Reoperation for refractory epilepsy in childhood: a second chance for selected patients

Lesion volume and spike frequency on EEG impact perfusion values in focal cortical dysplasia: a pediatric arterial spin labeling study

Arterial spin labelling (ASL), an MRI sequence non-invasively imaging brain perfusion, has yielded promising results in the presurgical workup of children with focal cortical dysplasia (FCD)-related epilepsy. However, the interpretation of ASL-derived perfusion patterns remains unclear. Hence, we compared ASL qualitative and quantitative findings to their clinical, EEG, and MRI counterparts. We included children with focal structural epilepsy related to an MRI-detectable FCD who underwent single delay pseudo-continuous ASL. ASL perfusion changes were assessed qualitatively by visual inspection and quantitatively by estimating the asymmetry index (AI). We considered 18 scans from 15 children. 16 of 18 (89%) scans showed FCD-related perfusion changes: 10 were hypoperfused, whereas six were hyperperfused. Nine scans had perfusion changes larger than and seven equal to the FCD extent on anatomical images. Hyperperfusion was associated with frequent interictal spikes on EEG (p = 0.047). Perfusion changes in ASL larger than the FCD corresponded to larger lesions (p = 0.017). Higher AI values were determined by frequent interictal spikes on EEG (p = 0.004). ASL showed FCD-related perfusion changes in most cases. Further, higher spike frequency on EEG may increase ASL changes in affected children. These observations may facilitate the interpretation of ASL findings, improving treatment management, counselling, and prognostication in children with FCD-related epilepsy.

Determinants of Functional Outcome after Pediatric Hemispherotomy

OBJECTIVE

We aimed to evaluate determinants of functional outcome after pediatric hemispherotomy in a large and recent multicenter cohort.

METHODS

We retrospectively investigated the functional outcomes of 455 children who underwent hemispherotomy at 5 epilepsy centers in 2000-2016. We identified determinants of unaided walking, voluntary grasping with the hemiplegic hand, and speaking through Bayesian multivariable regression modeling using missing data imputation.

RESULTS

Seventy-five percent of children were seizure-free, and 44% stopped antiseizure medication at a 5.1-year mean follow-up (range = 1-17.1). Seventy-seven percent of children could walk unaided, 8% could grasp voluntarily, and 68% could speak at the last follow-up. Children were unlikely to walk when they had contralateral magnetic resonance imaging (MRI) abnormalities (40/73, p = 0.04), recurrent seizures following hemispherotomy (62/109, p = 0.04), and moderately (50/61, p = 0.03) or severely impaired (127/199, p = 0.001) postsurgical intellectual functioning, but were likely to walk when they were older at outcome determination (p = 0.01). Children were unlikely to grasp voluntarily with the hand contralateral to surgery when they had Rasmussen encephalitis (0/61, p = 0.001) or Sturge-Weber syndrome (0/32, p = 0.007). Children were unlikely to speak when they had contralateral MRI abnormalities (30/69, p = 0.002) and longer epilepsy duration (p = 0.01), but likely to speak when they had Sturge-Weber syndrome (29/35, p = 0.01), were older at surgery (p = 0.04), and were older at outcome determination (p < 0.001).

INTERPRETATION

Etiology and bilaterality of structural brain abnormalities were key determinants of functional outcome after hemispherotomy. Longer epilepsy duration affected language outcomes. Not surprisingly, walking and talking ability increased with older age at outcome evaluation. ANN NEUROL 2024;95:377-387.

Long-term seizure and developmental outcomes of epilepsy surgery in children under 3 years old: A single-center study of 113 patients

AIMS

To investigate the clinical characteristics, surgical strategy, developmental and seizure outcomes, and predictors of surgical outcome in children with drug-resistant epilepsy (DRE) under 3 years old.

METHODS

One hundred thirteen consecutive children younger than 3 years of age with DRE underwent curative surgical treatment after multidisciplinary preoperative evaluation using the strategy developed in the pediatric epilepsy center of Peking University First Hospital (PKFHPEC) between 2014 and 2018. These patients were selected for retrospective study. The relevant clinical data were collected and analyzed. The surgical prognoses were classified using the Engel classification, and the developmental assessment results were collected. Statistical analysis of the clinical data was performed to analyze the predictors of seizure outcomes and their correlation with developmental outcomes.

RESULTS

All the patients were followed up for more than 3 years, and 98 (86.7%) patients had no seizure recurrence. One year after surgery, the seizure-free rate was 86.7%, which was as high as that at the last follow-up. Cortical dysplasia was the most frequent etiology of DRE in this cohort, accounting for 77.0%. According to the Engel classification, acute postoperative seizure (APOS; p < 0.001) was a predictor of seizure recurrence. No deaths occurred. No unpredicted long-term severe complications occurred except for one ventricular peritoneal shunt. The patients' neurodevelopmental statuses were improved after successful surgery, while the scores of the pre- and postoperative developmental assessments were closely correlated.

CONCLUSIONS

For children who are younger than 3 years old and have DRE and structural abnormalities, early curative treatment can lead to long-term good seizure outcomes and a low complication rate. The development of appropriate strategies for both presurgical evaluation and resection is crucial for the success of surgery.

Does Adjustment of Antiseizure Medication Regimen after Failed Epilepsy Surgery Improve Outcomes?

Background and Objectives: After failed epilepsy surgery, patients often revert to an antiseizure medication (ASM) ASM regimen, which can be adjusted or optimized in three ways: increasing the dose, alternative therapy, and combination therapy. It is unclear which type of antiseizure medication adjustment method can improve outcomes. Materials and Methods: Children who underwent failed epileptic resection surgery at the Department of Neurosurgery, Children's Hospital of Chongqing Medical University between January 2015 and December 2021 were included in this cohort, who were reviewed for whether they underwent adjustment of ASM with increased dose, alternative therapy, or combination therapy. The seizure outcome and quality of life (QoL) were assessed. Two-tailed Fisher exact test and Mann-Whitney U test were used for statistical analysis. Results: Sixty-three children with failed surgery were included for further analysis, with a median follow-up time of 53 months. The median seizure recurrence time was 4 months. At the last follow-up, 36.5% (n = 23) of patients achieved seizure freedom, 41.3% (n = 26) achieved seizure remission, and 61.9% (n = 39) had a good QoL. None of the three types of ASM adjustment improved children's outcomes, whether considered in terms of seizure-free rate, seizure remission rate, or QoL. Early recurrences were significantly associated with decreased probability of seizure freedom (p = 0.02), seizure remission (p = 0.02), and a good QoL (p = 0.01). Conclusions: Children who underwent failed epilepsy surgery remains some potential for late seizure remission from ASM. Yet adjusting ASM regimen does not increase the probability of seizure remission nor does it improve the QoL. Clinicians should complete evaluations and consider the need for other antiepileptic treatment as soon as possible after surgery failed, especially when dealing with children with an early recurrence.

