Neuropsychological outcomes following paediatric temporal lobe surgery for epilepsies: Evidence from a systematic review

Characterization and Prediction of Short-term Outcomes in Memory After Temporal Lobe Resection in Children With Epilepsy

BACKGROUND AND OBJECTIVES

The aim of this study was to characterize short-term outcomes in episodic memory, as assessed by the Children's Memory Scale (CMS), after temporal lobe resection in children with epilepsy using empirical methods for assessing cognitive change (i.e., reliable change indices [RCI] and standardized regression-based change scores [SRB]) and develop and internally validate clinically applicable models to predict postoperative memory decline.

METHODS

This retrospective cohort study included children aged 6-16 years who underwent resective epilepsy surgery that included the temporal lobe (temporal only: "temporal" and multilobar: "temporal plus") and who completed preoperative and postoperative neuropsychological assessments including the CMS. Change scores on the CMS delayed memory subtests (Faces, Stories, and Word Pairs) were classified as decline, no change, or improvement using epilepsy-specific RCI and SRB. Logistic regression models for predicting postoperative memory decline were developed and internally validated with bootstrapping.

RESULTS

Of the 126 children included, most of them demonstrated either no significant change (54%-69%) or improvement (8%-14%) in memory performance using RCI on individual measures at a median of 7 months after surgery. A subset of children (23%-33%) showed postoperative declines. Change distributions obtained using RCI and SRB were not statistically significantly different from each other. Preoperative memory test score, surgery side, surgery extent, and preoperative full-scale IQ were predictors of memory decline. Prediction models for memory decline included subsets of these variables with bias-corrected concordance statistics ranging from 0.70 to 0.75. The models were well calibrated although slightly overestimated the probability of verbal memory decline in high-risk patients.

DISCUSSION

This study used empiric methodology to characterize memory outcome in children after temporal lobe resection. Provided online calculator and nomograms may be used by clinicians to estimate the risk of postoperative memory decline for individual patients before surgery.

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.

Development of a core outcome set for quality of life for adults with drug-resistant epilepsy: A multistakeholder Delphi consensus study

OBJECTIVE

In 2017, the American Academy of Neurology (AAN) convened the AAN Quality Measurement Set working group to define the improvement and maintenance of quality of life (QOL) as a key outcome measure in epilepsy clinical practice. A core outcome set (COS), defined as an accepted, standardized set of outcomes that should be minimally measured and reported in an area of health care research and practice, has not previously been defined for QOL in adult epilepsy.

METHODS

A cross-sectional Delphi consensus study was employed to attain consensus from patients and caregivers on the QOL outcomes that should be minimally measured and reported in epilepsy clinical practice. Candidate items were compiled from QOL scales recommended by the AAN 2017 Quality Measurement Set. Inclusion criteria to participate in the Delphi study were adults with drug-resistant epilepsy diagnosed by a physician, no prior diagnosis of psychogenic nonepileptic seizures or a cognitive and/or developmental disability, or caregivers of patients meeting these criteria.

RESULTS

A total of 109 people satisfied inclusion/exclusion criteria and took part in Delphi Round 1 (patients, n = 95, 87.2%; caregivers, n = 14, 12.8%), and 55 people from Round 1 completed Round 2 (patients, n = 43, 78.2%; caregivers, n = 12, 21.8%). One hundred three people took part in the final consensus round. Consensus was attained by patients/caregivers on a set of 36 outcomes that should minimally be included in the QOL COS. Of these, 32 of the 36 outcomes (88.8%) pertained to areas outside of seizure frequency and severity.

SIGNIFICANCE

Using patient-centered Delphi methodology, this study defines the first COS for QOL measurement in clinical practice for adults with drug-resistant epilepsy. This set highlights the diversity of factors beyond seizure frequency and severity that impact QOL in epilepsy.

