Association between frequency of nocturnal epilepsy and language disturbance in children

In clinical practice, an association is commonly suggested between nocturnal epileptiform activity and language disorders in children. However, this association has not been studied systematically. This study explored the correlation between daily and nocturnal epileptiform discharges ratio, frequency of nocturnal epileptiform discharges, and severity of nocturnal seizures in correlation with the severity of language impairment. A total of 326 children referred to an epilepsy center were included. All children had a 24-hour electroencephalogram (EEG), a neuropsychologic assessment, and a reconfirmed diagnosis of epilepsy. The balance between verbal and performance IQ scores of the Wechsler Intelligence Scale for Children was a focus of the study. A significant correlation between the severity of nocturnal seizures and lower verbal IQ scores compared to performance IQ scores was found (P < 0.05). There was a clinically relevant difference between performance IQ and verbal IQ between the groups of children with only nocturnal epileptiform EEG discharges and only epileptiform EEG discharges during wake (P = 0.033). Children with nocturnal epileptiform EEG discharges have lower verbal than performance IQs when compared to children with only epileptiform EEG discharges during wake. Although a causal relationship is unclear, this indicates an association between the occurrence of nocturnal epileptiform EEG discharges and language disturbance.     

Psychological effects of subclinical epileptiform EEG discharges in children. II. General intelligence tests

Twenty-one children with suspected or proven epilepsy and subclinical epileptiform EEG discharges in the waking state were studied. The EEG was telemetered and behaviour recorded by closed-circuit television during performance of a general intelligence test (RAKIT, shortened version) which comprised 6 subtests. Mean total IQ was below that of control populations and the subtests profile was abnormal, due particularly to impaired performance on a subtest concerned with verbal short-term memory. This effect was accounted for by that subgroup of children who exhibited discharges during the test; those who did not show discharges at that time were unimpaired. Performance of 3 of the subtests was impaired when discharges occurred during presentation of the test item or between presentation and response. The findings suggest that cognitive impairment found in people with epilepsy may not only represent a more or less static disability, due to drugs, cerebral pathology, etc., but may in part be an intermittent process related to the occurrence of subclinical epileptiform discharges. These preliminary findings need to be amplified but have implications both for interpretation of neuropsychological studies in persons with epilepsy and also for the drug treatment of those who continue to exhibit subclinical EEG discharges when overt seizures have been controlled.     

Learning Disabilities in Epilepsy: Neurophysiological Aspects

Summary: Subclinical generalized spike-wave discharges are often accompanied by transitory cognitive impairment, demonstrable by psychological testing during EEG recording. Transitory cognitive impairment is demonstrated most readily by difficult tasks and during generalized regular spike-wave bursts lasting for more than 3 s, but can also be found during briefer and even focal discharges. That this is not simply a consequence of global inattention is shown by the fact that focal discharges exhibit some specificity: left-sided focal spiking is more likely to produce errors on verbal tasks, for instance, whereas right-sided discharges are more often accompanied by impairment in handling nonverbal material. Both learning difficulties in general and specific abnormal patterns of cognitive functioning are well documented in children with epilepsy and are most pronounced in those with frequent interictal discharges. However, there is now evidence that intermittent cognitive impairment due to the discharges themselves contributes significantly to such neurophysiological abnormalities. The significance of transitory cognitive impairment accompanying subclinical EEG discharges for everyday functioning is uncertain, but there is experimental evidence that subclinical discharges may be accompanied by disruption of educational skills in children or by impairment of driving performance in motorists. In some individuals, suppression of discharges by antiepileptic drugs has demonstrably improved psychological function, but further work is required to determine the indications for such treatment     

Cognitive and electrophysiological characteristics of children with specific language impairment and subclinical epileptiform electroencephalogram

The current study is a preliminary examination of cognitive profiles and cortical distribution of the spectral power of different electroencephalogram (EEG) rhythms in children with specific language impairment and subclinical epileptiform discharges. Although a number of empirical studies point to higher incidence of abnormal EEGs in children with specific language impairment, only a few studies were found examining electrophysiological characteristics, such as locus of discharges and connections with cognitive functioning in this population of children. The sample included 12 children with specific language impairment (SLI) and abnormal EEG who underwent testing of cognitive functioning using the Wechsler Intelligence Scale for Children (WISC). The control sample included 13 children with specific language impairment and regular EEG. Results point to lower scores on several subtests of the performance scale for children with abnormal EEG than for the group with regular EEG. Detailed EEG analysis of cortical distribution of the spectral power of different EEG rhythms partially confirms the results of neuropsychological assessment, pointing to abnormal function of frontal and temporal regions. Higher values of spectral power of the delta brain rhythm in frontal regions are associated with lower results on the WISC performance scale. Results are discussed in the context of subgroups of the population of children with SLI.     

