Neuropsychological assessment in children with absence epilepsy

Evaluation of Executive Functions in Patients With Childhood Absence Epilepsy

OBJECTIVE

The aim of this study was to evaluate the executive function of patients with typical absence epilepsy.

METHODS

Thirty-eight (19 healthy children and 19 patients) individuals were enrolled in this study. Neurocognitive function tests, such as the Serial Digit Learning Test, Wisconsin Card Sorting Test, Visual Aural Digit Span Test-Form B, KAS-Animal Test, Trail Making Test-A Time Test, and STROOP Test, were given to all of the participants.

RESULTS

There was a significant difference between the groups on the Serial Digit Learning Test (P = .037) and on a subtest of the Wisconsin Card Sorting Test. As for the Wisconsin Card Sorting Test performance, there were significant differences in perseverative errors and perseverative responses between the patient and control groups (P = .011 and P = .010, respectively).

CONCLUSION

Long-term risk for learning impairments, failure in executive abilities, and short-term memory and attention disorders can occur in children with absence epilepsy.

Reduction of thalamic and cortical Ih by deletion of TRIP8b produces a mouse model of human absence epilepsy

Absence seizures occur in several types of human epilepsy and result from widespread, synchronous feedback between the cortex and thalamus that produces brief episodes of loss of consciousness. Genetic rodent models have been invaluable for investigating the pathophysiological basis of these seizures. Here, we identify tetratricopeptide-containing Rab8b-interacting protein (TRIP8b) knockout mice as a new model of absence epilepsy, featuring spontaneous spike-wave discharges on electroencephalography (EEG) that are the electrographic hallmark of absence seizures. TRIP8b is an auxiliary subunit of the hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels, which have previously been implicated in the pathogenesis of absence seizures. In contrast to mice lacking the pore-forming HCN channel subunit HCN2, TRIP8b knockout mice exhibited normal cardiac and motor function and a less severe seizure phenotype. Evaluating the circuit that underlies absence seizures, we found that TRIP8b knockout mice had significantly reduced HCN channel expression and function in thalamic-projecting cortical layer 5b neurons and thalamic relay neurons, but preserved function in inhibitory neurons of the reticular thalamic nucleus. Our results expand the known roles of TRIP8b and provide new insight into the region-specific functions of TRIP8b and HCN channels in constraining cortico-thalamo-cortical excitability.

Preliminary neurocognitive outcomes in Jeavons syndrome

Jeavons syndrome (JS, eyelid myoclonia with absences [EMA]) consists of a triad of symptoms including eyelid myoclonia that may be accompanied by absence seizures, eye closure-induced EEG paroxysms or seizures, and photosensitivity. The age of onset ranges between 2 and 14 years with symptoms peaking between 6 and 8 years of age. Though investigation of the clinical, EEG, and neurological features of JS has occurred, neurocognitive functioning has not been well-delineated despite suggestion that a subtype of the syndrome is characterized in part by cognitive impairment. The purpose of this study was to define neurocognitive functioning in a more detailed manner by examining global IQ and relevant neurocognitive domains (i.e., verbal and nonverbal reasoning, attention, executive functioning, memory) in pediatric patients. The sample (N=6, 4 females) ranged in age from 8 to 15 years (M=11, SD=2.82). All participants completed neuropsychological evaluations. Statistical analyses revealed performance that was below average on measures of global IQ, processing speed and rote, verbal learning coupled with average nonverbal reasoning, and sustained attention. There was also evidence of impaired higher-level verbal reasoning. While global IQ ranged from low average to borderline impaired, no participant could be accurately described as impaired or having intellectual disability (ID) given the consistently average performance noted on some higher-order tasks including nonverbal reasoning.

Social cognition dysfunctions in patients with epilepsy: Evidence from patients with temporal lobe and idiopathic generalized epilepsies

BACKGROUND AND AIM

Despite an extensive literature on cognitive impairments in focal and generalized epilepsy, only a few number of studies specifically explored social cognition disorders in epilepsy syndromes. The aim of our study was to investigate social cognition abilities in patients with temporal lobe epilepsy (TLE) and in patients with idiopathic generalized epilepsy (IGE).

MATERIALS AND METHODS

Thirty-nine patients (21 patients with TLE and 18 patients with IGE) and 21 matched healthy controls (HCs) were recruited. All subjects underwent a basic neuropsychological battery plus two experimental tasks evaluating emotion recognition from facial expression (Ekman-60-Faces test, Ek-60F) and mental state attribution (Story-based Empathy Task, SET). In particular, the latter is a newly developed task that assesses the ability to infer others' intentions (i.e., intention attribution - IA) and emotions (i.e., emotion attribution - EA) compared with a control condition of physical causality (i.e., causal inferences - CI).

RESULTS

Compared with HCs, patients with TLE showed significantly lower performances on both social cognition tasks. In particular, all SET subconditions as well as the recognition of negative emotions were significantly impaired in patients with TLE vs. HCs. On the contrary, patients with IGE showed impairments on anger recognition only without any deficit at the SET task.

DISCUSSION

Emotion recognition deficits occur in patients with epilepsy, possibly because of a global disruption of a pathway involving frontal, temporal, and limbic regions. Impairments of mental state attribution specifically characterize the neuropsychological profile of patients with TLE in the context of the in-depth temporal dysfunction typical of such patients.

CONCLUSION

Impairments of socioemotional processing have to be considered as part of the neuropsychological assessment in both TLE and IGE in view of a correct management and for future therapeutic interventions.

