Cognitive outcome after extratemporal epilepsy surgery in childhood

Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy

Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.

Efficient organisation of the contralateral hemisphere connectome is associated with improvement in intelligence quotient after paediatric epilepsy surgery

OBJECTIVE

Aims of epilepsy surgery in childhood include optimising seizure control and facilitating cognitive development. Predicting which children will improve cognitively is challenging. We investigated the association of the pre-operative structural connectome of the contralateral non-operated hemisphere with improvement in intelligence quotient (IQ) post-operatively.

METHODS

Consecutive children who had undergone unilateral resective procedures for epilepsy at a single centre were retrospectively identified. We included those with pre-operative volume T1-weighted non-contrast brain magnetic resonance imaging (MRI), no visible contralateral MRI abnormalities, and both pre-operative and two years post-operative IQ assessment. The MRI of the hemisphere contralateral to the side of resection was anatomically parcellated into 34 cortical regions and the covariance of cortical thickness between regions was used to create binary and weighted group connectomes.

RESULTS

Eleven patients with a post-operative IQ increase of at least 10 points at two years were compared with twenty-four patients with no change in IQ score. Children who gained at least 10 IQ points post-operatively had a more efficiently structured contralateral hemisphere connectome with higher global efficiency (0.74) compared to those whose IQ did not change at two years (0.58, p = 0.014). This was consistent across thresholds and both binary and weighted networks. There were no statistically significant group differences in age, sex, age at onset of epilepsy, pre-operative IQ, mean cortical thickness, side or site of procedure, two year post-operative Engel scores or use of anti-seizure medications between the two groups.

CONCLUSIONS

Surgical procedures to reduce or stop seizures may allow children with an efficiently structured contralateral hemisphere to achieve their cognitive potential.

Lesion Extent Negatively Impacts Intellectual Skills in Pediatric Focal Epilepsy

BACKGROUND

Cognitive development in children and adolescents with focal lesional epilepsy is determined by the underlying epileptogenic lesion, in addition to epilepsy itself. However, the impact of lesion-related variables on intelligence quotient (IQ) and developmental quotient (DQ) remains largely unexplored. Here, we aimed to determine the effect of lesion-related predictors and their relation with epilepsy-related predictors of intellectual functioning.

METHODS

We retrospectively analyzed data from children with focal lesional epilepsy who underwent standardized cognitive evaluation yielding IQ/DQ in our institution.

RESULTS

We included 50 consecutive patients aged 0.5 to 17.5 years (mean, 9.3; S.D., 4.9) at cognitive assessment. Epilepsy duration was 0 to 15.5 years (mean, 3.8; S.D., 4.1). Of the total cohort, 30 (60%) patients had unilobar lesions, seven (14%) multilobar, 10 (20%) hemispheric, and three (6%) bilateral. Etiology was congenital in 32 (64%) cases, acquired in 14 (28%), and progressive in four (8%). For patients with unilobar lesions, the mean IQ/DQ was 97.1 ± 15.7, for multilobar 98.9 ± 20.2, for hemispheric 76.1 ± 20.5, and for bilateral 76.3 ± 4.5. Larger lesion extent, earlier epilepsy onset, and longer epilepsy duration correlated with lower IQ/DQ in the univariate analysis, whereas only lesion extent and epilepsy duration contributed significantly to the explanatory model in the multivariable analysis.

CONCLUSIONS

The present study demonstrates that lesion extent and epilepsy duration are important risk factors for intellectual impairment in pediatric patients with focal lesional epilepsy. These findings are useful for family counseling and the early consideration of interventions that may limit the duration of epilepsy.

Long-term full-scale intelligent quotient outcomes following pediatric and childhood epilepsy surgery: A systematic review and meta-analysis

OBJECTIVE

Cognitive measures are an important primary outcome of pediatric, adolescents, and childhood epilepsy surgery. The purpose of this systematic review and meta-analysis is to assess whether there are long-term alterations (≥ 5 years) in the Full-Scale Intelligence Quotient (FSIQ) of pediatric patients undergoing epilepsy surgery.

METHODS

Electronic databases (EMBASE, MEDLINE, and Scopus) were searched for English articles from inception to October 2022 that examined intelligence outcomes in pediatric epilepsy surgery patients. Inclusion criteria were defined as the patient sample size of ≥ 5, average follow- up of ≥5 years, and surgeries performed on individuals ≤ 18 years old at the time of surgery. Exclusion criteria consisted of palliative surgery, animal studies, and studies not reporting surgical or FSIQ outcomes. Publication bias was assessed using a funnel plot and the Quality in Prognosis Studies (QUIPS) toolset was used for quality appraisal of the selected articles. A random-effects network meta-analysis was performed to compare FSIQ between surgical patients at baseline and follow-up and Mean Difference (MD) was used to calculate the effect size of each study. Point estimates for effects and 95% confidence intervals for moderation analysis were performed on variables putatively associated with the effect size.

RESULTS

21,408 studies were screened for abstract and title. Of these, 797 fit our inclusion and exclusion criteria and proceeded to full-text screening. Overall, seven studies met our requirements and were selected. Quantitative analysis was performed on these studies (N = 330). The mean long-term difference between pre- and post- operative FSIQ scores across all studies was noted at 3.36 [95% CI: (0.14, 6.57), p = 0.04, I2 = 0%] and heterogeneity was low.

CONCLUSION

To our knowledge, this is the first meta-analysis to measure the long-term impacts of FSIQ in pediatric and adolescent epilepsy patients. Our overall results in this meta-analysis indicate that while most studies do not show long-term FSIQ deterioration in pediatric patients who underwent epilepsy surgery, there was an increase of 3.36 FSIQ points, however, the observed changes were not clinically significant. Moreover, at the individual patient level analysis, while most children did not show long-term FSIQ deterioration, few had significant decline. These findings indicate the importance of surgery as a viable option for pediatric patients with medically refractory epilepsy.

Sirolimus for epileptic seizures associated with focal cortical dysplasia type II

Objective

To determine whether sirolimus, a mechanistic target of rapamycin (mTOR) inhibitor, reduces epileptic seizures associated with focal cortical dysplasia (FCD) type II.

Methods

Sixteen patients (aged 6–57 years) with FCD type II received sirolimus at an initial dose of 1 or 2 mg/day based on body weight (FCDS‐01). In 15 patients, the dose was adjusted to achieve target trough ranges of 5–15 ng/mL, followed by a 12‐week maintenance therapy period. The primary endpoint was a lower focal seizure frequency during the maintenance therapy period. Further, we also conducted a prospective cohort study (RES‐FCD) in which 60 patients with FCD type II were included as an external control group.

Results

The focal seizure frequency reduced by 25% in all patients during the maintenance therapy period and by a median value of 17%, 28%, and 23% during the 1–4‐, 5–8‐, and 9–12‐week periods. The response rate was 33%. The focal seizure frequency in the external control group reduced by 0.5%. However, the background characteristics of external and sirolimus‐treated groups differed. Adverse events were consistent with those of mTOR inhibitors reported previously. The blood KL‐6 level was elevated over time.

