Neuropsychologic effects of frontal lobe epilepsy in children

Neuroimaging of memory in frontal lobe epilepsy

In a large percentage of epilepsies, seizures have focal onset. These epilepsies are associated with a wide range of behavioral and cognitive deficits sometimes limited to the functions encompassed within the ictal onset zone but, more frequently, expanding beyond it. The presence of impairments associated with neuroanatomical areas outside of the ictal onset zone suggests distal propagation of epileptic activity via brain networks and interconnected whole-brain neural circuitry. In patients with frontal lobe epilepsy (FLE), using functional magnetic resonance imaging (fMRI) to identify deficits in working, semantic, and episodic memory may provide a lens through which to understand typical and atypical network organization. A network approach to focal epilepsy is relevant in these patients because of the frequently noted early age of seizure onset. Early seizure-related disruption in healthy brain development may result in a significant brain reorganization, development of compensation-related mechanisms of dealing with function abnormalities and disruptions, and the propagation of epileptic activity from the focus to widespread brain areas (functional deficit zones). Benefits of a network approach in the study of focal epilepsy are discussed along with considerations for future neuroimaging studies of patients with FLE.

Cognitive control deficits in pediatric frontal lobe epilepsy

Executive dysfunction and behavioral problems are common in children with epilepsy. Inhibition and shifting, both aspects of cognitive control, seem related to behavior problems and are thought to be driven mainly by the frontal lobes. We investigated if inhibition and shifting deficits are present in children with frontal lobe epilepsy (FLE). Secondly, we studied the relationship between these deficits and behavior problems. Thirty-one children were administered the Stroop Color Word Test and a digital version of the Wisconsin Card Sorting Test (WCST). Parents completed the Behavioral Rating Inventory for Executive Function (BRIEF) and the Achenbach scale (Child Behavior Checklist (CBCL)). About 20% of the children displayed significant low results on the Stroop Effect. About 60% showed shifting problems on the WCST. Parents reported cognitive control and behavioral deficits in about a third of the children. Also, behavioral problems and deficits in inhibition and shifting in daily life (BRIEF) seem to be related. There were no correlations between questionnaires and the Stroop and the WCST. Only in the group of children with many perseverative errors there were especially high correlations between Inhibit of the BRIEF.

Positive outcome of visuospatial deficit rehabilitation in children with epilepsy using computer-based FORAMENRehab program

Children with epilepsy often show deficits in attention and visuospatial functions. Still, very few systematically controlled evidence-based pediatric neurorehabilitation methods exist. The aim was to assess the effectiveness of a computer-based rehabilitation program for visuospatial deficit remediation in children with epilepsy. Fifty-eight children aged 8-12 years participated: 17 children with epilepsy diagnosis in intervention group, 22 patients in waiting-list control group, and 19 healthy age equivalent controls. The intervention group received guided visuospatial functions rehabilitation with FORAMENRehab software twice a week for a 5-week period. Baseline assessments were carried out before and immediately after the intervention period, and as follow-up 1.31 years later. Intervention group showed positive immediate rehabilitation effect in 3 out of 4 visuospatial components: visual organization, visual attention, and visuospatial perception. A long-term rehabilitation effect in the study group was observed in all 4 of the trained components. Also, a positive generalized effect was confirmed by the parents' and children's qualitative feedback with some of the improved skills transferring to children's everyday life. One hundred percent compliance further confirmed the children's motivation to participate and the effectiveness of FORAMENRehab for pediatric neurorehabilitation.

Are frontal and temporal lobe epilepsy dissociable in their memory functioning?

There is controversy in the literature as to how dissociable frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE) are in terms of memory deficits. Some researchers have demonstrated that FLE is associated with greater executive dysfunction including working memory, whereas TLE is associated with greater memory impairment. Others have found the two groups to be comparable in memory functioning. Hence, we examined this question in children with FLE and TLE versus typically developing controls. We found most of the expected effects when the groups with focal onset epilepsy were compared to controls. Specifically, children with left TLE performed worse on verbal short-term memory/learning and long-term memory measures. In contrast, children with right TLE exhibited a more global pattern of difficulty on short-term memory/learning measures but performed worse than controls on long-term memory for faces. Children with FLE performed worse than controls on verbal working memory. Nevertheless, laterality effects were mild, as children with right and left TLE did not differ significantly from each other. Further, children with FLE did not differ from those with TLE on most measures except delayed facial recognition, where children with right TLE performed worse. In addition, attention problems and poor behavioral regulation were related to encoding problems in both the total epilepsy sample and in children with TLE specifically. Hence, our findings overall are consistent with prior studies indicating that children with TLE and FLE are commensurate in most aspects of memory impairment when compared to each other, likely related to rapid propagation between the frontal and temporal lobes, as would be expected with an excitatory lesion.