Cognitive impairments and neuronal injury in different brain regions of a genetic rat model of absence epilepsy

Growing numbers of evidence indicate that cognitive impairments are part of clinical profile of childhood absence epilepsy. Little is known on neuropathological changes accompanied by cognitive deficits in absence epilepsy. The aim of the present study was to investigate age-dependent neuropathological changes accompanied by learning and memory impairments in Wistar Albino Glaxo from Rijswijk (WAG/Rij) rat model of absence epilepsy. Experimental groups were divided into four groups of six rats of both WAG/Rij and Wistar strains with 2 and 6 months of age. The learning and memory performances were assessed using passive avoidance paradigm and neuropathological alterations were investigated by the evaluation of the number of dark neurons and apoptotic cells as well as the expression of caspase-3 in the neocortex, the hippocampus, and different regions of the thalamus. Results revealed a decline in learning and spatial memory of 6-month-old WAG/Rij rats compared to age-matched Wistar rats as well as 2-month-old WAG/Rij and Wistar rats. The mean number of dark neurons was significantly higher in the hippocampal CA1 and CA3 areas as well as in the laterodorsal, centromedial, and reticular thalamic nuclei and the somatosensory cortex of 6-month-old WAG/Rij rats. In addition, a higher number of apoptotic cells as well as a higher expression of caspase-3 was observed in the hippocampal CA1 and CA3 regions, the laterodorsal thalamic nucleus, and the somatosensory cortex of 6-month-old WAG/Rij rats compared to other animal groups. These results indicate significant enhancement of neuronal damage and cell death accompanied by memory deficits after seizure attacks in a rat model of absence epilepsy. Seizure-induced neuronal injury and death may underlie cognitive impairments in absence epilepsy.

Common pediatric epilepsy syndromes

Benign rolandic epilepsy (BRE), childhood idiopathic occipital epilepsy (CIOE), childhood absence epilepsy (CAE), and juvenile myoclonic epilepsy (JME) are some of the common epilepsy syndromes in the pediatric age group. Among the four, BRE is the most commonly encountered. BRE remits by age 16 years with many children requiring no treatment. Seizures in CAE also remit at the rate of approximately 80%; whereas, JME is considered a lifelong condition even with the use of antiepileptic drugs (AEDs). Neonates and infants may also present with seizures that are self-limited with no associated psychomotor disturbances. Benign familial neonatal convulsions caused by a channelopathy, and inherited in an autosomal dominant manner, have a favorable outcome with spontaneous resolution. Benign idiopathic neonatal seizures, also referred to as "fifth-day fits," are an example of another epilepsy syndrome in infants that carries a good prognosis. BRE, CIOE, benign familial neonatal convulsions, benign idiopathic neonatal seizures, and benign myoclonic epilepsy in infancy are characterized as "benign" idiopathic age-related epilepsies as they have favorable implications, no structural brain abnormality, are sensitive to AEDs, have a high remission rate, and have no associated psychomotor disturbances. However, sometimes selected patients may have associated comorbidities such as cognitive and language delay for which the term "benign" may not be appropriate.

L’absence épileptique de l’enfance dont le controle nécessite plus d’un medicament

Introduction:

Absence epilepsy is the most common primary generalized epilepsy syndrome encountered in pediatric practice. Treatment is pharmacologically specific and usually successful with a single medication. The objective of this study was to identify any clinical or electroencephalographic features at initial presentation in a consecutive cohort of children with absence epilepsy that may be associated with the need for a second medication.

Methods:

A computerized pediatric neurology database (1991-2007 inclusive) was retrospectively searched for all patients with typical absence seizures, 3 Hz spike and wave on EEG and no apparent symptomatic etiology who were over the age of two years at seizure onset with at least one year of follow-up. All such children were then divided into two groups; a) those requiring a single medication for seizure control (Group 1), and b) those requiring two medications for seizure control despite optimal management with the initial medication as determined by serum drug monitoring (Group 2). Clinical and electrographic features evident at diagnosis were then contrasted between Group 1 and 2.

Results:

Seventy-five children with absence seizures were initially identified with 52 meeting the study’s inclusion and none of the exclusion criteria. Of these 52 children, 43 required a single medication for seizure control (Group 1), while 9 required two or more medications for seizure control (Group 2). A significant difference (p<0.05) was apparent between Group 1 and 2 with respect to gender (16/43 males vs 8/9 males) and mean age of diagnosis (8.19 years +/− 3.00 vs 6.06 years +/− 2.22). Age of onset of seizures, interval duration of seizures prior to treatment initiation, duration of seizures, presence of automatisms, family history, presence of co-morbid conditions and EEG findings were not found to be significantly different between the two Groups.

Conclusions:

Male gender and an earlier age of diagnosis is associated with the need for two medications for seizure control in children with absence epilepsy. This observation may suggest the need for more intensive early programmatic follow-up for young male children with newly diagnosed absence epilepsy to effect more rapid attainment of seizure control.

Epidemiologic aspects: lost in transition

Population-based studies focusing on the long-term prognosis of childhood-onset epilepsy show that despite seizure remission in 70-80% of cases, cognitive, behavioral and psychosocial complications are common and will require management and monitoring in adulthood. This type of study design also demonstrates that death is rare in children who are intellectually and neurologically normal and followed for many years, which is the same for the general population. Only those children with neurologic problems sufficiently severe to interfere with activities of daily living have an increased risk of death in childhood. Investigation of potentially remediable complications is paramount, and the use of antiepileptic medications with potential adverse cognitive and behavioral effects should be identified and eliminated or reduced. In addition, education of the family should be improved. As well, identification and control of social and psychiatric complications is necessary and implies a comprehensive management of the patient before and after the transition from childhood into adulthood.

