Patterns of memory performance in children with controlled epilepsy on the CVLT-C

Verbal learning and memory in youth with neurofibromatosis type 1 and plexiform neurofibromas: Relationships with disease severity

AIM

To provide a comprehensive characterization of verbal learning and memory (VLM) abilities in youth with neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PNs) and to evaluate disease severity as a predictor of VLM functioning over time.

METHOD

As part of a longitudinal natural history study, youth with NF1 and PNs were administered repeat neuropsychological assessments, including measures of VLM and ratings of NF1 disease severity completed by a medical professional. This sub-study analyzed data from 89 patients (M age baseline = 13.1, SD = 4.3 years, range 6-24 years) who had completed tests of VLM abilities and verbal attention at either baseline and/or 36 months.

RESULTS

VLM scores across the sample fell predominantly within the average range of functioning at both time points. However, relative to peers with mild NF1 disease severity, youth with moderate/severe NF1 disease showed lower functioning across multiple VLM domains at 36 months, even after controlling for the effects of verbal attention.

INTERPRETATION

Exclusive use of overall domain scores does not fully characterize VLM functioning in youth with NF1 and PNs. Additionally, children and adolescents with more severe NF1 disease should be monitored more closely for verbal memory challenges and targeted for interventions.

Imaging episodic memory during development and childhood epilepsy

Epilepsy affects 2.2 million adults in the USA, with 1 in 26 people developing epilepsy at some point in their lives. Temporal lobe epilepsy (TLE) is the most common form of focal epilepsy as medial structures, and the hippocampus in particular, are prone to generating seizures. Selective anterior temporal resection (which removes the hippocampus) is the most effective intractable TLE treatment, but given the critical role of the mesial temporal lobe in memory functioning, resection can have negative effects on this crucial cognitive skill. To minimize the adverse impact of temporal lobe surgery on memory functioning, reliable pre-surgical guides are needed. Clinical functional magnetic resonance imaging (fMRI) provides reliable, noninvasive guidance of language functioning and plays a growing role in the pre-surgical evaluation for epilepsy patients; however, localization of memory function in children with epilepsy using fMRI has not been established. Aside from the lack of neuroimaging memory studies in children with TLE, studies of typical development are limited. This review will focus on the functional anatomy of memory systems throughout development, with a focus on TLE. TLE provides the ideal model from which to understand memory function and the limits of plasticity and compensation/reorganization throughout development.

The role of executive functioning in memory performance in pediatric focal epilepsy

OBJECTIVE

Learning and memory are essential for academic success and everyday functioning, but the pattern of memory skills and its relationship to executive functioning in children with focal epilepsy is not fully delineated. We address a gap in the literature by examining the relationship between memory and executive functioning in a pediatric focal epilepsy population.

METHODS

Seventy children with focal epilepsy and 70 typically developing children matched on age, intellectual functioning, and gender underwent neuropsychological assessment, including measures of intelligence (Wechsler Abbreviated Scale of Intelligence [WASI]/Differential Ability Scales [DAS]), as well as visual Children's Memory Scale (CMS Dot Locations) and verbal episodic memory (Wide Range Assessment of Memory and Learning [WRAML] Story Memory and California Verbal Learning Test for Children [CVLT-C]). Executive functioning was measured directly (WISC-IV Digit Span Backward; Clinical Evaluation of Language Fundamentals, Fourth Edition (CELF-IV) Recalling Sentences) and by parent report (Behavior Rating Inventory of Executive Function [BRIEF]).

RESULTS

Children with focal epilepsy had lower delayed free-recall scores than controls across visual and verbal memory tasks (p = 0.02; partial η² = 0.12). In contrast, recognition memory performance was similar for patients and controls (p = 0.36; partial η² = 0.03). Children with focal epilepsy demonstrated difficulties in working memory (p = 0.02; partial η² = 0.08) and planning/organization (p = 0.02) compared to controls. Working memory predicted 9-19% of the variance in delayed free recall for verbal and visual memory; organization predicted 9-10% of the variance in verbal memory. Patients with both left and right focal epilepsy demonstrated more difficulty on verbal versus visual tasks (p = 0.002). Memory performance did not differ by location of seizure foci (temporal vs. extratemporal, frontal vs. extrafrontal).

SIGNIFICANCE

Children with focal epilepsy demonstrated memory ability within age-level expectations, but delayed free recall was inefficient compared to typically developing controls. Memory difficulties were not related to general cognitive impairment or seizure localization. Executive functioning accounted for significant variance in memory performance, suggesting that poor executive control negatively influences memory retrieval.

