A New Method for Quantification and Assessment of Epileptiform Activity in EEG with Special Reference to Focal Nocturnal Epileptiform Activity

Spike count and morphology in the classification of epileptiform discharges

Purpose

The purpose of this study is to investigate the impact of Bergen Epileptiform Morphology Score (BEMS) and interictal epileptiform discharge (IED) candidate count in EEG classification.

Methods

We included 400 consecutive patients from a clinical SCORE EEG database during 2013-2017 who had focal sharp discharges in their EEG, but no previous diagnosis of epilepsy. Three blinded EEG readers marked all IED candidates. BEMS and IED candidate counts were combined to classify EEGs as epileptiform or non-epileptiform. Diagnostic performance was assessed and then validated in an external dataset.

Results

Interictal epileptiform discharge (IED) candidate count and BEMS were moderately correlated. The optimal criteria to classify an EEG as epileptiform were either one spike at BEMS > = 58, two at > = 47, or seven at > = 36. These criteria had almost perfect inter-rater reliability (Gwet's AC1 0.96), reasonable sensitivity of 56-64%, and high specificity of 98-99%. The sensitivity was 27-37%, and the specificity was 93-97% for a follow-up diagnosis of epilepsy. In the external dataset, the sensitivity for an epileptiform EEG was 60-70%, and the specificity was 90-93%.

Conclusion

Quantified EEG spike morphology (BEMS) and IED candidate count can be combined to classify an EEG as epileptiform with high reliability but with lower sensitivity than regular visual EEG review.

High incidence of early thalamic lesions in the Continuous Spike-Wave related with slow Sleep (CSWS)

OBJECTIVE

Continuous Spike-Wave during slow Sleep (CSWS) syndrome associates a clinically important neurocognitive regression with strong activation of non-REM sleep spikes. Its mechanisms remain unknown, but a contribution of rare perinatal thalamic injuries has been highlighted. We determine the incidence of such lesions in a cohort of CSWS patients.

METHODS

N = 65 patients with CSWS and a control group (N = 51) were studied. Spikes were quantified in long-term ambulatory EEGs, brain Magnetic Ressonance Imaging (MRI) structural lesions were assessed and thalamic volumetry was performed. A neurocognitive scale was used to assess dysfunction.

RESULTS

The most common etiologies in the control patients were not represented in the CSWS group. Structural lesions were detected in a minority of CSWS patients (25/53) but included a thalamic injury in the large majority (24/25). This ratio was 4/40 in controls. Lesions belonged to one of five types: 1. Circumscribed to the thalamus (N = 11); 2. Extending beyond the thalamus (N = 3); 3. Hypothalamic-Hamartomas (N = 4); 4. Periventricular-Leukomalacia (N = 4); 5. Hypoplasia-Polymicrogyria (N = 1). Most lesions were lateralized to one hemisphere, which in all cases corresponded to the lateralization of the CSWS.

SIGNIFICANCE

Thalamic lesions are present in most CSWS patients with abnormal MRIs, supporting an important role in its genesis.

Transcranial direct current stimulation (tDCS) in the management of epilepsy: A systematic review

PURPOSE

Current therapies for the management of epilepsy are still suboptimal for several patients due to inefficacy, major adverse events, and unavailability. Transcranial direct current stimulation (tDCS), an emergent non-invasive neuromodulation technique, has been tested in epilepsy samples over the past two decades to reduce either seizure frequency or electroencephalogram (EEG) epileptiform discharges.

METHODS

A systematic review was performed in accordance with PRISMA guidelines (PROSPERO record CRD42020160292). A thorough electronic search was completed in MEDLINE, EMBASE, CENTRAL and Scopus databases for trials that applied tDCS interventions to children and adults with epilepsy of any cause, from inception to April 30, 2020.

RESULTS

Twenty-seven studies fulfilled eligibility criteria, including nine sham-controlled and 18 uncontrolled trials or case reports/series. Samples consisted mainly of drug-resistant focal epilepsy patients that received cathodal tDCS stimulation targeted at the site with maximal EEG abnormalities. At follow-up, 84 % (21/25) of the included studies reported a reduction in seizure frequency and in 43 % (6/14) a decline in EEG epileptiform discharge rate was observed. No serious adverse events were reported.