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.

Developmental stage affects cognition in children with recently-diagnosed symptomatic focal epilepsy

This study explored the impact of developmental stage on cognitive function in children with recently-diagnosed epilepsy. In keeping with a neurodevelopmental framework, skills in a critical developmental period were expected to be more vulnerable than those stable at the time of seizure onset. We studied children with early-onset (EO) symptomatic focal epilepsy (onset: 3-5 years; n=18) and compared their performance with that of the group with late-onset (LO) epilepsy (onset: 6-8 years performance of; n=8) on a range of cognitive tasks. Performance of both groups was compared with normative standards. 'Critical' and 'stable' classifications were based on developmental research. Nonparametric analyses revealed that skills in a critical developmental period for the group with EO epilepsy fell below normative standards (Phonological Processing: p=.007, Design Copying: p=.01, Visuomotor Precision:, p=.02) and fell below the performance of the group with LO epilepsy (Design Copying: p=.03, Visuomotor Precision: p=.03). There were no differences between the group with EO epilepsy and the group with LO epilepsy on measures of receptive vocabulary and memory, which were proposed to be in a stable developmental period across both groups. Auditory span, as measured by Word Order, was reduced for both the group with EO epilepsy (p=.02) and the group with LO epilepsy (p=.02) relative to normative standards, but the groups did not differ from each other. These results are consistent with a prolonged period of critical development for this skill. These findings support the notion that skills in a critical phase of development are particularly vulnerable following the onset of symptomatic focal epilepsy in childhood.

Insights into the mechanisms of absence seizure generation provided by EEG with functional MRI

Absence seizures (AS) are brief epileptic events characterized by loss of awareness with subtle motor features. They may be very frequent, and impact on attention, learning, and memory. A number of pathophysiological models have been developed to explain the mechanism of absence seizure generation, which relies heavily on observations from animal studies. Studying the structural and functional relationships between large-scale brain networks in humans is only practical with non-invasive whole brain techniques. EEG with functional MRI (EEG-fMRI) is one such technique that provides an opportunity to explore the interactions between brain structures involved in AS generation. A number of fMRI techniques including event-related analysis, time-course analysis, and functional connectivity (FC) have identified a common network of structures involved in AS. This network comprises the thalamus, midline, and lateral parietal cortex [the default mode network (DMN)], caudate nuclei, and the reticular structures of the pons. The main component displaying an increase in blood oxygen level dependent (BOLD) signal relative to the resting state, in group studies, is the thalamus while the most consistent cortical change is reduced BOLD signal in the DMN. Time-course analysis shows that, rather than some structures being activated or inactivated during AS, there appears to be increase in activity across components of the network preceding or following the electro-clinical onset of the seizure. The earliest change in BOLD signal occurs in the DMN, prior to the onset of epileptiform events. This region also shows altered FC in patients with AS. Hence, it appears that engagement of this network is central to AS. In this review, we will explore the insights of EEG-fMRI studies into the mechanisms of AS and consider how the DMN is likely to be the major large-scale brain network central to both seizure generation and seizure manifestations.

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.

Structural and functional correlates of epileptogenesis - does gender matter?

In the majority of neuropsychiatric conditions, marked gender-based differences have been found in the epidemiology, clinical manifestations, and therapy of disease. One possible reason is that sex differences in cerebral morphology, structural and functional connections, render men and women differentially vulnerable to various disease processes. The present review addresses this issue with respect to the functional and structural correlates to some forms of epilepsy.

Sex differences in human epilepsy

In the majority of neuropsychiatric conditions, marked gender-based differences have been found in the epidemiology, clinical manifestations, and therapy of disease. Emerging data suggest that gender differences exist also in the epidemiology, and pathophysiology of epilepsy. The present review summarizes the current information regarding gender and epilepsy. These differences are regarded from the perspective of innate sex differences in cerebral morphology, structural and functional connections, and assuming that these differences may render men and women differently vulnerable to epileptogenicity.

Cognition, academic achievement, and epilepsy in school-age children: a case-control study in a developing country

We conducted a case-control study of 33 Jamaican children 7 to 12years old with uncomplicated epilepsy and 33 of their classroom peers matched for age and gender to determine whether epilepsy resulted in differences in cognitive ability and school achievement and if socioeconomic status or the environment had a moderating effect on any differences. Intelligence, language, memory, attention, executive function, and mathematics ability were assessed using selected tests from NEPSY, WISCR, TeaCh, WRAT3 - expanded, and Raven's Coloured Progressive Matrices. The child's environment at home was measured using the Middle Childhood HOME inventory. Socioeconomic status was determined from a combination of household, crowding, possessions, and sanitation. We compared the characteristics of the cases and controls and used random effects regression models (using the matched pair as the cluster) to examine the relationship between cognition and epilepsy. We found that there was no significant difference in IQ, but children with epilepsy had lower scores on tests of memory (p<0.05), language (p<0.05), and attention (p<0.01) compared with their controls. In random effects models, epilepsy status had a significant effect on memory (coefficient=-0.14, CI: -0.23, -0.05), language (coefficient=-0.13, CI: -0.23, -0.04), and mathematics ability (coefficient=-0.01, CI: -0.02, -0.00). Adjustment for the home environment and socioeconomic status and inclusion of interaction terms for these variables did not alter these effects. In conclusion, we found that epilepsy status in Jamaican children has a significant effect on performance on tests of memory, language, and mathematics and that this effect is not modified or explained by socioeconomic status or the child's home environment.

