, 65 patients were able to completely wean off anti- seizure medications successfully. Using survival analysis, the probability of Engel Class I outcome at one year after surgery was 81% (95% confidence interval [CI] 87%–75%). This dropped to 73% at two years (95% CI 81%–65%), 58% at five years (95% CI 67.8%–48%), and 47% at ten years. Proportional hazard modelling showed that the presence of moderate to severe developmental disability (HR 6.5; p = 0.02) and lack of complete resection (HR 0.4; p = 0.02) maintain association as negative predictors of seizure-free outcome. Our study demonstrates favorable long-term seizure control following pediatric epilepsy surgery and highlights important predictors of seizure outcome guiding case selection and counseling of expectations prior to surgery.

The Missed Value of Underutilizing Pediatric Epilepsy Surgery: A Systematic Review

Pediatric epilepsy surgery is underutilized. Only 1%-11% of children with drug resistant epilepsy (DRE) undergo surgical treatment, or less than half of those estimated to benefit. We conducted a systematic review of articles published in PubMed, EMBASE, and Web of Science in order to study the factors related to surgery underutilization as well as the impact on both the individual and the healthcare system. Our review demonstrates multiple factors leading to underutilization, including family misconceptions about epilepsy surgery, lack of provider knowledge, as well as systemic health disparities. While the upfront cost of epilepsy surgery is significant, the long-term financial benefits and reduced health resource utilization tilt the economic advantage in favor of surgery in children with DRE. Additionally, timely interventions improve seizure and cognitive outcomes with low risk of complications. Further interventions are needed at the levels of family, provider, and the healthcare system to increase access to pediatric epilepsy surgery.

Pediatric Epilepsy Surgery: Indications and Evaluation

Epilepsy is a common neurological condition in children. It is usually amenable to drug therapy. However, nearly one-third of patients may be refractory to antiseizure drugs. Poor compliance and nonepileptic events should be ruled out as possible causes of drug-resistant epilepsy (DRE). After failing adequate trials of two appropriate antiseizure drugs, patients with focal DRE or poorly classifiable epilepsy or epileptic encephalopathy with focal electro-clinical features should be worked up for surgical candidacy. A randomized controlled trial provided a class I evidence for epilepsy surgery in pediatric DRE. Pre-surgical screening workup typically includes a high-resolution epilepsy protocol brain magnetic resonance imaging (MRI) and a high-quality in-patient video electroencephalography evaluation. Advanced investigations such as positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetoencephalography (MEG) may be required in selected cases especially when brain MRI is normal, and further evidence for anatomo-electro-clinical concordance is necessary to refine candidacy for surgery and surgical strategy. Some children may also need functional MRI to map eloquent regions of interest such as motor, sensory, and language functions to avoid unacceptable neurological deficits after surgery. Selected children may need invasive long-term electroencephalographic monitoring using stereotactically implanted intracranial depth electrodes or subdural grids. Surgical options include resective surgeries (lesionectomy, lobectomy, multilobar resections) and disconnective surgeries (corpus callosotomy, etc.) with the potential to obtain seizure freedom. Other surgical procedures, typically considered to be palliative are neuromodulation [deep brain stimulation (DBS), vagal nerve stimulation (VNS), and responsive neural stimulation (RNS)]. DBS and RNS are currently not approved in children. Pediatric DRE should be evaluated early considering the risk of epileptic encephalopathy and negative impact on cognition.

Antiseizure Medication Withdrawal Following Epilepsy Surgery

As pediatric epilepsy surgery cases increase in number and complexity, there remains a paucity of data regarding how, when, and in whom to discontinue antiseizure medications postoperatively. The "TimeToStop" data has been influential to clinical practice, revealing that while early discontinuation of antiseizure medications may reveal surgical failures earlier, it does not ultimately lead to a change in long-term seizure outcomes. The authors of other studies have also shown cognitive improvements in children for whom medications were discontinued postoperatively. Survey results over the last 2 decades have shown that clinicians have started to discontinue antiseizure medications earlier. This is an individualized decision with numerous factors to consider. Further research is needed to explore the optimal timing of medication discontinuation in this heterogeneous population of children undergoing epilepsy surgery.

GATOR1-related focal cortical dysplasia in epilepsy surgery patients and their families: A possible gradient in severity?

BACKGROUND

Variants of GATOR1-genes represent a recognised cause of focal cortical dysplasia (FCD), the most common structural aetiology in paediatric drug-resistant focal epilepsy. Reports on familial cases of GATOR1-associated FCD are limited, especially with respect to epilepsy surgery outcomes.

METHODS

We present phenotypical manifestations of four unrelated patients with drug-resistant focal epilepsy, FCD and a first-degree relative with epilepsy. All patients underwent targeted gene panel sequencing as a part of the presurgical work up. Literature search was performed to compare our findings to previously published cases.

RESULTS

The children (probands) had a more severe phenotype than their parents, including drug-resistant epilepsy and developmental delay, and they failed to achieve seizure freedom post-surgically. All patients had histopathologically confirmed FCD (types IIa, IIb, Ia). In Patient 1 and her affected father, we detected a known pathogenic NPRL2 variant. In patients 2 and 3 and their affected parents, we found novel likely pathogenic germline DEPDC5 variants. In family 4, we detected a novel variant in NPRL3. We identified 15 additional cases who underwent epilepsy surgery for GATOR1-associated FCD, with a positive family history of epilepsy in the literature; in 8/13 tested, the variant was inherited from an asymptomatic parent.

CONCLUSION

The presented cases displayed a severity gradient in phenotype with children more severely affected than the parents. Although patients with GATOR1-associated FCD are considered good surgical candidates, post-surgical seizure outcome was poor in our familial cases, suggesting that accurate identification of the epileptogenic zone may be more challenging in this subgroup of patients.