CONCLUSIONS

Cathodal tDCS is both a safe and probably effective technique for seizure control in patients with drug-resistant focal epilepsy. However, published trials are heterogeneous regarding samples and methodology. More and larger sham-controlled randomized trials are needed, preferably with mechanistic informed stimulation protocols, to further advance tDCS therapy in the management of epilepsy.

Standard procedures for the diagnostic pathway of sleep-related epilepsies and comorbid sleep disorders: A European Academy of Neurology, European Sleep Research Society and International League against Epilepsy-Europe consensus review

BACKGROUND

Some epilepsy syndromes (sleep-related epilepsies [SRE]) have a strong link with sleep. Comorbid sleep disorders are common in patients with SRE and can exert a negative impact on seizure control and quality of life.

PURPOSES

To define the standard procedures for the diagnostic pathway of patients with possible SRE (scenario 1) and the general management of patients with SRE and comorbidity with sleep disorders (scenario 2).

METHODS

The project was conducted under the auspices of the European Academy of Neurology (EAN), the European Sleep Research Society (ESRS) and the International League against Epilepsy (ILAE) Europe. The framework of the document entailed the following phases: conception of the clinical scenarios; literature review; statements regarding the standard procedures. For literature search a step-wise approach starting from systematic reviews to primary studies was applied. Published studies were identified from the National Library of Medicine's MEDLINE database and Cochrane Library.

RESULTS

Scenario 1: despite a low quality of evidence, recommendations on anamnestic evaluation, tools for capturing the event at home or in the laboratory are provided for specific SRE. Scenario 2: Early diagnosis and treatment of sleep disorders (especially respiratory disorders) in patients with SRE are likely to be beneficial for seizures control.

CONCLUSIONS

Definitive procedures for evaluating patients with SRE are lacking. We provide advice that could be of help for standardising and improving the diagnostic approach of specific SRE. The importance of identifying and treating specific sleep disorders for the management and outcome of patients with SRE is underlined.

Standard procedures for the diagnostic pathway of sleep-related epilepsies and comorbid sleep disorders: an EAN, ESRS and ILAE-Europe consensus review

BACKGROUND AND PURPOSE

Some epilepsy syndromes (sleep-related epilepsies, SREs) have a strong link with sleep. Comorbid sleep disorders are common in patients with SRE and can exert a negative impact on seizure control and quality of life. Our purpose was to define the standard procedures for the diagnostic pathway of patients with possible SRE (scenario 1) and the general management of patients with SRE and comorbidity with sleep disorders (scenario 2).

METHODS

The project was conducted under the auspices of the European Academy of Neurology, the European Sleep Research Society and the International League Against Epilepsy Europe. The framework entailed the following phases: conception of the clinical scenarios; literature review; statements regarding the standard procedures. For the literature search a stepwise approach starting from systematic reviews to primary studies was applied. Published studies were identified from the National Library of Medicine's MEDLINE database and Cochrane Library.

RESULTS

Scenario 1: Despite a low quality of evidence, recommendations on anamnestic evaluation and tools for capturing the event at home or in the laboratory are provided for specific SREs. Scenario 2: Early diagnosis and treatment of sleep disorders (especially respiratory disorders) in patients with SRE are likely to be beneficial for seizure control.

CONCLUSIONS

Definitive procedures for evaluating patients with SRE are lacking. Advice is provided that could be of help for standardizing and improving the diagnostic approach of specific SREs. The importance of identifying and treating specific sleep disorders for the management and outcome of patients with SRE is underlined.

Regional White Matter Atrophy Correlates with Spike Activity in Encephalopathy Related to Status Epilepticus During Slow Sleep (ESES) After Early Thalamic Lesions

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is an age-related, epileptic syndrome, which associates cognitive/behavioral disturbances with a peculiar pattern of spike activity. One promising line of research is the study of ESES in cases of early thalamic lesions. We studied 7 ESES patients with unilateral thalamic lesions using magnetic resonance imaging to assess regional white matter (WM) and thalamic nuclei volume differences, and long-term electroencephalogram recordings to localize the epileptogenic cortex. N170 event-related potentials were used to demonstrate the dysfunctional character of the WM abnormalities. Diffusion-weighted images in a subset of 4 patients were used to parcellate the thalamus and evaluate volume asymmetries, based on cortical connectivity. Large WM regional atrophy in the hemisphere with the thalamic lesion was associated with both cortical dysfunction and epileptic activity. A correlation was demonstrated between lesions in the pulvinar and the mediodorsal thalamic nuclei and WM atrophy of the corresponding cortical projection areas. We propose that these abnormalities are due to the widespread structural disconnection produced by the thalamic lesions associated to a yet unknown age-dependent factor. Further exploration of WM regional atrophy association with the spike activity in other etiologies could lend support to the cortical disconnection role in ESES genesis.