Working memory in pediatric frontal lobe epilepsy

Thirty-two children with frontal lobe epilepsy (FLE) were assessed using different working memory measures. In addition, parents and teachers completed the working memory scale of the Behavioral Rating Inventory of Executive Functioning (BRIEF) to assess the children's "daily life behavior." Results suggested minimal working memory deficits as assessed with performance-based measures. However, the BRIEF showed more working memory deficits suggesting that, on a daily life level, working memory problems seem to be associated with FLE. We discuss why the results of the performance-based measures are not consistent with results of the BRIEF.HighlightsParents as well as teachers report working memory dysfunction in daily life to the same extent.Performance based measures show minimal deficits of working memory.Correlation between working memory tasks and proxy measures are low.

Clinical and electroencephalographic correlates of psychiatric features in children with frontal lobe epilepsy

BACKGROUND AND OBJECTIVE

Frontal lobe epilepsy (FLE) is often associated with psychiatric features, although the factors predisposing to the concurrence of these conditions have yet to be determined, especially in younger children. We aimed at defining possible clinical and electroencephalography (EEG) features that may enhance the psychiatric risk in pediatric FLE.

METHOD

We performed a structured psychiatric assessment of 59 children with FLE, using both categorical and dimensional approaches, correlated psychopathology with epilepsy data, and cognitive development.

RESULTS

About 1/3 of patients with FLE displayed intellectual disability (ID), and more than 2/3 displayed psychiatric disorders, including depression, disruptive behaviors, anxiety, and bipolar/psychotic disorders. Psychiatric dimensions such as impulse control problems, attentional deficits, social problems, and aggressive behaviors were frequent features of FLE. Intellectual disability was associated with an earlier onset of psychiatric disorders and more frequent disruptive behavior disorders and aggressiveness. Long-standing epilepsy and bilateral or anterior frontal EEG abnormalities also increased the risk of psychopathology. Finally, right-hemisphere lesions were associated with disruptive behavior disorders, fast EEG rhythms with attention/memory problems, and phases of seizure remission with impulse control problems.

CONCLUSIONS

Clinical and EEG markers of increased psychopathological risk may help in defining consistent at-risk subgroups within FLE and improving early diagnosis, prognosis, and treatment. Categorical and dimensional approaches to psychiatric diagnosis may generate new research hypotheses and support the investigation of the complex pathophysiological bases shared by different neurodevelopmental disturbances.

Executive and behavioral functioning in pediatric frontal lobe epilepsy

OBJECTIVE

Epilepsy, as a chronic and neurological disease, is generally associated with an increased risk for social and emotional behavior problems in children. These findings are mostly derived from studies on children with different epilepsy types. However, there is limited information about the associations between frontal lobe epilepsy (FLE) and cognitive and behavioral problems. The aim of this study was to examine relationships between FLE and executive and behavioral functioning reported by parents and teachers.

MATERIAL AND METHODS

Teachers and parents of 32 children (18 boys, 14 girls, mean age 9; 2 years ±1;6) with a confirmed diagnosis of FLE completed the Behavioral Rating Inventory of Executive Function (BRIEF), the Child Behavior Checklist (CBCL), and Teacher Report Form (TRF).

RESULTS

About 25 to 35% of the parents and teachers rated children in the abnormal range of the main scales of the BRIEF, CBCL, and TRF. Teachers tend to report more metacognition problems, whereas parents tend to report more behavior regulation problems. Children with left-sided FLE showed more problems than children with bilateral or right-sided FLE. The whole range of executive dysfunctioning is linked to behavioral dysfunctioning in FLE, but ratings vary across settings and informants. The epilepsy variables age of onset, lateralization, drug load, and duration of epilepsy had only a small and scattered contribution.

CONCLUSION

Ratings on the BRIEF, CBCL, and TRF are moderately to highly correlated, suggesting a (strong) link between executive and behavioral functioning. Subtle differences between parents and teachers ratings suggest different executive function demands in various settings.

Unique and shared areas of cognitive function in children with intractable frontal or temporal lobe epilepsy

OBJECTIVE

Previous findings have been mixed in terms of identifying a distinct pattern of neuropsychological deficits in children with frontal lobe epilepsy (FLE) and in those with temporal lobe epilepsy (TLE). The current study investigated the neuropsychological similarities and differences across these two pediatric medically intractable localization-related epilepsies.

METHOD

Thirty-eight children with FLE, 20 children with TLE, and 40 healthy children (HC) participated in this study. A comprehensive battery of standardized tests assessed five neuropsychological domains including intelligence, language, memory, executive function, and motor function. A principal component analysis (PCA) was used to distill our neuropsychological measures into latent components to compare between groups.