Current advances in childhood absence epilepsy

BACKGROUND

Childhood absence epilepsy is an age-dependent, idiopathic, generalized epilepsy with a characteristic seizure appearance. The disorder is likely to be multifactorial, resulting from interactions between genetic and acquired factors, but the debate is still open. We review recent studies on different aspects of childhood absence epilepsy and also to describe new concepts.

METHODS

Data for this review were identified using Medline and PubMed survey to locate studies dealing with childhood absence epilepsy. Searches included articles published between 1924 and 2013.

RESULTS

The diagnosis comprises predominant and associated seizure types associated with other clinical and electroencephalographic characteristics. Many studies have challenged the prevailing concepts, particularly with respect to the pathophysiological mechanisms underlying the electroencephalographic seizure discharges. Childhood absence epilepsy fits the definition of system epilepsy as a condition resulting from the persisting susceptibility of the thalamocortical system as a whole to generate seizures. This syndrome, if properly defined using strict diagnostic criteria, has a good prognosis. In some cases, it may affect multiple cognitive functions determining risk for academic and functional difficulties; the detection of children at risk allows tailored interventions. Childhood absence epilepsy is usually treated with ethosuximide, valproate, lamotrigine, or levetiracetam, but the most efficacious and tolerable initial empirical treatment has not been well defined.

CONCLUSIONS

We review recent studies and new concepts on the electroclinical features and pathophysiological findings of childhood absence epilepsy in order to highlight areas of consensus as well as areas of uncertainty that indicate directions for future research.

Altered thalamic GABAA-receptor subunit expression in the stargazer mouse model of absence epilepsy

PURPOSE

Absence seizures, also known as petit mal seizures, arise from disruptions within the cortico-thalamocortical network. Interconnected circuits within the thalamus consisting of inhibitory neurons of the reticular thalamic nucleus (RTN) and excitatory relay neurons of the ventral posterior (VP) complex, generate normal intrathalamic oscillatory activity. The degree of synchrony in this network determines whether normal (spindle) or pathologic (spike wave) oscillations occur; however, the cellular and molecular mechanisms underlying absence seizures are complex and multifactorial and currently are not fully understood. Recent experimental evidence from rodent models suggests that regional alterations in γ-aminobutyric acid (GABA)ergic inhibition may underlie hypersynchronous oscillations featured in absence seizures. The aim of the current study was to investigate whether region-specific differences in GABAA receptor (GABAAR) subunit expression occur in the VP and RTN thalamic regions in the stargazer mouse model of absence epilepsy where the primary deficit is in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) expression.

METHODS

Immunofluorescence confocal microscopy and semiquantitative Western blot analysis were used to investigate region-specific changes in GABAAR subunits in the thalamus of the stargazer mouse model of absence epilepsy to determine whether changes in GABAergic inhibition could contribute to the mechanisms underlying seizures in this model of absence epilepsy.

KEY FINDINGS

Immunofluorescence confocal microscopy revealed that GABAAR α1 and β2 subunits are predominantly expressed in the VP, whereas α3 and β3 subunits are localized primarily in the RTN. Semiquantitative Western blot analysis of VP and RTN samples from epileptic stargazers and their nonepileptic littermates showed that GABAAR α1 and β2 subunit expression levels in the VP were significantly increased (α1: 33%, β2: 96%) in epileptic stargazers, whereas α3 and β3 subunits in the RTN were unchanged in the epileptic mice compared to nonepileptic control littermates.

SIGNIFICANCE

These findings suggest that region-specific differences in GABAAR subunits in the thalamus of epileptic mice, specifically up-regulation of GABAARs in the thalamic relay neurons of the VP, may contribute to generation of hypersynchronous thalamocortical activity in absence seizures. Understanding region-specific differences in GABAAR subunit expression could help elucidate some of the cellular and molecular mechanisms underlying absence seizures and thereby identify targets by which drugs can modulate the frequency and severity of epileptic seizures. Ultimately, this information could be crucial for the development of more specific and effective therapeutic drugs for treatment of this form of epilepsy.

Spike-and-wave discharge mediated reduction in hippocampal HCN1 channel function associates with learning deficits in a genetic mouse model of epilepsy

The GABAAγ2(R43Q) mouse is an established model of absence epilepsy displaying spontaneous spike-and-wave discharges (SWD) and associated behavioral arrest. Absence epilepsy typically results from cortico-thalamic networks. Nevertheless, there is increasing evidence for changes in hippocampal metabolism and electrical behavior, consistent with a link between absence seizures and hippocampus-related co-morbidities. Hyperpolarization-activated-cyclic-nucleotide-gated (HCN) channels are known to be transcriptionally regulated in a number of seizure models. Here we investigate the expression and function of these channels in the hippocampus of the genetic epilepsy model. A reduction in HCN1, but not HCN2 transcript, was observed in GABAAγ2(R43Q) mice relative to their littermate controls. In contrast, no change in HCN1 transcript was noted at an age prior to seizure expression or in a SWD-free model in which the R43Q mutation has been crossed into a seizure-resistant genetic background. Whole-cell recordings from CA1 pyramidal neurons confirm a reduction in Ih in the GABAAγ2(R43Q) mouse. Further, a left-shift in half-activation of the Ih conductance-voltage relationship is consistent with a reduction in HCN1 with no change in HCN2 channel expression. Behavioral analysis using the Morris water maze indicates that GABAAγ2(R43Q) mice are unable to learn as effectively as their wildtype littermates suggesting a deficit in hippocampal-based learning. SWD-free mice harboring the R43Q mutation had no learning deficit. We conclude that SWDs reduce hippocampal HCN1 expression and function, and that the reduction associates with a spatial learning deficit.