Interictal spike quantification in continuous spike-wave of sleep (CSWS): Clinical usefulness of a wearable EEG device

INTRODUCTION

Continuous spike-wave of sleep (CSWS) syndrome is one of the most common epileptic encephalopathies of childhood. Because the associated cognitive/behavioral disturbances relate more to the amount of spike activity than of seizures, methods of spike quantification gained relevance in diagnosis and monitoring treatment. The conventional methodology for quantification of spike index (SI) relies on repeated full 10-20 long-term ambulatory electroencephalography (aEEG), which is both expensive and poorly tolerated.

OBJECTIVE

The objectives of this study were to demonstrate the clinical value of repeated SI assessments in CSWS and to build and validate a wearable device allowing inexpensive and well-tolerated, repeated quantifications.

METHODS

A group of N = 38 patients with CSWS were submitted to repeated SI quantifications based on aEEG, as seen fit by the medical clinical assistant. Responses to therapy with corticosteroids (N = 10), sulthiame (N = 7), and the ketogenic diet (N = 3) were monitored. We used a conventional method based on a semiautomatic template match spike search. The individual variability in time spans of days (N = 4) or months (N = 10) was assessed and used to determine the meaningful neurophysiological responses to the diverse therapies. A wearable device capable of recording 2 bipolar EEG channels for 24 h was used to simplify SI quantification.

RESULTS

Corticosteroids produced the most powerful SI reduction, but a large individual variability in both amount and time of onset of clinical response with some patients exhibiting recurrence shortly after therapy. A more frequent sampling of SI would provide a more accurate follow-up, with clinical benefit. The comparison of the SI obtained from standard 10-20 electrodes and 2 bipolar EEG channel subsets in aEEG or between the 10-20 and simultaneous wearable recordings, demonstrated that the new method provides an accurate SI quantification.

CONCLUSIONS

A wearable EEG device with 2 bipolar channels simplifies the process of obtaining repeated SI quantification allowing a more accurate follow-up of spike activity in the clinical setting.

Expanding the clinical and EEG spectrum of CNKSR2-related encephalopathy with status epilepticus during slow sleep (ESES)

OBJECTIVE

To investigate the clinical and EEG features of Encephalopathy with Status Epilepticus during slow Sleep (ESES) related to CNKSR2 pathogenic variants.

METHODS

Detailed clinical history, repeated wakefulness/overnight sleep EEGs, brain MRI were collected in five patients, including one female, with CNKSR2-related ESES.

RESULTS

Neurodevelopment in infancy was normal in two patients, delayed in three. Epilepsy onset (age range: 2-6 years) was associated with appearance or aggravation of cognitive impairment, language regression and/or behavioral disorders. Worsening of epilepsy and of cognitive/behavioral disturbances paralleled by enhancement of non-rapid eye movement (NREM) sleep-related, frontally predominant, EEG epileptic discharges [spike-wave-index (SWI): range 60-96%] was consistent with ESES. In three patients, episodes of absence status epilepticus or aggravation of atypical absences occurred, in this latter case associated with striking increment of awake SWI. Speech/oro-motor dyspraxia was diagnosed in four patients. In two patients, long-term follow-up showed epilepsy remission and persistence of mild/moderate cognitive disorders and behavioral disturbances into adulthood.

CONCLUSIONS

Novel findings of our study are occurrence also in females, normal neurodevelopment before epilepsy onset, epilepsy aggravation associated with enhanced awake SWI, mild/moderate evolution in adulthood and language disorder due to speech/oro-motor dyspraxia.

SIGNIFICANCE

Our findings expand the phenotypic spectrum of CNKSR2-related ESES.