Precision medicine in pediatric temporal epilepsy surgery: optimization of outcomes through functional MRI memory tasks and tailored surgeries

OBJECTIVE

The goal of epilepsy surgery is both seizure cessation and maximal preservation of function. In temporal lobe (TL) cases, the lack of functional MRI (fMRI) tasks that effectively activate mesial temporal structures hampers preoperative memory risk assessment, especially in children. This study evaluated pediatric TL surgery outcome optimization associated with tailored resection informed by an fMRI memory task.

METHODS

The authors identified focal onset TL epilepsy patients with 1) TL resections; 2) viable fMRI memory scans; and 3) pre- and postoperative neuropsychological (NP) evaluations. They retrospectively evaluated preoperative fMRI memory scans, available Wada tests, pre- and postoperative NP scores, postoperative MRI scans, and postoperative Engel class outcomes. To assess fMRI memory task outcome prediction, the authors 1) overlaid preoperative fMRI activation onto postoperative structural images; 2) classified patients as having "overlap" or "no overlap" of activation and resection cavities; and 3) compared these findings with memory improvement, stability, or decline, based on Reliable Change Index calculations.

RESULTS

Twenty patients met the inclusion criteria. At a median of 2.1 postoperative years, 16 patients had Engel class IA outcomes and 1 each had Engel class IB, ID, IIA, and IID outcomes. Functional MRI activation was linked to NP memory outcome in 19 of 20 cases (95%). Otherwise, heterogeneity characterized the cohort.

CONCLUSIONS

Functional MRI memory task activation effectively predicted individual NP outcomes in the context of tailored TL resections. Patients had excellent seizure and overall good NP outcomes. This small study adds to extant literature indicating that pediatric TL epilepsy does not represent a single clinical syndrome. Findings support individualized surgical intervention using fMRI memory activation to help guide this precision medicine approach.

Cognitive outcomes following pediatric epilepsy surgery

OBJECTIVES

To characterize outcomes following pediatric epilepsy surgery across a broad range of cognitive domains using empirical methods (i.e., reliable change indices: RCIs), compare these outcomes with those based on traditional methods (i.e., standard deviation: SD), and identify factors associated with postoperative cognitive declines and/or improvements.

METHODS

This retrospective cohort study included 186 children who underwent surgical resection for treatment of pharmacoresistant epilepsy and who completed pre- and postoperative neuropsychological assessments. Postoperative testing occurred approximately 6.5 months after surgery and included measures of intelligence, attention/working memory, processing speed, language, executive functioning, visuospatial skills, memory, and academic achievement. Change scores for each patient were classified as decline, no change, or improvement using epilepsy-specific RCIs. Chi-square goodness of fit tests were used to compare the distribution of outcomes as classified with RCIs to those obtained using a traditional one SD cutoff. Multinomial regression analyses were conducted to identify factors associated with cognitive decline and/or improvement.

RESULTS

While 18% of children demonstrated no postoperative declines or improvements in any cognitive domain, the majority demonstrated relatively focal changes (declines and/or improvements in 1-2 cognitive domains). Rates of postoperative decline and improvement across individual cognitive domains were variable and ranged from 4-35% and 2-31%, respectively. Compared to RCIs, SD methodology often overestimated postoperative improvements and varied with respect to declines. Factors associated with RCI decline or improvement included preoperative performance, age at surgery, surgery site, and postoperative seizures.

SIGNIFICANCE

Results suggest substantial variability in individual cognitive outcomes approximately 6.5 months following pediatric epilepsy surgery. The differences in change distributions obtained using epilepsy-specific RCIs versus SDs highlight the need for studies using empiric methodology to study postoperative cognitive change. Variables associated with postoperative cognitive change may be used to develop multivariable prediction models in future studies to aid clinical decision-making and patient counseling.

"Is this normal after such a major surgery?" Memory complaint after right temporal lobe excision in an adolescent

Memory deficits are commonly associated with temporal-lobe epilepsy. Memory may worsen after surgical resection of the temporal lobe. Risk factors for decline are structural integrity of the mesial temporal lobe structures and intact pre-operative memory. Subjective memory complaints are influenced by depression or other psychological disorders. A 16-year-old girl underwent resection from the right lateral and medial temporal lobe and after surgery she complained of a significant memory impairment, which was unexpected given her baseline assessment. Before undertaking a neuropsychological assessment, she was referred for a psychiatric consultation which revealed depression, leading to treatment with anditdepressant medication. Over time she also admitted to severe headaches and inadequate sleep. With these issues addressed, assessment indicated memory performance had not changed relative to her preoperative baseline with stability or improvement in memory across longitudinal assessments. This case illustrates the contribution of mood state and other potential factors in contributing to subjective memory complaints.

