A role for sleep disruption in cognitive impairment in children with epilepsy

A case-control study to investigate the prevalence of obstructive sleep apnea and the utility of the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire in children and young people with epilepsy

STUDY OBJECTIVES

Epilepsy and obstructive sleep apnea syndrome (OSAS) are each relatively common in children. OSAS may affect cognition, such that recognition of OSAS is important for children and young people with epilepsy (CYPWE). Published pilot data reported 55% of CYPWE had symptoms suggestive of OSAS, compared with 7% of typically developing controls. The primary aim of this study was to ascertain OSAS prevalence by polysomnography in CYPWE, with secondary aims being to evaluate the utility of sleep questionnaires in CYPWE.

METHODS

CYPWE and age- and sex-matched typically developing controls were studied. A single night of level I attended polysomnography was undertaken, along with questionnaires (Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire, Pittsburgh Sleep Quality Index, and the childhood and adolescent Epworth Sleepiness Scale). OSAS was defined as obstructive apnea-hypopnea index of ≥ 1 event/h.

RESULTS

Polysomnography was performed in 72 children including 48 CYPWE (60% male) and 24 controls (54% male). Mean age (11 years) was similar for CYPWE and controls (P = .42), with slightly higher body mass index z scores (0.7 vs 0.1, P = .03) noted in CYPWE. Mean obstructive apnea-hypopnea index was 0.61 in CYPWE vs 0.42 in controls (P = .62). Despite higher Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire scores in CYPWE (0.38 vs 0.12, P < .001), no difference in OSAS prevalence (10% vs 4%, P = .78) was found. CYPWE had higher childhood and adolescent Epworth Sleepiness Scale (6 vs 3.5, P = .01) and Pittsburgh Sleep Quality Index (5 vs 3.3, P = .02) scores, indicating greater levels of daytime sleepiness and poorer sleep quality.

CONCLUSIONS

The study found no evidence for increased OSAS prevalence in CYPWE, and the utility of the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire in predicting OSAS appears limited for CYPWE. CYPWE are, however, demonstrably sleepier and have poorer sleep quality. The cause for these findings remains unclear.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Investigation of Sleep Quality and Prevalence of Sleep-disordered Breathing in Children and Young People With Epilepsy; URL: https://www.clinicaltrials.gov/study/NCT03103841; Identifier: NCT03103841.

CITATION

Urquhart DS, McLellan AE, Hill LE, et al. A case-control study to investigate the prevalence of obstructive sleep apnea and the utility of the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire in children and young people with epilepsy. J Clin Sleep Med. 2024;20(7):1039-1047.

The course of sleep habits in newly diagnosed epilepsy in children: A prospective study

BACKGROUND

Epilepsy and sleep have a close, complex, and reciprocal relationship. Sleep may also be adversely affected by epilepsy and anti-seizure medication (ASM). This study sought to determine sleep-related problems before and after six months of treatment with ASMs follow-up in children with epilepsy, to reveal changes in sleep habits, and to determine the effect of ASMs on sleep in different types of epilepsy.

METHODS

This is a prospective study that included 61 children, aged 4-18 years with newly diagnosed epilepsy, who regularly had follow-up checks and used ASM for six months, and completed the Children's Sleep Habits Questionnaire (CSHQ). Children's Sleep Habits Questionnaire was completed before and after six months of ASM, allowing for assessments based on treatment group and type of epilepsy.

RESULTS

The mean ages of 61 children were 10.6 ± 3.9 years. The participants' post-treatment total scores on the CSHQ decreased by 2.9 ± 7.8 units on average compared to their pretreatment scores (p = 0.008; p < 0.01). In the levetiracetam group, post-treatment CSHQ subscale scores showed a mean decrease for bedtime resistance (p = 0.001), sleep duration (p = 0.005), sleep anxiety (p = 0.030), and total scores (p = 0.012) (p < 0.05). In the valproic acid group, post-treatment CSHQ subscale scores showed a mean decrease in sleep duration (p = 0.007) and a mean increase in daytime sleepiness (p = 0.03) (p < 0.05).