[Epileptiform activity index for the evaluation of treatment efficacy in patients with epileptic encephalopathy]

Continuous spike and waves during sleep (CSWS) may lead to different cognitive, motor and behavioral symptoms. CSWS is characterized by an electroencephalography (EEG) pattern of electrical status epilepticus during sleep (ESES). The article reviews the main criteria of ESES, localization of EEG-changes and main EEG-patterns. An analysis of abnormal neuroimaging findings in patients with ESES was performed. The main pathophysiologic theories of ESES pattern formation are reviewed. ESES diagnosis is usually based on rough visual assessment of the number of spikes and waves, but other methods of assessment are also utilized, including spike-wave index (SWI), which is widely used in clinical practice. SWI reflects the percentage of sleep covered with spikes and waves. Two different strategies of SWI calculation are used, but none of them is officially validated. Moreover, there is no consensus on the period of sleep to be used for the calculation of SWI. The article presents a detailed review of calculation and utilization of SWI. It is concluded that further research is needed to develop an optimal algorithm of SWI calculation.

Idiopathic encephalopathy related to status epilepticus during slow sleep (ESES) as a "pure" model of epileptic encephalopathy. An electroclinical, genetic, and follow-up study

OBJECTIVE

The objective of the study was to investigate electroclinical and neuropsychological features, genetic background, and evolution of children with idiopathic encephalopathy with status epilepticus during slow sleep (ESES), including Landau-Kleffner syndrome (LKS).

MATERIAL AND METHODS

All children diagnosed with idiopathic ESES at the Danish Epilepsy Centre between March 2003 and December 2014 were retrospectively reviewed. Repeated 24-hour electroencephalography (24-h EEG) recordings, neuropsychological assessments, and clinical-neurological evaluation were performed throughout the follow-up in all patients. In 13 children, genetic investigations were performed.

RESULTS

We collected 24 children (14 males and 10 females). Mean age at ESES diagnosis was 6 years, and mean ESES duration was 2 years and 7 months. Twenty-one children had epileptic seizures. Three children had LKS. Topography of sleep-related EEG epileptic abnormalities was diffuse in 3 subjects, hemispheric in 6, multifocal in 9, and focal in 6. During the active phase of ESES, all children presented with a heterogeneous combination of behavioral and cognitive disturbances. In 14 children, a parallel between severity of the clinical picture and spike-wave index (SWI) was observed. We could not find a strict correlation between the type and severity of neurobehavioral impairment and the side/topography of sleep-related EEG discharges during the active phase of ESES. At the last follow-up, 21 children were in remission from ESES. Complete recovery from neurobehavioral disorders was observed in 5 children. Genetic assessment, performed in 13 children, showed GRIN2A variant in two (15.4%).

SIGNIFICANCE

Our patients with idiopathic ESES showed a heterogeneous pattern of epileptic seizures, neurobehavioral disorders, and sleep EEG features. Only one-fourth of children completely recovered from the neuropsychological disturbances after ESES remission. Lack of correlation between severity/type of cognitive derangement and SWI and/or topography of sleep EEG epileptic abnormalities may suggest the contribution of additional factors (including impaired sleep homeostasis due to epileptic activity) in the neurobehavioral derangement that characterize ESES.

Anatomical and physiological basis of continuous spike-wave of sleep syndrome after early thalamic lesions

OBJECTIVE

Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children, and promise useful insights into the pathophysiology of the disease.

METHODS

We describe nine patients with unilateral neonatal thalamic lesions which progressed to CSWS. Longitudinal whole-night and high-density electroencephalograms (EEGs) were performed, as well as detailed imaging and clinical evaluation. Visual evoked potentials were used to probe cortical excitability.

RESULTS

Thalamic volume loss ranged from 19% to 94%, predominantly on medial and dorsal nuclei and sparing the ventral thalamus. Lesions produced white matter loss and ventricle enlargement on the same hemisphere, which in four patients was associated with selective loss of thalamic-cortical fibers. Cortical thickness quantification failed to reveal hemispheric asymmetries. Impact on EEG rhythms was mild, with a volume-loss-related decrease in alpha power and preservation of sleep spindles. The sleep continuous spiking was lateralized to the hemisphere with the lesion. Visual cortex stimulation in five patients with posterior cortex spiking revealed an abnormal frequency-dependent excitability at 10-20Hz on the side of the lesion.