Multilobar Epilepsy Surgery in Childhood and Adolescence: Predictors of Long-Term Seizure Freedom

BACKGROUND

Although multilobar resections correspond to one-fifth of pediatric epilepsy surgery, there are little data on long-term seizure control.

OBJECTIVE

To investigate the long-term seizure outcomes of children and adolescents undergoing multilobar epilepsy surgery and identify their predictors.

METHODS

In this retrospective study, we considered 69 consecutive patients that underwent multilobar epilepsy surgery at the age of 10.0 ± 5.0 yr (mean ± SD). The magnetic resonance imaging revealed a lesion in all but 2 cases. Resections were temporo-parieto(-occipital) in 30%, temporo-occipital in 41%, parieto-occipital in 16%, and fronto-(temporo)-parietal in 13% cases. Etiologies were determined as focal cortical dysplasia in 67%, perinatal or postnatal ischemic lesions in 23%, and benign tumors in 10% of cases.

RESULTS

At last follow-up of median 9 yr (range 2.8-14.8), 48% patients were seizure free; 33% were off antiepileptic drugs. 10% of patients, all with dysplastic etiology, required reoperations: 4 of 7 achieved seizure freedom. Seizure recurrence occurred mostly (80%) within the first 6 mo. Among presurgical variables, only an epileptogenic zone far from eloquent cortex independently correlated with significantly higher rates of seizure arrest in multivariate analysis. Among postsurgical variables, the absence of residual lesion and of acute postsurgical seizures was independently associated with significantly higher rates of seizure freedom.

CONCLUSION

Our study demonstrates that multilobar epilepsy surgery is effective regarding long-term seizure freedom and antiepileptic drug withdrawal in selected pediatric candidates. Epileptogenic zones-and lesions-localized distant from eloquent cortex and, thus, fully resectable predispose for seizure control. Acute postsurgical seizures are critical markers of seizure recurrence that should lead to prompt reevaluation.

Focal cortical dysplasia: etiology, epileptogenesis, classification, clinical presentation, imaging, and management

BACKGROUND

Focal cortical dysplasia (FCD) is the most prevalent cause of intractable epilepsy in children. It was first described by Taylor et al. in 1971. In 2011, the International League against Epilepsy described an international consensus of classification for FCD. However, the exact mechanism causing this pathology remains unclear. The diagnosis and recognition of FCD increase with the advances in neuroradiology and electrophysiology.

FOCUS OF REVIEW

In this paper, we discuss the literature regarding management of FCD with a focus on etiology, pathophysiology, classification, clinical presentation, and imaging modalities. We will also discuss certain variables affecting surgical outcome of patients with FCD.

CONCLUSION

Based on our review findings, it is concluded that surgical management with complete resection of the lesion following preoperative localization of the epileptogenic zone in patients with FCD subtypes can provide a seizure-free outcome.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Epilepsy surgery for Rasmussen encephalitis: the UCLA experience

OBJECTIVE

Rasmussen encephalitis (RE) is a rare inflammatory neurological disorder typically involving one hemisphere and resulting in drug-resistant epilepsy and progressive neurological decline. Here, the authors present seizure outcomes in children who underwent epilepsy surgery for RE at a single institution.

METHODS

The records of consecutive patients who had undergone epilepsy surgery for RE at the UCLA Mattel Children's Hospital between 1982 and 2018 were retrospectively reviewed. Basic demographic information, seizure history, procedural notes, and postoperative seizure and functional outcome data were analyzed.

RESULTS

The cohort included 44 patients, 41 of whom had sufficient data for analysis. Seizure freedom was achieved in 68%, 48%, and 22% of the patients at 1, 5, and 10 years, respectively. The median time to the first seizure for those who experienced seizure recurrence after surgery was 39 weeks (IQR 11-355 weeks). Anatomical hemispherectomy, as compared to functional hemispherectomy, was independently associated with a longer time to postoperative seizure recurrence (HR 0.078, p = 0.03). There was no statistically significant difference in postoperative seizure recurrence between patients with complete hemispherectomy and those who had less-than-hemispheric surgery. Following surgery, 68% of the patients could ambulate and 84% could speak regardless of operative intervention.

CONCLUSIONS

A large proportion of RE patients will have seizure relapse after surgery, though patients with anatomical hemispherectomies may have a longer time to postoperative seizure recurrence. Overall, the long-term data in this study suggest that hemispheric surgery can be seen as palliative treatment for seizures rather than a cure for RE.

'In the best case seizure-free' - Parental hopes and worries before and satisfaction after their child's epilepsy surgery

OBJECTIVE

The objective of this study was to gain a better understanding of parental hopes and worries before and subsequent experiences two years after their child had undergone epilepsy surgery.

METHODS

The parents of 107 children and young people who underwent epilepsy surgery at a single center completed surveys focusing on hopes and concerns before surgery and subsequent experiences at two-year follow-up. Responses were analyzed by thematic analysis.

RESULTS

Before surgery, parental hopes focus on not only seizure freedom or reduction but also potential improvements in child development and emotional-behavioral functioning. Worries before surgery include not only potential injury or loss of skills but also a concern that the surgical procedure would not lead to an improvement in the child's seizures. The vast majority of parents experienced positive aspects at the two-year follow-up including seizure freedom or reduction but also perceived improvements in behavior, development, and sleep. This suggests that for many, expectations for the surgery were met. A small number of parents reported negative effects of surgery including loss of skills, worsening/lack of improvement in seizure frequency, or negative impact on development.

SIGNIFICANCE

For the majority of parents whose children undergo surgery, expectations are met, and fears are not realized. Knowledge of parental hopes and worries before surgery as well as experiences after the operation is useful for improving pre- and postsurgical counseling.

