Interictal epileptiform discharges in persons without a history of seizures: what do they mean?

EEG before chimeric antigen receptor T-cell therapy and early after onset of immune effector cell-associated neurotoxicity syndrome

BACKGROUND

Immune effector cell-associated neurotoxicity syndrome (ICANS) is common after chimeric antigen receptor T-cell (CAR-T) therapy.

OBJECTIVE

This study aimed to assess the impact of preinfusion electroencephalography (EEG) abnormalities and EEG findings at ICANS onset for predicting ICANS risk and severity in 56 adult patients with refractory lymphoma undergoing CAR-T therapy.

STUDY DESIGN

EEGs were conducted at the time of lymphodepleting chemotherapy and shortly after onset of ICANS.

RESULTS

Twenty-eight (50%) patients developed ICANS at a median time of 6 days after CAR-T infusion. Abnormal preinfusion EEG was identified as a risk factor for severe ICANS (50% vs. 17%, P = 0.036). Following ICANS onset, EEG abnormalities were detected in 89% of patients [encephalopathy (n = 19, 70%) and/or interictal epileptiform discharges (IEDs) (n = 14, 52%)]. Importantly, IEDs seemed to be associated with rapid progression to higher grades of ICANS within 24 h.

CONCLUSIONS

If confirmed in a large cohort of patients, these findings could establish the basis for modifying current management guidelines, enabling the identification of patients at risk of neurotoxicity, and providing support for preemptive corticosteroid use in patients with both initial grade 1 ICANS and IEDs at neurotoxicity onset, who are at risk of neurological impairment.

Abnormal Electroencephalogram Findings and Its Correlation With Clinical Features From Pediatric Patients in Psychiatric Clinic

Objective: We aimed to evaluate the occurrence of electroencephalogram (EEG) abnormalities in pediatric patients attending an outpatient psychiatry clinic at a tertiary center. We examined the rates of abnormalities and specific findings based on demographics, specific diagnoses, and clinical severity. Methods: This study included pediatric patients who underwent EEG at the outpatient psychiatry clinic. Patient demographics, psychiatric diagnosis, intellectual disability, intelligent quotient (IQ) score, family history of psychiatric disorders, and Clinical Global Impression-Severity (CGI-S) score were obtained through retrospective electronic health record analysis. The rate of EEG abnormalities was calculated, and specific abnormal findings were reviewed. Relationships between the rate of EEG abnormalities and diagnosis, severity, IQ, and age at EEG examination were analyzed. Results: Of 319 patients who underwent EEG, 21.3% (68 patients) of patients exhibited abnormalities, including background abnormalities (14.7%, 47 patients), interictal epileptiform discharges (IEDs) (10.3%, 33 patients), and a slow posterior dominant rhythm (3.8%, 10 patients). The frontal region was the most commonly affected area. Neurodevelopmental disorders (NDDs) had the most frequent abnormalities (29.8%), followed by anxiety (16.7%), sleep (14.3%), mood (11.7%), psychotic (5%), and conduct disorders (0%). Disease severity did not correlate with the rate of EEG abnormalities. Adjusted for age, sex, severity, and family history, patients with EEG abnormalities exhibited lower IQ scores. Conclusion: EEG abnormalities were common in pediatric patients with psychiatric disorders, with background abnormalities detected as frequently as IEDs. Disease severity was not associated with EEG abnormality, while IQ scores showed a negative correlation.

Immature Status Epilepticus Alters the Temporal Relationship between Hippocampal Interictal Epileptiform Discharges and High-frequency Oscillations

The aim was to investigate the long-term effects of a single episode of immature Status Epilepticus (SE) on the excitability of the septal and temporal hippocampus in vitro, by studying the relationship between interictal-like epileptiform discharges (IEDs) and high-frequency oscillations (HFOs; Ripples, Rs and Fast Ripples, FRs). A pentylenetetrazol-induced Status Epilepticus-(SE)-like generalized seizure was induced at postnatal day 20 in 22 male and female juvenile rats, sacrificed >40 days later to prepare hippocampal slices. Spontaneous IEDs induced by Mg2+-free ACSF were recorded from the CA3 area of temporal (T) or septal (S) slices. Recordings were band-pass filtered off-line revealing Rs and FRs and a series of measurements were conducted, with mean values compared with those obtained from age-matched controls (CTRs). In CTR S (vs T) slices, we recorded longer R & FR durations, a longer HFO-IED temporal overlap, higher FR peak power and more frequent FR initiation preceding IEDs (% events). Post-SE, in T slices all types of events duration (IED, R, FR) and the time lag between their onsets (R-IED, FR-IED, R-FR) increased, while FR/R peak power decreased; in S slices, the IED 1st population spike and the FR amplitudes, the R and FR peak power and the (percent) events where Rs or FRs preceded IEDs all decreased. The CA3 IED-HFO relationship offers insights to the septal-to-temporal synchronization patterns; its post-juvenile-SE changes indicate permanent modifications in the septotemporal excitability gradient. Moreover, these findings are in line to region-specific regulation of various currents post-SE, as reported in literature.

Prevalence of epileptiform electroencephalographic abnormalities in people without a history of seizures: A systematic review and meta-analysis