Clinical course and seizure outcome of idiopathic childhood epilepsy: determinants of early and long-term prognosis

BACKGROUND

Idiopathic epilepsies and epileptic syndromes predominate childhood and adolescence epilepsy. The aim of the present study was to investigate the clinical course and outcome of idiopathic childhood epilepsy and identify variables determining both early and long-term prognosis.

METHODS

We followed 303 children with newly diagnosed idiopathic epilepsy aged 1-14 years old, both prospectively and retrospectively. Outcome was defined at one, 2 and 4 years of follow-up, as well as at the end of the study period for all patients. Based on the data collected, patients were classified in four patterns of clinical course: "excellent", "improving", "relapsing" and "poor". Variables defined at intake and after the initial year of treatment were analyzed for their prognostic relevance towards the clinical course and outcome of the patients.

RESULTS

The mean age at seizure onset was 6.7 years and the mean duration of follow-up was 8.3 years (range 2,0-22,0,SD 4,24). During the initial year of treatment, 70,3% of patients were seizure-free. The course of epilepsy was "excellent" in 53,1% of the subjects, "improving" in 22,8%, "relapsing" in 22,1% whereas only 6 children with idiopathic epilepsy (2%) had a "poor" clinical course exhibiting drug-resistance. After multivariate analysis, variables predictive of a poor initial response to therapy were early seizure onset, multiple seizure types and history of status epilepticus. At the end of follow-up, early response to treatment was of significant positive predictive value, while the presence of multiple seizure types and the history of migraine had a negative impact on prognosis.

CONCLUSIONS

In the vast majority of children, the long-term prognosis of idiopathic epilepsy is favorable. More than half of the patients attain seizure freedom immediately and their clinical course is considered "excellent". About one fifth exhibit either an improving or a fluctuating course. Early seizure onset, multiple seizure types and status epilepticus are predictive of an initial poor response to treatment in children with idiopathic epilepsy. Initial non-response to treatment, multiple seizure types and history of migraine are determinants of a less favorable final outcome after long-term follow-up.

Pretreatment cognitive deficits and treatment effects on attention in childhood absence epilepsy

OBJECTIVE

To determine the neurocognitive deficits associated with newly diagnosed untreated childhood absence epilepsy (CAE), develop a model describing the factorial structure of items measuring academic achievement and 3 neuropsychological constructs, and determine short-term differential neuropsychological effects on attention among ethosuximide, valproic acid, and lamotrigine.

METHODS

Subjects with newly diagnosed CAE entering a double-blind, randomized controlled clinical trial had neuropsychological testing including assessments of general intellectual functioning, attention, memory, executive function, and achievement. Attention was reassessed at the week 16-20 visit.

RESULTS

At study entry, 36% of the cohort exhibited attention deficits despite otherwise intact neurocognitive functioning. Structural equation modeling of baseline neuropsychological data revealed a direct sequential effect among attention, memory, executive function, and academic achievement. At the week 16-20 visit, attention deficits persisted even if seizure freedom was attained. More subjects receiving valproic acid (49%) had attention deficits than subjects receiving ethosuximide (32%) or lamotrigine (24%) (p = 0.0006). Parental assessment did not reliably detect attention deficits before or after treatment (p < 0.0001).

CONCLUSIONS

Children with CAE have a high rate of pretreatment attentional deficits that persist despite seizure freedom. Rates are disproportionately higher for valproic acid treatment compared with ethosuximide or lamotrigine. Parents do not recognize these attentional deficits. These deficits present a threat to academic achievement. Vigilant cognitive and behavioral assessment of these children is warranted.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that valproic acid is associated with more significant attentional dysfunction than ethosuximide or lamotrigine in children with newly diagnosed CAE.

The current state of absence epilepsy: can we have your attention?

Absence seizures are common within many different epilepsies and span all the ages. Even though absence seizures were described more than three centuries ago advances associated with its classification, pathophysiology, genetics, treatment, prognosis, and associated co-morbidities continue to be made.

Pretreatment EEG in childhood absence epilepsy: associations with attention and treatment outcome

OBJECTIVE

In children with newly diagnosed childhood absence epilepsy (CAE), determine pretreatment EEG features and their associations with baseline neuropsychological function and short-term treatment outcome.

METHODS

In a multicenter, randomized clinical trial, patients with CAE underwent a pretreatment, 1-hour video-EEG and neuropsychological testing with freedom-from-failure and seizure-freedom (SF) outcome assessed at the 16- to 20-week visit.

RESULTS

Detailed evaluation of the pretreatment EEG was possible for 99.8% of participants (445/446). Median time to first seizure was 6.0 minutes (range 0-59 minutes), median number of seizures was 5 (range 1-60), and median seizure duration was 10.8 seconds (range 3.3-77.6 seconds). Median duration of shortest seizure per EEG was 7.5 seconds (range 3.0-77.6 seconds). Seizure frequency was not associated with baseline measures of attention, executive function, or treatment outcome. Presence of a seizure lasting ≥20 seconds was noted in 29% of subjects (129/440); these children had higher median omissions T score on the Conners Continuous Performance Test (56.3 vs 51.6, p = 0.01). Patients with a shortest seizure of longer duration were more likely to demonstrate treatment success by both freedom-from-failure (p = 0.02) and SF (p = 0.005) criteria, even after controlling for age, treatment group, and number of seizures, with good predictive value (area under the curve 78% for SF).

CONCLUSIONS

CAE is reliably and quickly confirmed by EEG. Occurrence of a seizure ≥20 seconds, but not overall seizure frequency, was associated with differential baseline measures of attention. Patients whose shortest pretreatment EEG seizure was longer in duration were more likely to achieve SF, regardless of treatment.