Paroxysmal Discharges in Tissue Slices From Pediatric Epilepsy Surgery Patients: Critical Role of GABAB Receptors in the Generation of Ictal Activity

In the present study, we characterized the effects of bath application of the proconvulsant drug 4-aminopyridine (4-AP) alone or in combination with GABA_A and/or GABA_B receptor antagonists, in cortical dysplasia (CD type I and CD type IIa/b), tuberous sclerosis complex (TSC), and non-CD cortical tissue samples from pediatric epilepsy surgery patients. Whole-cell patch clamp recordings in current and voltage clamp modes were obtained from cortical pyramidal neurons (CPNs), interneurons, and balloon/giant cells. In pyramidal neurons, bath application of 4-AP produced an increase in spontaneous synaptic activity as well as rhythmic membrane oscillations. In current clamp mode, these oscillations were generally depolarizing or biphasic and were accompanied by increased membrane conductance. In interneurons, membrane oscillations were consistently depolarizing and accompanied by bursts of action potentials. In a subset of balloon/giant cells from CD type IIb and TSC cases, respectively, 4-AP induced very low-amplitude, slow membrane oscillations that echoed the rhythmic oscillations from pyramidal neurons and interneurons. Bicuculline reduced the amplitude of membrane oscillations induced by 4-AP, indicating that they were mediated principally by GABA_A receptors. 4-AP alone or in combination with bicuculline increased cortical excitability but did not induce seizure-like discharges. Ictal activity was observed in pyramidal neurons and interneurons from CD and TSC cases only when phaclofen, a GABA_B receptor antagonist, was added to the 4-AP and bicuculline solution. These results emphasize the critical and permissive role of GABA_B receptors in the transition to an ictal state in pediatric CD tissue and highlight the importance of these receptors as a potential therapeutic target in pediatric epilepsy.

Trends in pediatric epilepsy surgery in Europe between 2008 and 2015: Country-, center-, and age-specific variation

OBJECTIVE

To profile European trends in pediatric epilepsy surgery (<16 years of age) between 2008 and 2015.

METHODS

We collected information on volumes and types of surgery, pathology, and seizure outcome from 20 recognized epilepsy surgery reference centers in 10 European countries.

RESULTS

We analyzed retrospective aggregate data on 1859 operations. The proportion of surgeries significantly increased over time (P < .0001). Engel class I outcome was achieved in 69.3% of children, with no significant improvement between 2008 and 2015. The proportion of histopathological findings consistent with glial scars significantly increased between the ages of 7 and 16 years (P for trend = .0033), whereas that of the remaining pathologies did not vary across ages. A significant increase in unilobar extratemporal surgeries (P for trend = .0047) and a significant decrease in unilobar temporal surgeries (P for trend = .0030) were observed between 2008 and 2015. Conversely, the proportion of multilobar surgeries and unrevealing magnetic resonance imaging cases remained unchanged. Invasive investigations significantly increased, especially stereo-electroencephalography. We found different trends comparing centers starting their activity in the 1990s to those whose programs were developed in the past decade. Multivariate analysis revealed a significant variability of the proportion of the different pathologies and surgical approaches across countries, centers, and age groups between 2008 and 2015.

SIGNIFICANCE

Between 2008 and 2015, we observed a significant increase in the volume of pediatric epilepsy surgeries, stability in the proportion of Engel class I outcomes, and a modest increment in complexity of the procedures.

Pathological high frequency oscillations associate with increased GABA synaptic activity in pediatric epilepsy surgery patients

Pathological high-frequency oscillations (HFOs), specifically fast ripples (FRs, >250 Hz), are pathognomonic of an active epileptogenic zone. However, the origin of FRs remains unknown. Here we explored the correlation between FRs recorded with intraoperative pre-resection electrocorticography (ECoG) and spontaneous synaptic activity recorded ex vivo from cortical tissue samples resected for the treatment of pharmacoresistant epilepsy. The cohort included 47 children (ages 0.22-9.99 yr) with focal cortical dysplasias (CD types I and II), tuberous sclerosis complex (TSC) and non-CD pathologies. Whole-cell patch clamp recordings were obtained from pyramidal neurons and interneurons in cortical regions that were positive or negative for pathological HFOs, defined as FR band oscillations (250-500 Hz) at ECoG. The frequency of spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and IPSCs, respectively) was compared between HFO+ and HFO- regions. Regardless of pathological substrate, regions positive for FRs displayed significantly increased frequencies of sIPSCs compared with regions negative for FRs. In contrast, the frequency of sEPSCs was similar in both regions. In about one third of cases (n = 17), pacemaker GABA synaptic activity (PGA) was observed. In the vast majority (n = 15), PGA occurred in HFO+ areas. Further, fast-spiking interneurons displayed signs of hyperexcitability exclusively in HFO+ areas. These results indicate that, in pediatric epilepsy patients, increased GABA synaptic activity is associated with interictal FRs in the epileptogenic zone and suggest an active role of GABAergic interneurons in the generation of pathological HFOs. Increased GABA synaptic activity could serve to dampen excessive excitability of cortical pyramidal neurons in the epileptogenic zone, but it could also promote neuronal network synchrony.

Cognitive performance in distinct groups of children undergoing epilepsy surgery-a single-centre experience

Background

We aimed first to describe trends in cognitive performance over time in a large patient cohort (n = 203) from a single tertiary centre for paediatric epilepsy surgery over the period of 16 years divided in two (developing—pre-2011 vs. established—post-2011). Secondly, we tried to identify subgroups of epilepsy surgery candidates with distinctive epilepsy-related characteristics that associate with their pre- and post-surgical cognitive performance. Thirdly, we analysed variables affecting pre-surgical and post-surgical IQ/DQ and their change (post- vs. pre-surgical).

Methods

We analysed IQ/DQ data obtained using standardized neuropsychological tests before epilepsy surgery and one year post-surgically, along with details of patient’s epilepsy, epilepsy surgery and outcomes in terms of freedom from seizures. Using regression analysis, we described the trend in post-operative IQ/DQ. Cognitive outcomes and the associated epilepsy- and epilepsy surgery-related variables were compared between periods before and after 2011. Using multivariate analysis we analysed the effect of individual variables on pre- and post-operative IQ/DQ and its change.