Abnormal patterns identified on electroencephalogram (EEG) are one of the primary diagnostic tests for epilepsy. However, epidemiological studies have established that both benign and epileptiform abnormalities (EAs) occur on the EEG of nonepileptic, seizure-free people as well. The reported rates of EAs in nonepileptic, seizure-free populations vary, and the true prevalence is unknown. The primary objective of this systematic review and meta-analysis was to estimate the overall prevalence of EAs in the EEG of people without a history of seizures. Secondary aims were to characterize (1) the cortical localization of focal abnormalities, (2) the proportion of findings that occurred during standard EEG stimulation protocols, and (3) the persistence and implications of abnormalities at follow-up. A comprehensive electronic search of six bibliographic databases was completed: Embase, MEDLINE, PsycInfo, Cumulative Index of Nursing and Allied Health Literature, Cochrane Central Register for Controlled Trials, and Web of Science. No search date restrictions were applied. Overall effect size was calculated using a generalized linear mixed-effects model. Fifty-three studies, totaling 73 990 individuals, met our inclusion criteria. The overall point prevalence of EAs was 1.74% (95% confidence interval [CI] = 1.13-2.67). Due to the risk of bias in the literature, especially from participant selection, we believe this to be an overestimate of the true prevalence. Prevalence of EAs was greater in children (2.45%, 95% CI = 1.41-4.21) and the elderly (5.96%, 95% CI = 1.39-22.13) compared with adults (.93%, 95% CI = .48-1.80). Reports of developing epilepsy after an EA-positive EEG were rare. The likelihood of subsequent positive findings on follow-up EEG may be as high as 50%. Our study has limitations in that males were overrepresented in the study samples, there is substantial heterogeneity among studies, and many studies provided insufficient detail about their exclusion criteria. Nonetheless, our estimates provide benchmark data for future studies examining EAs in clinical populations, particularly behavioral and psychiatric populations.

Ripples of Hyperexcitability in Epilepsy, Autism, and Inattention

The Association Between Early Childhood Onset Epilepsy and Attention-Deficit Hyperactivity Disorder (ADHD) in 3237 Children and Adolescents With Autism Spectrum Disorder (ASD): A Historical Longitudinal Cohort Data Linkage Study Carson L, Parlatini V, Safa T, Baig B, Shetty H, Phillips-Owen J, Prasad V, Downs J. Eur Child Adolesc Psychiatry. 2022. doi:10.1007/s00787-022-02041-3 Children and young people with Autism Spectrum Disorder (ASD) have an increased risk of comorbidities, such as epilepsy and Attention-Deficit/Hyperactivity Disorder (ADHD). However, little is known about the relationship between early childhood epilepsy (below age 7) and later ADHD diagnosis (at age 7 or above) in ASD. In this historical cohort study, we examined this relationship using an innovative data source, which included linked data from routinely collected acute hospital paediatric records and childhood community and inpatient psychiatric records. In a large sample of children and young people with ASD (N = 3237), we conducted a longitudinal analysis to examine early childhood epilepsy as a risk factor for ADHD diagnosis while adjusting for potential confounders, including socio-demographic characteristics, intellectual disability, family history of epilepsy and associated physical conditions. We found that ASD children and young people diagnosed with early childhood epilepsy had nearly a twofold increase in risk of developing ADHD later in life, an association which persisted after adjusting for potential confounders (adjusted OR = 1.72, CI95% = 1.13-2.62). This study suggests that sensitive monitoring of ADHD symptoms in children with ASD who have a history of childhood epilepsy may be important to promote early detection and treatment. It also highlights how linked electronic health records can be used to examine potential risk factors over time for multimorbidity in neurodevelopmental conditions.

Computer-assisted analysis of routine electroencephalogram to identify hidden biomarkers of epilepsy: protocol for a systematic review

INTRODUCTION

The diagnosis of epilepsy frequently relies on the visual interpretation of the electroencephalogram (EEG) by a neurologist. The hallmark of epilepsy on EEG is the interictal epileptiform discharge (IED). This marker lacks sensitivity: it is only captured in a small percentage of 30 min routine EEGs in patients with epilepsy. In the past three decades, there has been growing interest in the use of computational methods to analyse the EEG without relying on the detection of IEDs, but none have made it to the clinical practice. We aim to review the diagnostic accuracy of quantitative methods applied to ambulatory EEG analysis to guide the diagnosis and management of epilepsy.

METHODS AND ANALYSIS

The protocol complies with the recommendations for systematic reviews of diagnostic test accuracy by Cochrane. We will search MEDLINE, EMBASE, EBM reviews, IEEE Explore along with grey literature for articles, conference papers and conference abstracts published after 1961. We will include observational studies that present a computational method to analyse the EEG for the diagnosis of epilepsy in adults or children without relying on the identification of IEDs or seizures. The reference standard is the diagnosis of epilepsy by a physician. We will report the estimated pooled sensitivity and specificity, and receiver operating characteristic area under the curve (ROC AUC) for each marker. If possible, we will perform a meta-analysis of the sensitivity and specificity and ROC AUC for each individual marker. We will assess the risk of bias using an adapted QUADAS-2 tool. We will also describe the algorithms used for signal processing, feature extraction and predictive modelling, and comment on the reproducibility of the different studies.

ETHICS AND DISSEMINATION

Ethical approval was not required. Findings will be disseminated through peer-reviewed publication and presented at conferences related to this field.

PROSPERO REGISTRATION NUMBER

CRD42022292261.

Is epileptiform activity related to developmental language disorder? Findings from the HelSLI study

Objective

To study if interictal epileptiform discharges (IEDs) are associated with language performance or pre-/perinatal factors in children with developmental language disorder (DLD).

Methods

We recorded routine EEG in wake and sleep in 205 children aged 2.9-7.1 years with DLD, without neurologic diseases or intellectual disability. We examined the language performance of the children and collected data on pre-/perinatal factors.

Results

Interictal epileptiform discharges were not associated with lower language performance. Children with so-called "rolandic", i.e. centrotemporoparietal, IEDs had better language skills, but age explained this association. Most pre-/perinatal factors evaluated did not increase the risk of rolandic IEDs, except for maternal smoking (OR 4.4, 95% CI 1.4-14). We did not find electrical status epilepticus during slow-wave sleep (ESES)/spike-and-wave activation in sleep (SWAS) in any children.

Conclusions

Interictal epileptiform discharges are not associated with lower language performance, and ESES/SWAS is not common in children with DLD.

Significance

Routine EEGs do not bring additional information about language performance in children with DLD who do not have any neurologic diseases, seizures, intellectual disability, or regression of language development.