Not surgical technique, but etiology, contralateral MRI, prior surgery, and side of surgery determine seizure outcome after pediatric hemispherotomy

OBJECTIVE

We aimed to assess determinants of seizure outcome following pediatric hemispherotomy in a contemporary cohort.

METHODS

We retrospectively analyzed the seizure outcomes of 457 children who underwent hemispheric surgery in five European epilepsy centers between 2000 and 2016. We identified variables related to seizure outcome through multivariable regression modeling with missing data imputation and optimal group matching, and we further investigated the role of surgical technique by Bayes factor (BF) analysis.

RESULTS

One hundred seventy seven children (39%) underwent vertical and 280 children (61%) underwent lateral hemispherotomy. Three hundred forty-four children (75%) achieved seizure freedom at a mean follow-up of 5.1 years (range 1 to 17.1). We identified acquired etiology other than stroke (odds ratio [OR] 4.4, 95% confidence interval (CI) 1.1-18.0), hemimegalencephaly (OR 2.8, 95% CI 1.1-7.3), contralateral magnetic resonance imaging (MRI) findings (OR 5.5, 95% CI 2.7-11.1), prior resective surgery (OR 5.0, 95% CI 1.8-14.0), and left hemispherotomy (OR 2.3, 95% CI 1.3-3.9) as significant determinants of seizure recurrence. We found no evidence of an impact of the hemispherotomy technique on seizure outcome (the BF for a model including the hemispherotomy technique over the null model was 1.1), with comparable overall major complication rates for different approaches.

SIGNIFICANCE

Knowledge about the independent determinants of seizure outcome following pediatric hemispherotomy will improve the counseling of patients and families. In contrast to previous reports, we found no statistically relevant difference in seizure-freedom rates between the vertical and horizontal hemispherotomy techniques when accounting for different clinical features between groups.

Diffusion tensor imaging discriminates focal cortical dysplasia from normal brain parenchyma and differentiates between focal cortical dysplasia types

OBJECTIVES

Although diffusion tensor imaging (DTI) may facilitate the identification of cytoarchitectural changes associated with focal cortical dysplasia (FCD), the predominant aetiology of paediatric structural epilepsy, its potential has thus far remained unexplored in this population. Here, we investigated whether DTI indices can differentiate FCD from contralateral brain parenchyma (CBP) and whether clinical features affect these indices.

METHODS

In this single-centre, retrospective study, we considered children and adolescents with FCD-associated epilepsy who underwent brain magnetic resonance (MRI), including DTI. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity, and radial diffusivity, were calculated in both FCD and CBP. The DTI indices best discriminating between FCD and CBP were subsequently used to assess the link between DTI and selected clinical and lesion-related parameters.

RESULTS

We enrolled 32 patients (20 male; median age at MRI 4 years), including 15 with histologically confirmed FCD. FA values were lower (p = 0.03), whereas MD values were higher in FCD than in CBP (p = 0.04). The difference in FA values between FCD and CBP was more pronounced for a positive vs. negative history of status epilepticus (p = 0.004). Among histologically confirmed cases, the difference in FA values between FCD and CBP was more pronounced for type IIb versus type I FCD (p = 0.03).

CONCLUSIONS

FA and MD discriminate between FCD and CBP, while FA differentiates between FCD types. Status epilepticus increases differences in FA, potentially reflecting changes induced in the brain. Our findings support the potential of DTI to serve as a non-invasive biomarker to characterise FCD in the paediatric population.

Can Presurgical Interhemispheric EEG Connectivity Predict Outcome in Hemispheric Surgery? A Brain Machine Learning Approach

OBJECTIVES

Hemispherotomy (HT) is a surgical option for treatment of drug-resistant seizures due to hemispheric structural lesions. Factors affecting seizure outcome have not been fully clarified. In our study, we used a brain Machine Learning (ML) approach to evaluate the possible role of Inter-hemispheric EEG Connectivity (IC) in predicting post-surgical seizure outcome.

METHODS

We collected 21 pediatric patients with drug-resistant epilepsy; who underwent HT in our center from 2009 to 2020; with a follow-up of at least two years. We selected 5-s windows of wakefulness and sleep pre-surgical EEG and we trained Artificial Neuronal Network (ANN) to estimate epilepsy outcome. We extracted EEG features as input data and selected the ANN with best accuracy.

RESULTS

Among 21 patients, 15 (71%) were seizure and drug-free at last follow-up. ANN showed 73.3% of accuracy, with 85% of seizure free and 40% of non-seizure free patients appropriately classified.

CONCLUSIONS

The accuracy level that we reached supports the hypothesis that pre-surgical EEG features may have the potential to predict epilepsy outcome after HT.

SIGNIFICANCE

The role of pre-surgical EEG data in influencing seizure outcome after HT is still debated. We proposed a computational predictive model, with an ML approach, with a high accuracy level.

Repeat surgery for pediatric epilepsy: a systematic review and meta-analysis of resection and disconnection approaches

OBJECTIVE

Resection and disconnection surgeries for epilepsy in the pediatric demographic (patients ≤ 18 years of age) are two separate, definitive intervention options in medically refractory cases. Questions remain regarding the role of surgery when seizures persist after an initial incomplete surgery. The aim of this study was to review the contemporary literature and summarize the metadata on the outcomes of repeat surgery in this specific demographic.

METHODS

Searches of seven electronic databases from inception to July 2022 were conducted using PRISMA guidelines. Articles were screened using prespecified criteria. Metadata from the articles were abstracted and pooled by random-effects meta-analysis of proportions.