Results

Epilepsy surgery tends to improve post-surgical IQ/DQ, most significantly in patients with lower pre-surgical IQ/DQ, and post-surgical IQ/DQ strongly correlates with pre-surgical IQ/DQ (Rho = 0.888, p < 0.001). We found no significant difference in pre-, post-surgical IQ/DQ and IQ/DQ change between the periods of pre-2011 and post-2011 (p = 0.7, p = 0.469, p = 0.796, respectively). Patients with temporal or extratemporal epilepsy differed in their pre-surgical IQ/DQ (p = 0.001) and in IQ/DQ change (p = 0.002) from those with hemispheric epilepsy, with no significant difference in post-surgical IQ/DQ (p = 0.888). Groups of patients with different underlying histopathology showed significantly different pre- and post-surgical IQ/DQ (p < 0.001 and p < 0.001 respectively) but not IQ/DQ change (p = 0.345).Variables associated with severe epilepsy showed effect on cognitive performance in multivariate model.

Discussion

Post-surgical IQ/DQ strongly correlates with pre-surgical IQ/DQ and greatest IQ/DQ gain occurs in patients with lower pre-surgical IQ/DQ scores. Cognitive performance was not affected by changes in paediatric epilepsy surgery practice. Pre- and post-operative cognitive performances, as well as patients’ potential for cognitive recovery, are highly dependent on the underlying aetiology and epileptic syndrome.

Genotype-phenotype correlations in focal malformations of cortical development: a pathway to integrated pathological diagnosis in epilepsy surgery

Malformations of cortical development (MCD) comprise a broad spectrum of developmental brain abnormalities. Patients presenting with MCDs often suffer from drug-resistant focal epilepsy, and some become candidates for epilepsy surgery. Their likelihood of achieving freedom from seizures, however, remains uncertain, and depends in a major part on the underlying pathology. Tissue samples obtained in epilepsy surgery form the basis of definite histopathological diagnosis; however, new molecular genetic methods have not yet been implemented in diagnostic processes for MCD cases. Furthermore, it has not been completely understood how the underlying pathology affects patients' outcomes after epilepsy surgery. We performed a systematic literature review of studies describing both histopathological and molecular genetic findings in MCD, along with studies on epilepsy surgery outcomes. We aimed to correlate the genetic causes with the underlying morphological abnormalities in focal cortical malformations and to stress the importance of the underlying biology for patient management and counseling. From the summarized findings of multiple authors, it is obvious that MCD may have a diverse genetic background despite a similar or even identical histopathological picture. Even though most of their molecular genetic findings converge on various levels of the PI3K/AKT/mTOR pathway, the exact mechanisms underlying MCD formation have not yet been completely described or indeed how this pathway generates a diverse range of histological abnormalities. Based on our findings, we therefore propose that all patients diagnosed and operated for drug-resistant epilepsy should have an integrated molecular and pathological diagnosis similar to the current practice in brain tumor diagnostic processes that might lead to more accurate diagnosis and effective stratification of patients undergoing epilepsy surgery.

Surgery for epilepsy

BACKGROUND

This is an updated version of the original Cochrane review, published in 2015.Focal epilepsies are caused by a malfunction of nerve cells localised in one part of one cerebral hemisphere. In studies, estimates of the number of individuals with focal epilepsy who do not become seizure-free despite optimal drug therapy vary between at least 20% and up to 70%. If the epileptogenic zone can be located, surgical resection offers the chance of a cure with a corresponding increase in quality of life.

OBJECTIVES

The primary objective is to assess the overall outcome of epilepsy surgery according to evidence from randomised controlled trials.Secondary objectives are to assess the overall outcome of epilepsy surgery according to non-randomised evidence, and to identify the factors that correlate with remission of seizures postoperatively.

SEARCH METHODS

For the latest update, we searched the following databases on 11 March 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to March 08, 2019), ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP).

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs) that included at least 30 participants in a well-defined population (age, sex, seizure type/frequency, duration of epilepsy, aetiology, magnetic resonance imaging (MRI) diagnosis, surgical findings), with an MRI performed in at least 90% of cases and an expected duration of follow-up of at least one year, and reporting an outcome related to postoperative seizure control. Cohort studies or case series were included in the previous version of this review.

DATA COLLECTION AND ANALYSIS

Three groups of two review authors independently screened all references for eligibility, assessed study quality and risk of bias, and extracted data. Outcomes were proportions of participants achieving a good outcome according to the presence or absence of each prognostic factor of interest. We intended to combine data with risk ratios (RRs) and 95% confidence intervals (95% CIs).