An interactive framework for the detection of ictal and interictal activities: Cross-species and stand-alone implementation

BACKGROUND AND OBJECTIVE

Despite advances on signal analysis and artificial intelligence, visual inspection is the gold standard in event detection on electroencephalographic recordings. This process requires much time of clinical experts on both annotating and training new experts for this same task. In scenarios where epilepsy is considered, the need for automatic tools is more prominent, as both seizures and interictal events can occur on hours- or days-long recordings. Although other solutions have already been proposed, most of them are not integrated on clinical and basic science environments due to their complexity and required specialization. Here we present a pipeline that arises from coordinated efforts between life-science researchers, clinicians and data scientists to develop an interactive and iterative workflow to train machine-learning tools for the automatic detection of electroencephalographic events in a variety of scenarios.

METHODS

The approach consists on a series of subsequent steps covering data loading and configuration, event annotation, model training/re-training and event detection. With slight modifications, the combination of these blocks can cope with a variety of scenarios. To illustrate the flexibility and robustness of the approach, three datasets from clinical (patients of Dravet Syndrome) and basic research environments (mice model of the same disease) were evaluated. From them, and in response to researchers' daily needs, four real world examples of interictal event detection and seizure classification tasks were selected and processed.

RESULTS

Results show that the current approach was of great aid for event annotation and model development. It was capable of creating custom machine-learning solutions for each scenario with slight adjustments on the analysis protocol, easily accessible to users without programming skills. Final annotator similarity metrics reached values above 80% on all cases of use, reaching 92.3% on interictal event detection on human recordings.

CONCLUSIONS

The presented framework is easily adaptable to multiple real world scenarios and the interactive and ease-to-use approach makes it manageable to clinical and basic researches without programming skills. Nevertheless, it is conceived so data scientists can optimize it for specific scenarios, improving the knowledge transfer between these fields.

Scalp HFO rates decrease after successful epilepsy surgery and are not impacted by the skull defect resulting from craniotomy

Epilepsy surgery can achieve seizure freedom in selected pediatric candidates, but reliable postsurgical predictors of seizure freedom are missing. High frequency oscillations (HFO) in scalp EEG are a new and promising biomarker of treatment response. However, it is unclear if the skull defect resulting from craniotomy interferes with HFO detection in postsurgical recordings. We considered 14 children with focal lesional epilepsy who underwent presurgical evaluation, epilepsy surgery, and postsurgical follow-up of ≥ 1 year. We identified the nearest EEG electrodes to the skull defect in the postsurgical MRI. We applied a previously validated automated HFO detector to determine HFO rates in presurgical and postsurgical EEG. Overall, HFO rates showed a positive correlation with seizure frequency (p < 0.001). HFO rates in channels over the HFO area decreased following successful epilepsy surgery, irrespective of their proximity to the skull defect (p = 0.005). HFO rates in channels outside the HFO area but near the skull defect showed no increase following surgery (p = 0.091) and did not differ from their contralateral channels (p = 0.726). Our observations show that the skull defect does not interfere with postsurgical HFO detection. This supports the notion that scalp HFO can predict postsurgical seizure freedom and thus guide therapy management in focal lesional epilepsy.

Microscale dynamics of electrophysiological markers of epilepsy

OBJECTIVE

Interictal discharges (IIDs) and high frequency oscillations (HFOs) are established neurophysiologic biomarkers of epilepsy, while microseizures are less well studied. We used custom poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) microelectrodes to better understand these markers' microscale spatial dynamics.

METHODS

Electrodes with spatial resolution down to 50 µm were used to record intraoperatively in 30 subjects. IIDs' degree of spread and spatiotemporal paths were generated by peak-tracking followed by clustering. Repeating HFO patterns were delineated by clustering similar time windows. Multi-unit activity (MUA) was analyzed in relation to IID and HFO timing.

RESULTS

We detected IIDs encompassing the entire array in 93% of subjects, while localized IIDs, observed across < 50% of channels, were seen in 53%. IIDs traveled along specific paths. HFOs appeared in small, repeated spatiotemporal patterns. Finally, we identified microseizure events that spanned 50-100 µm. HFOs covaried with MUA, but not with IIDs.

CONCLUSIONS

Overall, these data suggest that irritable cortex micro-domains may form part of an underlying pathologic architecture which could contribute to the seizure network.

SIGNIFICANCE

These results, supporting the possibility that epileptogenic cortex comprises a mosaic of irritable domains, suggests that microscale approaches might be an important perspective in devising novel seizure control therapies.

40-Hz auditory stimulation for intracranial interictal activity: A pilot study

OBJECTIVES

To study the effects of auditory stimuli on interictal epileptiform discharge (IED) rates evident with intracranial monitoring.

MATERIALS AND METHODS

Eight subjects undergoing intracranial EEG monitoring for refractory epilepsy participated in this study. Auditory stimuli consisted of a 40-Hz tone, a 440-Hz tone modulated by a 40-Hz sinusoid, Mozart's Sonata for Two Pianos in D Major (K448), and K448 modulated by a 40-Hz sinusoid (modK448). Subjects were stratified into high- and low-IED rate groups defined by baseline IED rates. Subject-level analyses identified individual responses to auditory stimuli, discerned specific brain regions with significant reductions in IED rates, and examined the influence auditory stimuli had on whole-brain sigma power (12-16 Hz).

RESULTS

All subjects in the high baseline IED group had a significant 35.25% average reduction in IEDs during the 40-Hz tone; subject-level reductions localized to mesial and lateral temporal regions. Exposure to Mozart K448 showed significant yet less homogeneous responses. A post hoc analysis demonstrated two of the four subjects with positive IED responses had increased whole-brain power at the sigma frequency band during 40-Hz stimulation.

CONCLUSIONS

Our study is the first to evaluate the relationship between 40-Hz auditory stimulation and IED rates in refractory epilepsy. We reveal that 40-Hz auditory stimuli may be a noninvasive adjunctive intervention to reduce IED burden. Our pilot study supports the future examination of 40-Hz auditory stimuli in a larger population of subjects with high baseline IED rates.