CONCLUSION

Our study found that children diagnosed with epilepsy had significantly higher rates of pretreatment sleep problems, which significantly decreased in patients who regularly attended follow-up examinations and received treatment. Except for the daytime sleepiness factor, our study found that sleep-related problems improved with treatment. It was observed that the initiation of epilepsy treatment had a positive effect on the patient's sleep, regardless of the type of treatment or epilepsy.

EEG-Findings during long-term treatment with Everolimus in TSC-associated and therapy-resistant epilepsies in children

AIM

This prospective observational study evaluated the long-term EEG changes in children treated with everolimus (EVO) for refractory TSC-associated epilepsy. Changes in EEG-abnormalities were related to developmental outcomes.

METHODS

Thirteen children treated with EVO were examined for EEG-recorded seizures and interictal epileptic discharges (IED) during a 72-hour-video-EEG-monitoring, which was performed at baseline and repeated at follow-up intervals of at least 9 months. Antiseizure medication was left unchanged for at least 27 months. Changes in cognitive developmental parameters were related to reduction of seizures and IED at the last monitoring.

RESULTS

We found a significant reduction of recorded seizures and IED during sleep at the first as well as the last follow-up recording. The reduction of IED was especially prominent during sleep. For patients who continued for more than one monitoring under EVO (n = 8), number of seizures further decreased. In patients with developmental examination (n = 9), we observed that only (nearly) full cessation of IED was related to acquisition of new skills.

DISCUSSION

In children with TSC, EVO was effective in reducing recorded seizures and IED; long-term EVO treatment led to a more pronounced reduction and an improvement of nocturnal IED even when the patient was initially not seizure-free. Cessation of IED in children with developmental improvement may point to the importance of healthy sleep for cognition.

Sleep homeostasis, seizures, and cognition in children with focal epilepsy

AIM

To investigate the link between sleep disruption and cognitive impairment in childhood epilepsy by studying the effect of epilepsy on sleep homeostasis, as reflected in slow-wave activity (SWA).

METHOD

We examined SWA from overnight EEG-polysomnography in 19 children with focal epilepsy (mean [SD] age 11 years 6 months [3 years], range 6 years 6 months-15 years 6 months; 6 females, 13 males) and 18 age- and sex-matched typically developing controls, correlating this with contemporaneous memory consolidation task scores, full-scale IQ, seizures, and focal interictal discharges.

RESULTS

Children with epilepsy did not differ significantly from controls in overnight SWA decline (p = 0.12) or gain in memory performance with sleep (p = 0.27). SWA was lower in patients compared to controls in the first hour of non-rapid eye movement sleep (p = 0.021), although not in those who remained seizure-free (p = 0.26). Full-scale IQ did not correlate with measures of SWA in patients or controls. There was no significant difference in SWA measures between focal and non-focal electrodes.

INTERPRETATION

Overnight SWA decline is conserved in children with focal epilepsy and may underpin the preservation of sleep-related memory consolidation in this patient group. Reduced early-night SWA may reflect impaired or immature sleep homeostasis in those with a higher seizure burden.

Sleep Characteristics Among Children with Idiopathic Generalized Epilepsy: A Polysomnography-Based Study

This study was designed to describe the sleep profile in a cohort of children 5-15 y with idiopathic generalized epilepsy (IGE) using polysomnography (PSG) and Children's Sleep Habits Questionnaire (CSHQ) and Pittsburg Sleep Quality Index (PSQI). The controls included age- and gender-matched healthy controls. A total of 30 cases of IGE and matched 30 controls were enrolled in study. The global CSHQ score [58.8 (10.8) vs. 32.3 (4.1); p < 0.01] and PSQI score [2.4 (1.6) vs. 0.9(0.3); p < 0.01] was significantly higher among children with IGE as compared to controls. REM sleep duration was significantly lower and other parameters including AHI [2.8 (1.9, 4.6) vs. 2.6 (1.3, 2.9); p = 0.04], frequency of arousals [51.5 (36.7, 71.5) vs. 27 (24, 43); p < 0.01], percentage of oxygen desaturation > 4% [23.5 (8, 36.5) vs. 4 (2, 8); p < 0.01], were significantly higher among children with IGE when compared to controls. Children with IGE have sleep disturbances and alteration in sleep architecture. They should be assessed   and screened for sleep characteristics.

