Verbal memory after epilepsy surgery in childhood

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.

Antiseizure medication use and medical resource utilization after resective epilepsy surgery in children in the United States: A contemporary nationwide cross-sectional cohort analysis

OBJECTIVE

Antiseizure drug (ASD) therapy can significantly impact quality of life for pediatric patients whose epilepsy remains refractory to medications and who experience neuropsychological side effects manifested by impaired cognitive and social development. Contemporary patterns of ASD reduction after pediatric epilepsy surgery across practice settings in the United States are sparsely reported outside of small series. We assessed timing and durability of ASD reduction after pediatric epilepsy surgery and associated effects on health care utilization.

METHODS

We performed a retrospective analysis of 376 pediatric patients who underwent resective epilepsy surgery between 2007 and 2016 in the United States using the Truven MarketScan database. Filled ASD prescriptions during the pre- and postoperative periods were compared. Univariate and multivariate analyses identified factors associated with achieving a stable discontinuation of or reduction in number of ASDs. Health care utilization and costs were systematically compared.

RESULTS

One hundred seventy-one patients (45.5%) achieved a >90-day ASD-free period after surgery, and 84 (22.3%) additional patients achieved a stable reduction in number of ASDs. Achieving ASD freedom was more common in patients undergoing total hemispherectomy (n = 21, p = .002), and less common in patients with tuberous sclerosis (p = .003). A higher number of preoperative ASDs was associated with a greater likelihood of achieving ASD reduction postoperatively (hazard ratio [HR]: 1.85, 95% confidence interval [CI]: 1.50-2.28), but was not associated with a significant difference in the likelihood of achieving ASD freedom (0.83, 95% CI: 0.49-1.39). Achieving an ASD-free period was associated with fewer hospital readmissions within the first year after surgery.

SIGNIFICANCE

Patterns of ASD use and discontinuation after pediatric epilepsy surgery provide an unbiased surgical outcome endpoint extractable from administrative databases, where changes in seizure frequency are not captured. This quantitative measure can augment traditional surgical outcome scales, incorporating a significant clinical parameter associated with improved quality of life.

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.

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.

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.

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.

Perceptual Function and Category-Selective Neural Organization in Children with Resections of Visual Cortex

The consequences of cortical resection, a treatment for humans with pharmaco-resistant epilepsy, provide a unique opportunity to advance our understanding of the nature and extent of cortical (re)organization. Despite the importance of visual processing in daily life, the neural and perceptual sequellae of occipitotemporal resections remain largely unexplored. Using psychophysical and fMRI investigations, we compared the neural and visuoperceptual profiles of 10 children or adolescents following unilateral cortical resections and their age- and gender-matched controls. Dramatically, with the exception of two individuals, both of whom had relatively greater cortical alterations, all patients showed normal perceptual performance on tasks of intermediate- and high-level vision, including face and object recognition. Consistently, again with the exception of the same two individuals, both univariate and multivariate fMRI analyses revealed normal selectivity and representational structure of category-selective regions. Furthermore, the spatial organization of category-selective regions obeyed the typical medial-to-lateral topographic organization albeit unilaterally in the structurally preserved hemisphere rather than bilaterally. These findings offer novel insights into the malleability of cortex in the pediatric population and suggest that, although experience may be necessary for the emergence of neural category-selectivity, this emergence is not necessarily contingent on the integrity of particular cortical structures.SIGNIFICANCE STATEMENT One approach to reduce seizure activity in patients with pharmaco-resistant epilepsy involves the resection of the epileptogenic focus. The impact of these resections on the perceptual behaviors and organization of visual cortex remain largely unexplored. Here, we characterized the visuoperceptual and neural profiles of ventral visual cortex in a relatively large sample of post-resection pediatric patients. Two major findings emerged. First, most patients exhibited preserved visuoperceptual performance across a wide-range of visual behaviors. Second, normal topography, magnitude, and representational structure of category-selective organization were uncovered in the spared hemisphere. These comprehensive imaging and behavioral investigations uncovered novel evidence concerning the neural representations and visual functions in children who have undergone cortical resection, and have implications for cortical plasticity more generally.

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.

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

OBJECTIVE

The systematic review aimed to assess the neuropsychological outcomes of temporal lobe resections for epilepsy in children. Additional objectives included determining whether earlier age at surgery leads to better neuropsychological outcomes; the relationships between and predictors of these outcomes.

METHODS

Using advanced search terms, a systematic review of electronic databases was conducted, comprising MEDLINE, Embase, PsycINFO, Global Health, Web of Science and CINAHL. Included studies reported on outcome following neurosurgical treatment for epilepsy. Specifically, studies were included if they reported neuropsychological outcomes and were concerned only with temporal lobe resection.