Subclinical epileptiform activity accelerates the progression of Alzheimer's disease: A long-term EEG study

OBJECTIVE

While many studies suggest that patients with Alzheimer's disease have a higher chance for developing epileptic seizures, only a few studies are available examining independent epileptic discharges. The major aims of our study was to determine the prevalence of subclinical epileptiform activity (SEA) in AD compared to healthy elderly controls with the hypothesis that SEA is more frequent in AD than in cognitively normal individuals. Another aim was to analyze the effect of baseline SEA captured with electroencephalography on the progression of the disease with longitudinal cognitive testing.

METHODS

We investigated 52 Alzheimer patients with no history of epileptic seizures and 20 healthy individuals. All participants underwent a 24-hour electroencephalography, neurology, neuroimaging and neuropsychology examination. Two independent raters analyzed visually the electroencephalograms and both raters were blind to the diagnoses. Thirty-eight Alzheimer patients were enrolled in a 3-year long prospective follow-up study with yearly repeated cognitive evaluation.

RESULTS

Subclinical epileptiform discharges were recorded significantly (p:0.018) more frequently in Alzheimer patients (54%) than in healthy elderly (25%). Epileptiform discharges were associated with lower performance scores in memory. Alzheimer patients with spikes showed 1.5-times faster decline in global cognitive scores than patients without (p < 0.001). The decline in cognitive performance scores showed a significant positive correlation with spike frequency (r:+0.664; p < 0.001).

CONCLUSIONS

Subclinical epileptiform activity occurs in half of Alzheimer patients who have never suffered epileptic seizures. Alzheimer patients with subclinical epileptiform activity showed accelerated cognitive decline with a strong relation to the frequency and spatial distribution (left temporal) of spikes.

SIGNIFICANCE

Our findings suggest the prominent role of epileptiform discharges in the pathomechanism of Alzheimer's disease which might serve as potential therapeutic target.

Ambulatory EEG to Classify the Epilepsy Syndrome

SUMMARY

Recording of interictal epileptiform discharges to classify the epilepsy syndrome is one of the most common indications for ambulatory EEG. Ambulatory EEG has superior sampling compared with standard EEG recordings and advantages in terms of cost-effectiveness and convenience compared with a prolonged inpatient EEG study. Ambulatory EEG allows for EEG recording in all sleep stages and transitional states, which can be very helpful in capturing interictal epileptiform discharges. In the absence of interictal epileptiform discharges or in patients with atypical events, the characterization of an epilepsy syndrome may require recording of the habitual events. Diagnostic ambulatory EEG can be a useful alternative to inpatient video-EEG monitoring in a selected number of patients with frequent events who do not require medication taper or seizure testing for surgical localization.

Scalp high-frequency oscillation rates are higher in younger children

High-frequency oscillations in scalp EEG are promising non-invasive biomarkers of epileptogenicity. However, it is unclear how high-frequency oscillations are impacted by age in the paediatric population. We prospectively recorded whole-night scalp EEG in 30 children and adolescents with focal or generalized epilepsy. We used an automated and clinically validated high-frequency oscillation detector to determine ripple rates (80-250 Hz) in bipolar channels. Children < 7 years had higher high-frequency oscillation rates (P = 0.021) when compared with older children. The median test-retest reliability of high-frequency oscillation rates reached 100% (iqr 50) for a data interval duration of 10 min. Scalp high-frequency oscillation frequency decreased with age (r = -0.558, P = 0.002), whereas scalp high-frequency oscillation duration and amplitude were unaffected. The signal-to-noise ratio improved with age (r = 0.37, P = 0.048), and the background ripple band activity decreased with age (r = -0.463, P = 0.011). We characterize the relationship of scalp high-frequency oscillation features and age in paediatric patients. EEG intervals of ≥ 10 min duration are required for reliable measurements of high-frequency oscillation rates. This study is a further step towards establishing scalp high-frequency oscillations as a valid epileptogenicity biomarker in this vulnerable age group.

Effect of Transcranial Alternating Current Stimulation for the Treatment of Chronic Insomnia: A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Clinical Trial

BACKGROUND

Not all adults with chronic insomnia respond to the recommended therapeutic options of cognitive behavioral therapy and approved hypnotic drugs. Transcranial alternating current stimulation (tACS) may offer a novel potential treatment modality for insomnia.

OBJECTIVES

This study aimed to examine the efficacy and safety of tACS for treating adult patients with chronic insomnia.

METHODS

Sixty-two participants with chronic primary insomnia received 20 daily 40-min, 77.5-Hz, 15-mA sessions of active or sham tACS targeting the forehead and both mastoid areas in the laboratory on weekdays for 4 consecutive weeks, followed by a 4-week follow-up period. The primary outcome was response rate measured by the Pittsburgh Sleep Quality Index (PSQI) at week 8. Secondary outcomes were remission rate, insomnia severity, sleep onset latency (SOL), total sleep time (TST), sleep efficiency, sleep quality, daily disturbances, and adverse events at the end of the 4-week intervention and at the 4-week follow-up.

RESULTS

Of 62 randomized patients, 60 completed the trial. During the 4-week intervention, 1 subject per group withdrew due to loss of interest and time restriction, respectively. Based on PSQI, at 4-week follow-up, the active group had a higher response rate compared to the sham group (53.4% [16/30] vs. 16.7% [5/30], p = 0.009), but remission rates were not different between groups. At the end of the 4-week intervention, the active group had higher response and remission rates than the sham group (p < 0.001 and p = 0.026, respectively). During the trial, compared with the sham group, the active group showed a statistically significant decrease in PSQI total score, a shortened SOL, an increased TST, improved sleep efficiency, and improved sleep quality (p < 0.05 or p < 0.001). Post hoc analysis revealed that, in comparison with the sham group, the active group had improved symptoms, except for daily disturbances, at the end of the 4-week intervention, and significant improvements in all symptoms at the 4-week follow-up. No adverse events or serious adverse responses occurred during the study.

CONCLUSION

The findings show that the tACS applied in the present study has potential as an effective and safe intervention for chronic insomnia within 8 weeks.