Sleep and epilepsy: unfortunate bedfellows

The relationship between sleep and seizure disorders is a particularly vicious cycle. Nocturnal seizures can interrupt sleep while a number of factors, including antiepileptics and sleep disorders that cause sleep fragmentation, can worsen seizures. Understanding and managing seizures and related sleep disturbance is therefore an important and treatable intervention target that could potentially improve children's sleep, but also their learning, mood, behaviour, seizures and parental quality of life.

Observational pilot study of reported symptoms of obstructive sleep apnoea in children with epilepsy

AIM

To estimate symptoms of obstructive sleep apnoea (OSA) and excessive daytime sleepiness (EDS) in children with epilepsy (CWE) compared with those in a typically developing comparison group. CWE are known to have poor sleep, with increased rates of OSA suggested.

METHOD

The Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire (PSQ-SRBD) was used to estimate OSA symptoms, with scores ≤0.33 known to be highly sensitive and specific for OSA. The Epworth Sleepiness Scale (ESS) was used to assess EDS, with scores of 10 or above considered abnormal.

RESULTS

Thirty-three CWE (21 males, 12 females) were studied (median age [interquartile range {IQR}] 9y [5-12]), along with 42 comparison children (20 males, 22 females; median age [IQR] 6y [4-8.5]). Fifty-five per cent of CWE scored 0.33 or higher on the PSQ-SRBD compared with 7% in the comparison group (p<0.001), and 30% of CWE had an abnormal ESS compared with 5% controls (p=0.003). Within the CWE cohort, PSQ-SRDB and ESS appeared higher in those taking antiepileptic drugs (AEDs); although PSQ-SRBD score for CWE not on AEDs was higher than in the comparison group.

INTERPRETATION

This study suggests higher rates of symptoms of OSA and EDS in CWE compared with typically developing children. AEDs may be a confounding factor, but do not alone account for the associations seen. Further studies including polysomnography to verify the presence (rather than suggestion by questionnaire) of OSA are warranted.

Interictal activity is an important contributor to abnormal intrinsic network connectivity in paediatric focal epilepsy

Patients with focal epilepsy have been shown to have reduced functional connectivity in intrinsic connectivity networks (ICNs), which has been related to neurocognitive development and outcome. However, the relationship between interictal epileptiform discharges (IEDs) and changes in ICNs remains unclear, with evidence both for and against their influence. EEG-fMRI data was obtained in 27 children with focal epilepsy (mixed localisation and aetiologies) and 17 controls. A natural stimulus task (cartoon blocks verses blocks where the subject was told "please wait") was used to enhance the connectivity within networks corresponding to ICNs while reducing potential confounds of vigilance and motion. Our primary hypothesis was that the functional connectivity within visual and attention networks would be reduced in patients with epilepsy. We further hypothesized that controlling for the effects of IEDs would increase the connectivity in the patient group. The key findings were: (1) Patients with mixed epileptic foci showed a common connectivity reduction in lateral visual and attentional networks compared with controls. (2) Having controlled for the effects of IEDs there were no connectivity differences between patients and controls. (3) A comparison within patients revealed reduced connectivity between the attentional network and basal ganglia associated with interictal epileptiform discharges. We also found that the task activations were reduced in epilepsy patients but that this was unrelated to IED occurrence. Unexpectedly, connectivity changes in ICNs were strongly associated with the transient effects of interictal epileptiform discharges. Interictal epileptiform discharges were shown to have a pervasive transient influence on the brain's functional organisation. Hum Brain Mapp 38:221-236, 2017. © 2016 Wiley Periodicals, Inc.

Is There a Relation between EEG-Slow Waves and Memory Dysfunction in Epilepsy? A Critical Appraisal

Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow-wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms, which result in peri-ictal slow-wave activity as detected by the electroencephalogram, could negatively affect memory processes. Slow waves (≤4 Hz) can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms, which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow-wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity. In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms, which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal-neocortical interactions during slow-wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic-clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline. This hypothesis can only be assessed in long-term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. By contrast, short-term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance.