Surgery for Intractable Epilepsy in Pediatrics, a Systematic Review of Outcomes other than Seizure Freedom

To perform a systematic review evaluating reported outcomes for epilepsy surgery in pediatric patients with pharmacoresistant epilepsy beyond seizure control, including impact on quality of life, behavioral, neurocognitive outcomes as well as complications, and death. We reviewed articles from both EMBASE and MEDLINE/PubMed articles that met formal criteria (patients ≤18 years, those with intractable epilepsy, at least 5 patients in the case series, published in peer-reviewed journal). Each reviewer independently reviewed the articles and those with discrepancies were discussed and consensus was reached. Out of a total of 536 abstracts obtained from EMBASE and MEDLINE/PubMed searches combined with additional cross-referencing, a total of 98 manuscripts ultimately met all inclusion criteria. The manuscripts were divided into 3 outcomes categories: Quality of Life (16), Cognitive Outcomes (60), and Deficits and Complications (50). Several papers fell into more than 1 category. These were separated by surgical types and evaluated. We found that overall reporting in all domains was variable and inconsistent amongst the different studies. This systematic review highlights the lack of completeness in reporting outcomes and complications involving pediatric epilepsy surgery and discordant results. This underscores the importance of multicenter systematic prospective data collection in pediatric patients who undergo pediatric epilepsy surgery.

Long-term outcomes of children with drug-resistant epilepsy across multiple cognitive domains

AIM

To simultaneously evaluate long-term outcomes of children with drug-resistant epilepsy (DRE) across multiple cognitive domains and compare the characteristics of participants sharing a similar cognitive profile.

METHOD

Participants were adolescents and young adults (AYAs) diagnosed with DRE in childhood, who completed a comprehensive neuropsychological battery evaluating intelligence, memory, academic, and language skills at the time of surgical candidacy evaluation and at long-term follow-up (4-11y later). Hierarchical k-means clustering identified subgroups of AYAs showing a unique pattern of cognitive functioning in the long-term.

RESULTS

Participants (n=93; mean age 20y 1mo [standard deviation {SD} 4y 6mo]; 36% male) were followed for 7 years (SD 2y 4mo), of whom 65% had undergone resective epilepsy surgery. Two subgroups with unique patterns of cognitive functioning were identified, which could be broadly categorized as 'impaired cognition' (45% of the sample) and 'average cognition' (55% of the sample); the mean z-score across cognitive measures at follow-up was -1.86 (SD 0.62) and -0.23 (SD 0.54) respectively. Surgical and non-surgical patients were similar with respect to seizure control and their long-term cognitive profile. AYAs in the average cognition cluster were more likely to have better cognition at baseline, an older age at epilepsy onset, and better seizure control at follow-up.

INTERPRETATION

The underlying abnormal neural substrate and seizure control were largely associated with long-term outcomes across cognitive domains.

Quantitative Meta-Analyses: Lateralization of Memory Functions Before and After Surgery in Children with Temporal Lobe Epilepsy

RATIONALE

Memory deficits in children with epilepsy have been reported in some but not all studies assessing the effects of side of seizures and resection from the temporal lobe on cognitive performance. This meta-analysis provides a quantitative systematic review of previous studies on this issue.

METHOD

A critical review and meta-analysis of the literature on memory performance in children with Temporal Lobe Epilepsy (TLE) was conducted. Search identified 25 studies, 13 of which compared children with TLE to healthy age-matched controls and 12 of which compared children with TLE before and after surgery.