SIGNIFICANCE

Unilateral selective thalamic-cortical disconnection is a common feature in our patients and is associated with both a focal pattern of CSWS and a pathological type of frequency-dependent excitability (peak: 10-20Hz). We propose that this excitability represents an abnormal synaptic plasticity previously described as the augmenting response. This synaptic plasticity has been described as absent in the corticocortical interactions in healthy experimental animals, emerging after ablation of the thalamus and producing a frequency-dependent potentiation with a peak at 10-20Hz. Because this response is potentiated by sleep states of reduced brainstem activation and by appropriate stimulating rhythms, such as sleep spindles, the simultaneous occurrence of these two factors in nonrapid-eye-movement sleep is proposed as an explanation for CSWS in our patients.

Immediate termination of electrical status epilepticus in sleep after hemispherotomy is associated with significant progress in language development

AIM

To study the effect of hemispherotomy on electrical status epilepticus in sleep (ESES) and language development.

METHOD

Children with a confirmed diagnosis of ESES prior to surgery and a minimum of 24 months of developmental follow-up data were compared with age-matched controls without ESES. Language quotients (LQs) were calculated before and after surgery.

RESULTS

Eleven patients (five females, six males) and 21 controls (11 females, 10 males) were included. Before surgery a significantly higher number of children in the study group (n=9) demonstrated severe developmental delay compared with children in the control group (n=13; p=0.015). In the study group ESES remitted immediately after surgery in 10 children, and a significant catch-up in LQs was observed in this group (preoperative mean 40.0 [standard deviation (SD) 22.2, interquartile range (IQR) 30.0-62.0]; postoperative mean 73.0 [SD 33.5, IQR 41.0-97.0]; p=0.037). There was no significant difference compared with controls at last follow-up after surgery (study group: five with severe impairment; control group: eight with severe impairment [p=0.971]). Overall, a favourable developmental outcome was associated with freedom from seizures (seizure-free group: median preoperative LQ 61.5, median postoperative LQ 78.0 [p=0.017]; seizure group: median preoperative LQ 35.5, median postoperative LQ 56.5 [p=0.273]) and antiepileptic drug withdrawal (off medication: median preoperative LQ 49.5, median postoperative LQ 78.0 [p=0.011]; on medication: median preoperative LQ 78.0, median postoperative LQ 83.5 [p=0.889]).

INTERPRETATION

Children with ESES showed significantly lower preoperative language abilities than children without ESES. In cases with remission of ESES after surgery, marked improvement in LQs was noticed. This improvement cannot be fully explained by seizure-freedom alone as seizure-free children without preoperative ESES showed less improvement.

Electroencephalography in the pediatric emergency department: when is it most useful?

This study aimed to identify the indications in which electroencephalography in the pediatric emergency department is most useful. We retrospectively reviewed the influence that the results of the emergent electroencephalogram had on the eventual disposition of patients at our pediatric emergency department. Sixty-eight children (mean age, 7.3 years; 32 males) underwent 70 emergent electroencephalograms. Fifty-seven emergent electroencephalograms were performed for the suspicion of ongoing seizures or status epilepticus. Thirteen of the 22 children (59.1%) discharged from the emergency department were sent home mainly based on the results of the emergent electroencephalogram, which prevented an admission. In particular, 11 of 38 children with frequent and recurrent paroxysmal events concerning for seizures and 2 of 19 children with suspected ongoing status epilepticus were discharged after excluding an epileptic disturbance. The emergent electroencephalogram provided meaningful clinical information that influenced disposition, especially in patients with ongoing events in which the clinical picture was clarified by a rapidly acquired electroencephalogram.

Measuring spike strength in patients with continuous spikes and waves during sleep: comparison of methods for prospective use as a clinical index

OBJECTIVE

To compare methods of estimating spike strength as a potential index in the assessment of continuous spikes and waves during sleep (CSWS).

METHODS

Spikes were searched and averaged automatically from pre- and postoperative EEGs of ten patients with CSWS who underwent corpus callosotomy (eight) or resective epilepsy surgery (two). From the most prominent spike, we measured peak amplitude and root mean square (RMS) over ±150ms window around the peak. In order to compensate for spatiotemporal instability of spikes, the cumulative amplitude and RMS were computed from the highest quartile of electrodes (Ampl-Q and RMS-Q, respectively). The stability of parameters was studied by comparing two ten minute epochs during the first hour of NREM sleep, as well as by analyzing overnight variation of indices in further ten patients with CSWS. The Ampl-Q and RMS-Q were compared between pre- and postoperative recordings.