Novel mechanisms, treatments, and outcome measures in childhood sleep

Sleep disorders and sleep of insufficient duration and quality are on the increase due to changes in our lifestyle, particularly in children and adolescents. Sleep disruption is also more common in children with medical conditions, compounding their difficulties. Recent studies have focused on new mechanisms that explain how learning and cognitive performance depend on a good night's sleep. Growing alongside this latest understanding is an innovative new field of non-drug interventions that improve sleep architecture, with resulting cognitive improvements. However, we need to rigorously evaluate such potentially popular and self-administered sleep interventions with equally state-of-the-art outcome measurement tools. Animated hand-held games, that incorporate embedded sleep-dependent learning tasks, promise to offer new robust methods of measuring changes in overnight learning. Portable computing technology has the potential to offer practical, inexpensive and reliable tools to indirectly assess the quality of sleep. They may be adopted in both clinical and educational settings, providing a unique way of monitoring the effect of sleep disruption on learning, leading also to a radical rethink of how we manage chronic diseases.

Primary sleep disorders in people with epilepsy: clinical questions and answers

The questions facing clinicians with patients with sleep disorder and epilepsy are addressed in this article. Both adult and child epilepsy are discussed in the context of the most typical questions a clinician would have, such as "Are parasomnias more common in people with epilepsy?", "Is sleep architecture abnormal in children with epilepsy", along with outcomes of numerous questionnaire-based, case-based, and double-blind placebo studies on such aspects as sleep duration, daytime sleepiness, anxiety and fears, limb movement, nocturnal seizures, agitation, behavioral disorders, and learning disorders.

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.

Key issues in addressing the comorbidity of attention deficit hyperactivity disorder and pediatric epilepsy

Attention deficit hyperactivity disorder (ADHD) is a common comorbidity of epilepsy encountered by clinicians. However, relatively little information is available to guide optimal diagnostic and treatment strategies. Differentiating ADHD from effects of epilepsy requires careful history taking and emphasis upon characteristic symptoms and course of illness. Rating scales for ADHD are well validated and may aid clinical management. Use of antiepileptic drugs may cause cognitive or behavioral side effects yet may improve behavior in some cases. Historically, clinicians have been hesitant to treat ADHD comorbidity for fear of lowering the seizure threshold. However, an aggregate of recent evidence now suggests that stimulants may be well tolerated and effective for ADHD comorbid with epilepsy. Studies that further clarify pathophysiology and treatment outcomes are needed in order to enhance clinical efficacy and quality of life for this population.

Cognitive impairment in temporal lobe epilepsy: role of online and offline processing of single cell information

Cognitive impairment is a common comorbidity in temporal lobe epilepsy (TLE) and is often considered more detrimental to quality of life than seizures. While it has been previously shown that the encoding of memory during behavior is impaired in the pilocarpine model of TLE in rats, how this information is consolidated during the subsequent sleep period remains unknown. In this study, we first report marked deficits in spatial memory performance and severe cell loss in the CA1 layer of the hippocampus lower spatial coherence of firing in TLE rats. We then present the first evidence that the reactivation of behavior-driven patterns of activity of CA1 place cells in the hippocampus is intact in TLE rats. Using a template-matching method, we discovered that real-time (3-5 s) reactivation structure was intact in TLE rats. Furthermore, we estimated the entropy rate of short time scale (∼250 ms) bursting activity using block entropies and found that significant, extended temporal correlations exist in both TLE and control rats. Fitting a first-order Markov Chain model to these bursting time series, we found that long sequences derived from behavior were significantly enriched in the Markov model over corresponding models fit on randomized data confirming the presence of replay in shorter time scales. We propose that the persistent consolidation of poor spatial information in both real time and during bursting activity may contribute to memory impairments in TLE rats.

Memory consolidation in children with epilepsy: does sleep matter?