Psychogenic Pseudosyncope: Clinical Features, Diagnosis and Management

Psychogenic Pseudosyncope (PPS) is the appearance of Transient Loss of Consciousness (TLOC) in which movements are absent, but there are no hemodynamic and electroencephalographic modifications as are induced by gravitational challenges which characterize syncope and true loss of consciousness. For younger and adult populations, a detailed history is crucial for the diagnosis. Clinical clues that should raise the suspicion for PPS include prolonged duration of the LOC, eye closure during the episode, unusual triggers, no recognizable prodromes and the high frequency of attacks. The presence of an established diagnosis of syncope should not deter from the concomitant diagnosis of PPS. The gold standard for a proper diagnosis of PPS is the documentation by a tilt test of normal hemodynamic and electroencephalographic parameters, when recorded during an attack. Treatment of PPS, based on the clear and empathetic communication of the diagnosis, can lead to an immediate reduction of attack frequency and lower the need to call on emergency services. Pharmacological treatment of associated psychiatric disorders and psychological interventions may be beneficial in patients with PPS. Cognitive-behavioural therapy holds the most reliable evidence of efficacy. In the present review, we aimed to address PPS with historical aspects, main clinical features and diagnostic tests, current diagnostic classification, underlying neurobiological abnormalities, management and therapy.

Seizures in Children

Epilepsy is one of the most common neurologic disorders seen in children, with the highest incidence in the first year of life. Diagnostic accuracy can be challenging because many seizure mimics must be considered. Electroencephalography and neuroimaging can be critical in determining etiology and syndrome. Genetic testing is a high-yield endeavor, particularly in early-life epilepsies. Up to one-fourth of children with epilepsy will develop drug-resistant seizures. Comorbidities are very common in children with epilepsy, including intellectual disability in 25% and learning disability and attention-deficit/hyperactivity disorder in a significant minority. These comorbidities must be recognized and addressed as part of the child's overall care.

Evaluation of electrocardiographic parameters in patients with epileptic seizure

The aim of the study is to evaluate the changes in electrocardiographic parameters, including QTc dispersion (QTcd), Tpeak-Tend (Tp-e)/QTc ratio and P-wave dispersion (Pd), during the period without seizure activation in patients, presented to the emergency department (ED) with epileptic seizures. This prospective case-control study was conducted between January 2017 and January 2018. Patients, over 18 years old and presented to the ED with epileptic seizure, were consecutively included in the study. Interictal period ECGs of patients were obtained at least 2 hours after the end of the postictal period. ST-segment changes, QT interval, corrected QT interval (QTc), QTd, Pd, Tp-e, Tp-e dispersion (Tp-ed), Tp-e/QTc ratio and arrhythmias were evaluated in interictal ECGs. A total of 103 epileptic patients and 31 control cases were included in the study. Heart rate, QTc, QTcd, Pd, Tp-ed and Tp-e/QTc ratio were significantly higher in the epilepsy group than in the control group (p < 0.05 for all values). No statistically significant difference in those parameters was observed between the patients with known epilepsy and the patients who had seizure for the first time. There was also no statistically significant difference between patients who had recurrent seizures during the observation period and who did not. The patients with epileptic seizures had increased Pd, QTd, QTcd, Tp-ed and Tpe/QTc ratio during interictal period compared to healthy subjects. These electrocardiographic changes might be associated with an increased risk of dysrhythmia. However, prospective large cohorts with short- and long-term follow-up are needed for clinical reflections.

A Framework Proposal to Follow-Up on Preclinical Convulsive Signals of a New Molecular Entity in First-in-Human Studies Using Electroencephalographic Monitoring

Traditionally, in dose-escalating first-in-human (FiH) studies, a dose cap with a 10-fold safety margin to the no observed effect level in animals is implemented if convulsive events are observed in animals. However, the convulsive risk seen in animals does not generally translate to humans. Several lines of evidence are summarized indicating that in a dose-escalating setting, electroencephalographic epileptiform abnormalities occur at lower doses than clinical convulsive events. Therefore, we propose to consider the occurrence of epileptiform abnormalities in toxicology studies as premonitory signals for convulsions in dose-escalating FiH studies. Compared with the traditional dose-cap approach, this may allow the exploration of higher doses in FiH and, subsequently, phase II studies without compromising human safety. Similarly, the presence or absence of electroencephalographic epileptiform abnormalities may also aid the assessment of proconvulsive risk in situations of increased perpetrator burden as potentially present in pharmacokinetic and/or pharmacodynamic drug-drug interactions.

Association between Interictal Epileptiform Discharges and Autistic Spectrum Disorder

It has been reported that bioelectric alterations in an electroencephalogram (EEG) may play an etiological role in neurodevelopmental disorders. The clinical impact of interictal epileptiform discharges (IEDs) in association with autistic spectrum disorder (ASD) is unknown. The Autism Diagnostic Interview-Revised (ADI-R) is one of the gold standards for the diagnosis of autistic spectrum disorder. Some studies have indicated high comorbidity of IED and ASD, while other studies have not supported an association between the central symptoms of autism and IED. This review examines the high comorbidity and clinical impact of IED; patients with epilepsy are excluded from the scope of this review. ASD can be disabling and is diagnosed at an average age of 5 years old, at which point the greatest neurological development has occurred. If an association between IED and ASD is identified, a clinical tool that entails an innocuous procedure could enable diagnosis in the first years of life. However, in the absence of reports that prove an association between IED and ASD, patients should not be subjected to expensive treatments, such as the administration of anticonvulsant therapies.

Valproic acid potently inhibits interictal-like epileptiform activity in prefrontal cortex pyramidal neurons

Valproic acid has a long-standing reputation of effectively treating the symptoms of not only epilepsy but also psychiatric conditions. In the latter, the exact mechanism by which valproate exerts its effect remains unclear. In this study, epileptiform bursts were recorded from pyramidal neurons in the prefrontal cortex (the brain region thought to be involved in psychiatric disorders) using the patch-clamp technique. An extracellular solution with no magnesium ions and elevated potassium levels that is known to induce epileptiform activity in vitro was used. Because of their short durations, the epileptiform bursts were regarded as interictal-like epileptiform activity, which is believed to be involved in cognitive impairment. Interictal discharges occur in many neuropsychiatric disorders as well as in healthy population. Epileptic activity in prefrontal cortex pyramidal neurons was potently inhibited by two therapeutic concentrations of valproic acid (20 μM and 200 μM). Moreover, valproate suppressed spontaneous excitatory postsynaptic potentials. Epileptiform bursts were fully inhibited by NMDA receptor antagonist, which suggests that epileptiform activity is driven by NMDA receptors. The inhibition of excitability in prefrontal cortex pyramidal neurons by valproate was also shown. This study shows that it is possible to evoke NMDA-dependent epileptiform activity in prefrontal cortex pyramidal neurons in vitro. We suggest that the prefrontal cortex is a good region for studying the influence of drugs on interictal epileptiform activity.