RESULTS

73 studies met inclusion criteria. For reported neuropsychological outcomes, the majority of participants remained stable after surgery; some declined and some improved. There was some evidence for increased material-specific memory deficits after temporal lobe surgery based on resection side, and more positive cognitive outcome for those with lower pre-surgical ability level.

SIGNIFICANCE

Retrieved evidence highlights the need for improvements to quality of methodology and reporting. Appropriately designed prospective multicentre trials should be conducted with adequate follow-up for long-term outcomes to be measured. Core outcome measures should be agreed between centres. This would permit higher quality evidence so that clinicians, young people and their families may make better informed decisions about whether or not to proceed with surgery and likely post-operative profile.

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.

Functional outcomes following lesions in visual cortex: Implications for plasticity of high-level vision

Understanding the nature and extent of neural plasticity in humans remains a key challenge for neuroscience. Importantly, however, a precise characterization of plasticity and its underlying mechanism has the potential to enable new approaches for enhancing reorganization of cortical function. Investigations of the impairment and subsequent recovery of cognitive and perceptual functions following early-onset cortical lesions in humans provide a unique opportunity to elucidate how the brain changes, adapts, and reorganizes. Specifically, here, we focus on restitution of visual function, and we review the findings on plasticity and re-organization of the ventral occipital temporal cortex (VOTC) in published reports of 46 patients with a lesion to or resection of the visual cortex early in life. Findings reveal that a lesion to the VOTC results in a deficit that affects the visual recognition of more than one category of stimuli (faces, objects and words). In addition, the majority of pediatric patients show limited recovery over time, especially those in whom deficits in low-level vision also persist. Last, given that neither the equipotentiality nor the modularity view on plasticity was clearly supported, we suggest some intermediate possibilities in which some plasticity may be evident but that this might depend on the area that was affected, its maturational trajectory as well as its structural and functional connectivity constraints. Finally, we offer suggestions for future research that can elucidate plasticity further.

Personality traits of children before and after epilepsy surgery

We studied how children with epilepsy (CWE) who are candidates for epilepsy surgery, perceive themselves with respect to overarching personality traits and whether the traits change after surgery. We explored influences of demographic and illness variables. A total of 23 CWE [mean age at inclusion 12.8 (sd 2.3); 12 girls] participated. Using the Dutch Personality Questionnaire Juniors (DPQ-J), we assessed 20 of the CWE shortly before epilepsy surgery and compared the results to those of 39 age- and gender-matched healthy controls. Furthermore, we obtained follow-up scores 6, 12 and 24 months after epilepsy surgery from the clinical group. CWE who were candidates for epilepsy surgery scored above average in inadequacy, perseverance, social inadequacy and recalcitrance, whereas healthy peers scored average. Over the two years' period after epilepsy surgery we found no changes, apart from a decrease of social inadequacy. Sporadic illness and demographic variables were related to some personality traits. However, neither post-surgical seizure freedom nor cessation of AEDs did noticeably change the self-evaluations of CWE. Asking CWE to evaluate their personality themselves may offer a shared basis for individually tailored behavior intervention in order to help them adapting to their ameliorated circumstances after surgery.

Verbal memory after temporal lobe epilepsy surgery in children: Do only mesial structures matter?

OBJECTIVE

Previous findings have been mixed regarding verbal memory outcome after left temporal lobectomy in children, and there are few studies comparing verbal memory change after lateral versus mesial temporal lobe resections. We compared verbal memory outcome associated with sparing or including the mesial structures in children who underwent left or right temporal lobe resection. We also investigated predictors of postsurgical verbal memory change.

METHODS

We retrospectively assessed verbal memory change approximately 1 year after unilateral temporal lobe epilepsy surgery using a list learning task. Participants included 23 children who underwent temporal lobe surgery with sparing of the mesial structures (13 left), and 40 children who had a temporal lobectomy that included resection of mesial structures (22 left).

RESULTS

Children who underwent resection from the left lateral and mesial temporal lobe were the only group to show decline in verbal memory. Furthermore, when we considered language representation in the left temporal resection group, patients with left language representation and spared mesial structures showed essentially no change in verbal memory from preoperative to follow-up, whereas those with left language representation and excised mesial structures showed a decline. Postoperative seizure status had no effect on verbal memory change in children after left temporal lobe surgery. Finally, we found that patients with intact preoperative verbal memory experienced a significant decline compared to those with below average preoperative verbal memory.

SIGNIFICANCE

Our findings provide evidence of significant risk factors for verbal memory decline in children, specific to left mesial temporal lobe epilepsy. Children who undergo left temporal lobe surgery that includes mesial structures may be most vulnerable for verbal memory decline, especially when language representation is localized to the left hemisphere and when preoperative verbal memory is intact.