RESULTS

Heterogeneity of the comparisons of children with TLE to healthy controls impeded drawing definitive conclusions. However, in 55% of the studies, verbal memory in children with left TLE (LTLE) was impaired as compared to healthy controls. Verbal memory performance slightly declines after pediatric LTLE surgery, but nonverbal memory tasks are not affected. By contrast, verbal memory performance is not affected by pediatric right TLE (RTLE) surgery.

CONCLUSIONS

The findings suggest that side of the epileptogenic zone and resection from the temporal lobe affect verbal memory in children with LTLE. Right resection seems to be safe with respect to verbal memory performance.

Assessing risk: Characterizing language performance in pediatric patients with intractable epilepsy pre- and post-surgical resection

Neuropsychologists play an important role in assessing risk for post-surgical cognitive decline in pediatric patients with medically refractory epilepsy. Families, neurologists, and neurosurgeons are particularly concerned about the possibility for language decline for patients with a dominant, most often left, hemisphere epileptic focus and planned surgical resection. This study aims to describe language functioning in pediatric epilepsy patients following resection and evaluate the accuracy of a clinical approach of assessing risk. This study proposes a risk assessment method that considers a patient's pattern of lateralized dysfunction across cognitive domains, suspected neuroanatomical reorganization of language functions, and planned site of resection. Pediatric patients (N = 47) were dichotomized as being at minimal risk or at greater risk for post-surgical language decline based on the proposed risk assessment method. Retrospective chart review was utilized to obtain neuropsychological (Boston Naming Test and Weschler Vocabulary subtest) and clinical variables of interest. Patients in the minimal risk group demonstrated significantly improved BNT scores at post-surgery. Most patients remained stable in their Vocabulary knowledge. The proposed risk assessment method correctly classified patients 77% of the time based on BNT performance. Cluster analysis examining the individual components of the proposed method revealed three distinct patient subgroups. Clinical implications are discussed.

Memory outcomes following hemispherectomy in children

OBJECTIVE

A vast proportion of children with epilepsy exhibit memory impairments. Although numerous studies have examined memory performance following pediatric resective epilepsy surgery, little is known about the memory outcomes following hemispherectomy. The few studies that report on memory performance typically include restricted measures, consist of case reports, or do not report on preoperative performance. Given the current limitations, the aim of this study was to delineate pre- and postoperative memory functioning in youth who underwent a hemispherectomy.

METHOD

Participants included patients who had undergone a hemispherectomy at the Hospital for Sick Children, between 1999 and 2016. Standardized neuropsychological assessments of verbal (digit span, word list recall, word pair recall, stories) and visual (faces, dot locations) memory abilities prior to and after surgery were reviewed. A Wilcoxon signed rank test and effect sizes was completed to compare patients' memory performance to population norms and to assess pre- to postoperative difference scores.

RESULTS

Thirteen participants were included in the study: five patients completed preoperative assessments only and eight patients completed pre- and postoperative assessments. Preoperatively, patients performed substantially worse relative to population norms as indicated by large effect sizes (r: 0.5-0.9). Postoperatively, effect sizes were large for the majority of the memory tests, demonstrating considerable differences in patients' memory scores over time. When clinically meaningful changes were examined, stable performance was evident on 63% of the memory tasks.

CONCLUSION

Overall, the results highlight that youth who are eligible for hemispherectomy demonstrate profound memory deficits prior to surgery. In addition, undergoing hemispherectomy was not necessarily associated with declined memory performance, with the majority of patients showing stable scores.

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.

Memory dysfunctions

Since the seminal work on the patient HM, who in his adulthood presented an acquired amnesic syndrome following the resection of the bilateral temporal lobe, other research has described several cases of isolated memory dysfunction in children. This chapter presents developmental and long-lasting memory disorders emerging from an organic or neurologic cause at birth or in infancy. More notably, we focus on developmental amnesic syndrome caused by neonatal bihippocampal damage and memory dysfunction caused by medial temporal developmental epilepsy. We describe these two pediatric populations and present the consequences of hippocampal/medial temporal lobe damage in the development of memory systems. We review episodic memory deficits in children with developmental amnesia and temporal lobe epilepsy and highlight their impact on new learning, personal memories, and independent life. Finally, we provide a brief overview of some of the insights and debates emerging from classic work and recent advances in the context of episodic memory dysfunction displayed by children with hippocampal/medial temporal lobe amnesia and propose new perspectives in child neuropsychology of memory, suggesting new avenues for more ecologic memory assessment and rehabilitation.