RESULTS

All four measures, amplitude, RMS, Ampl-Q and RMS-Q, were correlated with each other and highly dependent on NREM/REM-sleep stage and arousals. Expectedly, Ampl-Q and RMS-Q had the greatest intra-individual stability. The amplitude had up to 71% intra-individual variation making it unhelpful for clinical use. Ampl-Q and RMS-Q were comparable in assessing change following surgical treatment.

CONCLUSIONS

Computing an integrated RMS over multiple electrodes during steady NREM sleep offers a stable and reliable parameter for evaluating the strength of spikes in CSWS.

SIGNIFICANCE

Analyzing spike strength with RMS-Q may offer a clinically useful, supplementary index for EEG monitoring of CSWS where spike index has been of limited value.

Subclinical epileptiform activity in children with electrical status epilepticus during sleep: effects on cognition and behavior before and after treatment with levetiracetam

We performed a double-blind placebo-controlled crossover study of the effects of spike activity during sleep and when awake on learning, long-term memory, vigilance and behavior before and after treatment with levetiracetam in children with electrical status epilepticus during sleep. At baseline, verbal learning declined with increasing spike activity, but there were no relations between spike activity and memory, vigilance or behavior. Levetiracetam was effective in reducing sleep-related spike activity, but on a group level, this had no clear effects on behavior, vigilance or learning and memory. Our results do not allow firm conclusions whether to treat nocturnal epileptiform activity or not; larger samples and longer follow-up may be needed.

Automated quantification of spikes

Methods for rapid and objective quantification of interictal spikes in raw, unprocessed electroencephalogram (EEG) samples are scarce. We evaluated the accuracy of a tailored automated spike quantification algorithm. The automated quantification was compared with the quantification by two board-certified clinical neurophysiologists (gold-standard) in five steps: 1) accuracy in a single EEG channel (5 EEG samples), 2) accuracy in multiple EEG channels and across different stages of the sleep-wake cycles (75 EEG samples), 3) capacity to detect lateralization of spikes (6 EEG samples), 4) accuracy after application of a machine-learning mechanism (11 EEG samples), and 5) accuracy during wakefulness only (8 EEG samples). Our method was accurate during all stages of the sleep-wake cycle and improved after the application of the machine-learning mechanism. Spikes were correctly lateralized in all cases. Our automated method was accurate in quantifying and detecting the lateralization of interictal spikes in raw unprocessed EEG samples.

Electrical status epilepticus in sleep: clinical presentation and pathophysiology

Electrical status epilepticus in sleep involves an electroencephalographic pattern where interictal epileptiform activity is potentiated in the transition from wakefulness to sleep. Near-continuous spikes and waves that occupy a significant proportion of nonrapid eye movement sleep appear as a result of sleep-potentiated epileptiform activity. This electroencephalographic pattern appears in different electroclinical syndromes that present three common characteristics with different degrees of severity: seizures, sleep-potentiated epileptiform activity, and neuropsychologic regression. Continuous spikes and waves during sleep comprise the severest epileptic encephalopathy in the electroclinical spectrum. Landau-Kleffner syndrome presents with intermediate severity. Some "benign" pediatric focal epileptic syndromes represent the mildest end of this continuum. Based on published data, we provide a framework for clinical and electrical events. The underlying mechanisms leading to sleep potentiation of epileptiform activity in electrical status epilepticus in sleep are incompletely understood. A genetic basis or acquired early developmental insult may disrupt the normal maturation of neuronal networks. These factors may dynamically alter normal processes of brain development, leading to an age-related pattern of electroclinical expression of electrical status epilepticus in sleep.

The effect of levetiracetam on focal nocturnal epileptiform activity during sleep--a placebo-controlled double-blind cross-over study

Electric Status Epilepticus during Sleep (ESES) occurs in children with and without epilepsy. It may be related to disturbances as autism spectrum disorder, attention-deficit hyperactivity disorder and acquired aphasia (Landau-Kleffner syndrome). Antiepileptic drug (AED) treatment has been reported in small studies without placebo control. This study was designed to assess AED effect in a placebo-controlled double-blind cross-over study. Levetiracetam (LEV) was chosen based on clinical evidence. Eighteen patients fulfilled the inclusion criteria. The mean spike index at baseline was 56, falling to a mean of 37 at the end of the LEV treatment period. Assessed with a 2-way ANOVA, there is a significant treatment effect (p<0.0002). To the best of our knowledge, this is the first placebo-controlled double-blind cross-over study for any AED in patients with ESES. The effect of LEV is comparable with its effect in treatment of epileptic seizures.