INTRODUCTION

Children with epilepsy have frequent sleep disturbance and challenges in learning and memory. There is little research on the consolidation of memory during sleep in this population. The goal of this pilot study was to determine whether children with epilepsy are able to consolidate memories better after a sleep versus wake period as has been demonstrated in typically developing children.

METHODS

This study was a prospective evaluation of children with epilepsy to determine if sleep improved episodic memory (using word lists) as compared with memory following a wake period of similar duration. The study was conducted in patients in the Epilepsy Monitoring Unit at a single academic health science center. In the sleep recall condition, the learning trials were presented in the evening, and delayed recall of the words was tested in the morning. In the wake condition, the learning took place in the morning, and the delayed recall took place later in the day. Subjects wore an actigraph to evaluate sleep/wake patterns. Data regarding the children's epilepsy, antiepileptic medications, and frequency of interictal epileptiform discharges were also documented.

RESULTS

Ten children (agd 8-17years) participated in the study. For the entire sample, recall after sleep was better than recall after awake (p=0.03), and 7 of the 10 children showed this effect. However, reanalyses removing an outlier showed no difference between the two recall conditions. The mean number of interictal epileptiform discharges was 8.8 during the recall after sleep and 7.8 during the recall after awake. Three children had seizures during the evaluation.

CONCLUSION

In this pilot study, we demonstrated that a small cohort of children with epilepsy, with similar interictal epileptiform discharges during sleep and wake, showed no advantage in memory for a word list after a period of sleep than after a period of being awake. This finding requires further study in a larger cohort. Poor memory consolidation during sleep may contribute to the cognitive deficits in children with epilepsy.

The cooccurrence of interictal discharges and seizures in pediatric sleep-disordered breathing

Studies in the literature data have shown that the prevalence of obstructive sleep apnea (OSA) in children with epilepsy is high and that treatment for OSA leads to a reduction in the number of seizures; by contrast, few studies have demonstrated an increased prevalence of interictal epileptiform discharges (IEDs) or epilepsy in children with sleep-disordered breathing (SDB). The aim of the present study was to confirm the high prevalence of IEDs or epilepsy in a large sample of children with SDB and to collect follow-up data. Children were recruited prospectively and underwent their first video-polysomnography (video-PSG) for SDB in a teaching hospital sleep center. Of the 298 children who fulfilled the diagnostic criteria for sleep-disordered breathing, 48 (16.1%) children were found to have IEDs, three of these 48 children were also found to have nocturnal seizures (two females diagnosed with rolandic epilepsy and a male diagnosed with frontal lobe epilepsy). Only 11 subjects underwent a second video-PSG after 6months; at the second video-PSG, the IEDs had disappeared in six subjects, who also displayed a reduced AHI and an increased mean overnight saturation. Thirty-eight of the 250 children without IEDs underwent a second video-PSG after 6months. Of these 250 children, four, who did not display any improvement in the respiratory parameters and were found to experience numerous stereotyped movements during sleep, were diagnosed with nocturnal frontal lobe epilepsy. Our study confirms the high prevalence of IEDs in children with SDB. Follow-up data indicate that they may recede over time, accompanied by an improvement of sleep respiratory parameters.

Changes in gene expression in the frontal cortex of rats with pilocarpine-induced status epilepticus after sleep deprivation

Sleep and epilepsy present a bidirectional interaction. Sleep complaints are common in epilepsy, and sleep deprivation may provoke seizures. However, the mechanisms underlying this relationship are unknown. Thus, this study investigated the effects of paradoxical sleep deprivation (PSD24h) and total sleep deprivation (TSD6h) in the expression of genes related to reactive oxygen species and nitric oxide production in the frontal cortex of a rodent model of temporal lobe epilepsy (PILO). The data show that PILO rats had increased NOX-2 expression and decreased SOD expression, independent of sleep. Higher NOX-2 expression was observed only in PILO rats subjected to the control condition and TSD6h. Also, eNOS and DDAH1 were increased in the PILO group submitted to TSD6h. Moreover, CAT expression in the frontal cortex of PILO rats submitted to PSD24h was reduced compared to that of PILO rats that were not sleep-deprived. The molecular changes found in the frontal cortex of PILO rats following sleep deprivation suggest a mechanism via oxidative stress.