Interpretation

The reduction of focal seizures did not meet the predetermined level of statistical significance. The safety profile of the drug was tolerable. The potential for a reduction of focal seizures over time merit further investigations.

Development and Validation of Prediction Models for Developmental and Intellectual Outcome Following Pediatric Epilepsy Surgery

BACKGROUND AND OBJECTIVES

To (1) identify predictors of postoperative intelligence and developmental quotients (IQ/DQ) and (2) develop and validate clinically applicable IQ/DQ prediction models.

METHODS

We retrospectively analyzed neuropsychological outcomes and their possible determinants for children treated in Bethel and Utrecht since 1990. We performed separate analyses for patients with IQ and those with only DQ available. We developed prediction models based on presurgical determinants to predict dichotomized levels of performance (IQ≥85, IQ≥70, DQ≥50).

RESULTS

IQ/DQ data before and two years after surgery were available for 492 patients (IQ n=365, DQ n=127). At a cutoff-level ±10 points, the chance of improvement was considerably higher than the chance of deterioration (IQ 37.3% vs. 6.6% and DQ 31.5% vs. 15.0%, respectively). Presurgical IQ/DQ was the strongest predictor of postoperative cognition (IQ r=0.85, p<.001, DQ: r=0.57, p<.001).Two IQ models were developed in the Bethel cohort (n=258) and externally validated in the Utrecht cohort (n=102). For DQ, we developed the model in the Bethel cohort and used 10-fold cross-validation. Models allowed good prediction at all three cutoff-levels (correct classification for IQ≥85=86%, IQ≥70=91%, DQ≥50=76%). External validation of the IQ models showed high accuracy (IQ≥85: 0.82, CI 0.75-0.91, IQ≥70: 0.84, CI 0.77-0.92) and excellent discrimination (ROC curves IQ≥85: AUC 0.90, CI 0.84-0.96; IQ≥70: AUC 0.92, CI 0.87-0.97).

DISCUSSION

After epilepsy surgery in children, the risk of cognitive deterioration is very low. Presurgical development has a strong impact on the postoperative trajectory. The presented models can improve presurgical counseling of patients and parents by reliably predicting cognitive outcomes.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for children undergoing epilepsy surgery presurgical IQ/DQ was the strongest predictor of postoperative cognition.

Intellectual outcome from 1 to 5 years after epilepsy surgery in 81 children and adolescents: A longitudinal study

OBJECTIVE

This longitudinal study aimed to measure the time course of intellectual changes after pediatric focal resective epilepsy surgery and to identify their predictors.

METHODS

We analyzed a cohort of 81 school-aged children with focal epilepsy and intractable seizures who underwent neurosurgery (focal resection) from 2000 to 2018 in La Timone Hospital (Marseille). Neuropsychological assessments were carried out before and then 1, 2, 3, and 5 years after epilepsy surgery.

RESULTS

Eighty-one patients with a median age at surgery of 13.74 years [4.25] were enrolled. Overall, 45 of the 81 (55%) recruited patients were improved after the surgery on at least one of the five domains of the Wechsler Intelligence Scale. Temporal lobe localization and postoperative seizure freedom were the main prognostic factors impacting intellectual outcome (improvement and decline) after epilepsy surgery. Younger patients at surgery were less likely to have a postoperative IQ decline. Intellectual improvement after epilepsy surgery could be delayed for up to 5 years after surgery and concerned all intellectual domains except the Verbal Comprehension Index (VCI). Intellectual decline after epilepsy surgery occurred mainly during the first two years after the surgery and was reflected in full-scale intelligence quotient (FSIQ) and Working Memory Index (WMI).

CONCLUSIONS

Our study points out that children and adolescents with TLE who achieved freedom from seizure after epilepsy surgery are the leading candidates for achieving postoperative intellectual improvement. This enhancement in intellectual function shows a long time course, whereas intellectual decline is evidenced earlier.

Does etiology really matter for epilepsy surgery outcome?

Multiple factors influence the outcomes of epilepsy surgery. Prognostic indicators varying from clinical characteristics, imaging findings, ictal, and interictal electrophysiological activity have been linked to surgical outcomes. In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: 1)‐ does etiology matter? and 2)‐ how could it matter? The goal is to review the existing literature on the relationship between etiology and surgical outcomes to provide the best possible judgment as to whether a causal relationship exists between histopathology and the ultimate surgical outcome as an initial step. Then, we delve into the possible mechanisms via which such relationships can be explained. We conclude with a call to action to the epilepsy surgery and histopathology research community to push the mechanistic understanding of the pathology‐outcome interaction and identify actionable knowledge and biomarkers that could inform patient care in a timely fashion.

In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: (1) does etiology matter? and (2) how could it matter? We then delve into the mechanisms of these answers.

Developmental outcome after corpus callosotomy for infants and young children with drug-resistant epilepsy

AIM

To examine the developmental and seizure outcomes after corpus callosotomy (CC) in early childhood.

METHODS

We retrospectively identified 106 patients who underwent CC for drug-resistant epilepsy before the age of 6 years, at the Nagasaki Medical Center, between July 2002 and July 2016. Patients' developmental outcomes were evaluated one year after CC using the Kinder Infant Development Scale.

RESULTS

The mean preoperative developmental quotient (DQ) was 25.0 (standard deviation [SD], 20.8), and the mean difference between preoperative DQ and one-year postoperative DQ was -1.6 points (SD, 11.6). However, 42.5% of patients had a mean DQ increase of 6.5 points (SD, 6.4), one year after CC from that before surgery. Factors related to the improvement in postoperative DQ were 'low preoperative DQ', 'developmental gain 1 month postoperatively', and 'postoperative seizure-free state'. Approximately 21.7% of patients were seizure-free 1 year after CC.

INTERPRETATION

Performing CC, in infancy and early childhood for patients with drug-resistant epilepsy and severe developmental impairment, was associated with improved development in 42.5% of patients. Remission of seizures, even if only for a short period, contributed to developmental improvement. From a developmental perspective, CC for drug-resistant epilepsy in early childhood is an effective treatment.

Unilateral prefrontal lobotomy for epilepsy: technique and surgical anatomy

OBJECTIVE

Surgery for frontal lobe epilepsy remains a challenge because of the variable seizure outcomes after surgery. Disconnective procedures are increasingly applied to isolate the epileptogenic focus and avoid complications related to extensive brain resection. Previously, the authors described the anterior quadrant disconnection procedure to treat large frontal lobe lesions extending up to but not involving the primary motor cortex. In this article, they describe a surgical technique for unilateral disconnection of the prefrontal cortex, while providing an accurate description of the surgical and functional anatomy of this disconnective procedure.

METHODS

The authors report the surgical treatment of a 5-month-old boy who presented with refractory epilepsy due to extensive cortical dysplasia of the left prefrontal lobe. In addition, with the aim of both describing the subcortical intrinsic anatomy and illustrating the different connections between the prefrontal lobe and the rest of the brain, the authors dissected six human cadaveric brain hemispheres. These dissections were performed from lateral to medial and from medial to lateral to reveal the various tracts sectioned during the three different steps in the surgery, namely the intrafrontal disconnection, anterior callosotomy, and frontobasal disconnection.