Risks and benefits of epilepsy surgery in a pediatric population: Consequences for memory and academic skills

We examined benefits and risks for memory and academic functioning associated with epilepsy surgery in a pediatric population. A total of 46 patients with intractable seizures and a single seizure focus were divided into four groups according to focus localization: right temporal, left temporal, frontal, and parietal/occipital region. Pre- and postsurgery performance measures were compared across groups and with a fifth group of patients that had intractable seizures but did not undergo surgery. Both groups with temporal lobe epilepsy showed significant declines in memory test scores, while performance of the group with frontal lobe epilepsy improved. These changes were mirrored in parental reports of everyday memory. Consistent with other pediatric studies, no lateralized material-specific declines in the groups with temporal lobe epilepsy were found. When memory improved, the improvement was associated with decreases in seizure frequency and the number of anticonvulsant medications. Presurgical performance was the best predictor of declines in memory test performance. Deterioration of academic test scores in the group that did not have surgery exemplified a potential risk of living with seizures and antiepilepsy medication.

Cognitive consequences of early versus late antiepileptic drug withdrawal after pediatric epilepsy surgery, the TimeToStop (TTS) trial: study protocol for a randomized controlled trial

Background

The goals of intentional curative pediatric epilepsy surgery are to achieve seizure-freedom and antiepileptic drug (AED) freedom. Retrospective cohort studies have indicated that early postoperative AED withdrawal unmasks incomplete surgical success and AED dependency sooner, but not at the cost of long-term seizure outcome. Moreover, AED withdrawal seemed to improve cognitive outcome. A randomized trial is needed to confirm these findings. We hypothesized that early AED withdrawal in children is not only safe, but also beneficial with respect to cognitive functioning.

Design

This is a multi-center pragmatic randomized clinical trial to investigate whether early AED withdrawal improves cognitive function, in terms of attention, executive function and intelligence, quality of life and behavior, and to confirm safety in terms of eventual seizure freedom, seizure recurrences and “seizure and AED freedom.” Patients will be randomly allocated in parallel groups (1:1) to either early or late AED withdrawal. Randomization will be concealed and stratified for preoperative IQ and medical center. In the early withdrawal arm reduction of AEDs will start 4 months after surgery, while in the late withdrawal arm reduction starts 12 months after surgery, with intended complete cessation of drugs after 12 and 20 months respectively. Cognitive outcome measurements will be performed preoperatively, and at 1 and 2 years following surgery, and consist of assessment of attention and executive functioning using the EpiTrack Junior test and intelligence expressed as IQ (Wechsler Intelligence Scales). Seizure outcomes will be assessed at 24 months after surgery, and at 20 months following start of AED reduction. We aim to randomize 180 patients who underwent anticipated curative epilepsy surgery below 16 years of age, were able to perform the EpiTrack Junior test preoperatively, and have no predictors of poor postoperative seizure prognosis (multifocal magnetic resonance imaging (MRI) abnormalities, incomplete resection of the lesion, epileptic postoperative electroencephalogram (EEG) abnormalities, or more than three AEDs at the time of surgery).

Discussion

Growing experience with epilepsy surgery has changed the view towards postoperative medication policy. In a European collaboration, we designed a multi-center pragmatic randomized clinical trial comparing early with late AED withdrawal to investigate benefits and safety of early AED withdrawal. The TTS trial is supported by the Dutch Epilepsy Fund (NL 08-10) ISRCTN88423240/ 08/05/2013.

Two years after epilepsy surgery in children: Recognition of emotions expressed by faces

OBJECTIVES

The purpose of this study was to determine whether children with epilepsy surgery in their history are able to recognize emotions expressed by faces and whether this recognition is associated with demographic variables [age, sex, and verbal intelligence (VIQ)] and/or epilepsy variables (epilepsy duration, side of the surgery, surgery area, resection of the amygdala, etiology, antiepileptic drug use, and seizure freedom).

METHODS

Two years after epilepsy surgery, the Facial Expression of Emotion: Stimuli and Tests (FEEST) was administered to 41 patients (age: 4-20years, mean: 13.5years, 24 girls) and 82 age- and sex-matched healthy controls. Data obtained longitudinally (before surgery and 6, 12, and 24months after surgery) in a small subset (11 patients and 22 matched controls) were explored to obtain clues about the course of REEF from before surgery.

RESULTS

Corrected for VIQ, REEF scored significantly lower in the 41 surgically treated patients than in matched control children. No significant relationship was found between REEF and any epilepsy variable. Only age at assessment predicted REEF score in both patients and controls. The longitudinal data revealed a 'dip' in emotion recognition at the first postsurgical assessment in the six younger patients (age: <12.1years). The older patients (age: 13-17years) showed a continuous increase in REEF scores that was similar to that in controls. Two years after surgery, REEF of the younger patients recovered to, but did not exceed, the presurgical level.