MAIN RESULTS

We identified 182 studies with a total of 16,855 included participants investigating outcomes of surgery for epilepsy. Nine studies were RCTs (including two that randomised participants to surgery or medical treatment (99 participants included in the two trials received medical treatment)). Risk of bias in these RCTs was unclear or high. Most of the remaining 173 non-randomised studies followed a retrospective design. We assessed study quality using the Effective Public Health Practice Project (EPHPP) tool and determined that most studies provided moderate or weak evidence. For 29 studies reporting multivariate analyses, we used the Quality in Prognostic Studies (QUIPS) tool and determined that very few studies were at low risk of bias across domains.In terms of freedom from seizures, two RCTs found surgery (n = 97) to be superior to medical treatment (n = 99); four found no statistically significant differences between anterior temporal lobectomy (ATL) with or without corpus callosotomy (n = 60), between subtemporal or transsylvian approach to selective amygdalohippocampectomy (SAH) (n = 47); between ATL, SAH and parahippocampectomy (n = 43) or between 2.5 cm and 3.5 cm ATL resection (n = 207). One RCT found total hippocampectomy to be superior to partial hippocampectomy (n = 70) and one found ATL to be superior to stereotactic radiosurgery (n = 58); and another provided data to show that for Lennox-Gastaut syndrome, no significant differences in seizure outcomes were evident between those treated with resection of the epileptogenic zone and those treated with resection of the epileptogenic zone plus corpus callosotomy (n = 43). We judged evidence from the nine RCTs to be of moderate to very low quality due to lack of information reported about the randomised trial design and the restricted study populations.Of the 16,756 participants included in this review who underwent a surgical procedure, 10,696 (64%) achieved a good outcome from surgery; this ranged across studies from 13.5% to 92.5%. Overall, we found the quality of data in relation to recording of adverse events to be very poor.In total, 120 studies examined between one and eight prognostic factors in univariate analysis. We found the following prognostic factors to be associated with a better post-surgical seizure outcome: abnormal pre-operative MRI, no use of intracranial monitoring, complete surgical resection, presence of mesial temporal sclerosis, concordance of pre-operative MRI and electroencephalography, history of febrile seizures, absence of focal cortical dysplasia/malformation of cortical development, presence of tumour, right-sided resection, and presence of unilateral interictal spikes. We found no evidence that history of head injury, presence of encephalomalacia, presence of vascular malformation, and presence of postoperative discharges were prognostic factors of outcome.Twenty-nine studies reported multi-variable models of prognostic factors, and showed that the direction of association of factors with outcomes was generally the same as that found in univariate analyses.We observed variability in many of our analyses, likely due to small study sizes with unbalanced group sizes and variation in the definition of seizure outcome, the definition of prognostic factors, and the influence of the site of surgery AUTHORS' CONCLUSIONS: Study design issues and limited information presented in the included studies mean that our results provide limited evidence to aid patient selection for surgery and prediction of likely surgical outcomes. Future research should be of high quality, follow a prospective design, be appropriately powered, and focus on specific issues related to diagnostic tools, the site-specific surgical approach, and other issues such as extent of resection. Researchers should investigate prognostic factors related to the outcome of surgery via multi-variable statistical regression modelling, where variables are selected for modelling according to clinical relevance, and all numerical results of the prognostic models are fully reported. Journal editors should not accept papers for which study authors did not record adverse events from a medical intervention. Researchers have achieved improvements in cancer care over the past three to four decades by answering well-defined questions through the conduct of focused RCTs in a step-wise fashion. The same approach to surgery for epilepsy is required.

Evolution of pediatric epilepsy surgery program over 2000-2017: Improvement of care?

PURPOSE

We assessed trends in spectrum of candidates, diagnostic algorithm, therapeutic approach and outcome of a pediatric epilepsy surgery program between 2000 and 2017.

METHODS

All pediatric patients who underwent curative epilepsy surgery in Motol Epilepsy Center during selected period (n = 233) were included in the study and divided into two groups according to time of the surgery (developing program 2000-2010: n = 86, established program 2011-2017: n = 147). Differences in presurgical, surgical and outcome variables between the groups were statistically analyzed.

RESULTS

A total of 264 resections or hemispheric disconnections were performed (including 31 reoperations). In the later epoch median age of candidates decreased. Median duration of disease shortened in patients with temporal lobe epilepsy. Number of patients with non-localizing MRI findings (subtle or multiple lesions) rose, as well as those with epileptogenic zone adjacent to eloquent cortex. There was a trend towards one-step procedures guided by multimodal neuroimaging and intraoperative electrophysiology; long-term invasive EEG was performed in fewer patients. Subdural electrodes for long-term invasive monitoring were almost completely replaced by stereo-EEG. The number of focal resections and hemispherotomies rose over time. Surgeries were more often regarded complete. Histopathological findings of resected tissue documented developing spectrum of candidates. 82.0% of all children were seizure-free two years after surgery; major complications occurred in 4.6% procedures; both groups did not significantly differ in these parameters.

CONCLUSION

In the established pediatric epilepsy surgery program, our patients underwent epilepsy surgery at younger age and suffered from more complex structural pathology. Outcomes and including complication rate remained stable.

Multilobar Resections for 3T MRI-Negative Epilepsy: Worth the Trouble?

OBJECTIVE

Multilobar resection in magnetic resonance imaging (MRI)-negative drug-resistant epilepsy warrants attention because they account for up to one third of MRI-negative epilepsy surgery. Despite their high prevalence, data are sparse, and the risk/benefit ratio continues to be debated. The present study investigated the postoperative seizure outcomes in this especially challenging subgroup.

METHODS

We retrospectively analyzed the data of 4 consecutive patients with 3T MRI-negative findings and drug-resistant focal epilepsy who had undergone multilobar epilepsy surgery at our institution.

RESULTS

The mean age at first surgery was 28.5 years (range, 14-48); 1 patient required 2 consecutive reoperations. The final resection was in the frontotemporal and temporo-parieto-occipital regions in 2 patients each. Histopathological examination revealed mild malformations of cortical development in 2 patients and focal cortical dysplasia type Ia and type IIa in 1 patient each. At the last follow-up examination (median, 3.3 years; range, 1-11), 2 patients were completely seizure free (Engel class Ia), 1 patient had experienced some disabling seizures after surgery but had been free of disabling seizures for 2 years at the last follow-up examination (Engel class Ic), and 1 patient had experienced worthwhile improvement (Engel class IIb) and had been seizure free for 1 year at the last follow-up examination. No surgical complications developed.

CONCLUSIONS

Our results have demonstrated that multilobar epilepsy surgery is effective for lasting seizure control for selected 3T MRI-negative candidates, leading to favorable outcomes for all 4 of our patients. Comprehensive multimodal preoperative evaluation is a prerequisite for postoperative success. Reevaluation should be considered for patients with seizure recurrence, because reoperation could be especially beneficial for selected patients who have not responded to an initially limited resection.

Quality of Life After Epilepsy Surgery in Children: A Systematic Review and Meta-Analysis

BACKGROUND

Pediatric epilepsy surgery is a treatment modality appropriate for select patients with debilitating medication-resistant seizures. Previous publications have studied seizure freedom as the main outcome of epilepsy surgery. However, there has been no systematic assessment of the postoperative life quality for these children.