RESULTS

The first step of the dissection involves cutting the U-fibers. During the anterior intrafrontal disconnection, the superior longitudinal fasciculus in the depth of the middle frontal gyrus, the uncinate fasciculus, and the inferior frontooccipital fasciculus in the depth of the inferior frontal gyrus at the level of the anterior insular point are visualized and sectioned, followed by sectioning of the anterior limb of the internal capsule. Once the frontal horn is reached, the anterior callosotomy can be performed to disconnect the genu and the rostrum of the corpus callosum. The intrafrontal disconnection is deepened toward the falx, and at the medial surface, the cingulum is sectioned. The frontobasal disconnection involves cutting the anterior limb of the anterior commissure.

CONCLUSIONS

This technique allows selective isolation of the epileptogenic focus located in the prefrontal lobe to avoid secondary propagation. Understanding the surface and white matter fiber anatomy is essential to safely perform the procedure and obtain a favorable seizure outcome.

A methodological perspective on the cognitive outcome of epilepsy surgery in children and adolescents

PURPOSE

The purpose of the study was to explore the impact of timing and test specificity of cognitive outcome measures after pediatric epilepsy surgery.

METHODS

A consecutive national cohort of 114 children with medically resistant epilepsy having had resective epilepsy surgery were screened for children tested with a complete age-appropriate Wechsler Intelligence test at two or three time-points. This provided 43 children for analyses. Composite subscale scores were assessed in comparison to index and intelligence quotient (IQ) scores.

RESULTS

We found a main effect of time in seizure-free children for full-scale IQ (FSIQ); F(2, 42) = 6.49 with higher T2 measures compared with T1 (M_Diff = 5.46, p = .006). There was a difference in FSIQ scores between seizure-free and nonseizure-free children at T2; M = 7.31, 95% confidence interval (CI) [0.05 to 14.57], t(38) = 2.04, p = .049, favoring seizure-free children. A statistical difference between composite scale scores and index scores was found with medium to large effect. The correlation of medical treatment (anti-epileptic drug (AED)) change and score differences in FSIQ outcome was significant (p = .041), with less AED correlated with a higher FSIQ. All children with left-temporal surgery had a stable or improved verbal comprehension composite subscale score outcome at T2 regardless of seizure status.

CONCLUSION

Our results correspond to some longitudinal studies with outcome measures >2 years, in contrast to short-term studies ≤2 years with a stable outcome. Our study supports the fact that the specificity of the used tests and the timing of assessments after pediatric epilepsy surgery are essential factors for the clinical validity of outcome measures. However, there are further needs of extensive longitudinal studies to provide a better understanding of life-long cognitive development and impact after childhood 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.

Risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia

OBJECTIVE

The purpose of this study was to identify the risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia (FCD).

METHODS

77 patients with histopathologically confirmed FCD were studied. The statistical relationship between cognition levels and clinical factors at presurgical evaluation was analyzed. Cognitive function was evaluated by development quotient or intelligence quotient (DQ-IQ).

RESULTS

Ages at seizure onset were younger than 15 years (mean ± SD; 5.0 ± 4.2 years). Mean disease duration was 14.5 ± 8.5 years. Mean age at pre-surgical DQ-IQ evaluation was 34.8 ± 10.7 years. Mean DQ-IQ was 60.5 ± 20.5, and 41 of 77 (53.2%) patients had mental retardation (DQ-IQ < 70). Younger seizure onset and seizure clustering were significantly associated with lower DQ-IQ (p < 0.001). A multiple regression study identified higher seizure frequency pattern, a history of epileptic spasm and status epilepticus as aggravating factors of DQ-IQ decline (R² = 0.63, p < 0.001). On the other hand, the risk was decreased in patients with habitual focal aware seizure and transient seizure-free periods up to 6 months in the course of epilepsy. FCD location (FCD site, extent of radiological lesion and laterality) and histopathology of FCD did not affect DQ-IQ.

CONCLUSIONS

Our study suggests that seizure characteristics including higher seizure frequency pattern, a history of epileptic spasm, status epilepticus, seizure clustering and early onset of seizure are risk factors of cognitive impairment in FCD patients.

Benign and severe early-life seizures: a round in the first year of life

BACKGROUND

At the onset, differentiation between abnormal non-epileptic movements, and epileptic seizures presenting in early life is difficult as is clinical diagnosis and prognostic evaluation of the various seizure disorders presenting at this age. Seizures starting in the first year of life including the neonatal period might have a favorable course, such as in infants presenting with benign familial neonatal epilepsy, febrile seizures simplex or acute symptomatic seizures. However, in some cases, the onset of seizures at birth or in the first months of life have a dramatic evolution with severe cerebral impairment. Seizure disorders starting in early life include the "epileptic encephalopathies", a group of conditions characterized by drug resistant seizures, delayed developmental skills, and intellective disability. This group of disorders includes early infantile epileptic encephalopathy also known as Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, infantile spasms syndrome (also known as West syndrome), severe myoclonic epilepsy in infancy (also known as Dravet syndrome) and, myoclonic encephalopathies in non-progressive disorder. Here we report on seizures manifesting in the first year of life including the neonatal period. Conditions with a benign course, and those with severe evolution are presented. At this early age, clinical identification of seizures, distinction of each of these disorders, type of treatment and prognosis is particularly challenging. The aim of this report is to present the clinical manifestations of each of these disorders and provide an updated review of the conditions associated with seizures in the first year of life.

Cognitive Outcome After Epilepsy Surgery in Children

Cognitive dysfunction in children with epilepsy is primarily contributed by etiology, seizures, frequency of interictal epileptiform discharges, and adverse effects of antiepileptic drugs. The direct effect of epilepsy surgery on cognitive outcome depends on two key factors: the function that is present in the epileptogenic zone to be removed, and the dysfunction outside the epileptogenic zone caused by epilepsy. Studies on cognitive outcome in children after various types of epilepsy surgery estimate "no significant change" in about 70% of children, improvement in cognition in 10%-15%, and decline in 10%-15%. In young children with epileptic encephalopathy, the reversible dysfunction outside the epileptogenic zone is larger and hence carry better chances of improved outcome after successful surgery. If the epileptogenic zone harbors significant cognitive function (memory, language, or other function), then a decline in function may occur with its resection. Understanding the pathophysiological basis for the cognitive changes after epilepsy surgery assists in counseling patients and families before surgery.