RESULTS

Principal component analysis extracted 5 latent components: executive function (F1), verbal semantics (F2), motor (F3), nonverbal cognition/impulsivity (F4), and verbal cognition/attention (F5). The group with FLE differed from the HC group on F1, F2, F4, and F5, and had worse performance than the group with TLE on F1; the group with TLE had lower performance relative to the HC group on F2.

CONCLUSION

Our findings suggest that, in comparison with neurotypically developing children, children with medically intractable FLE have more widespread neuropsychological impairments than do children with TLE. The differences between the two patient groups were greatest for the factor score most clearly related to executive function. The results provide mixed support for the concept of specificity in neuropsychological dysfunction among different subtypes of localization-related medically intractable childhood epilepsies.

Seizure-related variables are predictive of attention and memory in children with epilepsy

Children with epilepsy (CWE) are at greater risk for cognitive deficits and behavioral difficulties than are typically developing healthy children, and particular epileptic symptoms and treatments may contribute to this risk. The current study examined the relationships between four seizure-related variables and attention and memory functioning in a sample of 207 CWE (ages 6-16) using both neurocognitive and parent/teacher-report measures. Sociodemographic, medical, and neuropsychological data were collected from patients' medical charts in a retrospective fashion. Hierarchical multiple regressions were performed with sociodemographic variables (age, gender, race) entered as step one and seizure-related variables (number of anti-epileptic drugs [AEDs], EEG laterality, EEG lobe of focus, lifetime seizure duration) entered as step two. Results indicated that seizure-related variables were consistently predictive of poor cognitive performances above and beyond sociodemographic variables, although only minimally predictive of parent/teacher-reports. A longer duration of seizure burden and greater number of AEDs were robust predictors of performances on most cognitive measures. These findings indicate that CWE with long lifetime seizure durations and multiple AEDs are at risk for inefficiencies in attention and memory. Knowledge of this risk will allow treating providers greater accuracy and precision when planning medical treatment and making recommendations to families.

Neuropsychological profiles and outcomes in children with new onset frontal lobe epilepsy

Frontal lobe epilepsy (FLE) is the second most frequent type of localization-related epilepsy, and it may impact neurocognitive functioning with high variability. The prevalence of neurocognitive impairment in affected children remains poorly defined. This report outlines the neuropsychological profiles and outcomes in children with new onset FLE, and the impact of epilepsy-related factors, such as seizure frequency and antiepileptic drug (AED) load, on the neurocognitive development. Twenty-three consecutive children (15 males and 8 females) with newly diagnosed cryptogenic FLE were enrolled; median age at epilepsy onset was 7 years (6-9.6 years). They underwent clinical and laboratory evaluation and neuropsychological assessment before starting AED treatment (time 0) and after one year of treatment (time 1). Twenty age-matched patients affected by idiopathic generalized epilepsy (10 male and 10 females) and eighteen age-matched healthy subjects (9 males and 9 females) were enrolled as controls and underwent the same assessment. All patients with FLE showed a significant difference in almost all assessed cognitive domains compared with controls, mainly in frontal functions and memory. At time 1, patients were divided into two groups according to epilepsy-related factors: group 1 (9 patients) with persisting seizures despite AED polytherapy, and group 2 (14 patients) with good seizure control in monotherapy. A significant difference was highlighted in almost all subtests in group 1 compared with group 2, both at time 0 and at time 1. In children with FLE showing a broad range of neurocognitive impairments, the epilepsy-related factors mostly related to a worse neurocognitive outcome are poor seizure control and the use of AED polytherapy, suggesting that epileptic discharges may have a negative impact on the functioning of the involved cerebral regions.

Patterns of verbal learning and memory in children with intractable temporal lobe or frontal lobe epilepsy

PURPOSE

The objective of this study was to provide a better understanding of the verbal learning and memory (VLM) patterns that might differentiate children with frontal lobe epilepsy (FLE) from children with temporal lobe epilepsy (TLE) and to examine the impact of variables thought to influence outcomes (seizure laterality, age at seizure onset, age at assessment, epilepsy duration, number of antiepileptic drugs).

METHODS

Retrospective analyses were carried out for children with intractable unilateral TLE (n=100) and FLE (n=27) who completed standardized measures of VLM entailing lists of single words or lists of word pairs.

RESULTS

Mean intelligent quotients and VLM scores on single words fell within the average range for both groups, whereas scores fell within the low average to borderline range on word pairs. No significant overall differences in VLM were found between the group with TLE and the group with FLE. Older age at assessment and older age at seizure onset were generally associated with better VLM in both groups but were related to better performance in a number of indices in the group with TLE and only fewer intrusions in the group with FLE.

CONCLUSIONS

The VLM profiles of children with TLE and FLE are generally similar. Older age at assessment and older age at seizure onset have a favorable impact on both groups but are related to better encoding, retrieval, and monitoring processes for the group with TLE and improved memory monitoring (i.e., as indicated by fewer intrusions) in the group with FLE.