Functional imaging of seizures and epilepsy: evolution from zones to networks

PURPOSE OF REVIEW

Epilepsy research has extended from studies at the cellular level to the investigation of interactions of large neuronal populations distant from one another: 'epileptic networks'. This article underlines the concept of epilepsies as network disorders, adding empirical evidence from electroencephalography-combined functional MRI (EEG-fMRI) studies.

RECENT FINDINGS

These noninvasive in-vivo EEG-fMRI epilepsy studies have characterized the ictal temporal-spatial evolution and the interictal persistence of altered activity in typical sets of (sub)cortical brain regions responsible for the clinical manifestation of the disease and its underlying encephalopathy, for example, thalamus vs. cortex in generalized; hippocampus vs. cortex in temporal lobe; a frontal near-piriform region universally in focal epilepsies. Models exist validated against intracranial EEG that can explain interictal and ictal activity based on statistical coupling between different brain regions, and if extended could guide the design of new treatments.

SUMMARY

The appreciation of epileptic processes at the network level will foster the development of both anticonvulsive as well as true antiepileptic treatment strategies locally modulating hub regions within the epileptic network architecture as well as entire networks by targeting their characteristic properties such as neurotransmitter or neuronal firing profiles. Treatment should reach beyond seizure control and include the improvement of cognitive function.

Health inequalities experienced by children and young people with intellectual disabilities: a review of literature from the United Kingdom

This literature review aimed to synthesize evidence on the prevalence and determinants of health conditions and impairments among children and young people with intellectual disability in the United Kingdom. Several databases were systematically searched for studies conducted with children under the age of 18 living in the United Kingdom and published in 2010-11. Evidence from a 2002 and a 2010 literature review on health inequalities among individuals of all ages with intellectual disability was also reviewed. We conclude there is an increased prevalence of a number of health conditions and impairments among children with intellectual disability and evidence that these health inequalities are associated with several preventable environmental determinants.

Impact of focal interictal epileptiform discharges on behaviour and cognition in children

It is hypothesised that focal interictal epileptiform discharges (IED) may exert a deleterious effect on behaviour and cognition in children. This hypothesis is supported by the abnormally high prevalence of IED in several developmental disorders, like specific language impairment, and of cognitive and behavioural deficits in epileptic children after excluding confounding factors such as underlying structural brain lesions, drug effects, or the occurrence of frequent or prolonged epileptic seizures. Neurophysiological and functional neuroimaging evidence suggests that IED may impact cognition through either transient effects on brain processing mechanisms, or through more long-lasting effects leading to prolonged inhibition of brain areas distant from but connected with the epileptic focus (i.e. remote inhibition effect). Sustained IED may also impair sleep-related learning consolidation processes. Nowadays, the benefits of anti-epileptic treatment aimed at reducing IED are not established except in specific situations like epileptic encephalopathies with continuous spike and waves during slow-wave sleep. Well-designed pharmacological studies are still necessary to address this issue.

Is sleep-related consolidation impaired in focal idiopathic epilepsies of childhood? A pilot study

We investigated sleep-related declarative memory consolidation in four children with focal idiopathic epilepsy. In a population of healthy control children, recall of learned pairs of words was increased after a night of sleep, but not after a daytime wakefulness period. In children with epilepsy (1 case of benign epilepsy with centro-temporal spikes, 1 case of benign childhood epilepsy with occipital paroxysms, and 2 cases of epileptic encephalopathy (EE) with continuous spike and waves during slow-wave sleep, CSWS), recall performance significantly decreased overnight, suggesting impairment in sleep-related declarative memory consolidation. Hydrocortisone treatment in one patient with EE with CSWS resulted in normalization of the sleep EEG together with normalization of overnight memory performance, which was not the case in the other EE/CSWS patient whose sleep EEG was only partially improved. These preliminary results suggest that interictal epileptiform discharges in idiopathic focal epilepsies may disrupt the brain processes underlying sleep-related memory consolidation.