Cognitive impairment during epileptiform discharges: is it ever justifiable to treat the EEG?

Epileptiform EEG discharges are not confined to people with epilepsy, and their frequency is only weakly related to severity. A fundamental principle of EEG practice is, therefore, to avoid overinterpretation of epileptiform activity. Epileptiform discharges not accompanied by obvious clinical events are generally regarded as subclinical or interictal. However, in many patients sensitive methods of observation, notably continuous psychological testing, show brief episodes of impaired cognitive function during such discharges. This phenomenon of transitory cognitive impairment (TCI) is found in about 50% of patients who show discharges during testing. TCI is not simple inattention. The effects are material and site specific: lateralised discharges are associated with deficits of functions mediated by the hemisphere in which the discharges occur. Conversely, specific tasks can activate or suppress focal discharges over the brain regions that mediate the cognitive activity in question. TCI clearly contributes to the cognitive problems of some people with epilepsy and may cause deficits that pass unrecognised. TCI is demonstrable in many cases of benign partial epilepsy of childhood, a disorder once thought to have no adverse psychological effects. TCI can contribute to abnormalities of psychological test profiles and interferes with daily tasks, such as reading and driving. In children it may be associated with behavioural disorders. An important practical issue is whether TCI materially impairs psychosocial function and, if so, whether drug treatment is desirable or effective. Uncontrolled reports and two preliminary randomised controlled trials of antiepileptic treatment of TCI have suggested that suppression of discharges is associated with significant improvement in psychosocial function.     

Psychological effects of subclinical epileptiform EEG discharges. I. Scholastic skills

The possible effects of subclinical epileptiform EEG discharges on educational skills have been studied. Twenty children with proven or suspected epilepsy and known subclinical EEG discharges underwent telemetric EEG and video monitoring during standard tasks of reading, mental arithmetic and manual dexterity, and at rest. The discharge rate was significantly lower at rest than during execution of a task. For both reading and arithmetic, the discharge rate was higher when the child was presented with material appropriate to his own level of ability than when easier or more difficult material was given. High discharge rates were associated with low test performance particularly for arithmetic. Reading speed was significantly increased during the discharges, but overall reading efficiency was significantly reduced with respect to the non-discharge condition. The decrement of reading efficiency was greater for longer than for shorter discharges. The findings confirm that otherwise subclinical EEG discharges may be accompanied by momentary impairment of scholastic skills. The interaction between discharges and cognitive function is, however, complex and the nature and level of difficulty of the task in turn affects the rate of EEG discharge.     

Acute effects of subclinical epileptiform EEG discharges on cognitive activation

In this prospective, open, clinical comparative study we analyzed impairments of cognitive activation occurring during, immediately before and immediately after epochs with epileptiform EEG discharges of 3 seconds or longer, in an attempt to establish whether cognitive slowing occurs in direct association with an epoch with epileptiform EEG discharges and whether cognitive impairments precede or follow such an epoch. All children were assessed with EEG/video (Brainlab) simultaneously with computerized neuropsychological testing (FePsy): a test for cognitive activation (simple visual and auditory reaction time measurement). Thirty-seven epochs with epileptiform EEG discharges without clinical signs of a seizure (subclinical epileptiform EEG discharges) were evaluated. The results showed a statistically significant and clinically relevant slowing (35% compared to the overall reaction time), occurring during the epoch with epileptiform EEG discharges (repeated measurement analysis of variance p = < .05; df = 3; F-value: 3.293). No statistically significant slowing was found for the periods 'post-discharge' or 'pre-discharge'. Type of discharge was important and effects on cognitive activation were found exclusively for generalized discharges. This effect was, however, also seen in the remaining period, outside the 'peri-discharge' periods and thus seemed to represent a more general effect of the type of epilepsy on cognitive activation. Our results show that the acute effect of short epileptiform EEG discharges (duration 4.14 sec; sd 1.38) may be impressive, causing impairment (slowing) of cognitive activation. This effect was limited to generalized discharges. This effect was not observed for focal discharges, even during longer periods with discharges. However, it is reassuring that this impact on cognitive activation is limited to the actual period in which the discharges occur and does not have 'post-discharge' effects. The risk of accumulating effects that may have longer-lasting repercussions on higher-order cognitive functions therefore seems to be negligible.     