Early Life Epilepsies are a Comorbidity of Developmental Brain Disorders

Early-life epilepsies are a series of disorders frequently accompanied by a broad range of morbidities that include cognitive, behavioral, neuromuscular, and sleep disturbances; enteric and other forms of autonomic dysfunction; sensory processing difficulties; and other issues. Usually these morbidities cluster together in a single patient. Rather than these being separate conditions, all, including the seizures, are manifestations or coexpressions of developmental brain disorders. Instead of viewing epilepsy as the disease and the other features as comorbidities, approaching early-life epilepsies as part of the spectrum of developmental brain disorders could have implications for multidisciplinary care models, anticipatory guidance, and counseling of parents, as well as the design of randomized trials and targeting important outcomes. Ultimately, such an approach could improve understanding and help optimize outcomes in these difficult to treat disorders of early childhood.

Cognitive outcome after epilepsy surgery in children: A controlled longitudinal study

OBJECTIVE

To analyze the determinants of cognitive outcome two years after surgery for drug-resistant epilepsy in a cohort of 31 children when compared to a control group of 14 surgical candidates who had yet to undergo surgery two years after the first neuropsychological assessment.

METHODS

Controlled longitudinal study including three evaluations of IQ (Intelligence Quotient) scores or GDQ (General Developmental Quotient) for each group depending on the patient's age: prior to surgery (T0), one year (T1) and two years (T2) after surgery for the surgical group; baseline (T0) and one year (T1) and 2years (T2) after the first evaluation for the control-group. At follow-up, 25 children (80%) of the surgical group were seizure free, while seizure outcome was unsatisfactory in the remaining six (20%). To analyze language, visuomotor skills, memory, reading, visual attention, and behavior, we selected 11 school age children in the surgical group and nine controls. We reported performance prior to (T0) and one year after surgery (T1).

RESULTS

There was a significant correlation between earlier age at seizure onset and lower IQ/GDQ at T0 (r=0.39; p=0.03) in the overall cohort. IQ/GDQ scores did not significantly differ between the surgical and control groups when analyzed at T0 and T2. However, they evolved differently with an improved developmental trajectory becoming identifiable only in the surgical group (F_1,31=5.33 p=0.028; η²=0.15). There was also a significant increase of forward digit span (Z=2.33; p=0.02) and Rey recall scores (Z=1.97; p=0.049) in the surgical school age subgroup at T1 versus T0.

SIGNIFICANCE

We identified significantly different developmental trajectories in operated versus non- operated children with improved IQ/GDQ scores in operated children only. We also observed a significant increase of digit span scores and Rey recall scores a year after surgery. Further studies including larger samples with longer follow-ups are needed to confirm these preliminary findings.

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.

Novel surface features for automated detection of focal cortical dysplasias in paediatric epilepsy

Focal cortical dysplasia is a congenital abnormality of cortical development and the leading cause of surgically remediable drug-resistant epilepsy in children. Post-surgical outcome is improved by presurgical lesion detection on structural MRI. Automated computational techniques have improved detection of focal cortical dysplasias in adults but have not yet been effective when applied to developing brains. There is therefore a need to develop reliable and sensitive methods to address the particular challenges of a paediatric cohort. We developed a classifier using surface-based features to identify focal abnormalities of cortical development in a paediatric cohort. In addition to established measures, such as cortical thickness, grey-white matter blurring, FLAIR signal intensity, sulcal depth and curvature, our novel features included complementary metrics of surface morphology such as local cortical deformation as well as post-processing methods such as the "doughnut" method - which quantifies local variability in cortical morphometry/MRI signal intensity, and per-vertex interhemispheric asymmetry. A neural network classifier was trained using data from 22 patients with focal epilepsy (mean age = 12.1 ± 3.9, 9 females), after intra- and inter-subject normalisation using a population of 28 healthy controls (mean age = 14.6 ± 3.1, 11 females). Leave-one-out cross-validation was used to quantify classifier sensitivity using established features and the combination of established and novel features. Focal cortical dysplasias in our paediatric cohort were correctly identified with a higher sensitivity (73%) when novel features, based on our approach for detecting local cortical changes, were included, when compared to the sensitivity using only established features (59%). These methods may be applicable to aiding identification of subtle lesions in medication-resistant paediatric epilepsy as well as to the structural analysis of both healthy and abnormal cortical development.

Surgical Management of Pediatric Epilepsy: Decision-Making and Outcomes

First-line treatment for epilepsy is antiepileptic drug and requires an interdisciplinary approach and enduring commitment and adherence from the patient and family for successful outcome. Despite adherence to antiepileptic drugs, refractory epilepsy occurs in approximately 30% of children with epilepsy, and surgical treatment is an important intervention to consider. Surgical management of pediatric epilepsy is highly effective in selected patients with refractory epilepsy; however, an evidence-based protocol, including best methods of presurgical imaging assessments, and neurodevelopmental and/or behavioral health assessments, is not currently available for clinicians. Surgical treatment of epilepsy can be critical to avoid negative outcomes in functional, cognitive, and behavioral health status. Furthermore, it is often the only method to achieve seizure freedom in refractory epilepsy. Although a large literature base can be found for adults with refractory epilepsy undergoing surgical treatment, less is known about how surgical management affects outcomes in children with epilepsy. The purpose of the review was fourfold: (1) to evaluate the available literature regarding presurgical assessment and postsurgical outcomes in children with medically refractory epilepsy, (2) to identify gaps in our knowledge of surgical treatment and its outcomes in children with epilepsy, (3) to pose questions for further research, and (4) to advocate for a more unified presurgical evaluation protocol including earlier referral for surgical candidacy of pediatric patients with refractory epilepsy. Despite its effectiveness, epilepsy surgery remains an underutilized but evidence-based approach that could lead to positive short- and long-term outcomes for children with refractory epilepsy.

Predictors of intellectual functioning after epilepsy surgery in childhood: The role of socioeconomic status

OBJECTIVE

The objective of this study was to evaluate the association between socioeconomic status and intellectual functioning in children with medically refractory epilepsy, before and after resective epilepsy surgery. Family environment is a strong contributor to cognitive development in children and has been recently shown to play a significant role in intellectual outcome after surgery in children with epilepsy.

METHODS

One hundred children who had undergone resective epilepsy surgery and completed preoperative and postoperative assessments of IQ as part of clinical care were included in the study. We evaluated the impact of epilepsy-related variables, income quintile, and residence location on IQ.

RESULTS

Greater improvements in IQ after surgery were associated with an older age at surgery (β=.235, p=.018). Higher IQ scores at follow-up were associated with an older age of seizure onset (β=.371, p<.001), older age at surgery (β=.356, p<.001), unilobar epileptogenic focus (β=.394, p<.001), and mesial temporal sclerosis (β=.338, p=.001) or tumor (β=.457, p<.001) in comparison with malformation of cortical development; age at seizure onset did not remain as a significant predictor in multivariable regression analysis. Income quintile, residence location, seizure control, and antiepileptic medication use were not significant predictors.

CONCLUSIONS

Epilepsy-related variables were the strongest predictors of IQ and postoperative change in IQ. We were unable to identify a significant association between IQ and socioeconomic status. Future research should evaluate the impact of multiple aspects of family environment.

What is more harmful, seizures or epileptic EEG abnormalities? Is there any clinical data?