RESULTS

Eleven studies describing 12 cohorts satisfied all criteria, reporting outcomes of 170 pediatric patients with epilepsy who underwent repeat resection or disconnection surgery. Of these patients, 55% were male, and across all studies, median ages at initial and repeat surgeries were 7.2 and 9.4 years, respectively. The median follow-up duration after repeat surgery was 47.7 months. The most commonly reported etiology for epilepsy was cortical dysplasia. Overall, the estimated incidence of complete seizure freedom (Engel class I) following repeat surgery was 48% (95% CI 40%-56%, p value for heterogeneity = 0.93), and the estimated incidence of postoperative complications following repeat surgery was 25% (95% CI 12%-39%, p = 0.04). There were six cohorts each that described outcomes for repeat resection and repeat disconnection surgeries. There was no statistical difference between these two subgroups with respect to estimated incidence of complete seizure freedom (p value for interaction = 0.92), but postoperative complications were statistically more common following repeat resection (p ≤ 0.01).

CONCLUSIONS

For both resection and disconnection surgeries, repeat epilepsy surgery in children is likely to confer complete seizure freedom in approximately half of the patients who experience unsuccessful initial incomplete epilepsy surgery. More data are needed to elucidate the impact on efficacy based on surgical approach selection. Judicious discussion and planning between the patient, family, and a multidisciplinary team of epilepsy specialists is recommended to optimize expectations and outcomes in this setting.

Scalp HFO rates decrease after successful epilepsy surgery and are not impacted by the skull defect resulting from craniotomy

Epilepsy surgery can achieve seizure freedom in selected pediatric candidates, but reliable postsurgical predictors of seizure freedom are missing. High frequency oscillations (HFO) in scalp EEG are a new and promising biomarker of treatment response. However, it is unclear if the skull defect resulting from craniotomy interferes with HFO detection in postsurgical recordings. We considered 14 children with focal lesional epilepsy who underwent presurgical evaluation, epilepsy surgery, and postsurgical follow-up of ≥ 1 year. We identified the nearest EEG electrodes to the skull defect in the postsurgical MRI. We applied a previously validated automated HFO detector to determine HFO rates in presurgical and postsurgical EEG. Overall, HFO rates showed a positive correlation with seizure frequency (p < 0.001). HFO rates in channels over the HFO area decreased following successful epilepsy surgery, irrespective of their proximity to the skull defect (p = 0.005). HFO rates in channels outside the HFO area but near the skull defect showed no increase following surgery (p = 0.091) and did not differ from their contralateral channels (p = 0.726). Our observations show that the skull defect does not interfere with postsurgical HFO detection. This supports the notion that scalp HFO can predict postsurgical seizure freedom and thus guide therapy management in focal lesional epilepsy.

Stereotactic Radiosurgery for Treatment of Operculoinsular Refractory Epilepsy After Incomplete Resection in a Child

A 13-year-old right-handed girl had operculoinsular refractory epilepsy with several seizures per week after temporal lobe epilepsy surgery despite appropriate anticonvulsant therapy. Instead of reoperation, she underwent stereotactic radiosurgery (SRS), which was performed using a linac-based Elekta Axesse SRS machine with a marginal dose of 24 Gy (gross target volume: 6.67 cm³) in one fraction. Post-radiosurgery, she had no clinical or radiological complications. She was maintained on two anti-seizure medications following treatment (valproate and levetiracetam) and was seizure free at the time of this report (during four weeks after SRS). Monthly follow-up was planned for the evaluation of long-term outcomes. SRS may be a safe option for treating intractable focal epilepsy or recurrent epilepsy after surgery failure in children.

Changes in the Functional Brain Network of Children Undergoing Repeated Epilepsy Surgery: An EEG Source Connectivity Study

About 30% of children with drug-resistant epilepsy (DRE) continue to have seizures after epilepsy surgery. Since epilepsy is increasingly conceptualized as a network disorder, understanding how brain regions interact may be critical for planning re-operation in these patients. We aimed to estimate functional brain connectivity using scalp EEG and its evolution over time in patients who had repeated surgery (RS-group, n = 9) and patients who had one successful surgery (seizure-free, SF-group, n = 12). We analyzed EEGs without epileptiform activity at varying time points (before and after each surgery). We estimated functional connectivity between cortical regions and their relative centrality within the network. We compared the pre- and post-surgical centrality of all the non-resected (untouched) regions (far or adjacent to resection) for each group (using the Wilcoxon signed rank test). In alpha, theta, and beta frequency bands, the post-surgical centrality of the untouched cortical regions increased in the SF group (p < 0.001) whereas they decreased (p < 0.05) or did not change (p > 0.05) in the RS group after failed surgeries; when re-operation was successful, the post-surgical centrality of far regions increased (p < 0.05). Our data suggest that removal of the epileptogenic focus in children with DRE leads to a gain in the network centrality of the untouched areas. In contrast, unaltered or decreased connectivity is seen when seizures persist after surgery.

Epilepsy surgery: Late seizure recurrence after initial complete seizure freedom

OBJECTIVE

This study was undertaken to improve understanding of late relapse following epilepsy surgery in pharmacoresistant epilepsy.

METHODS

Retrospective comparison was made of 99 of 1278 patients undergoing surgery during 1999-2015 with seizure relapses after at least 2 years of complete seizure freedom with matched controls experiencing continued long-term seizure freedom. Univariate and multivariate analyses were performed.

RESULTS

With a mean follow-up of 9.7 years, mean time to seizure relapse was 56.6 months. In multivariate analysis, incomplete resection based on magnetic resonance imaging (MRI), bilateral lesions on preoperative MRI, and epilepsy onset in the first year of life carried a significantly higher risk of late relapse. In patients with late relapse, additional functional imaging with positron emission tomography had been performed significantly more often. Although the differences were not significant in multivariate analysis, doses of antiepileptic drugs were higher in the relapse group preoperatively and in the first 24 months and complete withdrawal was more frequent in the control group (68% vs. 51%). Regarding seizure frequency, most patients had mild seizure relapse (single relapse seizure or <1/month).

SIGNIFICANCE

In our predominantly lesional cohort, complete resection of the MRI lesion is the most important factor to maintain long-term seizure freedom. Two patterns of recurrence were identified: (1) incomplete resected lesions with seizure generation in proximity to the initial resection and (2) epileptogenic networks not detected preoperatively or evolving in the postoperative interval and manifesting with new clinical and diagnostic features.

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.

[Redo surgery in children with epilepsy]

OBJECTIVE

To analyze the causes of ineffective operations and the results of redo surgery in children with recurrent epileptic seizures.

MATERIAL AND METHODS

The results of redo surgery were analyzed in 41 (10.6%) out of 387 children with drug resistant epilepsy treated surgically at the Russian Polenov Neurosurgical Institute for the period from 1994 to 2014. Patients with recurrent epilepsy after temporal resection (n=20), extratemporal resection (n=7), multifocal resection (n=6), callosotomy and stereotaxic destruction (n=8) were selected for analysis.