Attention impairment in childhood absence epilepsy: an impulsivity problem?

Although attention problems have often been described in children with childhood absence epilepsy (CAE), the use of different methodological approaches, neuropsychological tests, and heterogeneous experimental groups has prevented identification of the selective areas of attention deficit in this population. In this study, we investigated several components of attention in children with CAE using a unique computerized test battery for attention performance. Participants included 24 patients with CAE and 24 controls matched for age and sex. They were tested with a computerized test battery, which included the following tasks: selective attention, impulsivity, focused attention, divided attention, alertness, and vigilance. Compared with healthy controls, patients with CAE made more commission errors in the Go/No-Go task and more omission errors in the divided attention task. Childhood absence epilepsy patients also showed decreased reaction times in measures of selective attention and a great variability of reaction times in alertness and Go/No-Go tasks. Our findings suggest that patients with CAE were impaired in tonic and phasic alertness, divided attention, selective attention, and impulsivity.

Ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy: initial monotherapy outcomes at 12 months

PURPOSE

Determine the optimal initial monotherapy for children with newly diagnosed childhood absence epilepsy (CAE) based on 12 months of double-blind therapy.

METHODS

A double-blind, randomized controlled clinical trial compared the efficacy, tolerability, and neuropsychological effects of ethosuximide, valproic acid, and lamotrigine in children with newly diagnosed CAE. Study medications were titrated to clinical response, and subjects remained in the trial unless they reached a treatment failure criterion. Maximal target doses were ethosuximide 60 mg/kg/day or 2,000 mg/day, valproic acid 60 mg/kg/day or 3,000 mg/day, and lamotrigine 12 mg/kg/day or 600 mg/day. Original primary outcome was at 16-20 weeks and included a video-electroencephalography (EEG) assessment. For this report, the main effectiveness outcome was the freedom from failure rate 12 months after randomization and included a video-EEG assessment; differential drug effects were determined by pairwise comparisons. The main cognitive outcome was the percentage of subjects experiencing attentional dysfunction at the month 12 visit.

KEY FINDINGS

A total of 453 children were enrolled and randomized; 7 were deemed ineligible and 446 subjects comprised the overall efficacy cohort. There were no demographic differences between the three cohorts. By 12 months after starting therapy, only 37% of all enrolled subjects were free from treatment failure on their first medication. At the month 12 visit, the freedom-from-failure rates for ethosuximide and valproic acid were similar (45% and 44%, respectively; odds ratio [OR]with valproic acid vs. ethosuximide 0.94; 95% confidence interval [CI] 0.58-1.52; p = 0.82) and were higher than the rate for lamotrigine (21%; OR with ethosuximide vs. lamotrigine 3.08; 95% CI 1.81-5.33; OR with valproic acid vs. lamotrigine 2.88; 95% CI 1.68-5.02; p < 0.001 for both comparisons). The frequency of treatment failures due to lack of seizure control (p < 0.001) and intolerable adverse events (p < 0.037) was significantly different among the treatment groups. Almost two thirds of the 125 subjects with treatment failure due to lack of seizure control were in the lamotrigine cohort. The largest subgroup (42%) of the 115 subjects discontinuing due to adverse events was in the valproic acid group. The previously reported higher rate of attentional dysfunction seen at 16-20 weeks in the valproic acid group compared with the ethosuximide or lamotrigine groups persisted at 12 months (p < 0.01).

SIGNIFICANCE

As initial monotherapy, the superior effectiveness of ethosuximide and valproic acid compared to lamotrigine in controlling seizures without intolerable adverse events noted at 16-20 weeks persisted at 12 months. The valproic acid cohort experienced a higher rate of adverse events leading to drug discontinuation as well as significant negative effects on attentional measures that were not seen in the ethosuximide cohort. These 12-month outcome data coupled with the study's prespecified decision-making algorithm indicate that ethosuximide is the optimal initial empirical monotherapy for CAE. This is the first randomized controlled trial meeting International League Against Epilepsy (ILAE) criteria for class I evidence for CAE (or for any type of generalized seizure in adults or children). (NCT00088452.).

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.

Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy

Recent clinical studies revealed emotional and cognitive impairments associated with absence epilepsy. Preclinical research with genetic models of absence epilepsy however have primarily focused on dysfunctional emotional processes and paid relatively less attention to cognitive impairment. In order to bridge this gap, we investigated age-dependent changes in learning and memory performance, anxiety-like behavior, and locomotor activity of WAG/Rij rats (a valid model of generalized absence epilepsy) using passive avoidance, Morris water maze, elevated plus maze, and locomotor activity cage. We tested 5 month-old and 13 month-old WAG/Rij rats and compared their performance to age-matched Wistar rats. Results revealed a decline in emotional and spatial memory of WAG/Rij rats compared to age-matched Wistar rats only at 13 months of age. Importantly, there were no significant differences between WAG/Rij and Wistar rats in terms of anxiety-like behavior and locomotor activity at either age. Results pointed at age-dependent learning and memory deficits in the WAG/Rij rat model of absence epilepsy.

Cognitive function of idiopathic childhood epilepsy

Most children with epilepsy are of normal intelligence. However, a significant subset will have temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the underlying neuropathology of the epilepsy, seizures, epileptiform discharges, psychosocial problems, age at seizure onset, duration of epilepsy, and side effects associated with antiepileptic drugs. This review article discusses cognitive function in children with idiopathic epilepsy and the effects of antiepileptic drugs on cognitive function in children.