Electroencephalogram (EEG) for children with autism spectrum disorder: evidential considerations for routine screening

Routine electroencephalograms (EEG) are not recommended as a screen for epileptic discharges (EDs) in current practice guidelines for children with autism spectrum disorder (ASD). However, a review of the research from the last three decades suggests that this practice should be reevaluated. The significant comorbidity between epilepsy and ASD, its shared biological pathways, risk for developmental regression, and cognitive challenges demand increased clinical investigation requiring a proactive approach. This review highlights and explains the need for screening EEGs for children with ASD. EEG would assist in differentiating EDs from core features of ASD and could be included in a comprehensive assessment. EEG also meets the demand for evidence-based precision medicine and focused care for the individual, especially when overlapping processes of development are present.

Electroencephalographic Patterns During Routine Polysomnography in Childhood and Association With Future Epilepsy Diagnosis

STUDY OBJECTIVES

Evaluate the frequency of abnormal electroencephalograph (EEG) records during pediatric polysomnography (PSG) at a tertiary referral center and determine frequency with which these records may predict future seizures and a diagnosis of epilepsy.

METHODS

Retrospective review of all pediatric PSG reports from 2013 was performed. Demographics, medical history, indications, diagnoses, and EEG reports were collected. Patients were evaluated for follow-up of future diagnosis of seizure or epilepsy over a 30-month period.

RESULTS

A total of 1,969 studies (56.9% males, median age 7 years) were analyzed. Abnormal EEG results were detected in 314 studies (15.9%); abnormalities included slowing in 75 (3.8%) and interictal epileptiform discharges (IEDs) in 239 (12.1%). Incidental abnormal EEG recordings were found in 186 patients (9.4%) without a prior diagnosis of seizure or epilepsy. Incidental IEDs were recorded in 126 (6.4%) and were most commonly focal (66.7%). Ten patients received follow-up EEG without clinical follow-up, 68 received clinical follow-up without follow-up EEG, and 29 received both within a 30-month period. Follow-up EEG was normal in only 30.8% of cases. Thirteen patients in the 30-month window received a new diagnosis of epilepsy. Each new diagnosis occurred in patients with preexisting neurodevelopmental disorders at high risk for seizures.

CONCLUSIONS

Abnormal EEG during pediatric PSG without additional history of seizure is a poor prognosticator for a future diagnosis of epilepsy. Abnormalities detected on PSG did not always portend abnormal diagnostic EEG and thus its utility to corroborate findings does not appear to be supported without additional clinical context concerning for seizure.

Paediatric electroencephalograph: The benefits of guidelines

AIM

The electroencephalogram (EEG) is an important but often over-relied upon investigation in evaluating paroxysmal events of childhood. The UK National Institute for Health and Care Excellence (NICE) guidelines for epilepsy help clinicians decide which children should/should not have an EEG. Would introduction of these guidelines in our hospital change the ordering practices of our hospital clinicians? Would introduction reduce unnecessary tests and improve rapidity of obtaining an EEG?

METHODS

Paediatric EEG requests, results and, where possible, the patient hospital chart were reviewed before and after introduction of an EEG request form (Appendix I) which provided ordering advice as per the NICE epilepsy guideline. Patient age, sex, distance from hospital and ethnicity were reviewed. Also evaluated was clinical indication and time from ordering to performing the EEG.

RESULTS

Prior to the new EEG form, 56% of the EEG requests fulfilled the NICE criteria; after its introduction, this increased to 83%. EEGs ordered within the NICE guidelines were abnormal on 61% of occasions, but when ordered outside of the guidelines they were abnormal only 4% of the time (P < 0.0001). After its introduction there was poor use of the new form in practice (only 29% of requests). However, the EEGs were more likely to meet ordering criteria and fewer tests were required, leading to more rapid turn-around times.

CONCLUSION

This study demonstrates the value of using guidelines to improve timeliness and reduce over-utilisation of EEGs in general paediatric practice.

Role of Epileptic Activity in Older Adults With Delirium, a Prospective Continuous EEG Study

Background/Objectives: Delirium occurs in up to 50 % of hospitalized old patients and is associated with increased morbidity and mortality. Acute medical conditions favor delirium, but the pathophysiology is unclear. Preliminary evidence from retrospective and prospective studies suggests that a substantial minority of old patients with unexplained delirium have non-convulsive seizures or status epilepticus (NCSE). Yet, seeking epileptic activity only in unexplained cases of delirium might result in misinterpretation of its actual prevalence. We aimed to systematically investigate the role of epileptic activity in all older patients with delirium regardless of the underlying etiology.

Design, Setting: Prospective observational study in a tertiary medical center. Adults >65 years with delirium underwent at least 24 h of continuous electro-encephalographic monitoring (cEEG). Background patterns and ictal and interictal epileptic discharges were identified, as well as clinical and biological characteristics.

Participants: Fifty patients were included in the study.

Results: NCSE was found in 6 (12%) patients and interictal discharges in 15 (30%). There was no difference in the prevalence of epileptic activity rates between delirium associated with an acute medical condition and delirium of unknown etiology.

Conclusion: Epileptic activity may play a substantial role in the pathophysiology of delirium by altering brain functioning and neuronal metabolism. No clinical or biological marker was found to distinguish delirious patients with or without epileptic activity, underlining the importance of cEEG in this context.