RESULTS

Seizure-free period ranged from early postoperative period to 4 years. According to MRI data, lesions were not completely resected during primary surgery in 23 (56.1%) children. The causes of inefficiency of primary operations were inaccurate identification of epileptic focus in 15 (36.6%) patients; incomplete resection of epileptogenic and / or epileptic foci or incomplete disconnection of paroxysmal activity distribution pathways in 14 (34.1%) cases; epileptic foci de novo in 8 (19.5%) cases; inadequate surgical strategy in 4 (9.8%) patients. Redo surgery usually implied an extended previous resection in 34 (82.9%) patients. Engel I outcome after 3 years was achieved in 41.1% of patients, after 5 years - 38.3%, after 10 years - 36.4%.

CONCLUSION

Redo surgery is quite effective and minimally traumatic. Therefore, patients with recurrent epileptic seizures should be considered as candidates for repeated operations if previous interventions turned out to be ineffective.

Risk factors and results of hemispherotomy reoperations in children

OBJECTIVE

The goal of this study was to perform an analysis of a single-center experience with hemispherotomy reoperations for refractory hemispheric pediatric epilepsy due to persistence of seizures after initial surgery. The authors also identify possible anatomical and neurophysiological reasons for hemispherotomy failure, as well as risk factors and surgical options for this subgroup of patients.

METHODS

A review was performed of the medical records in 18 consecutive cases in which candidates for redo hemispherotomy were treated between 2003 and 2018 at the authors’ epilepsy surgery center. Fourteen patients underwent reoperation due to seizure recurrence and were studied herein, whereas in 3 the initial surgical procedure was stopped because of uncontrollable bleeding, and the remaining patient refused to undergo a reoperation in spite of seizure recurrence and went on to have a vagus nerve stimulation device placed.

RESULTS

Among the 14 patients whose seizures recurred and in whom reoperations were done, the etiology of epilepsy consisted of 7 cases with malformations of cortical development (50%), 5 cases of Rasmussen encephalitis (35.8%), 1 case of porencephaly (7.1%), and 1 case of Sturge-Weber syndrome (7.1%). Eleven patients had radiological evidence of incomplete disconnection. After reoperation, 6 patients were Engel class IA, 1 was Engel II, 5 were Engel III, and 2 were Engel IV, within a mean follow-up of 48.4 months.

CONCLUSIONS

Patients with malformations of cortical development have a higher risk of seizure recurrence, and these malformations comprised the main etiology in the reoperation series. Failure of an initial hemispherotomy usually occurs due to incomplete disconnection and needs to be extensively assessed. Outcomes of reoperation are most often favorable, with acceptable complication rates.

Long-term outcomes of reoperations in epilepsy surgery

OBJECTIVE

To analyze longitudinal seizure outcomes following epilepsy surgery, including reoperations, in patients with intractable focal epilepsy.

METHODS

Clinicoradiological characteristics of patients who underwent epilepsy surgery from 1995 to 2016 with follow-up of ≥1 year were reviewed. In patients undergoing reoperations, the latest resection was considered the index surgery. The primary outcome was complete seizure freedom (Engel I) at last follow-up. Potentially significant outcome variables were first identified using univariate analyses and then fit in multivariate Cox proportional hazards models.

RESULTS

Of 898 patients fulfilling study criteria, 110 had reoperations; 92 had one resection prior to the index surgery and 18 patients had two or more prior resective surgeries. Two years after the index surgery, 69% of patients with no prior surgeries had an Engel score of I, as opposed to only 42% of those with one prior surgery, and 33% of those with two or more prior resections (P < .001). Among surgical outcome predictors, the number of prior epilepsy surgeries, female sex, lesional initial magnetic resonance imaging, no prior history of generalization, and pathology correlated with better seizure outcomes on univariate analysis. However, only sex (P = .011), history of generalization (P = .016), and number of prior surgeries (P = .002) remained statistically significant in the multivariate model.

SIGNIFICANCE

Although long-term seizure control is possible in patients with failed prior epilepsy surgery, the chances of success diminish with every subsequent resection. Outcome is additionally determined by inherent biological markers (sex and secondary generalization tendency), rather than traditional outcome predictors, supporting a hypothesis of "surgical refractoriness."

Measure thrice, cut twice: On the benefit of reoperation for failed pediatric epilepsy surgery

OBJECTIVE

To determine whether clinical outcomes are improved after repeat surgery for medically refractory epilepsy in children.

METHODS

This is a single-center retrospective cohort analysis of all patients who received repeat resective surgery for ongoing seizures from 2000-2017. From a total of 251 consecutive individual epilepsy surgical patients for focal resection, 53 patients met study inclusion criteria and had adequate follow-up documented.

RESULTS

Median age of seizure-onset was 2.0-years-old (IQR 0.3-5.5 years). The median age at first epilepsy surgery was 6.3-years-old (IQR 2.9-9.2 years) and at second epilepsy surgery was 8.4-years-old (IQR 4.7-12.6 years). Overall, 53 % (n = 28) of this series achieved Engel Class I (seizure freedom); with improved seizure control (Engel Class I-II) in 83 % (n = 44) of the cohort. 64 % (n = 34) had one reoperation; 26 % (n = 14) had two; and 9% (n = 5) had three. Pathology: 58 % (n = 31) had focal cortical dysplasia; 13 % (n = 10) tumor; 9% (n = 5) encephalitis; 6% (n = 3) gliosis; 4% (n = 2) mesial temporal sclerosis; and 2% (n = 1) hemimegalencephaly. Tumor pathology was associated with increased chance (p = 0.01) for seizure freedom (90 % of tumor patients had Engel Class I outcome). MTS had worse outcome with both patients having ongoing seizures (Engel II-IV). There were 6 patients who developed post-operative hemiparesis; one was unplanned but resolved.

SIGNIFICANCE

Reoperation for pediatric epilepsy surgery can lead to seizure freedom in many cases and improved seizure control in most cases. Reoperation for brain tumor pathology is associated with a high rate of seizure freedom.