A mechanistic appraisal of cognitive dysfunction in epilepsy

A strong relationship between the clinical characteristics of epilepsy and the nature of cognitive impairments associated with the condition has been found, but the nature of this relationship appears to be quite complex and not well understood. This review presents a summary of the research on the interaction between cognition and epilepsy, surveyed from a mechanistic perspective with the aim of clarifying factors that contribute to the co-existence of both disorders. The physiological basis underpinning cognitive processing is first reviewed. The physiology of epilepsy is reviewed, with emphasis placed on interictal discharges and seizures. The nature of the impact of epilepsy on cognition is described, with transient and prolonged effects distinguished. Finally, the complexity of the co-morbidity between cognitive dysfunction and epilepsy is discussed in relation to childhood and adult-onset epilepsy syndromes and severe epileptic encephalopathies. Structural and functional abnormalities exist in patients with epilepsy that may underpin both the cognitive dysfunction and epilepsy, highlighting the complexity of the association. Research, possibly of a longitudinal nature, is needed to elucidate this multifactorial relationship between cognitive dysfunction and epilepsy.

The cognitive effects of interictal epileptiform EEG discharges and short nonconvulsive epileptic seizures

PURPOSE

Educational difficulties or even severe cognitive deterioration is seen in many childhood epilepsy syndromes. Many of those cognitive deficits are related directly to the brain disorder underlying the epilepsy syndrome. However, in other types of epilepsy, the epileptic seizures and/or epileptiform activity can be the dominant factor. This is especially unknown for the more "subtle" short nonconvulsive seizure types. For this reason, we analyzed a new cohort of children.

METHODS

A cross-sectional study of 188 children with epilepsy. Electroencephalography (EEG)-video recordings and cognitive testing were performed simultaneously. The results of children with short nonconvulsive seizures during a 2-h testing session were compared with all children with epilepsy without seizures during the 2-h cognitive testing session and with controls without epilepsy. In a second analysis the cognitive effects of frequency of epileptiform EEG discharges were analyzed.

KEY FINDINGS

The cognitive effects of short nonconvulsive seizures were large, ranging from 0.5 to 1 standard deviation and concerned global cognitive function, speed of central information processing, and memory function. In children without seizures during cognitive testing, the occurrence of frequent epileptiform discharges showed more subtle effects. These effects were independent from the occurrence of short nonconvulsive seizures.

SIGNIFICANCE

We concluded that although the effect is less pronounced in number of areas involved and magnitude, the type of association between frequent epileptiform activity (>1% of the time) and cognitive function in children with epilepsy is comparable to the association between short nonconvulsive seizures and cognitive function.

Verbal Memory and IQ in Children who Undergo Focal Resection for Intractable Epilepsy:A Clinical Review

Previous studies have indicated an increased likelihood of intellectual and memory impairments in children with epilepsy. It has been argued that early surgical intervention in children with intractable seizures might be advantageous to their development. We conducted a retrospective review of pre- and postoperative IQ and verbal memory scores in 16 paediatric patients who underwent temporal (N = 10) or extra-temporal (N = 6) focal surgery for epilepsy. Patients with an extratemporal seizure focus performed significantly worse than patients with a temporal lobe seizure focus on Full Scale IQ and Verbal IQ before surgery. Postoperatively a statistically significant decline in verbal memory, but not in any of the IQ indices was noticed in the extratemporal group. Individual outcome analyses revealed a significant decline in verbal memory in 22% of temporal lobectomy and 60% of extratemporal cases. Our review suggests that verbal memory but not IQ is vulnerable to postoperative decline in children who undergo focal extratemporal surgery for intractable epilepsy. The findings raise the possibility that extratemporal regions play a role in anterograde memory in children. Given the small number of subjects in this study, further investigations into the cognitive effects of paediatric surgical intervention are recommended.

Effects of childhood absence epilepsy on associations between regional cortical morphometry and aging and cognitive abilities

In this study, we used surface-based morphometry to examine whether age-related changes in gray matter tissue thickness and depth of sulcal regions at high spatial resolution across the cortex differed in children with childhood absence epilepsy (CAE) compared to healthy control subjects. In addition, the possibility of variable brain-cognition relationships in the CAE compared to the control group was investigated. The main findings of this study are as follows: (1) From the developmental perspective, children with CAE did not demonstrate the normal regional age-related changes involving a decrease in cortical thickness and increase in sulcal depth. (2) None of the seizure variables, including age of onset, seizure frequency, and AEDs had a significant effect on the association between age and cortical morphometry measures in the CAE population. (3) Even though the CAE group had mean VIQ and PIQ scores in the average range, our findings suggest that they use different brain regions to perform these cognitive functions compared to healthy controls. This first study on brain morphometry and cognition in children with childhood absence seizures has important implications for advancing our understanding of brain development and cognitive comorbidity in CAE, as well as for revisiting the clinical notion that CAE is a benign disorder.

Characteristics of successful recruitment in prospective pediatric pharmacogenetic studies

BACKGROUND

There is a need to explore feasible means of accruing an appropriate study cohort to help fill the knowledge gap between pharmacogenetic contributions to drug response and clinical application in the pediatric population.

OBJECTIVES

The aim of this study was to identify factors affecting recruitment of eligible subjects in pharmacogenetic studies at a large Midwestern pediatric academic medical center. The objectives were to evaluate recruitment success of ongoing trials and ascertain contributors to differential recruitment rates. We hypothesized that studies with good recruitment of eligible subjects would share characteristics not present in studies with lower than anticipated recruitment. The goal was to better understand barriers to good recruitment in pharmacogenetic studies to help inform future trial and infrastructure design.