[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.

Assessment of everyday executive functioning in children with frontal or temporal epilepsies

Executive functions are particularly vulnerable in case of brain disruption during childhood, when the brain is not fully mature. Some studies showed impairments of executive functions in children with epilepsy, but only a few of them investigated the impact of executive dysfunctions on daily life. The aim of this study was to understand the everyday executive functioning of children with epilepsy both at home and in school. We administered the Behavior Rating Inventory of Executive Function to parents and teachers of 53 children (7-16 years of age) with structural epilepsies or epilepsies of unknown cause of temporal lobe (n=25) or frontal lobe (n=28). The results indicated a global executive impairment in the whole group of patients, compared with normative data, with no difference between the group with temporal lobe epilepsy (TLE) and that with frontal lobe epilepsy (FLE), except for monitor domain, which seemed more frequently impaired in the group with FLE. Congruence between parent and teacher ratings was found. The frequency of seizures was not related to executive dysfunction, whereas the number of antiepileptic drugs tended to positively correlate with working memory impairment. Onset of epilepsy at a younger age was also related to more executive difficulties but only according to teacher ratings. Lastly, duration of epilepsy was strongly associated with executive deficits reported in the context of school. Our results support the executive dysfunction hypothesis in daily life of children with structural focal epilepsy or focal epilepsy of unknown cause and are consistent with the early brain vulnerability hypothesis currently prevalent in the context of child neuropsychology. The BRIEF appears to be a clinically useful tool for assessing executive function impairment in this clinical population.

Intellectual functioning in children with epilepsy: frontal lobe epilepsy, childhood absence epilepsy and benign epilepsy with centro-temporal spikes

PURPOSE

The purpose of our study is to describe intellectual functioning in three common childhood epilepsy syndromes - frontal lobe epilepsy (FLE), childhood absence epilepsy (CAE) and benign epilepsy with centro-temporal spikes (BECTS). And also to determine the influence of epilepsy related variables, type of epilepsy, age at epilepsy onset, duration and frequency of epilepsy, and treatment on the scores.

METHODS

Intellectual functioning was examined in a group of 90 children with epilepsy (30 FLE, 30 CAE, 30 BECTS), aged 6-15 years, and compared with a control group (30). All subjects obtained a Full Scale IQ ≥ 70 and they were receiving no more than two antiepileptic medications. Participants completed the Wechsler Intelligence Scale for Children - Third Edition. The impact of epilepsy related variables (type of epilepsy, age at epilepsy onset, duration of epilepsy, seizure frequency and anti-epileptic drugs) on intellectual functioning was examined.

RESULTS

Children with FLE scored significantly worse than controls on WISC-III Verbal IQ, Full Scale IQ and Processing Speed Index. There was a trend for children with FLE to have lower intelligence scores than CAE and BECTS groups. Linear regression analysis showed no effect for age at onset, frequency of seizures and treatment. Type of epilepsy and duration of epilepsy were the best indicators of intellectual functioning.

CONCLUSION

It is crucial that children with FLE and those with a longer active duration of epilepsy are closely monitored to allow the early identification and evaluation of cognitive problems, in order to establish adequate and timely school intervention plans.

Congenital brain damage: cognitive development correlates with lesion and electroencephalographic features

The purpose of this study was to assess cognitive development in 26 children with congenital focal brain lesion and unilateral spastic cerebral palsy first diagnosed and followed up for rehabilitation at our institution. Mean intelligence quotients (IQs) were correlated not only to the different features of the cerebral lesions, but also to the different types of electroencephalographic abnormalities. We also examined individual scores. We found that about 70% of the children had values of Full-Scale, Verbal, and Performance IQs within the normal range. No differences were found between left and right injured children. Different Verbal IQ-Performance IQ profiles were observed. Larger lesions and some electroencephalographic features, mainly signal slowing/attenuation as signs of structural brain damage, were significantly associated with lower intellectual abilities. The role of other factors, including genetic and environmental background variability, as well as rehabilitative treatments, on cognitive sequelae in such patients was discussed.

Cognitive disorders in pediatric epilepsy

Childhood epilepsy may cause cognitive disorders and the intellectual quotient is indeed not normally distributed in epileptic children, a fair proportion of whom show an IQ in the deficient range. Some epileptic syndromes happen during vulnerability periods of brain maturation and interfere with the development of specific cognitive functions. This is the case for the Landau-Kleffner syndrome, which generally appears during speech development and affects language. Similarly, West syndrome - or infantile spasms - is an epileptogenic encephalopathy appearing during the first years of life and induces a major delay in social and oculo-motor development. Specific impairments can also be identified in partial childhood epilepsies in relation with seizure focus localization. For instance, left temporal and frontal epilepsies are frequently associated with verbal impairments. Moreover, episodic memory disorders have been described in children suffering from temporal lobe epilepsy whereas executive deficits (planning, self-control, problem solving) have been reported in frontal lobe epilepsy. In most cases, including its mildest forms, childhood epilepsy induces attention deficits, which may affect academic achievement. These observations militate in favor of individual neuropsychological assessments as well as early interventions in order to provide the child with an optimal individualized treatment program.