The Concept of Drug-Resistant Epileptogenic Zone

Resective surgery is the most effective way to treat drug-resistant epilepsy. Despite extensive pre-surgical evaluation, only 30–70% patients would become seizure-free after surgery. New approaches and strategies are needed to improve the outcome of epilepsy surgery. It is commonly observed in clinical practice that antiepileptic drugs (AEDs) could maintain seizure freedom in a large proportion of patients after surgery, who were uncontrolled before the operation. In some patients cessation of AEDs leads to seizure recurrence which, in most cases, can be controlled by resuming AEDs. These observations suggest that the surgery has converted the epilepsy from drug-resistant to drug-responsive, implying that the operation has removed the brain tissue accounting for pharmacoresistance, rather than the pathological substrate of epilepsy (at least not completely). Based on these observations, it is hypothesized that there is a drug-resistant epileptogenic zone (DREZ) which overlaps with the epileptogenic zone (EZ), and has both epileptogenic and drug-resistant properties. DREZ is necessary and sufficient to cause drug-resistant epilepsy, and its remove would render the epilepsy drug-responsive. Testing the hypothesis requires the development of new methods to define the DREZ, which may be used to guide surgical planning when the epileptogenic zone cannot be completely excised. This concept can also help understand the mechanisms of drug-resistant epilepsy, leading to new therapeutic strategies.

Outcome after hemispherotomy in patients with intractable epilepsy: Comparison of techniques in the Italian experience

OBJECTIVE

The objective of the study was to evaluate clinical characteristics and outcome of hemispherotomy in children and adolescents with hemispheric refractory epilepsy in an Italian cohort of patients.

METHODS

We retrospectively evaluated the clinical course and outcome of 92 patients with refractory epilepsy who underwent hemispherotomy in three Italian epilepsy centers between 2006 and 2016. Three different approaches for hemispherotomy were used: parasagittal, modified parasagittal, and lateral.

RESULTS

Mean age at epilepsy onset was 1.8 ± 2.51 years, and mean duration of epilepsy prior to surgery was 7.4 ± 5.6 years. Mean age at surgery was 9.2 ± 8.0 years. After a mean follow-up of 2.81 ± 2.4 years, 66 of 90 patients (two lost from follow-up, 73.3%) were seizure-free (Engel class I). The etiology of epilepsy was related to acquired lesions (encephalomalacia or gliosis) in 44 patients (47.8%), congenital malformations (cortical dysplasia, hemimegalencephaly, other cortical malformations) in 38 (41.3%), and progressive conditions (Rasmussen or Sturge-Weber syndrome) in 10 patients (10.9%). Regarding seizure outcome, we could not identify statistically significant differences between vertical and lateral approaches (p = 0.154). Seizure outcome was not statistically different in patients with congenital vs acquired or progressive etiologies (p = 0.43). Acute postoperative seizures (APOS) correlated with poor outcome (p < 0.05). On multivariate analysis, presurgical focal to bilateral tonic-clonic seizures (Odds Ratio (OR) = 3.63, 95% Confidence Interval (CI): 1.86-15.20, p = 0.048) independently predicted seizure recurrence. Twenty-one patients (22.8%) exhibited postoperative complications, with no unexpected and persistent neurological deficit. More than 50% of the patients completely tapered drugs.

SIGNIFICANCE

Our data confirm hemispherotomy to be a safe and effective procedure in patients with drug resistant epilepsies due to hemispheric lesions. Presurgical focal to bilateral tonic-clonic seizures are the strongest predictor of seizure recurrence after surgery, independently from the type of hemispherotomy.

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.

Rates and predictors of success and failure in repeat epilepsy surgery: A meta-analysis and systematic review

OBJECTIVE

Medically refractory epilepsy is a debilitating disorder that is particularly challenging to treat in patients who have already failed a surgical resection. Evidence regarding outcomes of further epilepsy surgery is limited to small case series and reviews. Therefore, our group performed the first quantitative meta-analysis of the literature from the past 30 years to assess for rates and predictors of successful reoperations.

METHODS

A PubMed search was conducted for studies reporting outcomes of repeat epilepsy surgery. Studies were excluded if they reported fewer than five eligible patients or had average follow-ups < 1 year, and patients were excluded from analysis if they received a nonresective intervention. Outcomes were stratified by each variable of interest, and quantitative meta-analysis was performed to generate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Seven hundred eighty-two patients who received repeat resective epilepsy surgery from 36 studies were included. Engel I outcome was observed in 47% (n = 369) of patients. Significant predictors of seizure freedom included congruent over noncongruent electrophysiology data (OR = 3.6, 95% CI = 1.6-8.2), lesional over nonlesional epilepsy (OR = 3.2, 95% CI = 1.9-5.3), and surgical limitations over disease-related factors associated with failure of the first surgery (OR = 2.6, 95% CI = 1.3-5.3). Among patients with at least one of these predictors, seizure freedom was achieved in 58%. Conversely, the use of invasive monitoring was associated with worse outcome (OR = 0.4, 95% CI = 0.2-0.9). Temporal lobe over extratemporal/multilobe resection (OR = 1.5, 95% CI = 0.8-3.0) and abnormal over normal preoperative magnetic resonance imaging (OR = 1.9, 95% CI = 0.6-5.4) showed nonsignificant trends toward seizure freedom.

SIGNIFICANCE

This analysis supports considering further resection in patients with intractable epilepsy who continue to have debilitating seizures after an initial surgery, especially in the context of factors predictive of a favorable 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.

Frontal Lobe Epilepsy Surgery in Childhood and Adolescence: Predictors of Long-Term Seizure Freedom, Overall Cognitive and Adaptive Functioning

BACKGROUND

Although frontal lobe resections account for one-third of intralobar resections in pediatric epilepsy surgery, there is a dearth of information regarding long-term seizure freedom, overall cognitive and adaptive functioning.

OBJECTIVE

To identify outcome predictors and define the appropriate timing for surgery.

METHODS

We retrospectively analyzed the data of 75 consecutive patients aged 10.0 ± 4.9 yr at surgery that had an 8.1 yr mean follow-up.

RESULTS

Etiology comprised focal cortical dysplasia (FCD) in 71% and benign tumors in 16% cases. All patients but one had a magnetic resonance imaging-visible lesion. At last follow-up, 63% patients remained seizure-free and 37% had discontinued antiepileptic drugs. Presurgical predictors of seizure freedom were a shorter epilepsy duration, strictly regional epileptic discharges in electroencephalography (EEG), and an epileptogenic zone and/or lesion distant from eloquent cortex. Postsurgical predictors were the completeness of resection and the lack of early postoperative seizures or epileptic discharges in EEG. Higher presurgical overall cognitive and adaptive functioning was related to later epilepsy onset and to a sublobar epileptogenic zone and/or lesion. Following surgery, scores remained stable in the majority of patients. Postsurgical gains were determined by higher presurgical performance and tumors vs FCD.