Cognitive impairment is a common and often devastating co-morbidity of childhood epilepsy. While the aetiology of the epilepsy is a critical determinant of cognitive outcome, there is considerable evidence from both rodent and human studies that indicate that seizures and interictal epileptiform abnormalities can contribute to cognitive impairment. A critical feature of childhood epilepsy is that the seizures and epileptiform activity occur in a brain with developing, plastic neuronal circuits. The consequences of seizures and interictal epileptiform activity in the developing brain differ from similar paroxysmal events occurring in the relatively fixed circuitry of the mature brain. In animals, it is possible to study interictal spikes independently from seizures, and it has been demonstrated that interictal spikes are as detrimental as seizures during brain development. In the clinic, distinguishing the differences between interictal spikes and seizures is more difficult, since both typically occur together. However, both seizures and interictal spikes result in transient cognitive impairment. Recurrent seizures, particularly when frequent, can lead to cognitive regression. While the clinical data linking interictal spikes to persistent cognitive impairment is limited, interictal spikes occurring during the formation and stabilization of neuronal circuits likely contribute to aberrant connectivity. There is insufficient clinical literature to indicate whether interictal spikes are more detrimental than seizures during brain development.

Surgical versus medical treatment for children with epileptic encephalopathy in infancy and early childhood: Results of an international multicenter cohort study in Far-East Asia (the FACE study)

OBJECTIVE

To compare the seizure and developmental outcomes in infants and young children with epileptic encephalopathy who have undergone surgical and medical treatments.

METHODS

An international, multicenter, observational cohort study was undertaken. A total of 317 children aged <6 years, who had frequent disabling seizures despite intensive medical treatments, were registered. Among the enrolled children, 250 were treated medically (medical group), 31 underwent resective surgery (resective group), and 36 underwent palliative surgery [callosotomy (n=30) or vagal nerve stimulation (n=6); palliative group] on admission. Seizure and developmental outcomes were obtained for 230 children during the 3-year follow-up period. Cox proportional hazard model was used to adjust for clinical backgrounds among treatment groups when comparing the seizure-free survival rates.

RESULTS

At the 3-year follow-up, seizure-free survival was 15.7%, 32.1%, and 52.4% in the medical, palliative, and resective groups, respectively. The adjusted hazard ratios for seizure recurrence in the resective and palliative groups versus the medical group were 0.43 (95% CI, 0.21-0.87, P=0.019) and 0.82 (95% CI, 0.46-1.46, P=0.50), respectively; the former was statistically significant. Regarding the developmental outcome, the mean DQs in the resective group increased significantly compared to those in the medical group during the follow-up (P<0.01). As for subgroup analysis, better seizure and development outcomes were demonstrated in the resective group compared to the medical group in children with nonsyndromic epilepsies (those to which no known epilepsy syndromes were applicable).

SIGNIFICANCE

These results suggest that surgical treatments, particularly resective surgeries, are associated with better seizure and developmental outcomes compared with successive medical treatment. The present observations may facilitate the identification of infants and young children with epileptic encephalopathy who could benefit from surgery.

Impact of epilepsy surgery on development of preschool children: identification of a cohort likely to benefit from early intervention

OBJECT

Outcomes of focal resection in young children with early-onset epilepsy are varied in the literature due to study differences. In this paper, the authors sought to define the effect of focal resection in a small homogeneous sample of children who were otherwise cognitively intact, but who required early surgical treatment. Preservation of and age-appropriate development of intelligence following focal resection was hypothesized.

METHODS

Cognitive outcome after focal resection was retrospectively reviewed for 15 cognitively intact children who were operated on at the ages of 2-6 years for lesion-related, early-onset epilepsy. Intelligence was tested prior to and after surgery. Effect sizes and confidence intervals for means and standard deviations were used to infer changes and differences in intelligence between 1) groups (pre vs post), 2) left versus right hemisphere resections, and 3) short versus long duration of seizures prior to resection.

RESULTS

No group changes from baseline occurred in Full Scale, verbal, or nonverbal IQ. No change from baseline intelligence occurred in children who underwent left or right hemisphere surgery, including no group effect on verbal scores following surgery in the dominant hemisphere. Patients with seizure durations of less than 6 months prior to resection showed improvement from their presurgical baseline in contrast to those with seizure duration of greater than 6 months prior to surgery, particularly in Wechsler Full Scale IQ and nonverbal intelligence.

CONCLUSIONS

This study suggests that surgical treatment of focal seizures in cognitively intact preschool children is likely to result in seizure remediation, antiepileptic drug discontinuation, and no significant decrement in intelligence. The latter finding is particularly significant in light of the longstanding concern associated with performing resections in the language-dominant hemisphere. Importantly, shorter seizure duration prior to resection can result in improved cognitive outcome, suggesting that surgery for this population should occur sooner to help improve intelligence outcomes.

Surgery for epilepsy

BACKGROUND

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 according to the age of the participants and which focal epilepsies are included, but have been reported as at least 20% and in some studies 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.The secondary objectives are to assess the overall outcome of epilepsy surgery according to non-randomised evidence and to identify the factors that correlate to remission of seizures postoperatively.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (June 2013), the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 6), MEDLINE (Ovid) (2001 to 4 July 2013), ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) for relevant trials up to 4 July 2013.

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs), cohort studies or case series, with either a prospective and/or retrospective design, including at least 30 participants, a well-defined population (age, sex, seizure type/frequency, duration of epilepsy, aetiology, magnetic resonance imaging (MRI) diagnosis, surgical findings), 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 relating to postoperative seizure control.

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 proportion 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 (RR) and 95% confidence intervals.

MAIN RESULTS

We identified 177 studies (16,253 participants) investigating the outcome of surgery for epilepsy. Four studies were RCTs (including one that randomised participants to surgery or medical treatment). The risk of bias in the RCTs was unclear or high, limiting our confidence in the evidence that addressed the primary review objective. Most of the remaining 173 non-randomised studies had a retrospective design; they were of variable size, were conducted in a range of countries, recruited a wide demographic range of participants, used a wide range of surgical techniques and used different scales used to measure outcomes. We performed quality assessment 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 the domains.In terms of freedom from seizures, one RCT found surgery to be superior to medical treatment, two RCTs found no statistically significant difference between anterior temporal lobectomy (ATL) with or without corpus callosotomy or between 2.5 cm or 3.5 cm ATL resection, and one RCT found total hippocampectomy to be superior to partial hippocampectomy. We judged the evidence from the four RCTs to be of moderate to very low quality due to the lack of information reported about the randomised trial design and the restricted study populations.Of the 16,253 participants included in this review, 10,518 (65%) 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 the recording of adverse events to be very poor.In total, 118 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: an abnormal pre-operative MRI, no use of intracranial monitoring, complete surgical resection, presence of mesial temporal sclerosis, concordance of pre-operative MRI and electroencephalography (EEG), 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 or presence of postoperative discharges were prognostic factors of outcome. We observed variability between studies for many of our analyses, likely due to the small study sizes with unbalanced group sizes, variation in the definition of seizure outcome, definition of the prognostic factor and the influence of the site of surgery, all of which we observed to be related to postoperative seizure outcome. Twenty-nine studies reported multivariable models of prognostic factors and the direction of association of factors with outcome was generally the same as found in the univariate analyses. However, due to the different multivariable analysis approaches and selective reporting of results, meaningful comparison of multivariate analysis with univariate meta-analysis is difficult.