List-learning and verbal memory profiles in childhood epilepsy syndromes

Findings of material-specific influences on memory performance in pediatric epilepsy are inconsistent and merit further investigation. This study compared 90 children (aged 6years to 16years) with childhood absence epilepsy (CAE), frontal lobe epilepsy (FLE), and temporal lobe epilepsy (TLE) to determine whether they displayed distinct list-learning and verbal memory profiles on the California Verbal Learning Test - Children's Version (CVLT-C). Group comparison identified greater risk of memory impairment in children with TLE and FLE syndromes but not for those with CAE. While children with TLE performed worst overall on Short Delay Free Recall, groups with TLE and FLE performed similarly on Long Delay Free Recall. Contrast indices were then employed to explore these differences. Children with TLE demonstrated a significantly greater retroactive interference (RI) effect compared with groups with FLE and CAE. Conversely, children with FLE demonstrated a significantly worse learning efficiency index (LEI), which compares verbal memory following repetition with initial recall of the same list, than both children with TLE and CAE. These findings indicated shallow encoding related to attentional control for children with FLE and retrieval deficits in children with TLE. Finally, our combined sample showed significantly higher rates of extreme contrast indices (i.e., 1.5 SD difference) compared with the CVLT-C standardization sample. These results underscore the high prevalence of memory dysfunction in pediatric epilepsy and offer support for distinct patterns of verbal memory performance based on childhood epilepsy syndrome.

[Formula: see text]Differences in memory functioning between children with attention-deficit/hyperactivity disorder and/or focal epilepsy

Prior research has shown that attention-deficit/hyperactivity disorder (ADHD) and epilepsy are frequently comorbid and that both disorders are associated with various attention and memory problems. Nonetheless, limited research has been conducted comparing the two disorders in one sample to determine unique versus shared deficits. Hence, we investigated differences in working memory (WM) and short-term and delayed recall between children with ADHD, focal epilepsy of mixed foci, comorbid ADHD/epilepsy and controls. Participants were compared on the Core subtests and the Picture Locations subtest of the Children's Memory Scale (CMS). Results indicated that children with ADHD displayed intact verbal WM and long-term memory (LTM), as well as intact performance on most aspects of short-term memory (STM). They performed worse than controls on Numbers Forward and Picture Locations, suggesting problems with focused attention and simple span for visual-spatial material. Conversely, children with epilepsy displayed poor focused attention and STM regardless of the modality assessed, which affected encoding into LTM. The only loss over time was found for passages (Stories). WM was intact. Children with comorbid ADHD/epilepsy displayed focused attention and STM/LTM problems consistent with both disorders, having the lowest scores across the four groups. Hence, focused attention and visual-spatial span appear to be affected in both disorders, whereas additional STM/encoding problems are specific to epilepsy. Children with comorbid ADHD/epilepsy have deficits consistent with both disorders, with slight additive effects. This study suggests that attention and memory testing should be a regular part of the evaluation of children with epilepsy and ADHD.

There are laterality effects in memory functioning in children/adolescents with focal epilepsy

In a sample of individuals with childhood focal epilepsy, children/adolescents with left hemisphere foci outperformed those with right foci on both measures of nonverbal learning. Participants with left foci performed worse than controls on paired associate delayed recall and semantic memory, and they had greater laterality effects in IQ. Participants with right foci performed worse than controls on delayed facial recognition. Both groups displayed reduced focused attention and poor passage retention over time. Although participants with bilateral foci displayed poor learning and lower IQ than controls, they did not have worse impairment than those with a unilateral focus.

Memory in children with epilepsy: a systematic review

PURPOSE

Research suggests an increased risk for cognitive impairment in childhood epilepsy with memory being one area of cognition most likely to be affected. Understanding the prevalence and predictors of memory difficulties may help improve awareness of the difficulties and allow efficacious supports to be put in place.

METHOD

A systematic review was carried out using the search terms 'memory', 'children' and 'epilepsy' in the database PUBMED. Eighty-eight studies met inclusion criteria. The review focuses on comparisons of memory scores of children with epilepsy and controls, and comparison of memory scores of children with epilepsy to normative scores. Predictors of memory impairment and the effect of surgery on memory functioning are also reviewed.

RESULTS

The majority (78%) of studies reviewed revealed that children with epilepsy scored lower than controls and normative scores on measures of memory. Post-surgery, memory scores were reported to improve in 50% of studies. Predictors of memory impairment included a greater number of AEDs used, younger age of onset, increased seizure frequency and longer duration of epilepsy.

CONCLUSION

Children with epilepsy have a high frequency of memory impairments. However, the exact prevalence of difficulties is not clear due to the lack of population-based data. Most studies have not controlled for IQ and thus it is unclear if difficulties are always related to global cognitive difficulties. There is need for future population-based studies and studies focussing on the neurobiology of memory problems in children with epilepsy.