Multiple hippocampal transections for refractory pediatric mesial temporal lobe epilepsy: seizure and neuropsychological outcomes

OBJECTIVE

Temporal lobe epilepsy (TLE) is the most common focal epilepsy across adult and pediatric age groups. It is also the most amenable to surgery, with excellent long-term seizure outcome. Most TLE cases have an epileptogenic zone in the mesial temporal structures, namely the hippocampus. Resecting the dominant hippocampus has been shown to be associated with significant verbal memory deficits, especially in patients with intact verbal memory scores presurgically. Multiple hippocampal transection (MHT) is a relatively new surgical technique designed to interrupt the longitudinal hippocampal circuitry involved in seizure propagation yet preserve the circular fibers involved in memory function. This technique has been used to treat mesial TLE in both dominant- and nondominant-hemisphere cases, almost exclusively in adults. It has been applied to normal and sclerotic hippocampi.

METHODS

In this study, information on 3 pediatric patients who underwent MHT for mesial TLE at Children's Wisconsin between 2017 and 2018 is included. Clinical, electroencephalographic, and neuropsychological features and outcomes are described in detail.

RESULTS

MRI revealed a tumor in the amygdala with a normal hippocampus in 1 patient and hippocampal sclerosis in 2 patients. All patients underwent stereoelectroencephalography confirming the involvement of the hippocampus in seizure onset. MHTs were completed under intraoperative monitoring, with amygdala and temporal tip resection in all patients due to early spread to these regions. All patients had excellent seizure outcomes at 1 year, and 2 of the 3 patients remain seizure free at last follow-up (range 20-36 months), all with stable or improved neuropsychological profiles, including verbal memory.

CONCLUSIONS

MHT is a relatively new surgical procedure designed to preserve essential memory circuitry while disrupting seizure propagation pathways in the hippocampus. A growing body of literature shows good seizure and neuropsychological results, but mainly in adults. This is the first series of MHTs used exclusively in children at one medical center, showcasing excellent seizure control and preservation of neuropsychological functioning. One of the patients is also the first described to have MHT in the setting of an amygdalar tumor abutting the hippocampus, further expanding the pathological setting in which MHT can be used effectively.

Neuropsychological outcomes after pediatric epilepsy surgery: Role of electrical stimulation language mapping

PURPOSE

We studied the association between electrical stimulation mapping (ESM) with a visual naming task and post-operative neuropsychological outcomes after pediatric epilepsy surgery.

METHODS

Children who underwent epilepsy surgery, having pre- and 1-year post-surgery neuropsychological evaluation (NPE) available, were included. NPE scores were transformed using principal components (PC) analysis. The relationship between post-surgical PC scores, adjusted for pre-surgery PC scores, and ESM was analyzed. Clinical variables influencing this relationship were also sought.

RESULTS

One hundred and four children (89 patients >5 years-old, and 15 patients 3-5 years-old) were included. Among children >5 years-of-age, a significant effect of language ESM was observed on all 3 post-surgery PC scores adjusted for respective pre-surgery PC scores. Specifically, only 30 % patients who underwent language ESM had a decrease in PC1 scores ≥1-year after epilepsy surgery, compared to 68 % those who did not undergo language ESM (p = 0.001). Seizure outcomes, age at the time of surgery, predominant seizure type, and family history of epilepsy were other significant determinants of post-surgical PC scores including a change in PC scores from pre-surgery baseline. Combinations of pre-surgical variables were able to predict post-surgical PC scores with high specificity. In children aged 3-5 years, no significant effect of language ESM was seen on post-surgery PC scores adjusted for respective pre-surgery PC scores.