OBJECTIVE

To estimate the quality of life (QOL) long-term outcomes after surgery for intractable epilepsy in pediatric patients.

METHODS

A systematic search of the PubMed and Cochrane databases was performed. Studies reporting questionnaire-assessed QOL at least 12 months postoperatively were included. QOL means and standard deviations were compared between surgically and medically managed patients, between the preoperative and postoperative state of each patient, and were further stratified into patients achieving seizure freedom, and those who did not. Meta-analysis was performed using fixed effects models for weighted mean differences (WMD), 95% confidence intervals (CI) and sensitivity analyses. Funnel plots and Begg's tests were utilized to detect publication bias.

RESULTS

The search yielded 18 retrospective studies, reporting 890 surgical patients. Following epilepsy surgery, children had significant QOL improvement compared to their preoperative state (WMD: 16.71, 95% CI: 12.19-21.22, P < .001) and better QOL than matched medically treated controls (WMD: 12.42, 95% CI: 6.25-18.58, P < .001). Patients achieving total seizure freedom after surgery had significant postoperative QOL improvement (WMD: 16.12, 95% CI: 7.98-24.25, P < .001), but patients not achieving seizure freedom did not achieve statistical significance (P = .79).

CONCLUSION

Epilepsy surgery can effectively improve QOL in children with medication-resistant seizures, through seizure freedom, which was associated with the greatest improvement in life quality.

Long-term seizure outcome in pediatric patients with focal cortical dysplasia undergoing tailored and standard surgical resections

PURPOSE

Focal cortical dysplasia (FCD) is the major cause of focal intractable epilepsy in childhood. Here we analyze the factors influencing the success of surgical treatment in a large cohort of children with histologically ascertained FCD.

METHOD

A retrospective study of the effects of FCD type, surgical intervention, and age at surgery in a pediatric cohort.

RESULTS

A total of 113 patients (71 male; mean age at surgery 10.3 years; range 0-18) were analyzed; 45 had undergone lesionectomy, 42 lobectomy, 18 multi-lobectomy, and eight hemispherotomy. Complete seizure control (Engel Ia) was achieved in 56% after two years, 52% at five years, and 50% at last follow-up (18-204 months). Resections were more extensive in younger patients (40% of the surgeries affecting more than one lobe in patients aged nine years or younger vs. 22% in patients older than nine years). While resections were more limited in older children, their long-term outcome tended to be superior (42% seizure freedom in patients aged nine years or younger vs. 56% in patients older than nine years). The outcome in FCD I was not significantly inferior to that in FCD II.

CONCLUSIONS

Our data confirm the long-term efficacy of surgery in children with FCD and epilepsy. An earlier age at surgery within this cohort did not predict a better long-term outcome, but it involved less-tailored surgical approaches. The data suggest that in patients with an unclear extent of the dysplastic area, later resections may offer advantages in terms of the precision of surgical-resection planning.

Postoperative seizure outcome and timing interval to start antiepileptic drug withdrawal: A retrospective observational study of non-neoplastic drug resistant epilepsy

This study aimed to investigate the impact of timing interval to start AED withdraw (TIW) after surgery on the seizure outcome in non-neoplastic drug resistant epilepsy (DRE). TIW were divided into three groups (respectively,<1 year, 1-<2 years, and ≥2 years). The seizure outcome at the different time points after starting AED withdrawal were compared among three groups. Other factors that related to seizure recurrence and TIW were included into the multiple analysis to investigate the predictors of seizure-free. Altogether, 205 patients were involved in the study. 102 individuals (50%) had seizure recurrence and 127 (62%) had seizure-free at the final follow up. 115 of them have attempted AED reduction and had not seizure recurrence before AED reduction. The rate of seizure-free had no significant difference among people with different TIW. Multiple analysis indicated that temporal surgery is a favorable predictor of seizure-free at the first year after starting AED withdrawal, and preoperative secondary generalized seizures is an unfavorable predictor of seizure-free at the final follow up. In patients with non-neoplastic DRE, TIW is not the mainly influence factor on seizure outcome, however, preoperative secondary generalized seizures and extra-temporal surgery are negatively associated with seizure-free.

Cellular antiseizure mechanisms of everolimus in pediatric tuberous sclerosis complex, cortical dysplasia, and non-mTOR-mediated etiologies

The present study was designed to examine the potential cellular antiseizure mechanisms of everolimus, a mechanistic target of rapamycin (mTOR) pathway blocker, in pediatric epilepsy cases. Cortical tissue samples obtained from pediatric patients (n = 11, ages 0.67–6.75 years) undergoing surgical resections for the treatment of their pharmacoresistant epilepsy were examined electrophysiologically in ex vivo slices. The cohort included mTOR‐mediated pathologies (tuberous sclerosis complex [TSC] and severe cortical dysplasia [CD]) as well as non–mTOR‐mediated pathologies (tumor and perinatal infarct). Bath application of everolimus (2 μm) had practically no effect on spontaneous inhibitory postsynaptic activity. In contrast, long‐term application of everolimus reduced spontaneous excitatory postsynaptic activity, burst discharges induced by blockade of γ‐aminobutyric acid A (GABA_A) receptors, and epileptiform activity generated by 4‐aminopyridine, a K⁺ channel blocker. The antiseizure effects were more pronounced in TSC and CD cases, whereas in non–mTOR‐mediated pathologies, the effects were subtle at best. These results support further clinical trials of everolimus in mTOR pathway–mediated pathologies and emphasize that the effects require sustained exposure over time.

Potential delays in referral and assessment for epilepsy surgery in children with drug-resistant, early-onset epilepsy

OBJECTIVE

To study potential delays in epilepsy surgery in children with drug-resistant epilepsy (DRE) of early-onset.