Memory functioning in children with epilepsy: frontal lobe epilepsy, childhood absence epilepsy, and benign epilepsy with centrotemporal spikes

Specific cognitive deficits have been identified in children with epilepsy irrespective of results on intelligence tests. Memory deficits are traditionally attributed to temporal lobe epilepsy, whereas the impact of frontal lobe epilepsy on memory functions has remained controversial. The aim of this study was the examination of memory abilities in other childhood common epilepsy syndromes (frontal lobe epilepsy (FLE), childhood absence epilepsy (CAE), and benign epilepsy with centrotemporal spikes (BECTS)) and the influence of epilepsy-related variables. Memory was examined in 90 children with epilepsy (each epilepsy group consisted of 30 children), aged 6–15, and compared with 30 control children. Children with FLE showed significant deficits in verbal and visual memory. In addition, type of epilepsy, earlier age at epilepsy onset, and longer active duration of epilepsy were associated with memory problems. Seizure frequency and treatment, however, did not influence memory performance. This study indicates that children with FLE show greater risk of developing memory deficits than children with CAE or BECTS, thus highlighting the importance of assessing also memory functions in frontal lobe epilepsy.

Neurocognitive profiles in children with epilepsy

PURPOSE

The presence of specific neurocognitive deficits may help explain why school achievement and psychosocial functioning are often worse in children with epilepsy than would be predicted by their global intellectual functioning. This study compared children with two forms of epilepsy: localization-related epilepsy with complex partial seizures (CPS) and childhood absence epilepsy (CAE), to determine whether they display distinct neurocognitive profiles.

METHODS

Fifty-one children with CPS, 31 children with CAE, and 51 controls underwent neuropsychological testing assessing verbal memory, visual memory, and executive functioning. Groups were compared in these cognitive domains. Within-group analyses were also conducted to examine seizure-related factors that may be related to neuropsychological test performance.

KEY FINDINGS

When compared to controls, children with CPS showed a mild generalized cognitive deficit, whereas children with CAE did not. When we controlled for intelligent quotient (IQ), both epilepsy groups showed poorer performance relative to controls in the domain of verbal memory. When the epilepsy groups were compared to one another, the CPS group performed significantly poorer than the CAE group on a test of generalized cognitive functioning. However, in the specific domains of executive functioning, verbal memory, and visual memory the epilepsy groups did not differ when compared to one another.

SIGNIFICANCE

Neurocognitive deficits present in the context of grossly intact global intellectual functioning highlight the importance of neuropsychological screening in both children with CPS and children with CAE.

Cluster subtypes on the California verbal learning test-children's version after pediatric traumatic brain injury

The purpose of this study is to determine the presence of profile subtypes on the California Verbal Learning Test-Children's Version (CVLT-C; Delis, Kramer, Kaplan, and Ober, 1994) in 175 children with traumatic brain injury (TBI). Four key z score variables are used in a 2-stage cluster analysis that reveal 4 reliable subtypes. No meaningful differences among the clusters are found on demographic variables. In contrast, statistically significant differences among the 4 clusters in both level and pattern of performance are found on injury severity parameters and the 4 factor index scores from an independent measure of psychometric intelligence (Wechsler Intelligence Scale for Children-Third Edition; Wechsler, 1991). This study concludes that although no unique profile is found on the CVLT-C after TBI in children, performance on this test is affected strongly by injury severity, with a mediating contribution by speed of information processing.

The Factor Structure of the CVLT-C in Pediatric Epilepsy

The current study used archival data to evaluate the fit of six latent variable models, originally generated by Donders (1999), for the California Verbal Learning Test-Children's Version (CVLT-C; Delis, Kramer, Kaplan, & Ober, 1994) in a large (N = 289) sample of pediatric epilepsy cases presenting at three tertiary treatment centers. Using confirmatory factor analysis, we found that a model including factors of Attention Span, Learning Efficiency, Free Delayed Recall, Cued Delayed Recall, and Inaccurate Recall demonstrated the best relative fit for our data. These findings are consistent with those reported by Donders (1999) in his reanalysis of the CVLT-C standardization sample data, supporting the validity of this factorial model in pediatric epilepsy populations.

A Comparison of Children with Epilepsy to an Age- and IQ-Matched Control Group on the Children's Memory Scale

Past research has found that children with epilepsy exhibit decreased memory skills. In addition, some studies have found that children with epilepsy obtain significantly lower IQ scores than controls. In an effort to examine whether children with epilepsy have specific memory weaknesses versus global cognitive difficulties, the present study compared the performance of 62 children (age range = 6-16 years). Thirty-one children with epilepsy were compared to 31 age- and IQ-matched controls on the Children's Memory Scale (CMS) to determine whether differences in memory skills persist when IQ is matched. An independent t-test comparing index and scaled scores was performed. The results indicated that with the exception of the Word Pairs subtest (p < .01), children with epilepsy did not differ significantly on the CMS subtests when IQ was matched. This suggests that list-learning paradigms may be particularly sensitive to memory impairments in children with epilepsy and/or that children with epilepsy have more global cognitive impairments.