Cognitive and behavioural findings in children with frontal lobe epilepsy

BACKGROUND

Frontal Lobe Epilepsy (FLE) is the second most frequent type of partial epilepsy and its onset is generally in childhood. Though cognitive and behavioural impairments have been described as co-morbid disorders in epilepsy, their extent in FLE, particularly in children, remains unknown.

AIMS

In this study, we assess cognitive skills and behaviour in a cohort of paediatric FLE patients.

METHODS

We measured the performance of 71 children with cryptogenic FLE on intelligence tests, neuropsychological tests, and behavioural questionnaires. Age-dependent normative values were used for reference. Results were related to epilepsy-factors including age at epilepsy onset, duration of epilepsy, seizure frequency, localisation of the epileptic focus and drug load.

RESULTS

Paediatric FLE patients performed worse on intellectual and neuropsychological tests compared to reference values, and had a delay in school achievement. The performance of patients was typically worse on tasks measuring visual-spatial functions, memory, psychomotor speed and alertness. High seizure frequency was associated with lower scores on the arithmetic subtest of the intelligence scale; the other epilepsy-factors had no statistically significant influence on intelligence test or neuropsychological test outcome. Behavioural problems included attention problems, anxiety and internalising behaviour. These were not significantly related to epilepsy-factors.

CONCLUSIONS

Children with cryptogenic FLE show a broad range of cognitive and behavioural impairments, compared to reference values. While high seizure frequency may affect performance on selected cognitive measures, other epilepsy-factors do not seem to influence cognition and behaviour. Study of micro-structural or functional brain abnormalities that underlie these cognitive and behavioural impairments are warranted.

Memory in frontal lobe epilepsy: an fMRI study

PURPOSE

Focal epilepsies are often associated with structural and functional changes that may extend beyond the area of seizure onset. In this study we investigated the functional anatomy of memory in patients with frontal lobe epilepsy (FLE), focusing on the local and remote effects of FLE on the networks supporting memory encoding.

METHODS

We studied 32 patients with drug-resistant FLE and 18 controls using a functional magnetic resonance imaging (fMRI) memory encoding paradigm.

KEY FINDINGS

During encoding of stimuli, patients with FLE recruited more widely distributed areas than healthy controls, in particular within the frontal lobe contralateral to the seizure onset. Normal memory performance was associated with increased recruitment of frontal areas, and conversely a poor performance was associated with an absence of this increased recruitment and decreased activation in mesial temporal lobe areas.

SIGNIFICANCE

In patients with FLE, recruitment of wider areas, particularly in the contralateral frontal lobe, appears to be an effective compensatory mechanism to maintain memory function. Impaired hippocampal activation is relatively rare and, in turn, associated with poor recognition memory.

Cognitive and behavioral complications of frontal lobe epilepsy in children: a review of the literature

Frontal lobe epilepsy (FLE) is considered the second most common type of the localization-related epilepsies of childhood. Still, the etiology of FLE in children, its impact on cognitive functioning and behavior, as well as the response to antiepileptic drug treatment in children has not been sufficiently studied. This review focuses on these aspects of FLE in childhood, and reveals that FLE in childhood is most often cryptogenic, and impacts on a broad range of cognitive functions. The nature and severity of cognitive deficits are highly variable, although impaired attention and executive functions are most frequent. Young age at seizure onset is the only potential risk factor for poor cognitive outcome that has been consistently reported. The behavioral disturbances associated with FLE are also highly variable, although attention deficit/hyperactivity disorder seems most frequent. In 40% of children with FLE satisfactory seizure control could not be achieved. This is a higher percentage than reported for the general population of children with epilepsy. Therefore, pediatric FLE, even if cryptogenic in nature, is frequently complicated by impairment of cognitive function, behavioral disturbances, and therapy-resistance. Given the impact of these complications, there is a need for studies of the etiology of frontal lobe epilepsy-associated cognitive and behavioral disturbances, as well as pharmacotherapy-resistance.

Neuropsychological development in children with Dravet syndrome

PURPOSE

Aim of this study is to report a detailed profile of neuropsychological development in children with Dravet syndrome.

METHODS

Twelve children with Dravet syndrome were longitudinally assessed using a detailed clinical and neuropsychological evaluation. Six had typical features of severe myoclonic epilepsy in infancy (SMEI) whereas the other six resulted borderline. All twelve underwent serial neuropsychological assessments with neurodevelopmental scales and further assessment of specific cognitive abilities.