Adult EEG

After more than 85 years of development and use in clinical practice, the electroencephalogram (EEG) remains a dependable, inexpensive, and useful diagnostic tool for the investigation of the electrophysiologic activity of the brain. The advent of digital technology has led to greater sophistication and multiple software applications to extend the utility of EEG beyond the confines of the laboratory. Despite the discovery of new waveforms, basic neurophysiologic principles remain essential to the clinical care of patients. Patterns in the interictal EEG make it possible to clarify the differential diagnosis of paroxysmal neurological events, classify seizure type and epilepsy syndromes, and characterize and quantify seizures when ictal recordings are obtained. EEG can also demonstrate cerebral dysfunction when structural imaging is normal to detect focal or lateralized abnormalities in patients with encephalopathy. High-density EEG with electrical source imaging has improved localization in candidates for epilepsy surgery. Quantitative EEG and broadband EEG are advancing our understanding of the functional processes of the brain itself.

Neuropsychiatric effects of epilepsy in developmental disorders

PURPOSE OF REVIEW

The overlap of neuropsychiatric illness and developmental disability continues to be prominently recognized in clinical practice and in the academic literature. Theoretical and practical considerations may represent a frontier for understanding brain and behavior relationships. The purpose of this review is to explore this common relationship and report on recent literature that helps advance the larger fields of psychiatry and neurology.

RECENT FINDINGS

Overlap between developmental disability, epilepsy, and neuropsychiatric illness may be more common than originally thought. Excessive excitatory neurotransmitter activity may be present in epilepsy and in autism spectrum disorder. Specific seizure types may be associated with features of developmental disabilities and neuropsychiatric conditions.

SUMMARY

Neuropsychiatric illness is common in epilepsy and more frequent in developmental disabilities than generally recognized. Seizure foci in the temporal lobe may play a significant role. Brain connectivity and specific neurotransmitter systems are active areas of investigation. Antiepileptic drugs may improve neuropsychiatric symptoms in persons with developmental disability and epilepsy.

Critérios de decisão para a definição de exames médicos ocupacionais em atividades críticas: proposição de modelo e exemplos de aplicação no trabalho em altura

Resumo Introdução: no Brasil, tem-se observado uma grande disparidade entre os protocolos de exames médicos utilizados para avaliar trabalhadores que exercem atividades críticas. Objetivo: propor e verificar a aplicabilidade de um modelo baseado em critérios para a tomada de decisão na definição de exames médicos ocupacionais na avaliação de aptidão de trabalhadores que executam atividades críticas de trabalho. Métodos: ensaio baseado em pesquisa bibliográfica. O modelo proposto baseia-se no princípio As Low As Reasonably Practicable (ALARP), do Health and Safety Executive (HSE). O modelo foi aplicado a duas condições clínicas que podem resultar em eventos agudos de perda de consciência e levar à queda durante o trabalho em altura, caso falhem ou não tenham sido adotadas medidas de segurança: diabetes e epilepsia. Discussão: verificou-se que o modelo proposto se mostrou aplicável para os dois exemplos analisados, oferecendo subsídios para a tomada de decisão do médico do trabalho em relação à necessidade de se investigar condições clínicas que podem ocasionar acidentes fatais durante a realização de atividades críticas de trabalho.

Incidence and impact of subclinical epileptiform activity in Alzheimer's disease

OBJECTIVE

Seizures are more frequent in patients with Alzheimer's disease (AD) and can hasten cognitive decline. However, the incidence of subclinical epileptiform activity in AD and its consequences are unknown. Motivated by results from animal studies, we hypothesized higher than expected rates of subclinical epileptiform activity in AD with deleterious effects on cognition.

METHODS

We prospectively enrolled 33 patients (mean age, 62 years) who met criteria for AD, but had no history of seizures, and 19 age-matched, cognitively normal controls. Subclinical epileptiform activity was assessed, blinded to diagnosis, by overnight long-term video-electroencephalography (EEG) and a 1-hour resting magnetoencephalography exam with simultaneous EEG. Patients also had comprehensive clinical and cognitive evaluations, assessed longitudinally over an average period of 3.3 years.

RESULTS

Subclinical epileptiform activity was detected in 42.4% of AD patients and 10.5% of controls (p = 0.02). At the time of monitoring, AD patients with epileptiform activity did not differ clinically from those without such activity. However, patients with subclinical epileptiform activity showed faster declines in global cognition, determined by the Mini-Mental State Examination (3.9 points/year in patients with epileptiform activity vs 1.6 points/year in patients without; p = 0.006), and in executive function (p = 0.01).

INTERPRETATION

Extended monitoring detects subclinical epileptiform activity in a substantial proportion of patients with AD. Patients with this indicator of network hyperexcitability are at risk for accelerated cognitive decline and might benefit from antiepileptic therapies. These data call for more sensitive and comprehensive neurophysiological assessments in AD patient evaluations and impending clinical trials. Ann Neurol 2016;80:858-870.

Association of Interictal Epileptiform Discharges with Sleep and Anti-Epileptic Drugs

BACKGROUND

The presence of interictal epileptiform discharges (IEDs) in electroencephalogram (EEG) is diagnostic of epilepsy. Latent IEDs are activated during sleep. Anti-epileptic drugs (AEDs) improve sleep. AEDs, sleep, and IEDs may interact and affect epilepsy management.

PURPOSE

To explore the occurrence of IEDs and its association with sleep and AED status in suspected patients of epilepsy.

METHODS

EEG records were collected of suspected patients of epilepsy who reported to the electrophysiology laboratory of a tertiary care hospital during 1 year. The anthropometric details, clinical presentations, and AED status of the patients were recorded from the EEG records. Patients were divided into 2 categories based on whether AEDs had been started prior to the EEG evaluation (category-I) or not (category-II). The occurrences of IEDs in EEG recordings in both categories were analyzed.

RESULTS

In 1 year, 138 patients were referred for diagnostic EEG evaluation. One-hundred-two patients fulfilled the inclusion criteria, of which 57 patients (53%) belonged to category-I and 45 patients (47%) belonged to category-II. Incidence of IEDs, suggestive of definite diagnosis of epilepsy in category-I was 88% and in category-II was 69%, and this difference was statistically significant (p = 0.02).