METHODS

Investigators designed a survey with proposed elements of success, which was then completed by lead and/or site investigators of all pharmacogenetics studies at the institution. Results were evaluated using an investigator-developed likelihood of success scoring system.

RESULTS

Two studies recruited >95% of the approached eligible patients; 4 studies were consistent with investigator-anticipated recruitment (>50%), and 1 study did not meet expected recruitment. A study's total score on the investigator-devised scoring tool correlated well with the proportion of approached patients recruited (Pearson's correlation, r = 0.82; P < 0.001). Multiple factors impacted successful recruitment into these pharmacogenetic studies. Features of studies with successful recruitment included standardized clinical care, an ongoing team-patient relationship, severe and/or life-threatening outcome measures, study coordinator with experience in clinical research, a study medication with few or no alternative treatment options, and active involvement of the research team in clinical care.

CONCLUSIONS

A scoring system for study characteristics may be useful to calculate the risk of failure for successful recruitment, allow discrimination among characteristics contributing to the risk, and permit study design alterations to improve likelihood of successful recruitment in pediatric pharmacogenetic studies.

Cognitive functioning and behaviour of epileptic children in parents' assessment

BACKGROUND AND PURPOSE

Cognitive functioning and behaviour of chronically ill children are affected by many factors, including anxiety due to hospitalization, persistent symptoms of sickness and adverse side effects of medications. The aim of this work was to seek out parents' opinion concerning cognitive functioning and behaviour of children with epilepsy.

MATERIAL AND METHODS

The study comprised 156 children with epilepsy aged 7-18 and treated in the Department of Developmental Neurology at Karol Marcinkowski Poznan University of Medical Sciences and in an outpatient clinic. The research tool used was the questionnaire Quality of Life in Childhood Epilepsy (QOLCE) completed by parents. Assessment of cognitive functioning and behaviour was based on the analysis of the areas V (cognitive processes) and VII (behaviour).

RESULTS

Parents assessed children's functioning in the areas of cognitive processes and behaviour at a similar level - 55 points. In the area of cognitive processes, concentration while performing some tasks and reading was assessed as the worst. A significant difference in caregivers' assessment was found according to age, frequency of seizures and duration of disease. In the area analysing the child's behaviour, parents indicated getting angry easily and not being upset by other people's opinions. The display of aggression towards others got the lowest number of comments.

CONCLUSIONS

The children's functioning was assessed by parents as rather poor in both analysed areas. Parents of children treated with polytherapy noticed more difficulties in cognitive functioning and behaviour than parents of children treated with one medication.

Cognitive and neurodevelopmental effects of antiepileptic drugs

This article primarily represents the contributions of two young investigators to the understanding of the neuropsychological consequences of epilepsy and its treatment. The authors have reviewed two key areas of importance: the complex relationship between cognitive dysfunction and epilepsy and the risks of cognitive dysfunction in children as a consequence of in utero exposure to antiepileptic drug treatment. The work of two young investigators is presented and future research needs are outlined.

Altered functional connectivity in default mode network in absence epilepsy: a resting-state fMRI study

Dysfunctional default mode network (DMN) has been observed in various mental disorders, including epilepsy (see review Broyd et al. [2009]: Neurosci Biobehav Rev 33:279–296). Because interictal epileptic discharges may affect DMN, resting-state fMRI was used in this study to determine DMN functional connectivity in 14 healthy controls and 12 absence epilepsy patients. To avoid interictal epileptic discharge effects, testing was performed within interictal durations when there were no interictal epileptic discharges. Cross-correlation functional connectivity analysis with seed at posterior cingulate cortex, as well as region-wise calculation in DMN, revealed decreased integration within DMN in the absence epilepsy patients. Region-wise functional connectivity among the frontal, parietal, and temporal lobe was significantly decreased in the patient group. Moreover, functional connectivity between the frontal and parietal lobe revealed a significant negative correlation with epilepsy duration. These findings indicated DMN abnormalities in patients with absence epilepsy, even during resting interictal durations without interictal epileptic discharges. Abnormal functional connectivity in absence epilepsy may reflect abnormal anatomo-functional architectural integration in DMN, as a result of cognitive mental impairment and unconsciousness during absence seizure.

Early-onset pure absence epilepsy: a distinct epileptic syndrome

Early-onset pure absence epilepsy has not yet considered in the International League Against Epilepsy classification, but several reports have supported its existence as a distinct epileptic syndrome primarily manifesting with typical absences in early childhood. This review summarizes the current understanding on this epilepsy.

CONCLUSIONS

  Early-onset pure absence epilepsy is a distinct epilepsy characterized by absences starting from a few months to 4 years of age, normal early psychomotor development, good antiepileptic drug seizure control and normal intellectual outcome.

Dysfunction of executive and related processes in childhood absence epilepsy

The nature and extent of the neuropsychological difficulties associated with childhood absence epilepsy (CAE) remain unclear. Because aberrant thalamocortical rhythms have been implicated in the pathogenesis of CAE, it was hypothesized that children with CAE would show greater difficulties in neuropsychological domains that are thought to be subserved by basal ganglia-thalamocortical circuits. Multivariate analysis of variance was used to compare the neuropsychological functioning of 16 children with CAE with that of 14 children with type 1 diabetes mellitus and 15 healthy children. The CAE group did not perform differently from the other groups on measures of intellectual functioning, memory, academic achievement, fine motor speed, or processing speed. In contrast, significant differences were found in problem solving, letter fluency, complex motor control, attention/behavioral inhibition, and psychosocial functioning. These results suggest that children with CAE show difficulties in neuropsychological functions thought to be subserved by the same regions implicated in the pathogenesis of the disorder.