CONCLUSIONS

Speech/language ESM should be performed more widely in patients >5 years-of-age undergoing epilepsy surgery. Also, more efficient brain mapping techniques and language paradigms are needed for younger children.

Parents' view of the cognitive outcome one year after pediatric epilepsy surgery

OBJECTIVES

The cognitive outcome of pediatric epilepsy surgery has mainly been examined on the basis of standardized tests. Here, we analyzed the outcome in six cognitive domains from the parents' view.

METHODS

Included were consecutive surgical pediatric patients whose parents filled-in a comprehensive questionnaire on cognitive problems in children and adolescents (Kognitive Probleme bei Kindern und Jugendlichen (KOPKIJ); Gleissner et al. 2006) at the preoperative baseline (T1) as well as twelve months thereafter (T2). All children also underwent standard neuropsychological assessments at T1 and T2.

RESULTS

Parents of 96 patients provided pre- and postoperative KOPKIJ data. Overall, 80% of the children became seizure-free at the follow-up. Group means indicated a strong positive effect of time on KOPKIJ and neuropsychological performance. We found postoperative improvements in five out of six cognitive domains (language, memory, executive functions, attention, school; unchanged: visuospatial abilities). Individually, improvements were twice as likely as declines. However, 33 patients (35%) experienced significant decline in at least one cognitive domain. Later onset of epilepsy resulted in better performance but had no effect on change scores. Seizure-free status, lower antiseizure drug load, and stronger drug reduction after surgery contributed to postoperative cognitive improvements as perceived by the parents; no other effects of clinical factors were obtained (e.g., localization/lateralization). Despite their similar outcome patterns, change scores as derived from parental ratings and neuropsychological assessment were not correlated.

CONCLUSIONS

Parents acknowledged the overall positive neurocognitive development after pediatric epilepsy surgery as previously shown by standardized tests. Seizure freedom and lower antiseizure drug load contributed to the beneficial cognitive outcome. Even if cognitive improvements outweighed declines, a risk for cognitive decline with impact on everyday functioning does exist.

Verbal associative memory outcomes in pediatric surgical temporal lobe epilepsy: Exploring the impact of mesial structures

OBJECTIVE

We examined verbal associative memory outcomes in children with left- or right-sided temporal lobe epilepsy (TLE) who received combined lateral and mesial resections versus lateral resections sparing mesial structures. We hypothesized that children who underwent left-sided resections including mesial structures would show the greatest verbal associative memory declines following surgery.

METHOD

We retrospectively analyzed neuropsychology assessment results from a sample of 65 children with TLE who completed pre- and postoperative evaluation at the Hospital for Sick Children in Toronto, Canada. We examined verbal associative memory score changes between groups by laterality (left versus right) and resection type (lateral only versus lateral and mesial resection). We also explored potential associations between certain epilepsy-related characteristics and verbal associative memory changes.

RESULTS

Postoperative decline was found in children with left-sided resections, but not those with right-sided resections. In children who received left-sided resections, there was some suggestion of verbal associative memory decline in those who had both lateral and mesial tissues excised, but not in those with lateral resections only. Notably, there was also a language dominance (typical versus atypical) by resection type interaction. Specifically, for the typical language group, children with left lateral plus mesial resections (but not mesial sparing resections) showed postoperative verbal associative memory declines, whereas the opposite was true for the atypical language group.

SIGNIFICANCE

These data contribute to our growing understanding of verbal memory outcomes following TLE in childhood, with consideration of the extent of resection to mesial structures. Our findings also highlight the importance of language laterality when interpreting neuropsychological assessment findings and making predictions regarding risk of functional loss following surgery.