Automatic detection and analysis of the EEG sharp wave-slow wave patterns evoked by fluorinated inhalation anesthetics

OBJECTIVE

The aim of this study was to develop a method for the automatic detection of sharp wave-slow wave (SWSW) patterns evoked in EEG by volatile anesthetics and to identify the patterns' characteristics.

METHODS

The proposed method consisted in the k-NN classification with a reference set obtained using expert knowledge, the morphology of the EEG patterns and the condition for their synchronization. The decision rules were constructed and evaluated using 24h EEG records in ten patients.

RESULTS

The sensitivity, specificity and selectivity of the method were 0.88 ± 0.10, 0.81 ± 0.13 and 0.42 ± 0.16, respectively. SWSW patterns' recruitment was strictly dependent on anesthetic concentration. SWSW patterns evoked by different types of anesthetics expressed different characteristics.

CONCLUSIONS

Synchronization criterion and adequately selected morphological features of "slow wave" were sufficient to achieve the high sensitivity and specificity of the method.

SIGNIFICANCE

The monitoring of SWSW patterns is important in view of possible side effects of volatile anesthetics. The analysis of SWSW patterns' recruitment and morphology could be helpful in the diagnosis of the anesthesia effects on the CNS.

Levetiracetam reduces the frequency of interictal epileptiform discharges during NREM sleep in children with ADHD

BACKGROUND

Symptoms of attention deficit hyperactivity disorder (ADHD) are more common in children with epilepsy than in the general paediatric population. Epileptiform discharges in EEG may be seen in children with ADHD also in those without seizure disorders. Sleep enhances these discharges which may be suppressed by levetiracetam.

AIM

To assess the effect of levetiracetam on focal epileptiform discharges during sleep in children with ADHD.

METHOD

In this retrospective study a new semi-automatic quantitative method based on the calculation of spike index in 24-h ambulatory EEG recordings was applied. Thirty-five ADHD children, 17 with focal epilepsy, one with generalised epilepsy, and 17 with no seizure disorder were evaluated. Follow-up 24-h EEG recordings were performed after a median time of four months.

RESULTS

Mean spike index was 50 prior to levetiracetam treatment and 21 during treatment. Seventeen children had no focal interictal epileptiform discharges in EEG at follow-up. Five children had a more than 50% reduction in spike index. Thus, a more than 50% reduction in spike index was found in 22/35 children (63%). Out of these an improved behaviour was noticed in 13 children (59%).

CONCLUSION

This study shows that treatment with levetiracetam reduces interictal epileptiform discharges in children with ADHD. There is a complex relationship between epilepsy, ADHD and epileptiform activity, why it is a need for prospective studies in larger sample sizes, also to ascertain clinical benefits.

Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were recruited. Cathodal tDCS and sham stimulation were applied to the epileptic focus, before sleep (1 mA; 20 min). Cathodal tDCS did not reduce the spike-index in any of the patients.

Landau-Kleffner syndrome in Norway: long-term prognosis and experiences with the health services and educational systems

We have conducted a retrospective study based on the medical records of 19 children with Landau-Kleffner syndrome and semistructured interviews of their parents. There was considerable heterogeneity in the children's symptoms. Eleven children were followed for more than 10 years (mean=14.4 years); four have normal language, four have moderate language problems, and three have no functional verbal language today. Late-onset language decline, short duration of the initial aphasic period, and marked fluctuations in speech abilities appeared to be associated with a positive outcome with respect to future language skills. The parents reported having to argue strongly with the health authorities and educational system to obtain a correct diagnosis and receive adequate help. Their main concern was not being taken seriously when they expressed their worries, and they expressed a strong wish for someone who could ensure that appropriate support measures were implemented and who could coordinate assistance.

Do sleep-deprived EEG recordings reflect spike index as found in full-night EEG recordings?