Predictors of Cognitive Functions in Children With Sturge–Weber Syndrome: A Longitudinal Study

BackgroundSturge–Weber syndrome is often accompanied by seizures and neurocognitive deterioration, although previous studies have suggested that early functional brain reorganization may diminish the cognitive sequelae in some children with unilateral Sturge–Weber syndrome. The “rules” governing these plasticity mechanisms are poorly understood. In this study, we evaluated longitudinal changes of cognitive functioning (intelligence quotient [IQ]) and assessed the performance of clinical, electroencephalography (EEG), and magnetic resonance imaging (MRI) variables for predicting IQ in children with Sturge–Weber syndrome.MethodsThirty-three young children (mean age: 3.3 years at baseline) with unilateral Sturge–Weber syndrome underwent MRI, scalp EEG, and neuropsychology evaluation twice, with a median follow-up of 2 years. None of the children had epilepsy surgery. Longitudinal IQ changes were calculated. Seizure variables, interictal EEG abnormalities, and extent and location of MRI brain involvement were correlated with IQ assessed at follow-up.ResultsGlobal IQ showed a highly variable course with both increases and decreases over time. Lower IQ at baseline was associated with interval IQ increase. In univariate analyses, lower outcome IQ was associated with baseline EEG abnormalities (P < 0.001), young age at seizure onset (P = 0.001), high seizure frequency (P = 0.02), and early frontal-lobe involvement on MRI (P = 0.01). In multivariate analysis, EEG abnormalities at baseline remained a robust, independent predictor of outcome IQ.ConclusionsThe early trajectory of cognitive changes in children with unilateral Sturge–Weber syndrome is highly variable; children with improving IQ likely undergo effective unimpeded functional reorganization. Early onset, frequent seizures, and interictal epileptiform abnormalities on EEG likely interfere with this process resulting in poor cognitive functions. Future studies assessing interventions should target this high-risk subgroup to optimize cognitive outcome in Sturge–Weber syndrome.     

Ictal and interictal EEG abnormalities in ADHD children recorded over night by video-polysomnography

In this paper we explore the prevalence of ictal and interictal epileptiform discharges (IEDs) and sleep disorders in ADHD children referred to a sleep clinic for all night video-PSG. Forty-two ADHD outpatients (35 males and 7 females) underwent video-PSG and a behavioural/neuropsychological assessment. Spearman correlation coefficients (p<0.05 criterion level) were used to assess the association between cognitive, behavioural, clinical (co-morbidity), sleep (sleep efficiency) and EEG (seizures, IEDs, localization of IEDs foci) variables. Sleep disorders were found in 86% of ADHD children; among these, 26% had RLS. 53.1% of ADHD children had IEDs (28.2% centro-temporal spikes, 12.5% frontal spikes, 9.3% temporal-occipital spikes and 2.3% generalized S-W). Nocturnal seizures were recorded in three patients: two with atypical interictal rolandic spikes and one with left frontal slow abnormalities. A significant relationship (p<0.05) emerges between nocturnal seizures and WISC-R IQ score and visual-spatial memory test and between some cognitive variables and interictal rolandic spikes. High levels of inattention, impulsivity/hyperactivity and oppositional behaviours were related (p<0.01 or 0.05) with Restless Leg Syndrome diagnosis. In conclusion, ADHD is a condition often associated with EEG epileptiform abnormalities. Seizures/IEDs presence seems to play a role on cognitive abilities, conversely sleep disorders have a stronger impact on behavioural rather than cognitive indicators.     