METHODS

Medical records were reviewed from 87 children with DRE and seizure onset before age 3 years who underwent epilepsy surgery between 2006 and 2015. Information was obtained about each child's epilepsy, treatment and specific time points in management. Time intervals along diagnostic, investigative, treatment and referral pathways were calculated.

RESULTS

Median ages at seizure onset, when seen in the epilepsy surgery program and surgery were 5.9 (IQR 10), 19 (IQR 29) and 36 (IQR 67) months; the median delay from seizure onset to surgery was 30 (IQR 67) months. Most children were promptly diagnosed, treated, investigated and seen by a pediatric neurologist. Focal abnormalities were reported on initial EEGs and MRIs in most children, and DRE developed within a median of 6.3 months from commencement of medication. There were median durations of 6.2 months between seeing a neurologist and being seen in the epilepsy surgery program, and then 6.1 months in determining surgical candidacy. Median durations from potential indications for a surgical evaluation to agreed surgical candidacy were 10 (DRE), 12 (focal MRI) and 17 (focal EEG) months. Children received a median of six antiepileptic drugs prior to surgery. Median interval from agreed surgical candidacy to surgery was only 3 months. There were longer durations from seizure onset to surgery in children needing PET (p = 0.001) and in children with seizure-free periods (p < 0.001), and shorter durations in children with a history of infantile spasms (p = 0.01).

SIGNIFICANCE

Delays in referral of children for epilepsy surgery are reported. Delays in assessment may be specific to centralized children's hospitals in public health systems.

Electro-clinical criteria and surgical outcome: Is there a difference between mesial and lesional temporal lobe epilepsy?

OBJECTIVES

Mesial temporal lobe epilepsy syndrome (MTLE) with specific electrophysiological and clinical characteristics and hippocampal sclerosis (HS) on MRI is considered the prototype of a syndrome with good surgical prognosis. Ictal onset zones in MTLE have been found to extend outside the hippocampus and neocortical seizures often involve mesial structures. It can, thus, be questioned whether MTLE with HS is different from lesional temporal epilepsies with respect to electro-clinical characteristics and surgical prognosis. We assessed whether MTLE with HS is distinguishable from lesional TLE and which criteria determine surgical outcome.

METHODS

People in a retrospective cohort of 389 individuals with MRI abnormalities who underwent temporal lobectomy, were divided into "HS only" or "lesional" TLEs. Twenty-six presented with dual pathology and were excluded from further analysis. We compared surgical outcome and electro-clinical characteristics.

RESULTS

Over half (61%) had "HS only." Four electro-clinical characteristics (age at epilepsy onset, febrile seizures, memory dysfunction and contralateral dystonic posturing) distinguished "HS only" from "lesional" TLE, but there was considerable overlap. Seizure freedom 2 years after surgery (Engel class 1) was similar: 67% ("HS only") vs 69% ("lesional" TLE). Neither presence of HS nor electro-clinical criteria was associated with surgical outcome.

CONCLUSIONS

Despite small differences in electrophysiological and clinical characteristics between MTLE with HS and lesional TLE, surgical outcomes are similar, indicating that aetiology seems irrelevant in the referral for temporal surgery.

Histopathological Findings in Brain Tissue Obtained during Epilepsy Surgery

BACKGROUND

Detailed neuropathological information on the structural brain lesions underlying seizures is valuable for understanding drug-resistant focal epilepsy.

METHODS

We report the diagnoses made on the basis of resected brain specimens from 9523 patients who underwent epilepsy surgery for drug-resistant seizures in 36 centers from 12 European countries over 25 years. Histopathological diagnoses were determined through examination of the specimens in local hospitals (41%) or at the German Neuropathology Reference Center for Epilepsy Surgery (59%).

RESULTS

The onset of seizures occurred before 18 years of age in 75.9% of patients overall, and 72.5% of the patients underwent surgery as adults. The mean duration of epilepsy before surgical resection was 20.1 years among adults and 5.3 years among children. The temporal lobe was involved in 71.9% of operations. There were 36 histopathological diagnoses in seven major disease categories. The most common categories were hippocampal sclerosis, found in 36.4% of the patients (88.7% of cases were in adults), tumors (mainly ganglioglioma) in 23.6%, and malformations of cortical development in 19.8% (focal cortical dysplasia was the most common type, 52.7% of cases of which were in children). No histopathological diagnosis could be established for 7.7% of the patients.

CONCLUSIONS

In patients with drug-resistant focal epilepsy requiring surgery, hippocampal sclerosis was the most common histopathological diagnosis among adults, and focal cortical dysplasia was the most common diagnosis among children. Tumors were the second most common lesion in both groups. (Funded by the European Union and others.).

Anti-epileptic effect of ifenprodil on neocortical pyramidal neurons in patients with malformations of cortical development

Ifenprodil has been demonstrated to reduce spontaneous action potentials observed by local field potential in animal models. To investigate whether ifenprodil exerts an anti-epileptic effect on neuronal levels in humans, whole-cell patch clamp recordings were used to study the electrophysiological membrane properties of neocortical pyramidal neurons in human brain tissues. Electrophysiological membrane properties and spontaneous spikes of neocortical pyramidal neurons were investigated by using whole-cell patch clamp recordings, prior to and following the application of ifenprodil. In the present study, ifenprodil significantly decreased the membrane input resistance (P<0.01), membrane time constant (P<0.01), action potential amplitude (P<0.01), action potential rising rate (P<0.05) and falling rate (P<0.05) on neocortical pyramidal neurons in patients with epilepsy caused by malformations of cortical development (MCD). These results suggested that ifenprodil decreased neuronal excitability of neocortical pyramidal neurons in patients with epilepsy and MCD and demonstrated that ifenprodil may be a potentially specific treatment for refractory epilepsy caused by MCD.

Increasing volume and complexity of pediatric epilepsy surgery with stable seizure outcome between 2008 and 2014: A nationwide multicenter study

OBJECTIVE

The objective of the study was to assess common practice in pediatric epilepsy surgery in Italy between 2008 and 2014.