CONCLUSION

Neither poor REEF present two years after childhood epilepsy surgery, nor the aberrant course of REEF in younger patients (age: <12.1years) was explained by epilepsy variables or poor verbal intelligence. Disentangling the mechanism of the abnormality is urgently needed, as recognizing emotional expressions is a key component in the development of more complex social perception skills.

Parenting stress does not normalize after child's epilepsy surgery

PURPOSE

This study aimed to investigate parenting stress expressed by parents before and two years after their children's epilepsy surgery.

SUBJECTS

Parents of 31 consecutively included surgery patients with epilepsy and parents of 31 healthy sex- and age-matched control children were the subjects of this study. Materials and procedure: The questionnaire 'Parenting Stress Index', which distinguishes a Parent domain (stress leading parents to feel themselves inadequate) from a Child domain (child features felt by parent to cause stress) was completed before surgery of the patients and two years thereafter. At both time points, intelligence examination of the child was part of a comprehensive neuropsychological assessment, as were evaluations of recent stress-enhancing life events and epilepsy severity.

RESULTS

Prior to surgery, total parenting stress was significantly higher in parents of patients than in parents of controls. Two years after surgery, total parenting stress had decreased significantly in parents of patients. The scores on parent-related subscales Role Restriction and Spouse and on the child-related subscale Distractibility/Hyperactivity, all relatively high before surgery, decreased significantly. Still, parents of patients experienced significantly more stress compared with parents of controls mainly because of persistently higher stress scores in parents of patients on the subscale Role Restriction (Parent domain) and on five of six subscales in the Child domain. Intelligence of the child was associated with parenting stress: the lower the child's intelligence, the higher the stress score on the subscale Distractibility/Hyperactivity and the lower the stress score on the subscale Mood. Stress decreased more in parents of patients who became seizure-free after surgery than in parents of patients with recurrent seizures.

CONCLUSIONS

Parenting stress decreases but does not normalize in the first two years after epilepsy surgery. Parents should be offered counseling on epilepsy-related intricacies contributing to parenting stress, immediately after diagnosis as well as after epilepsy surgery, notwithstanding the resulting seizure status of the child.

Temporal lobe surgery in childhood and neuroanatomical predictors of long-term declarative memory outcome

See Berg (doi:10.1093/brain/awu320) for a scientific commentary on this article.

In a long-term follow-up study of children who underwent temporal lobe surgery for treatment of epilepsy, Skirrow et al. identify no significant pre-to-post-surgery memory losses, but instead robust improvements in memory functions supported by the unoperated temporal lobe. The integrity of remaining temporal lobe structures places constraints on long-term memory outcomes.

The temporal lobes play a prominent role in declarative memory function, including episodic memory (memory for events) and semantic memory (memory for facts and concepts). Surgical resection for medication-resistant and well-localized temporal lobe epilepsy has good prognosis for seizure freedom, but is linked to memory difficulties in adults, especially when the removal is on the left side. Children may benefit most from surgery, because brain plasticity may facilitate post-surgical reorganization, and seizure cessation may promote cognitive development. However, the long-term impact of this intervention in children is not known. We examined memory function in 53 children (25 males, 28 females) who were evaluated for epilepsy surgery: 42 underwent unilateral temporal lobe resections (25 left, 17 right, mean age at surgery 13.8 years), 11 were treated only pharmacologically. Average follow-up was 9 years (range 5–15). Post-surgical change in visual and verbal episodic memory, and semantic memory at follow-up were examined. Pre- and post-surgical T₁-weighted MRI brain scans were analysed to extract hippocampal and resection volumes, and evaluate post-surgical temporal lobe integrity. Language lateralization indices were derived from functional magnetic resonance imaging. There were no significant pre- to postoperative decrements in memory associated with surgery. In contrast, gains in verbal episodic memory were seen after right temporal lobe surgery, and visual episodic memory improved after left temporal lobe surgery, indicating a functional release in the unoperated temporal lobe after seizure reduction or cessation. Pre- to post-surgical change in memory function was not associated with any indices of brain structure derived from MRI. However, better verbal memory at follow-up was linked to greater post-surgical residual hippocampal volumes, most robustly in left surgical participants. Better semantic memory at follow-up was associated with smaller resection volumes and greater temporal pole integrity after left temporal surgery. Results were independent of post-surgical intellectual function and language lateralization. Our findings indicate post-surgical, hemisphere-dependent material-specific improvement in memory functions in the intact temporal lobe. However, outcome was linked to the anatomical integrity of the temporal lobe memory system, indicating that compensatory mechanisms are constrained by the amount of tissue which remains in the operated temporal lobe. Careful tailoring of resections for children undergoing epilepsy surgery may enhance long-term memory outcome.

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.