Subclinical temporal EEG seizure pattern in LGI1‐antibody–mediated encephalitis

Leucine‐rich glioma inactived‐1 (LGI1) antibodies are associated with limbic encephalitis and distinctive seizure types, which are typically immunotherapy‐responsive. Although nonspecific electroencephalography (EEG) abnormalities are commonly seen, specific EEG characteristics are not currently understood to be useful for suspecting the clinical diagnosis. Based on initial observations in two patients, we analyzed the clinical features and EEG recordings in a larger series of patients (n = 9) and describe a novel ictal pattern that can suggest the diagnosis of LGI1‐antibody–mediated encephalitis, even in the absence of typical clinical features. As expected, psychiatric and cognitive symptoms were common, as were tonic seizures associated with EEG electrodecremental events (often with the so‐called faciobrachial dystonic semiology). Remarkably, in five patients, a near absence of interictal epileptiform discharges contrasted with frequent subclinical temporal lobe seizures, at times triggered by hyperventilation. This latter EEG pattern may facilitate early diagnosis of this serious but potentially treatable condition.     

Neuropsychological Assessment of Cognitive Functioning in Children with Epilepsy

Summary: The variety of cognitive dysfunctions related to learning disabilities in children with epilepsy have been studied by linking electroencephalogram (EEG) and computerized neuropsychological testing. This showed that "subclinical" discharges impaired performance in 61% of the patients on a simple and a choice reaction time test, although some discharges lasted 1 s only. Neuropsychological investigation of subclinical EEG discharges may help to determine their adverse effect on learning.     

Acquired epileptic frontal syndrome as long-term outcome in two children with CSWS

Continuous spikes and waves during slow sleep (CSWS) are a well-known EEG pattern that can be associated with cognitive and behavioural deterioration. We present the long-term clinical, neuropsychological and EEG follow-up of two patients who developed CSWS during childhood. In both the CSWS onset was followed immediately by rapid cognitive and behavioural deterioration. Later the CSWS fragmented or fluctuated and the spike-wave discharges diminished and this was associated with progressive clinical improvement. At the same time bilateral frontal EEG abnormalities appeared awake and in sleep. After the initial period of rapid cognitive and linguistic improvement both patients stabilised. The latest neuropsychological assessment showed a frontal syndrome. The presence of frontal EEG abnormalities superimposed on CSWS, their persistence after CSWS resolution and, in addition, the finding of subtle frontal-type neuropsychological alterations early in recovery may indicate poor long-term outcome.     

Interactions of epileptiform EEG discharges and cognition

Interactions of subclinical epileptiform EEG discharges and cognitive functioning were studied in 91 patients with epilepsy, under video monitoring, to exclude overt clinical ictal phenomena during the investigations. A short-term memory test was presented as an engaging television game, in two versions, using spatial, or verbal material. Transitory cognitive impairment (TCI) was demonstrated during EEG discharges, either generalised or focal, in half the patients. Right-sided discharges were associated with impairment of the spatial task and left-sided with errors on the verbal version. TCI was demonstrable only when the discharge occurred during presentation of the material to be recalled. Increasing task difficulty, up to the patients' limit of performance, was associated with increasing susceptibility to TCI. Sixteen patients showed a significant effect of task on discharge rate, but in some this increased during the stimulus and in others while responding. There are thus complex interactions of epileptiform EEG activity on cognitive function and vice versa.     

Neuropsychological correlates of subclinical paroxysmal EEG activity in children with epilepsy. 2: Quantitative aspects

Altered cognitive functioning has often been reported in patients with epilepsy. In our study we looked for quantitative correlation between the recurrence of Subclinical Spike-and-Wave Discharges (SSWD) during EEG recording, the scores on the intelligence test (WISC) and the electro-clinical characteristics of 29 epileptic children with subclinical discharges of generalized spike-and-wave complexes. In our sample we found a below-normal mean IQ, with greater impairment on performance than on verbal tasks. No clear quantitative correlation was found between the weighted scores on the various subtests and the "time density" of the spike-and-wave complexes. These findings suggest that the SSWD interfere with cognitive development (mainly with visuo-spatial and sensorimotor coordination abilities) and selectively impair some of the functions involved in the cognitive processes.     

The association between cognition and functional outcome in first‐episode patients with schizophrenia: mystery resolved?

OBJECTIVE: The presence of a prospective association between cognition and functional outcome in first episode patients with schizophrenia is much debated. METHOD: Associations between Intelligence Quotient (IQ) measures and functional outcome were assessed at the first hospitalization and after 10 years follow-up. RESULTS: Functional outcome was associated with estimated premorbid IQ and IQ at 10-year follow-up, but not with IQ assessed at first hospitalization. CONCLUSION: The presence of a prospective as well as a cross-sectional relationship of the global cognitive measure IQ with 10-year functional outcome could be established. However, assessing associations between cognitive measures assessed at first hospitalization and subsequent functional outcome, can give inconclusive results due to non-uniform intellectual deterioration from premorbid level in the period preceding the first hospitalization.     