AUTHORS' CONCLUSIONS

The 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 outcome. Future research should be of high quality, have 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 the extent of resection. Prognostic factors related to the outcome of surgery should be investigated via multivariable statistical regression modelling, where variables are selected for modelling according to clinical relevance and all numerical results of the prognostic models are fully reported. Protocols should include pre- and postoperative measures of speech and language function, cognition and social functioning along with a mental state assessment. Journal editors should not accept papers where adverse events from a medical intervention are not recorded. Improvements in the development of cancer care over the past three to four decades have been achieved 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.

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.

Developmental outcome after surgery in focal cortical dysplasia patients with early-onset epilepsy

The purpose of this study was to investigate the developmental outcome after surgery for early-onset epilepsy in patients with focal cortical dysplasia (FCD). Among 108 patients with histopathologically confirmed FCD operated between 1985 and 2008, we selected 17 patients with epilepsy onset up to 3 years of age. Development was evaluated by the developmental quotient or intelligence quotient (DQ-IQ) and mental age was measured by the Mother-Child Counseling baby test or the Tanaka-Binet scale of intelligence. Postsurgical development outcome was evaluated by the changes in DQ-IQ and mental age as well as rate of increase in mental age (RIMA) after surgery. RIMA was calculated as the increase in mental age per chronological year (months/year; normal average rate: 12 months/year). Age at epilepsy onset of 17 patients ranged from 15 days to 36 months (mean±SD, 11.0±10.0 months). Age at surgery ranged from 18 to 145 months (75.1±32.4 months). Evaluation just before surgery showed that 13 of 17 (76.4%) patients had DQ-IQ below 70. Ten patients (58.8%) were seizure-free throughout the postsurgical follow-up period. After surgery, DQ-IQ was maintained within 10 points of the presurgical level in 13 patients (76.4%), and increased by more than 10 points in one patient (5.9%). After surgery, RIMA in patients with Engel's class I (7.5±3.8) was higher than patients with Engel's class II-IV (2.6±3.4) (unpaired t-test with Welch's correction, t=2.99, df=15, p=0.0092). RIMA was particularly low in two patients with spasm. In four patients with presurgical DQ-IQ<70, seizure-free after surgery and without spasm, DQ-IQ did not increase but RIMA improved from 3.6±2.8 before surgery to 6.9±2.5 months/year after surgery. RIMA became better from 2 years after surgery. In four patients with presurgical DQ-IQ≥70 and no spasm, two showed the same or higher RIMA than normal average after surgery. In 58.8% of FCD patients with early onset epilepsy, epilepsy surgery effectively controlled seizures, and in 82.3% of patients, epilepsy surgery preserved or improved development. Residual seizures after surgery and lower DQ-IQ before surgery might be potential risk factors for poor development after surgery. In patients of Engel's class I with lower presurgical DQ-IQ, catch-up increase in mental age was observed after two years following surgery.

Visual memory after epilepsy surgery in children: a standardized regression-based analysis of group and individual outcomes

Visual memory is vulnerable to epilepsy surgery in adults, but studies in children suggest no change or small improvements. We investigated visual memory after epilepsy surgery, both group-wise and in individual children, using two techniques to assess change: 1) repeated measures analysis of variance (ANOVA) and 2) an empirically based technique for detecting cognitive change [standardized regression-based (SRB) analysis]. A prospective cohort consisting of 21 children completed comprehensive assessments of memory both before surgery (T0) and 6 (T1), 12 (T2), and 24 months (T3) after surgery. For each patient, two age- and gender-matched controls were assessed with the same tests at the same intervals. Repeated measures ANOVA replicated the results of previous studies reporting no change or minor improvements after surgery. However, group analysis of SRB results eliminated virtually all improvements, indicating that the ANOVA results were confounded by practice effects. Standardized regression-based group results showed that in fact patients scored lower after surgery than would be predicted based on their presurgical performance. Analysis of individual SRB results showed that per visual memory measure, an average of 18% of patients obtained a significantly negative SRB score, whereas, on average, only 2% obtained a significantly positive SRB score. At T3, the number of significantly negative SRB scores outweighed the number of significantly positive SRB scores in 62% of patients. There were no clear associations of clinical variables (including side and site of surgery and postsurgical seizure freedom) with memory outcome. The present analysis revealed that given their individual presurgical functioning, many children obtained disappointing results on some visual memory tests after epilepsy surgery. Comparison of the SRB analysis with ANOVA results emphasizes the importance of empirically based techniques for detecting cognitive effects of epilepsy surgery in childhood.

Patient considerations in the management of focal seizures in children and adolescents

Focal epilepsy accounts for approximately one-half to two-thirds of new-onset epilepsy in children. Etiologies are diverse, and range from benign epilepsy syndromes with normal neuroimaging and almost certain remission to focal malformations of cortical development or hippocampal sclerosis with intractable seizures persisting lifelong. Other important etiologies in children include pre-, peri-, or postnatal brain injury, low-grade neoplasms, vascular lesions, and neuroimmunological disorders. Cognitive, behavioral, and psychiatric comorbidities are commonly seen and must be addressed in addition to seizure control. Given the diverse nature of focal epilepsies in children and adolescents, investigations and treatments must be individualized. First-line therapy consists of prophylactic antiepileptic drugs; however, prognosis is poor after failure of two to three drugs for lack of efficacy. Refractory cases should be referred for an epilepsy surgery workup. Dietary treatments and neurostimulation may be considered in refractory cases who are not good candidates for surgery.

The medical and surgical treatment of tumoral seizures: current and future perspectives

Epilepsy surgery represents the main treatment option for epileptogenic brain tumors. Scalp video-electroencephalography (EEG) and magnetic resonance imaging (MRI) may suffice for defining lesional area and seizure-onset zone in discrete, surgically resectable lesions. The choice of timing for surgery requires a multidisciplinary evaluation, especially in children, when a "wait and see" approach is chosen. Discordant electroclinical and neuroimaging data and an ill-defined epileptogenic lesion require invasive investigations. A multimodal integrated approach may maximize the extent of resection while preserving cerebral function in the eloquent cortex. Radical removal of the tumor is the most important predictor of seizure freedom. Additional predictors include histopathology, age at surgery, duration of epilepsy, and seizure type. Patients with brain tumors are highly vulnerable in relation to the frequent drug-resistance of seizures, the potential interactions between antiepileptic drugs (AEDs) and chemotherapeutic agents (CMTs), and the risk of AED-related cognitive adverse events (24% higher than in the rest of the epilepsy population), in addition to brain damage resulting from tumor itself, surgery, and radiotherapy. No robust, randomized, controlled evidence supports the choice of AEDs for the treatment of seizures in patients with brain tumors. Newer AEDs have limited or no enzyme-inducing profile, prevalent renal excretion, lower plasma protein binding and, consequently, fewer interactions with CMTs. Enzyme-inducing AEDs can lower serum levels of concomitantly administered CMTs. Class I evidence suggests that in patients with brain tumors who do not have a history of seizures, prophylactic use of AEDs is neutral or ineffective.