RESULTS

Our results reported an apparent normal development before disease onset, a general evolution in two main stages, more active the first one and with a general trend towards a clinical stabilization afterwards. The onset of cognitive decline was generally later than what is reported in other series; furthermore, the impairment of cognitive development is less severe, especially in borderline cases. As to specific cognitive competence, attention, visual motor integration, visual perception as well as executive functions are the most impaired abilities; language appears less involved, with a predominance of phonological defects.

CONCLUSIONS

In our cohort the global development of patients appear less affected than in previous studies. Furthermore, our study points out an impairment of several specific cognitive skills even in patients with a developmental quotient apparently in the normal range. Language and other cognitive skill impairment such as attention, visuo-spatial organization, working memory and executive function appear consistent with what is usually found in cerebellar disorders.

Surgery of children with frontal lobe lesional epilepsy: neuropsychological study

AIM OF THE STUDY

was to provide new data about the evolution of neuropsychological findings in patients with lesional frontal lobe epilepsy (FLE) operated on with lesion excision.

PATIENTS AND METHODS

Twelve patients with lesional FLE underwent full clinical examination including neurological, neuropsychological and developmental assessments, high-resolution magnetic resonance imaging (MRI), ictal and interictal prolonged EEG monitoring and evaluation of seizure semeiology before and after surgery. The mean follow-up duration was 2 years and 10 months (range=14 months-7 years). Another group of lesional temporal lobe epilepsy, matched for the age at surgery and side of surgery, was likewise studied in order to compare neuropsychological patterns and to try to find out specific features in frontal lobe epilepsy evolution.

RESULTS

All patients resulted seizure free at outcome except one belonging to Engel's class II. Before surgery general intelligence was similar in FLE as well as in TLE group. Executive functions and motor coordination were frequently affected in FLE whereas patients with TLE often presented with deficits in naming, visual memory and visuo-spatial attention. After surgery there was a frequent decline of IQ in FLE group together with a slight deterioration, especially of executive functions in some patients. An improvement of behaviour was often observed in both groups.

CONCLUSIONS

As already reported in literature, neuropsychological pre-surgical data confirms the involvement of attention and executive functions in lesional FLE. No significant neuropsychological improvement was produced by surgery that determined in some cases a slight decline of general intelligence and specific frontal abilities. Yet, generally behaviour improved and seizures were controlled.

Impaired spatial working memory in children with well-controlled epilepsy: an event-related potentials study

PURPOSE

To find out whether children with epilepsy did show different event-related potentials (ERP) compared to healthy children during performance in a visuo-spatial working memory (WM) task.

METHODS

Multichannel ERPs were measured during a visuo-spatial backmatching task. A quantitative analysis technique, based on Statistical Parametric Mapping, was used to analyze the ERP data. 62 children were tested (6-16 years old): 31 children with well-controlled epilepsy and 31 age- and intelligence-matched healthy children. One-backmatching (BM1) and two-backmatching (BM2) tasks were performed. Behavioral performance and target and nontarget ERPs were compared across groups in both tasks.

RESULTS

No behavioral differences were found between groups in the easy BM1 task. In the difficult BM2 task, children with epilepsy made significantly more omission errors. ERP analysis showed significantly higher amplitudes over frontal and central regions between 300 and 500 ms poststimulus in the epilepsy group compared to the control group. This effect was most pronounced in BM2.

DISCUSSION

This study shows that children with well-controlled epilepsy and normal intelligence demonstrate compensatory recruitment of their WM network during a visuo-spatial working memory task. Increasing the difficulty of the task (BM2) enhances this general neurophysiological finding and parallels the behavioral performance.

SIGNIFICANCE

Our results illustrate that epilepsy induces different cortical activity during working memory tasks, even when behavioral performance is normal.

Working memory in children with epilepsy: an event-related potentials study

PURPOSE

The aim of this study was to find out whether children with idiopathic epilepsy did show different cortical activation patterns compared to non-epileptic children during performance of a working memory task. To this end event-related potentials (ERPs) were measured during a visual 1-backmatching task. A quantitative analysis technique to analyze the ERP data, without any 'a priori' decisions on 'peak' presence, amplitudes or latencies, is used.

METHODS

46 children were tested (6-16 years old): 21 children with well-controlled "benign" epilepsy (benign rolandic epilepsy, n=9, idiopathic generalized epilepsy, n=12) and a control group of 25 non-epileptic children. Behavioral task performance and ERPs following both target and nontarget stimuli were compared across both study groups.

RESULTS

No differences were found in the number of omission errors or commission errors or in the reaction times between groups. However, ERPs following target stimuli showed significantly higher amplitude in the epilepsy group compared to the control group over frontal and central regions within the time window between 250 and 425 ms poststimulus, what coincides with the time window of target-nontarget stimulus discrimination.