METHODS

A survey was conducted among nine Italian epilepsy surgery centers to collect information on presurgical and postsurgical evaluation protocols, volumes and types of surgical interventions, and etiologies and seizure outcomes in pediatric epilepsy surgery between 2008 and 2014.

RESULTS

Retrospective data on 527 surgical procedures were collected. The most frequent surgical approaches were temporal lobe resections and disconnections (133, 25.2%) and extratemporal lesionectomies (128, 24.3%); the most frequent etiologies were FCD II (107, 20.3%) and glioneuronal tumors (105, 19.9%). Volumes of surgeries increased over time independently from the age at surgery and the epilepsy surgery center. Engel class I was achieved in 73.6% of patients (range: 54.8 to 91.7%), with no significant changes between 2008 and 2014. Univariate analyses showed a decrease in the proportion of temporal resections and tumors and an increase in the proportion of FCDII, while multivariate analyses revealed an increase in the proportion of extratemporal surgeries over time. A higher proportion of temporal surgeries and tumors and a lower proportion of extratemporal and multilobar surgeries and of FCD were observed in low (<50surgeries/year) versus high-volume centers. There was a high variability across centers concerning pre- and postsurgical evaluation protocols, depending on local expertise and facilities.

SIGNIFICANCE

This survey reveals an increase in volume and complexity of pediatric epilepsy surgery in Italy between 2008 and 2014, associated with a stable seizure outcome.

Reoperation after failed resective epilepsy surgery in children

OBJECTIVE Although epilepsy surgery is an effective treatment option, at least 20%-40% of patients can continue to experience uncontrolled seizures resulting from incomplete resection of the lesion, epileptogenic zone, or secondary epileptogenesis. Reoperation could eliminate or improve seizures. Authors of this study evaluated outcomes following reoperation in a pediatric population. METHODS A retrospective single-center analysis of all patients who had undergone resective epilepsy surgery in the period from 2001 to 2013 was performed. After excluding children who had repeat hemispherotomy, there were 24 children who had undergone a second surgery and 2 children who had undergone a third surgery. All patients underwent MRI and video electroencephalography (VEEG) and 21 underwent magnetoencephalography (MEG) prior to reoperation. RESULTS The mean age at the first and second surgery was 7.66 (SD 4.11) and 10.67 (SD 4.02) years, respectively. The time between operations ranged from 0.03 to 9 years. At reoperation, 8 patients underwent extended cortical resection; 8, lobectomy; 5, lesionectomy; and 3, functional hemispherotomy. One year after reoperation, 58% of the children were completely seizure free (International League Against Epilepsy [ILAE] Class 1) and 75% had a reduction in seizures (ILAE Classes 1-4). Patients with MEG clustered dipoles were more likely to be seizure free than to have persistent seizures (71% vs 40%, p = 0.08). CONCLUSIONS Reoperation in children with recurrent seizures after the first epilepsy surgery could result in favorable seizure outcomes. Those with residual lesion after the first surgery should undergo complete resection of the lesion to improve seizure outcome. In addition to MRI and VEEG, MEG should be considered as part of the reevaluation prior to reoperation.

Intraoperative fast ripples independently predict postsurgical epilepsy outcome: Comparison with other electrocorticographic phenomena

In the surgical management of epilepsy, the resection of cortex exhibiting interictal fast ripples (250-500Hz) on electrocorticography has been linked to postoperative seizure-freedom. Although fast ripples appear to accurately identify the epileptogenic zone-the minimum tissue that must be removed at surgery to achieve seizure-freedom-it has not been established that fast ripples are a superior biomarker in comparison with multimodal presurgical neuroimaging and other electrocorticography abnormalities. Hence, in the prediction of postoperative seizure-freedom, we compared the value of fast ripples with other intraoperative electocorticography abnormalities including focal slowing, paroxysmal fast activity, intermittent spike discharges, continuous epileptiform discharges, focal attenuation, and intraoperative seizures, as well as complete resection of the lesion defined by MRI and other neuroimaging. In a cohort of 60 children with lesional epilepsy and median postsurgical follow-up exceeding 4 years, who underwent resective epilepsy surgery with intraoperative electrocorticography, we evaluated the extent to which removal of each intraoperative electrocorticography abnormality impacts time to first postoperative seizure using the Kaplan-Meier method and Cox proportional hazards regression. Secondly, we contrasted the predictive value of resection of each competing electrocorticography abnormality using standard test metrics (sensitivity, specificity, positive predictive value, and negative predictive value). In contrast with all other intraoperative electrocorticography abnormalities, fast ripples demonstrated the most favorable combination of positive predictive value (100%) and negative predictive value (76%) in the prediction of postoperative seizures. Among all candidate electrocorticography features, time to first postoperative seizure was most strongly associated with incomplete resection of fast ripples (hazard ratio=19.8, p<0.001). In multivariate survival analyses, postoperative seizures were independently predicted by incomplete resection of cortex generating fast ripples (hazard ratio=25.4, 95%CI 6.71-96.0, p<0.001) and focal slowing (hazard ratio=5.79, 95%CI 1.76-19.0, p=0.004), even after adjustment for the impact of an otherwise complete resection. All children with incomplete resection of interictal FR-generating cortex exhibited postoperative seizures within six months. Notably, this cohort included many patients with large resections and thus limited opportunity to exhibit unresected fast ripples. Future study in a cohort with small resection volume, or a clinical trial in which resection margins are guided by fast ripple distribution, would likely yield a more precise estimate of the risk posed by unresected fast ripples. With a high detection rate during brief intraoperative electrocorticography and favorable positive and negative predictive value, interictal fast ripple characterization during surgery is a feasible and useful adjunct to standard methods for epilepsy surgery planning, and represents a valuable spatially-localizing biomarker of the epileptogenic zone, without the need for prolonged extraoperative electrocorticography.