Construct validity of the California Verbal Learning Test--Children's Version (CVLT-C) after pediatric traumatic brain injury

The purpose of this study was to determine the latent structure of the California Verbal Learning Test--Children's Version (CVLT-C; D. Delis, J. Kramer, E. Kaplan, & B. Ober, 1994) in a sample of 175 children with traumatic brain injury (TBI). Maximum-likelihood confirmatory factor analyses were performed to test 6 competing hypothetical models for fit and parsimony. A 4-factor model consisting of Attention Span, Learning Efficiency, Delayed Recall, and Inaccurate Recall provided the best fit to the data. The results support the construct validity of the CVLT-C in children with TBI and suggest that a multifactorial interpretation of quantitative indexes from this instrument is appropriate for clinical practice.

Performance discrepancies on the California Verbal Learning Test-Children's Version (CVLT-C) in children with traumatic brain injury

One hundred sixty-seven children with traumatic brain injury (TBI), selected from an 8-year series of consecutive referrals to a Midwestern rehabilitation hospital, completed the California Verbal Learning Test-Children's Version (CVLT-C) and the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) within 1 year after injury. A large proactive interference (PI) effect, defined as performance on the second list that was at least 1.5 standard deviations below that on the 1st one, was statistically significantly more common in this clinical sample (21%) than in the CVLT-C standardization sample (11%). Other performance discrepancies, including retroactive interference, rapid forgetting, and retrieval problems, occurred at approximately the same rate in the clinical and standardization samples. Children with anterior cerebral lesions were about 3 times less likely to have a large PI effect than children without such lesions, but the former group performed worse on the first CVLT-C list. The impact of pediatric TBI on a wide range of CVLT-C quantitative variables was mediated by speed of information processing, as assessed by the WISC-III Processing Speed factor index. It is concluded that failure to release from PI is somewhat common, although certainly not universal, in children with TBI. Unlike with adults, anterior cerebral lesions are not associated selectively with an increased risk for PI after pediatric TBI but rather with a reduced efficiency of allocation of cognitive resources. Deficits in speed of information processing appear to be primarily responsible for the learning deficits on the CVLT-C after pediatric TBI.

Multidisciplinary approach to childhood epilepsy: exploring the scientific rationale and practical aspects of implementation

The management of childhood epilepsy requires attention to more than seizure control because children with epilepsy often suffer from comorbidities that lead to an increased frequency of psychiatric disease, learning difficulties, and other problems of psychosocial development. These comorbidities can stem in part from the same genetic traits that determine seizure susceptibility. Thus, mutations affecting potassium, calcium, and sodium channels have been linked with epilepsy syndromes and affective and behavioral abnormalities. It is important to consider the effect of antiepilepsy drugs on comorbid conditions and the effect on seizures of drugs used to treat comorbidities. A number of antiepilepsy drugs are available that have minimal adverse cognitive effects, and some can have positive effects on mood and behavior. Epilepsy in a child is a condition that affects and is affected by the entire family situation. In addition to appropriate neuropsychologic evaluation, optimal management of childhood epilepsy also can require the involvement of the social worker, advanced practice nurse, and educational specialist. Many elements of the multidisciplinary team approach can be instituted by the child neurologist in community practice and at large, specialized epilepsy centers.

Memory in children with temporal or extra-temporal excisions

Memory was assessed before and after surgery in 44 children and adolescents with focal epilepsy who underwent either right temporal, left temporal or extra-temporal excisions. Measures included tests of verbal (story recall, and verbal list learning) and visually mediated (recall of a complex design, face recognition) memory. Changes in children's memory from pre- to post-operative assessment were examined and individual differences in outcome were evaluated. Although substantial variability existed in performance, no group differences or post-operative changes were found for measures of verbal memory or design recall. For face recognition, all groups improved after surgery, although children with right temporal resections performed more poorly than the other groups. Finally, with the exception of face recognition, no material-specific effects were observed before or after surgery.

Should every child with epilepsy undergo a neuropsychological evaluation?

Neuropsychological (NP) testing has always been an important part of the presurgical workup of patients with epilepsy. Yet, there is no agreement on the timing or circumstances in which NP testing should be ordered in the evaluation of children with epilepsy. This article addresses this controversial question. The early identification of learning or of mental health problems constitutes one of the arguments in support of NP testing. The relative unavailability and high cost of NP testing, the potential inappropriate labeling of children as "learning disabled," and the risk of attached stigma are some of the arguments in support of limiting NP testing to children suspected of having cognitive or behavioral problems. Nevertheless, we concur that at the least, the need for NP testing should be considered by clinicians in the course of their evaluation of every child with epilepsy.