CONCLUSION

Our findings highlight the favorable long-term outcomes following frontal lobe epilepsy surgery in childhood and adolescence and underline the importance of early surgical intervention in selected candidates. Early postsurgical relapses and epileptic discharges in EEG constitute key markers of treatment failure and should prompt timely reevaluation. Postsurgical overall cognitive and adaptive functioning is stable in most patients, whereas those with benign tumors have higher chances of improvement.

Prediction of seizure outcome improved by fast ripples detected in low-noise intraoperative corticogram

OBJECTIVE

Fast ripples (FR, 250-500Hz) in the intraoperative corticogram have recently been proposed as specific predictors of surgical outcome in epilepsy patients. However, online FR detection is restricted by their low signal-to-noise ratio. Here we propose the integration of low-noise EEG with unsupervised FR detection.

METHODS

Pre- and post-resection ECoG (N=9 patients) was simultaneously recorded by a commercial device (CD) and by a custom-made low-noise amplifier (LNA). FR were analyzed by an automated detector previously validated on visual markings in a different dataset.

RESULTS

Across all recordings, in the FR band the background noise was lower in LNA than in CD (p<0.001). FR rates were higher in LNA than CD recordings (0.9±1.4 vs 0.4±0.9, p<0.001). Comparison between FR rates in post-resection ECoG and surgery outcome resulted in positive predictive value PPV=100% in CD and LNA, and negative predictive value NPV=38% in CD and NPV=50% for LNA. Prediction accuracy was 44% for CD and 67% for LNA.

CONCLUSIONS

Prediction of seizure outcome was improved by the optimal integration of low-noise EEG and unsupervised FR detection.

SIGNIFICANCE

Accurate, automated and fast FR rating is essential for consideration of FR in the intraoperative setting.

Repeat surgery for focal cortical dysplasias in children: indications and outcomes

OBJECTIVE Focal cortical dysplasia (FCD) is a common cause of medically intractable epilepsy that often may be treated by surgery. Following resection, many patients continue to experience seizures, necessitating a decision for further surgery to achieve the desired seizure outcomes. Few studies exist on the efficacy of reoperation for intractable epilepsy due to FCD in pediatric cohorts, including the definition of prognostic factors correlated with clinical benefit from further resection. METHODS The authors retrospectively analyzed the medical records and MR images of 22 consecutive pediatric patients who underwent repeat FCD resection after unsuccessful first surgery at the Children's National Health System between March 2005 and April 2015. RESULTS Accounting for all reoperations, 13 (59%) of the 22 patients achieved complete seizure freedom and another 5 patients (23%) achieved significant improvement in seizure control. Univariate analysis demonstrated that concordance in electrocorticography (ECoG) and MRI localization (p = 0.005), and completeness of resection (p = 0.0001), were associated with seizure freedom after the first reoperation. Patients with discordant ECoG and MRI findings ultimately benefited from aggressive multilobe lobectomy or hemispherectomy. Repeat lesionectomies utilizing intraoperative MRI (iMRI; n = 9) achieved complete resection and seizure freedom in all cases. CONCLUSIONS Reoperation may be clinically beneficial in patients with intractable epilepsy due to FCD. Patients with concordant intraoperative ECoG and MRI localization may benefit from extended resection of residual dysplasia at the margins of the previous lesional cavity, and iMRI may offer benefits as a quality control mechanism to ensure that a complete resection has been accomplished. Patients with discordant findings may benefit from more aggressive resections at earlier stages to achieve better seizure control and ensure functional plasticity.

Posterior cortex epilepsy surgery in childhood and adolescence: Predictors of long-term seizure outcome

OBJECTIVE

We aimed to investigate the long-term seizure outcome of children and adolescents who were undergoing epilepsy surgery in the parietooccipital cortex and determine their predictive factors.

METHODS

We retrospectively analyzed the data of 50 consecutive patients aged 11.1 (mean) ± 5.1 (standard deviation) years at surgery. All patients but one had a magnetic resonance imaging (MRI)-visible lesion. Resections were parietal in 40%, occipital in 32%, and parietooccipital in 28% cases; 24% patients additionally underwent a resection of the posterior border of the temporal lobe. Etiology included focal cortical dysplasia in 44%, benign tumors (dysembryoplastic neuroepithelial tumor, ganglioglioma, angiocentric glioma, and pilocystic astrocytoma) in 32%, peri- or postnatal ischemic lesions in 16%, and tuberous sclerosis in 8% cases.

RESULTS

At last follow-up (mean 8 years, range 1.5-18 years), 60% patients remained seizure-free (Engel class I): 30% had discontinued and 20% had reduced antiepileptic drugs. Most seizure recurrences (71%) occurred within the first 6 months, and only three patients presented with seizures ≥2 years after surgery. Independent predictors of seizure recurrence included left-sided as well as parietal epileptogenic zones and resections. Longer epilepsy duration to surgery was identified as the only modifiable independent predictor of seizure recurrence.

SIGNIFICANCE

Our study demonstrates that posterior cortex epilepsy surgery is highly effective in terms of lasting seizure control and antiepileptic drug cessation in selected pediatric candidates. Most importantly, our data supports the early consideration of surgical intervention in children and adolescents with refractory posterior cortex epilepsy.

Re-review of MRI with post-processing in nonlesional patients in whom epilepsy surgery has failed

Management of MRI-negative patients with intractable focal epilepsy after failed surgery is particularly challenging. In this study, we aim to investigate whether MRI post-processing could identify relevant targets for the re-evaluation of MRI-negative patients who failed the initial resective surgery. We examined a consecutive series of 56 MRI-negative patients who underwent resective surgery and had recurring seizures at 1-year follow-up. T1-weighted volumetric sequence from the pre-surgical MRI was used for voxel-based MRI post-processing which was implemented in a morphometric analysis program (MAP). MAP was positive in 15 of the 56 patients included in this study. In 5 patients, the MAP+ regions were fully resected. In 10 patients, the MAP+ regions were not or partially resected: two out of the 10 patients had a second surgery including the unresected MAP+ region, and both became seizure-free; the remaining 8 patients did not undergo further surgery, but the unresected MAP+ regions were concordant with more than one noninvasive modality in 7. In the 8 patients who had unresected MAP+ regions and intracranial-EEG before the previous surgery, the unresected MAP+ regions were concordant with ictal onset in 6. Our data suggest that scrutiny of the presurgical MRI guided by MRI post-processing may reveal relevant targets for reoperation in nonlesional epilepsies. MAP findings, when concordant with the patient's other noninvasive data, should be considered when planning invasive evaluation/reoperation for this most challenging group of patients.