The role of task-based neural activation research in understanding cognitive deficits in pediatric epilepsy

Children with epilepsy can experience significant cognitive dysfunction that can lead to academic underachievement. Traditionally believed to be primarily due to the effects of factors such as the chronicity of epilepsy, medication effects, or the location of the primary epileptogenic lesion;, recent evidence has indicated that disruption of cognition-specific distributed neural networks may play a significant role as well. Specifically, over the last decade, researchers have begun to characterize the mechanisms underlying disrupted cognitive substrates by evaluating neural network abnormalities observed during specific cognitive tasks, using task-based functional magnetic resonance imaging (fMRI). This targeted review assesses the current literature investigating the relationship between neural network abnormalities and cognitive deficits in pediatric epilepsy. The findings indicate that there are indeed neural network abnormalities associated with deficits in executive function, language, processing speed, and memory. Overall, cognitive dysfunction in pediatric epilepsy is associated with a decrease in neural network activation/deactivation as well as increased recruitment of brain regions not typically related to the specific cognitive task under investigation. The research to date has focused primarily on children with focal epilepsy syndromes with small sample sizes and differing research protocols. More extensive research in children with a wider representation of epilepsy syndromes (including generalized epilepsy syndromes) is necessary to fully understand these relationships and begin to identify underlying cognitive phenotypes that may account for the variability observed across children with epilepsy. Furthermore, more uniformity in fMRI protocols and neuropsychological tasks would be ideal to advance this literature.

Predictors of meaningful improvement in quality of life after selective amygdalohippocampectomy in Chinese patients with refractory temporal lobe epilepsy: A prospective study

PURPOSE

Our aim was to determine the independent predictors of minimum clinically important difference (MCID) in quality of life (QOL) after selective amygdalohippocampectomy (SAH) among Chinese patients with refractory mesial temporal lobe epilepsy (MTLE).

METHODS

We conducted a prospective study and enrolled 50 consecutive patients with refractory MTLE who underwent SAH after their presurgical evaluations. The variables independently associated with MCID in the Quality of Life in Epilepsy Inventory-31 (QOLIE-31) overall score 1 year after SAH were analyzed by multiple binary logistic regression analysis.

RESULTS

Significant improvements in the QOLIE-31 overall score and all subscale scores were observed after SAH (p < 0.001). Among 50 patients with refractory MTLE, 78% reached the criteria for MCID of QOL overall score after SAH. In the multiple binary logistic regression model, the presurgical independent predictors of significant improvement by MCID in QOL were absence of depression diagnosis (adjusted odds ratio [OR] = 8.391, 95% confidence interval [CI] = 1.240-56.776, p = 0.029) and good cognitive function (adjusted OR = 8.427, 95% CI = 1.115-63.670, p = 0.039); the postoperative independent predictor was seizure freedom (adjusted OR = 8.477, 95% CI = 1.195-60.122, p = 0.032). The sensitivity and specificity for significant improvement in the QOL were 97.4% and 45.5% respectively, with an overall model accuracy of 86.0%.

CONCLUSIONS

Presurgical depression, cognitive function, and postsurgical seizure freedom are independent predictors for meaningful improvement in QOL after SAH among the Chinese patients with refractory MTLE. Preoperative evaluation of patients with refractory MTLE should consider the cognitive dysfunction and psychological disorders.

Social functioning of children after epilepsy surgery: A literature review

This literature review on social functioning of children after epilepsy surgery is based on 24 papers addressing two categories of social functioning: social cognition (n = 4) and general social functioning (n = 20). Overall, studies that compared with healthy peers revealed children who had undergone epilepsy surgery to have more problems in both social cognition and general social functioning. Half of the studies found some improvement in social functioning in the first year(s) after epilepsy surgery, but this pertained to general social functioning, not to social cognition. The persistence of the problems in social cognition after surgery may be related to the critical period of brain maturation, lacking improvement of impairments in related cognitive domains or to a defective underlying brain condition - rather than to the epilepsy. Problems in general social functioning may be explained by the adjustments the children and their families had to make because of the child's drug-resistant epilepsy and difficulties to adjust to the new situation after surgery. The neurological and behavioral explanations are likely to be interrelated in light of the multifaceted and complex nature of social functioning. Epilepsy surgery does not appear to solve the problems in social functioning associated with having had drug-resistant epilepsy. As social functioning is an important aspect of healthy development, it should be assessed comprehensively in order to obtain a knowledge base that allows 1) proper treatment of children with epilepsy (CwE) and 2) counseling patients and families prior to and after epilepsy surgery.