Long-term developmental outcome after early hemispherotomy for hemimegalencephaly in infants with epileptic encephalopathy

This study aimed to identify the effect of early hemispherotomy on development in a consecutive series of 12 infants with hemimegalencephaly (HME) demonstrating epileptic encephalopathy. Mean age at onset was 20.4 days (range, 1-140), mean age at surgery was 4.3 months (range, 2-9), and mean follow-up time was 78.8 months (range, 36-121). Eleven patients had a history of early infantile epileptic encephalopathy. Vertical parasagittal hemispherotomy was performed without mortality or severe morbidities. At follow-up, seizure freedom was obtained in 8 patients (66.7%), who showed significantly higher postoperative developmental quotient (DQ) (mean, 31.3; range, 7-61) than those with seizures (mean, 5.5; range, 3-8) (p=0.02). Within the seizure-free group, postoperative DQ correlated with preoperative seizure duration (r=-0.811, p=0.01). Our results showed that shorter seizure duration during early infancy could provide better postoperative DQ in infants with HME and epileptic encephalopathy.

Cognitive outcome after epilepsy surgery in children

The ultimate goal of epilepsy surgery in young children is to stop seizures, interrupt the downhill course of the epileptic encephalopathy, and improve developmental capacities. Postoperative outcome after childhood epilepsy surgery should therefore not only be expressed in terms of seizure freedom, cognitive outcome is an equally important outcome measure. Insight in the mutually dependent variables that can determine pre and postoperative cognitive developmental abilities will improve prediction of outcome and presurgical counseling of parents. The purpose of this review is to discuss the literature regarding cognitive outcome and the predictors of postoperative cognitive functioning after epilepsy surgery in children, particularly those with "catastrophic" epilepsy. There are only few studies in which the relation between possible determinants and cognitive outcome or change was statistically tested in a multivariable manner. Duration of epilepsy, presurgical Developmental Quotient (DQ) or Intelligence Quotient (IQ), and postoperative seizure freedom were the only factors reported in different studies to be independently related to eventual cognitive outcome after epilepsy surgery. Underlying etiology, gender, age at surgery, presurgical DQ/IQ, postoperative seizure freedom, cessation of antiepileptic medication, and follow-up interval have all been described in different surgical cohorts to be independently related to a postoperative change of IQ or DQ scores. To appreciate how each of the pre-epileptic, presurgical, and postoperative variables may independently influence eventual cognitive outcome and postoperative cognitive improvement, we need multicenter studies with large homogenous surgical populations, using standardized tests and multivariable analyses.

How to establish causality in epilepsy surgery

Focality in electro-clinical or neuroimaging data often motivates epileptologists to consider epilepsy surgery in patients with medically-uncontrolled seizures, while not all focal findings are causally associated with the generation of epileptic seizures. With the help of Hill's criteria, we have discussed how to establish causality in the context of the presurgical evaluation of epilepsy. The strengths of EEG include the ability to determine the temporal relationship between cerebral activities and clinical events; thus, scalp video-EEG is necessary in the evaluation of the majority of surgical candidates. The presence of associated ictal discharges can confirm the epileptic nature of a particular spell and whether an observed neuroimaging abnormality is causally associated with the epileptic seizure. Conversely, one should be aware that scalp EEG has a limited spatial resolution and sometimes exhibits propagated epileptiform discharges more predominantly than in situ discharges generated at the seizure-onset zone. Intraoperative or extraoperative electrocorticography (ECoG) is utilized when noninvasive presurgical evaluation, including anatomical and functional neuroimaging, fails to determine the margin between the presumed epileptogenic zone and eloquent cortex. Retrospective as well as prospective studies have reported that complete resection of the seizure-onset zone on ECoG was associated with a better seizure outcome, but not all patients became seizure-free following such resective surgery. Some retrospective studies suggested that resection of sites showing high-frequency oscillations (HFOs) at >80Hz on interictal or ictal ECoG was associated with a better seizure outcome. Others reported that functionally-important areas may generate HFOs of a physiological nature during rest as well as sensorimotor and cognitive tasks. Resection of sites showing task-related augmentation of HFOs has been reported to indeed result in functional loss following surgery. Thus, some but not all sites showing interictal HFOs are causally associated with seizure generation. Furthermore, evidence suggests that some task-related HFOs can be transiently suppressed by the prior occurrence of interictal spikes. The significance of interictal HFOs should be assessed by taking into account the eloquent cortex, seizure-onset zone, and cortical lesions. Video-EEG and ECoG generally provide useful but still limited information to establish causality in presurgical evaluation. A comprehensive assessment of data derived from multiple modalities is ultimately required for successful management.

Psychiatric symptoms in children prior to epilepsy surgery differ according to suspected seizure focus

PURPOSE

Children and adolescents with epilepsy have an overrepresentation of psychiatric illness. However, few studies in pediatrics have characterized specific psychiatric conditions associated with seizure localization. In addition, degree to which psychiatric illness may be more prominent in children refractory to standard medical treatment for epilepsy is not known. The aim of this study was to assess psychiatric symptoms in children with medically refractory epilepsy and ascertain whether symptoms were associated with specific localization.

METHODS

Case records were reviewed for 40 children with medically refractory epilepsy at the time of their referral for presurgical evaluation. Patients received a clinical psychiatric evaluation and parents completed the Child Behavioral Checklist (CBCL). Seizure localization was verified by pediatric epileptologists, and suitability for surgical procedures was verified by neurosurgical specialists. Groups were compared based on localization of seizure foci, either in the temporal lobe or predominantly extratemporal.

KEY FINDINGS

The majority of the sample had psychiatric diagnoses and behavior problems, well beyond the level reported in chronic epilepsy populations. In addition, children with temporal lobe seizure foci had more CBCL behavioral problem categories rated in the clinically significant range, and also were more likely to have clinical diagnoses of depression.

SIGNIFICANCE

Routine psychiatric evaluation prior to epilepsy surgery may be important for pediatric patients with medically refractory epilepsy. Psychiatric illness, particularly depression, may be especially prominent for those with temporal lobe seizure foci.

Seizure outcome after extratemporal epilepsy surgery in childhood

AIM

The aim of the study was to describe seizure outcome following surgery for focal extratemporal epilepsy and identify factors associated with prolonged postsurgical freedom from seizures.

METHOD

In this retrospective cohort study, children with drug-resistant focal extratemporal epilepsy were treated surgically and followed up in a single tertiary care centre between 1997 and 2008.