Resective surgery for focal cortical dysplasia in children: a comparative analysis of the utility of intraoperative magnetic resonance imaging (iMRI)

PURPOSE

Seizure freedom following resection of focal cortical dysplasia (FCD) correlates with complete resection of the dysplastic cortical tissue. However, difficulty with intraoperative identification of the lesion may limit the ability to achieve the surgical objective of complete extirpation of these lesions. Intraoperative magnetic resonance imaging (iMRI) may aid in FCD resections. The objective of this study is to compare rates of postoperative seizure freedom, completeness of resection, and need for reoperation in patients undergoing iMRI-assisted FCD resection versus conventional surgical techniques.

METHODS

We retrospectively reviewed the medical records of pediatric subjects who underwent surgical resection of FCD at Children's National Medical Center between March 2005 and April 2015.

RESULTS

At the time of the last postoperative follow-up, 11 of the 12 patients (92 %) in the iMRI resection group were seizure free (Engel Class I), compared to 14 of the 42 patients (33 %) in the control resection group (p = 0.0005). All 12 of the iMRI patients (100 %) achieved complete resection, compared to 24 of 42 patients (57 %) in the control group (p = 0.01). One (8 %) patient from the iMRI-assisted resection group has required reoperation, compared to 17 (40 %) patients in the control resection group.

CONCLUSION

Our results suggest that the utilization of iMRI during surgery for resection of FCD results in improved postoperative seizure freedom, completeness of lesion resection, and reduction in the need for reoperation.

Factors associated with failed focal neocortical epilepsy surgery

BACKGROUND

Seizure outcomes after focal neocortical epilepsy (FNE) surgery are less favorable than after temporal lobectomy, and the reasons for surgical failure are incompletely understood. Few groups have performed an in-depth examination of seizure recurrences to identify possible reasons for failure.

OBJECTIVE

To elucidate factors contributing to FNE surgery failures.

METHODS

We reviewed resections for drug-resistant FNE performed at our institution between 1998 and 2011. We performed a quantitative analysis of seizure outcome predictors and a detailed qualitative review of failed surgical cases.

RESULTS

Of 138 resections in 125 FNE patients, 91 (66%) resulted in freedom from disabling seizures (Engel I outcome). Mean ± SEM patient age was 20.0 ± 1.2 years; mean follow-up was 3.8 years (range, 1-17 years); and 57% of patients were male. Less favorable (Engel II-IV) seizure outcome was predicted by higher preoperative seizure frequency (odds ratio = 0.85; 95% confidence interval, 0.78-0.93), a history of generalized tonic-clonic seizures (odds ratio = 0.42; 95% confidence interval, 0.18-0.97), and normal magnetic resonance imaging (odds ratio = 0.30; 95% confidence interval, 0.09-1.02). Among 36 surgical failures examined, 26 (72%) were related to extent of resection, with residual epileptic focus at the resection margins, whereas 10 (28%) involved location of resection, with an additional epileptogenic zone distant from the resection. Of 16 patients who received reoperation after seizure recurrence, 10 (63%) achieved seizure freedom.

CONCLUSION

Insufficient extent of resection is the most common reason for recurrent seizures after FNE surgery, although some patients harbor a remote epileptic focus. Many patients with incomplete seizure control are candidates for reoperation.

MR-guided laser interstitial thermal therapy for pediatric drug-resistant lesional epilepsy

OBJECTIVE

To report the feasibility, safety, and clinical outcomes of an exploratory study of MR-guided Laser Interstitial Thermal Therapy (MRgLITT) as a minimally invasive surgical procedure for the ablation of epileptogenic foci in children with drug-resistant, lesional epilepsy.

METHODS

Retrospective chart review of all MRgLITT procedures at a single tertiary care center. All procedures were performed using a U.S. Food and Drug Administration (FDA)-cleared surgical laser ablation system (Visualase Thermal Therapy System). Predefined clinical and surgical variables were extracted from archived medical records.

RESULTS

Seventeen patients underwent 19 MRgLITT procedures from May 2011 to January 2014. Mean age at seizure onset was 7.1 years (range 0.1-14.8 years). Mean age at surgery was 15.3 years (range 5.9-20.6 years). Surgical substrates were mixed but mainly composed of focal cortical dysplasia (n = 11). Complications occurred in four patients. Average length of hospitalization postsurgery was 1.56 days. Mean follow-up was 16.1 months (n = 16; range 3.5-35.9 months). Engel class I outcome was achieved in seven patients (7/17; 41%), Engel class II in one (1/17; 6%), Engel class III in three (3/17; 18%), and Engel class IV in six (6/17; 35%). Three patients (3/8; 38%) with class I and II outcomes and five patients (5/9; 56%) with class III and IV outcomes had at least one prior resection. Fisher's exact test was not statistically significant for the association between Engel class outcome and previous resection (p = 0.64).

SIGNIFICANCE

This study provides descriptive results regarding the use of MRgLITT in a mixed population of pediatric, lesional, drug-resistant epilepsy cases. The ability to classify case-specific outcomes and reduce technical complications is anticipated as experience develops. Further multicenter, prospective studies are required to delineate optimal candidates for MRgLITT, and larger cohorts are needed to more accurately define outcome and complication rates.