DISCUSSION

Our study shows that children with benign, well-controlled epilepsy show a different cortical activation pattern during a visual working memory task. We hypothesize that they need more brain processing effort to achieve the same performance level as their age matched controls.

Memory performance on the California Verbal Learning Test of children with benign childhood epilepsy with centrotemporal spikes

Verbal learning and retrieval, as well as the use of learning strategies, were assessed in 24 children with benign epilepsy with centrotemporal spikes (BECTS) and 16 controls, using the California Verbal Learning Test-Children's Version. Neuropsychological data were correlated with EEG features. Compared with age-matched controls, the children with BECTS younger than 10 exhibited significant learning difficulties and were less efficient in using a semantic clustering strategy, whereas no such difference emerged for subjects older than 10. This suggests that the capacity for spontaneous use of a more efficient strategy matures later in children with BECTS. Moreover, the majority of those younger than 10 had multifocal anomalies, suggesting that the difficulties encountered might be caused by the presence of additional foci.

Brain oscillatory EEG event-related desynchronization (ERD) and -sychronization (ERS) responses during an auditory memory task are altered in children with epilepsy

PURPOSE

Children with epilepsy are in risk for cognitive impairment, but reliable methods, other than neuropsychological testing, to verify such a decline are few. The purpose of this study was to assess the effect of infrequent seizures on cognitive skills in children with non-symptomatic focal epilepsy taking antiepileptic medication but still having infrequent seizures.

METHODS

EEG (electroencephalogram) brain electric oscillatory responses of the 4-6Hz, 6-8Hz, 8-10Hz and 10-12Hz EEG frequency bands were studied. These responses, assessed by means of the event-related desynchronization (ERD) and synchronization (ERS) method, were recorded in 6 children with epilepsy (mean age 11.3 years) and in 11 control children (mean age 12 years) while they performed an auditory memory task. All subjects also underwent a comprehensive neuropsychological test battery.

RESULTS

The differences in the 4-6Hz ERD/ERS responses between encoding and recognition were smaller in the children with epilepsy as compared to those of the control children. In the 6-8Hz frequency band, the responses of the two groups dissociated most notably in the frontal electrodes. No statistically significant differences in the alpha frequency range (8-12Hz) were observed between the groups.

CONCLUSIONS

Significant alterations in the lower EEG frequency (4-8Hz) ERD/ERS responses in children with epilepsy during auditory memory processing, as compared to age-matched, healthy children may suggest that seizures affect memory and underlying brain processes, indexed also by poorer performance particularly in neuropsychological subtests related to language functions.

Neuropsychologic performance of children with epilepsy on the NEPSY

Neuropsychologic test scores from a group of children with epilepsy were compared to the standardization sample of the NEPSY: A Developmental Neuropsychological Assessment, a relatively new neuropsychologic testing instrument. Nineteen children with a confirmed diagnosis of epilepsy (11 boys, 8 girls), aged 3-12 years, participated. Attention/executive function, language, sensorimotor, visuospatial, and learning/memory domain scores were examined, as well as individual subtest scores. The mean scores on the attention/executive function, language, and sensorimotor domains were >1.5 standard deviations below the normative mean, and significantly lower than the mean visuospatial domain score (P < 0.05). The mean language domain score was also significantly lower than the learning/memory score (P < 0.05). Mean subdomain scores varied, with impairment on two tasks measuring rapid automatic processing and graphomotor precision, respectively. On the majority of subtests, 15% or more of the sample scored in the impaired range. Associations between patient age, seizure onset age, seizure frequency, and antiepileptic medication status were not associated with outcome, perhaps due in part to the small sample size. The strengths and weaknesses of the NEPSY as a measure of neuropsychologic functioning in children with epilepsy, and its utility in highlighting risks to academic achievement are discussed.

Intellectual and language findings and their relationship to EEG characteristics in benign childhood epilepsy with centrotemporal spikes

Recent research has revealed that benign childhood epilepsy with centrotemporal spikes (BECTS) causes deficient performance in various neuropsychological areas, without arriving at a definition of a uniform profile. The purpose of this study was to examine intelligence and certain language functions in 24 children with an active centrotemporal focus, comparing them with a group of 16 controls matched for age and schooling. Test results were correlated with several EEG characteristics, including focal versus multifocal presentation of interictal epileptiform activity, lateralization, spike maximum on midtemporal or extratemporal electrodes, and rate of interictal activity when awake and during non-REM sleep. Our study demonstrated that children with BECTS have mild language defects, revealed by tests measuring phonemic fluency, verbal re-elaboration of semantic knowledge, and lexical comprehension. Interictal EEG discharges demonstrated that a high rate of occurrence while awake, multifocal location, and temporal prominence seem to impair the efficiency of some of the neuropsychological functions investigated. However, because the last EEG was obtained within the last 2 months (on average) before the assessment, and because BECTS is a form of epilepsy with signs of cortical hyperexcitability that vary over time in terms of rate, side, and location, the pattern of neuropsychological deficiencies could have changed (at least to some degree) by the time of the test, with respect to the EEG variables considered.