The sleep EEGs of many children with neurodevelopmental disorders reveal epileptiform activity. The aim of this study was to compare spike index (SI) in full-night recordings with SI in sleep-deprived EEGs in the morning; EEGs were obtained over 24 hours using ambulatory equipment. Sixteen children between the ages of 7 and 12 years were included in the study. They had to wake up at 3:00 AM and go to sleep again at 7:30 AM. Epileptiform activity was quantified, and SIs of full-night and morning recordings were compared. Two patients did not fall asleep. In one recording there was a technical problem that made calculations impossible. SIs calculated from EEGs obtained during a short nap in the morning were comparable to those calculated from full-night recordings. There seems to be a higher failure rate during morning recordings because of patients not falling asleep.

Attention-deficit hyperactivity disorder and nocturnal epileptiform activity in children with epilepsy admitted to a national epilepsy center

The aim of this study was to determine if there exists a relationship between attention-deficit hyperactivity disorder (ADHD) and the quantity of focal nocturnal epileptiform activity on the EEG (FNEA) measured as the percentage of epileptiform activity during non-REM sleep (spike index). This was accomplished with a prospective study of children aged 6-14 years consecutively admitted to our center. Of 362 patients, 44 (12.2%) had previously been diagnosed with ADHD. Twenty-four-hour ambulatory EEG recording and assessment of ADHD according to DSM-IV were performed in 46 children suspected of having ADHD. ADHD was diagnosed in 30. We could not find any correlation between the spike index in 8 children with FNEA and the severity of their ADHD symptoms. This study is underpowered and should be considered a pilot study. There is a need for further investigation of a possible causal effect of FNEA on ADHD symptoms in larger cohorts of patients with FNEA.

Decrease in propagation of interictal epileptiform activity after introduction of levetiracetam visualized with electric source imaging

Different neuroimaging techniques (fMRI, spectroscopy, PET) are being used to evaluate candidate drugs in pharmacological development. In patients with epilepsy fast propagation of the epileptiform activity between different brain areas occurs. Electric Source Imaging (ESI), in contrast to the aforementioned techniques, has a millisecond time resolution, allowing visualization of this fast propagation. The purpose of the current project was to use ESI to investigate whether introduction of an antiepileptic drug (levetiracetam, LEV) would change the propagation patterns of the interictal epileptiform activity. Thirty patients with epilepsy were subject to an EEG recording before (pre-LEV) and after (in-LEV) introduction of LEV. Interictal spikes with similar topographic distribution were averaged within each subject, and a distributed source model was used to localize the EEG sources of the epileptiform activity. The temporal development of the activity within 20 regions of interest (ROIs) was determined, and source propagation between different regions was compared between the pre-LEV and in-LEV recordings. Patients with epileptic seizures showed propagation in 22/24 identified spike types in the pre-LEV recordings. In the in-LEV recordings only 7/15 spike types showed propagation, and six of these seven propagating spikes were recorded in patients with poor effect of treatment. Also in patients without seizures LEV tended to suppress propagation. We conclude that the observed suppression of source propagation can be considered as an indicator of effective antiepileptic treatment. ESI might thus become a useful tool in the early clinical evaluation of new candidate drugs in pharmacological development.

The slow-wave component of the interictal epileptiform EEG discharges

The interictal epileptiform discharges (IEDs) consist of a fast component (FC; spike or sharp-wave) followed by a slow-wave component (SC). Our purpose was to assess the intra-individual variance, the diagnostic significance and the effect of sleep on the SC. Ninety-nine EEG recordings from 50 consecutive patients with IEDs were analysed. We measured the duration (ms) of the SC (SC-duration), while the amplitude of the SC was divided by the amplitude of the FC yielding a normalized value (SC/FC amplitude-ratio). Intra-individual, intra- and inter-recording coefficients of variation (CV) were calculated for the SC-duration and SC/FC amplitude-ratio. The correlation with the diagnosis, and the effect of sleep was analysed. The SC-duration and the SC/FC amplitude-ratio had low CV (<27%). The SC-duration was not correlated with the diagnosis. The SC/FC amplitude-ratio was significantly higher in the patients with generalized epilepsies as compared with the localization-related ones, and it was higher in the patients with idiopathic epilepsies as compared with the symptomatic ones. These predictors were independent. The SC/FC amplitude-ratio of the patients with idiopathic epilepsy increased significantly during sleep. We conclude that the SC-duration and SC/FC amplitude-ratio are stable parameters. The amplitude of the SC in relation to the fast component is larger in patients with generalized and idiopathic epilepsies, suggesting higher degree of cortical inhibition in these patients, possibly corresponding to specific protective mechanisms.