Repeat resective surgery in complex pediatric refractory epilepsy: lessons learned

OBJECT Resection can sometimes offer the best chance of meaningful seizure reduction in children with medically intractable epilepsy. However, when surgery fails to achieve the desired outcome, reoperation may be an option. The authors sought to investigate outcomes following resective reoperation in pediatric patients with refractory epilepsy, excluding tumoral epilepsies. Differences in preoperative workup between surgeries are analyzed to identify factors influencing outcomes and complications in this complex group. METHODS Medical records were reviewed for all pediatric patients undergoing a repeat resective surgery for refractory epilepsy at the authors' institution between 2005 and 2012. Tumor and vascular etiologies were excluded. Preoperative evaluation and outcomes were analyzed for each surgery and compared. RESULTS Ten patients met all inclusion criteria. The median age at seizure onset was 4.5 months. Preoperative MRI revealed no lesion in 30%. Nonspecific gliosis and cortical dysplasia were the most common pathologies. The majority of preoperative workups included MRI, video-electroencephalography (EEG), and SISCOM. Intracranial EEG was performed for 60% for the first presurgical evaluation and 70% for the second evaluation. The goal of surgery was palliative in 4 patients with widespread cortical dysplasia. The final Engel outcome was Class I in 50%. The rate of favorable outcome (Engel Class I-II) was 70%. The complication rate for the initial surgery was 10%. However, the rate increased to 50% with the second surgery, and 3 of these 5 complications were pseudomeningoceles requiring shunt placement (2 of the 3 patients underwent hemispherotomy). CONCLUSIONS Resective reoperation for pediatric refractory epilepsy has a high rate of favorable outcome and should be considered in appropriate candidates, even as a palliative measure. Intracranial EEG monitoring should be considered on initial workup in cases where the results of imaging or EEG studies are ambiguous or conflicting. Epilepsy secondary to cortical dysplasia, especially if the dysplasia is not seen clearly on MRI, can be difficult to cure surgically. Therefore, in these cases, as large a resection as can be safely accomplished should be done, particularly when the goal is palliative. The rate of complications, particularly pseudomeningocele ultimately requiring shunt placement, is much higher following reoperation, and patients should be counseled accordingly.

Yield and Predictors of Epilepsy Surgery Candidacy in Children Admitted for Surgical Evaluation

OBJECTIVE

The aim of this study was to identify preadmission variables that are prognostic of epilepsy surgical candidacy for children admitted into an epilepsy-monitoring unit.

METHODS

This study is a retrospective review of patients 0-18 years who were admitted into the pediatric epilepsy-monitoring unit at Mayo Clinic between November 2010 and December 2013 to assess for surgery candidacy for medically intractable epilepsy. Demographic data, epilepsy details, treatments, electroencephalograph and imaging results, and the consensus notes of the epilepsy surgery conferences were collected.

RESULTS

One hundred and forty eight children underwent inpatient, prolonged video-electroencephalograph monitoring for presurgical evaluation, of which 136 had their typical events recorded. Five recommended for callosotomy alone were excluded and 131 composed the study group. Of these 131, the epilepsy surgery conference consensus deemed that 69 were surgical candidates, of which 45 (65%) underwent resective surgery. Chi-square analysis found seven preadmission predictors of surgical candidacy: single semiology at seizure onset (P < 0.001), structural etiology (P < 0.001), one or more interictal foci all in the same hemisphere (P < 0.004), focal background electroencephalograph slowing (P < 0.001), focal or hemispheric abnormality on magnetic resonance imaging (P < 0.001), male sex (P = 0.02), and normal development (P = 0.04).

CONCLUSIONS

The presence of fewer than four predictors was suggestive of low likelihood of candidacy (<31%), whereas if more than four factors were present, 91% were found to be surgical candidates. These findings facilitate clinical decision-making for providers in a cost-effective manner and provide realistic expectations for families.

Epilepsy surgery for glioneuronal tumors in childhood: avoid loss of time

BACKGROUND

In contrast to the abundance of seizure outcome reports in epilepsy surgery for glioneuronal tumors in childhood and adolescence, there is a dearth of information regarding cognitive outcomes.

OBJECTIVE

To investigate the seizure and cognitive outcome of children and adolescents that underwent resective surgery for glioneuronal tumor-associated refractory epilepsy and determine their predictive factors.

METHODS

We retrospectively analyzed the presurgical findings, resection types, and outcomes over 1.3 to 12.3 years (mean, 7.3) of 29 consecutive patients, who underwent resection in 2000 to 2011. The mean age at epilepsy onset was 7.9 years (range, 0-15.4), the mean age at surgery was 11.7 years (range, 2.6-17.3), and the mean epilepsy duration to surgery was 3.8 years (range, 0.3-15.3). Etiology comprised 13 dysembryoplastic neuroepithelial tumors and 16 gangliogliomas, with additional focal cortical dysplasia in 5 cases.

RESULTS

Eighty-six percent of children were seizure free 12 months after surgery; at final follow-up, 76% remained seizure free and 62% had discontinued antiepileptic drugs. Gross total resection was related to significantly higher rates of seizure freedom. Higher presurgical cognitive functioning (full-scale IQ, verbal IQ) was related to shorter epilepsy duration to surgery independent of age at epilepsy onset, thus determining postsurgical functioning. Improvements in verbal IQ, performance IQ, and visual memory as well as a trend toward improvement in full-scale IQ were established after surgery. Despite individual losses in full-scale IQ, verbal or visual memory, no deterioration was noted in any cognitive variable on a group level.

CONCLUSION

Completeness of resection predisposes to favorable outcomes regarding seizure alleviation. Whereas cognitive functioning deteriorates with time in glioneuronal tumor-related refractory epilepsy, surgery is linked to improvement rather than to deterioration on a group level.

Epilepsy surgery failure in children: a quantitative and qualitative analysis

OBJECT

Resection is a safe and effective treatment option for children with pharmacoresistant focal epilepsy, but some patients continue experience seizures after surgery. While most studies of pediatric epilepsy surgery focus on predictors of postoperative seizure outcome, these factors are often not modifiable, and the reasons for surgical failure may remain unclear.

METHODS

The authors performed a retrospective cohort study of children and adolescents who received focal resective surgery for pharmacoresistant epilepsy. Both quantitative and qualitative analyses of factors associated with persistent postoperative seizures were conducted.

RESULTS

Records were reviewed from 110 patients, ranging in age from 6 months to 19 years at the time of surgery, who underwent a total of 115 resections. At a mean 3.1-year follow-up, 76% of patients were free of disabling seizures (Engel Class I outcome). Seizure freedom was predicted by temporal lobe surgery compared with extratemporal resection, tumor or mesial temporal sclerosis compared with cortical dysplasia or other pathologies, and by a lower preoperative seizure frequency. Factors associated with persistent seizures (Engel Class II-IV outcome) included residual epileptogenic tissue adjacent to the resection cavity (40%), an additional epileptogenic zone distant from the resection cavity (32%), and the presence of a hemispheric epilepsy syndrome (28%).

CONCLUSIONS

While seizure outcomes in pediatric epilepsy surgery may be improved by the use of high-resolution neuroimaging and invasive electrographic studies, a more aggressive resection should be considered in certain patients, including hemispherectomy if a hemispheric epilepsy syndrome is suspected. Family counseling regarding treatment expectations is critical, and reoperation may be warranted in select cases.