Nonlesional Frontal Lobe Epilepsy (FLE) of Childhood: Clinical Presentation, Response to Treatment and Comorbidity

RATIONALE

Few studies have looked at long-term epileptic and cognitive outcome of frontal lobe epilepsy (FLE) in children. Most are limited by inclusion of lesional and nonlesional patients.

GOAL

To define the epileptic and functional outcome of children with nonlesional FLE.

METHODS

We reviewed medical records and neuropsychological evaluations of patients with nonlesional FLE diagnosed between 1994 and 2004. We included children with either focal or regional frontal EEG and/or functional imaging abnormalities. We reviewed their charts for seizure and neuropsychological outcome.

RESULTS

We included 21 children. Twelve (57.1%) presented with daily seizures. Seizures were nocturnal in 8 of 21, secondarily generalized in 6 of 21, adversive in 5 of 21, and focal motor in 6 of 21. Although, initial seizure control was poor in 14 of 21, long-term control was achieved in 10 of 21 after 14.6+/-22.3 months. Early development was normal in 12 of 21 but at later formal neuropsychological evaluation only 3 of 12 still had a normal profile. The majority of children had learning difficulties requiring special education prior to seizure onset (6 of 10). A clearly defined regression after seizure onset was observed in three children. The majority exhibited attention deficit and hyperactivity or impulsivity (14 of 21), behavioral problems (8 of 21), and cognitive impairments (10 of 21). Early seizure control was associated with a better cognitive outcome.

CONCLUSION

Nonlesional FLE is associated with poor seizure and behavioral outcomes. Whether this is secondary to MRI-silent developmental lesions or to the progressive repercussion of seizures on frontal lobe functions remains uncertain. A prospective study with early neuropsychological assessment could help confirm the latter.

Cognitive effects of seizures

We aimed to review recent prospective and cross-sectional studies regarding the gradual and chronic effects of (cumulative) seizures on cognition. In contrast with the increasing evidence of structural changes in the brain associated with repeated seizures, its functional repercussions remain unclear. Methodological difficulties of cross-sectional and prospective studies are addressed. It appears that all but one of the prospective studies available on children are limited to measures of intelligence. Most studies revealed no significant adverse effects, although there appears to be a subgroup of about 10-25% of children that shows a clinically significant intellectual decline. Children with generalized symptomatic epilepsies, frequent seizures, high antiepileptic drug use, and early onset of epilepsy appear at risk, although psychosocial factors may also play an important role. Five of the six prospective studies on adults report evidence of a mild decline in cognition in patients with a (longstanding) history of pharmacoresistant epilepsy. The adverse effect on cognitive abilities, memory in particular, seems somewhat more robust than that on measures of intelligence. A significant association between cognitive decline and seizure related variables is rarely substantiated in prospective research and cross-sectional studies show contradicting results. Taken together, the data suggest a mild but measurable decline of intellectual performance in children and adults. Decline of specific cognitive abilities in children is impossible to evaluate given the very little data available. In adults, memory appears to be the most vulnerable cognitive function. Due to many confounding variables, the effect of seizures per se is difficult to estimate, but appears limited.

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.

Executive function impairment in early-treated PKU subjects with normal mental development

Executive functions were studied in 14 early and continuously treated PKU subjects (age 10.8 years, range 8-13) in comparison with controls matched for IQ, sex, age and socioeconomic status. Brain MRI examination was normal in all PKU patients. Neuropsychological evaluation included Wisconsin Card Sorting Test, Rey-Osterreith Complex Figure Test, Elithorn's Perceptual Maze Test, Weigl's Sorting Test, Tower of London, Visual Search and Motor Motor Learning Test. Whatever the IQ, PKU subjects performed worse than controls in tests exploring executive functions. Subgrouping the PKU subjects according to the quality of dietary control for the entire follow-up period (using 400 micromol/L as cut-off value for blood phenylalanine (Phe) concentration) showed that patients with worse dietary control performed more poorly than both the PKU group with the best dietary control and the control group. However, a mild impairment of executive functions was still found in PKU patients with a good dietary control (Phe <400 micromol/L) compared to controls. Concerning the PKU group as a whole, no linear correlation was found between neuropsychological performance and historical and concurrent biochemical parameters. We conclude that (a) PKU patients, even when treated early, rigorously and continuously, show an impairment of frontal lobe functions; (b) a protracted exposure to moderately high levels of Phe can affect frontal lobe functions independently of the possible effect of the same exposure on IQ; (c) in order to reduce the risk of frontal lobe dysfunction, the target of dietary therapy should be to maintain blood Phe concentration below 400 micromol/L.