The electroencephalogram of idiopathic generalized epilepsy

Idiopathic generalized epilepsy (IGE) is classified into several subsyndromes based on clinical and electroencephalography (EEG) features. The EEG signature of IGE is bisynchronous, symmetric, and generalized spike-wave complex; although focal, irregular, and so called "fragments" of discharges are not uncommon. Other characteristic EEG features include polyspikes, polyspike-wave discharges, occipital intermittent rhythmic delta activity, and photoparoxysmal response. Both human and animal data suggest involvement of the thalamus and the cortex in the generation of spike-wave discharges in IGE. Circadian variations of generalized epileptiform discharges are well described, and these can be useful in diagnostic confirmation. Those discharges tend to occur more often after awakening and during cyclic alternating pattern phase-A of non-rapid eye movement sleep. Activation procedures such as hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are useful techniques to increase the yield of both interictal and ictal EEG abnormalities. Although not in routine use, specific triggers such as pattern stimulation and cognitive tasks may also be of value in eliciting rare reflex seizure-related EEG abnormalities. Variations of EEG abnormalities are evident between different electroclinical syndromes. EEG is also affected by certain external as well as internal factors, which should be borne in mind when interpreting EEG studies in IGE.     

Interictal paroxysmal epileptic discharges during sleep in childhood: phenotypic variability in a family

We report three children of the same parents who exhibited various types of cognitive disorders, ranging from severe mental deficiency with transient autistic-like regression to specific neuropsychological disabilities, associated with paroxysmal EEG abnormalities with various patterns of severity. This familial association highly suggests a genetic factor responsible for both epileptic discharges on EEG and cognitive dysfunction.     

Behavioral correlates of epileptiform abnormalities in autism

There is a high incidence of epileptiform abnormalities in children with autism even in the absence of clinical seizures. These findings are most prominent during sleep recordings. The significance of these abnormalities is unclear. Although studies do not all agree, there may be some association between cognitive function, behavior, and the presence or absence of epileptiform discharges. Small studies of anticonvulsant treatment mostly suggest an improvement in certain aspects of cognitive or behavioral functioning in these children, but larger and more comprehensive studies are needed to determine the potential relationship between epileptiform discharges on EEG, cognitive and behavioral functioning, and treatment effects in the population with autism.This article is part of a Special Issue entitled “Autism and Epilepsy”.     

Reflex epilepsy evoked by specific psychic activity. A case report

A patient with epileptic seizures and epileptiform EEG abnormalities precipitated by specific type of intellectual activity is presented. Clinical and subclinical epileptic seizures were accompanied by specific EEG discharges--the left parieto-occipito-temporal spike-and-wave complexes with various grade of generalization. On the basis of detailed EEG and activation studies, it is concluded that seizures in this patient were evoked by higher cognitive processes associated with decision making, anticipation and spatial function.     

The impact of subclinical epileptiform discharges on complex tasks and cognition: relevance for aircrew and air traffic controllers

Subtle seizures consisting of brief alteration of consciousness with or without automatisms may go unnoticed in daily life, but can be detected more easily with electroencephalographic (EEG)/video recordings. Generalized and partial epileptiform EEG discharges can nevertheless be subclinical (subclinical epileptiform discharges, SEDs). When appropriate complex tasks are presented, it has been shown that even very short SEDs of 0.5 second disrupt cognition. In daily life this has been shown during automobile driving: half of the subjects showed significant deviations in lateral position of the car during SEDs and made more errors in an attention task while driving. Individual differences in the cognitive effects of SEDs are, however, striking and may be partly due to interaction between level of performance and frequency of spontaneous EEG discharges, as has been shown in another driving study: about 75% of subjects showed suppression of SEDs by driving, which is a combination of sensory, mental, and motor activity. Not only can SEDs negatively influence performance, but in some cases mental activities can provoke epileptiform discharges. It is important to realize that these mechanisms exist and that only detailed EEG studies can clarify these issues. In air traffic controllers, brief alterations of consciousness and cognitive impairment have occurred but cannot be accepted for safety reasons; therefore, Eurocontrol has used the EEG as a screening tool since 1995.