RESULTS

Eighty children were identified for inclusion in the study (42 males, 38 females; median age 9y 1mo, range 3mo-18y 7mo). The aetiology was identified as focal cortical dysplasia (n=37), low-grade tumour (n=22), tuberous sclerosis (n=9), or non-specific (n=12). Children were followed for a median of 3 years 1 month (range 8mo-10y 7mo) after surgery. Overall, at last follow-up, 50% of the children had been completely seizure free since surgery (Engel class Ia); of these 40 individuals, 15 had discontinued all antiepileptic drugs. Several presurgical factors were associated with a favourable outcome. However, after controlling for confounding factors, aetiology appeared to be the only determinant of long-term seizure outcome as non-specific lesion pathology was associated with seizure recurrence (hazard ratio 10.43; 95% confidence interval 3.26-33.39).

INTERPRETATION

In 50% of cases, children with surgically treated drug-resistant extratemporal epilepsies have an excellent long-term outcome. The aetiology of the epileptogenic lesion appears to be the only significant determinant of surgical outcome in this population of children. It is difficult to correctly identify non-specific pathology on presurgical magnetic resonance imaging.

Age at onset of epilepsy, pharmacoresistance, and cognitive outcomes: a prospective cohort study

OBJECTIVES

Increasing evidence suggests that uncontrolled seizures have deleterious effects on cognition and behavior, particularly in the developing brain.

METHODS

In a community-based cohort, 198 children, aged <8 years with new-onset epilepsy were followed prospectively and reassessed with the Wechsler Intelligence Scales for Children, Third Edition (WISC-III) 8-9 years later. Linear regression analyses with interactions between age at onset (age) and pharmacoresistance (PR) were used to test whether earlier onset conveyed greater vulnerability to the effects of uncontrolled seizures. Full-scale IQ (FSIQ) and the 4 subdomain scores were examined. Adjustment for adaptive behavior scores in a subset was performed. A dichotomous indicator for IQ <80 or ≥80 was used to permit inclusion of children who were not tested, particularly those who were untestable.

RESULTS

FSIQ was not correlated with age. PR was associated with an 11.4 point lower FSIQ (p = 0.002) and similar decrements in each WISC-III domain. There were substantial age-PR interactions for FSIQ (p = 0.003) and 3 domain scores, indicating a lessening impact of PR with increasing age. The dichotomous IQ indicator was strongly correlated with age at onset in the pharmacoresistant group (p < 0.0001) and not in the non-pharmacoresistant group (p = 0.61). Adjustment for adaptive behavior measured near onset did not alter the conclusions.

CONCLUSIONS

Uncontrolled seizures impair cognitive function with effects being most severe in infancy and lessening with increasing age at onset. These findings further emphasize the need for early aggressive treatment and seizure control in infants and young children.

Impaired default mode network on resting-state FMRI in children with medically refractory epilepsy

BACKGROUND AND PURPOSE

Resting-state networks including the DMN have been shown to be abnormal in adults with temporal lobe epilepsy. However, little is known about the DMN in children with medically refractory epilepsy. The aim was to determine whether there was a difference in the DMN in children with medically refractory epilepsy relative to controls.

MATERIALS AND METHODS

Eleven children with medically refractory epilepsy and 11 age-matched healthy controls underwent resting-state fMRI. IC analysis was used to identify the DMN. A random-effects analysis was performed on the Z-maps of the DMN within each group and between groups. We calculated the temporal correlation coefficients of pairs of ROIs: PCC/PCUN, mPFC, and left and right lateral parietal cortices. The relations between z scores of temporal correlation coefficients of pairs of ROIs and clinical seizure parameters and IQ were assessed.

RESULTS

The patients demonstrated decreased DMN connectivity in the PCC/PCUN, bilateral lateral parietal cortex, and anterior and midcingulate relative to controls. There was reduced connectivity between the mPFC-right lateral parietal cortex, the PCC/PCUN-left lateral parietal cortex, and the PCC/PCUN-right lateral parietal cortex pairs of ROIs in patients compared with controls. There were no significant correlations between the z scores of temporal correlation coefficients of the 6 pairs of ROIs in patients and age of seizure onset, duration of epilepsy, number of medications, seizure frequency, and IQ.

CONCLUSIONS

We have found reduced connectivity in the DMN in children with medically refractory epilepsy. Further studies are needed to determine whether different seizure types have different effects on the DMN and whether the impaired connectivity is related to cognitive functions subserved by the DMN.

Cognitive development from two to ten years after pediatric epilepsy surgery

The development of cognitive functions and the sustainability of seizure control between two and ten years after epilepsy surgery were prospectively investigated in 17 children and adolescents. Intelligence quotient remained stable. Learning capacity improved. Verbal memory improved in half of the subjects and declined in half, whereas figurative memory declined in most patients. Working memory improved as did attention regarding sustained attention and impulse control. In contrast, reaction times were longer, and the auditory attention span was shorter. Executive functions were not affected. Six subjects (35%) were seizure free at the 10-year follow-up, and a seizure reduction of more than 75% had been achieved in 13 (76%). Seizure control improved in five and seizures recurred in two subjects between the two- and the 10-year follow-up.

Psychopathology in children before and after surgery for extratemporal lobe epilepsy

AIM

To establish the rates and types of psychiatric disorder in children before and after surgery for extratemporal epilepsy. Relationships between psychiatric morbidity and demographic/clinical variables were examined.

METHOD

A retrospective case note review of 71 children undergoing extratemporal focal resection for drug resistant epilepsy in a specialist epilepsy surgery programme between 1997 and 2008. Psychiatric diagnoses were derived from pre- and postoperative assessments according to DSM-IV criteria.

RESULTS

Seventy-one children (38 males, 33 females) were eligible for this study. Mean age (SD) at surgery was 9 (5) years. Frontal resections were performed in 73% of the children, parietal in 17%, and occipital in 10%. Mental health problems were present in 37 of 71 (52%) children pre- and/or postoperatively. A similar proportion of children had psychiatric diagnoses pre- and postoperatively: 31 of 71 (44%) and 32 of 71 (45%) respectively.

INTERPRETATION

Psychopathology is common in children with extratemporal epilepsy. In this sample, the impact of surgery on psychiatric symptoms was not predictable: some children were unchanged, others improved, and others acquired new psychiatric diagnoses postoperatively. Given the high rates of psychiatric disorder in this group of patients, detection and treatment of mental health needs may be important.

Paediatric intractable epilepsy syndromes: changing concepts in diagnosis and management

Epilepsy surgery for drug-resistant childhood epilepsy is not new. However, brain imaging, surgical and anaesthetic techniques have improved to the extent that they are now as much safer and realistic option than they were in the past. Further, the range of surgical candidates is wide, and previous concepts about likely surgical candidates are now challenged as children with previously thought widespread or apparent multifocal disease are evaluated. Outcomes for seizure freedom range from 40 to 80 % depending on the underlying aetiology and the extent of resection. However, the aims of surgery may include seizure reduction in some and improvement in neurodevelopment and behaviour in others, which are less -predictable. Epilepsy surgery in children is no longer a last resort. Children thought to be likely candidates should be evaluated early in their natural history to optimise outcomes in the long term.