CONCLUSION

The increased proportion of IEDs in category-I patients may be due to high clinical suspicion or compounding interaction of AEDs and sleep. More extensive studies are required to delineate the complex interaction of AEDs, sleep, and IEDs so that judicious yet prompt management of epilepsy can be carried out.

Epileptiform activity in the electroencephalogram of 6-year-old children of women with epilepsy

Purpose:

To study the epileptiform discharges (EDs) in the electroencephalogram (EEG) of 6-8-year-old children of women with epilepsy (WWE).

Materials and Methods:

All children born to women with epilepsy and prospectively followed up through the Kerala Registry of Epilepsy and Pregnancy (KREP), aged 6–8 years, were invited (n = 532). Out of the 254 children who responded, clinical evaluations and a 30-min digital 18 channel EEG were completed in 185 children.

Results:

Of the 185 children examined, 37 (20%) children (19 males, 18 females) had ED in their EEG. The EDs were generalized in 7 children, and focal in 30 children. The EDs were present in the sleep record only of 16 (43%) children and in the awake record only of 6 (16%) children. Out of the 94 children for whom seizure history was available, 7 children (7.4%) had seizures (neonatal seizures: 4, febrile seizure: 1, and single nonfebrile seizure: 2) and none had history of epilepsy or recurrent nonfebrile seizures. The odds ratio (OR) for occurrence of ED in the EEG was significantly higher for children of WWE [OR = 3.5, 95% confidence interval (CI) 2.3-6.0] when compared to the published data for age-matched children of mothers without epilepsy. There was no association between the occurrence of ED and the children's maternal characteristics [epilepsy syndrome, seizures during pregnancy, maternal intelligence quotient (IQ)] or the children's characteristics [antenatal exposure to specific antiepileptic drugs (AEDs), birth weight, malformations, IQ].

Conclusion:

Children of WWE have a higher risk of epileptiform activity in their EEG when compared to healthy children in the community though none had recurrent seizures.

Interplay between interictal spikes and behavioral seizures in young, but not aged pilocarpine-treated epileptic rats

Interictal spike activity is commonly observed in the EEG of patients with epilepsy, but the causal interrelationship between interictal spikes and behavioral seizures is poorly understood. We performed long-term video-EEG monitoring of 16 epileptic rats after pilocarpine-induced status epilepticus and five control animals. To quantify the interplay between periods of spikes and seizures, we calculated the time spent with spikes as well as the time spent with seizures for each animal. Within a given subject, we found a significant correlation between these two measures in 7/11 young epileptic rats (<400 days); this correlation was positive in six cases and negative in one. By contrast, none of five aged pilocarpine-treated animals exhibited significant correlation coefficients between spike periods and seizures (>600 days, P<0.05). Instead, aged epileptic rats showed a prominent predominance for either spike periods or seizures, which might explain the absence of significant correlation in this population. We found that there is a significant interplay between interictal periods of spikes and behavioral seizures in young epileptic animals, but this association is absent during aging.

Should epileptiform discharges be treated?

To evaluate the impact of epileptiform discharges (EDs) that do not occur within seizure patterns--such as spikes, sharp waves or spike waves--on cognitive function and to discuss the circumstances under which treatment of EDs might be considered. Methods used in this article is "Review of the literature". EDs may disrupt short-term cognition in humans. Frequent EDs for a prolonged period can potentially impair long-term cognitive function in humans. However, there is conflicting evidence on the impact of EDs on long-term cognitive outcome because this relationship may be confounded by multiple factors such as underlying etiology, seizures, and medication effects. Limitations of existing studies include the lack of standardized ED quantification methods and of widely accepted automated spike quantification methods. Although there is no solid evidence for or against treatment of EDs, a non-evidence-based practical approach is suggested. EDs in otherwise asymptomatic individuals should not be treated because the risks of treatment probably outweigh its dubious benefits. A treatment trial for EDs may be considered when there is cognitive dysfunction or regression or neurologic symptoms that are unexplained by the underlying etiology, comorbid conditions, or seizure severity. In patients with cognitive or neurologic dysfunction with epilepsy or EDs, treatment may be warranted to control the underlying epileptic syndrome. EDs may cause cognitive or neurologic dysfunction in humans in the short term. There is conflicting evidence on the impact of EDs on long-term cognitive outcome. There is no evidence for or against treatment of asymptomatic ED.

Incidental epileptiform discharges in patients of a tertiary centre

OBJECTIVE

This controlled study set out to assess the rate of incidental epileptiform discharges (ED) during routine EEG and the incidence of epilepsy within a 4-year follow-up period in patients without a history of epilepsy.

METHODS

We retrospectively analyzed electroencephalography (EEG) recordings of 1750 consecutive patients referred to the Department of Neurology at the Vienna General Hospital between January 1 and December 31, 2009. The incidence of epilepsy in patients with ED and no prior history of epilepsy was compared with a disease control group matched for gender and neuroimaging findings.

RESULTS

ED were identified in 26 (4%) of 629 patients without a history of epilepsy. Sixteen (62%) of these patients developed epilepsy during follow-up compared with five (19%) of the disease controls (p=0.01), yielding an adjusted odds ratio of 8.8 (95% CI 2.1-37.7) for developing epilepsy in patients with ED and no prior history of epilepsy.

CONCLUSIONS

Incidental ED during routine EEG significantly increase the likelihood of developing epilepsy.

SIGNIFICANCE

Patients with incidental ED should be specifically asked for any signs and symptoms suggestive of seizures, since they appear more prone to develop epilepsy.

Electrophysiological biomarkers of epilepsy

In patients being evaluated for epilepsy and in animal models of epilepsy, electrophysiological recordings are carried to capture seizures to determine the existence of epilepsy. Electroencephalography recordings from the scalp, or sometimes directly from the brain, are also used to locate brain areas where seizure begins, and in surgical treatment help plan the area for resection. As seizures are unpredictable and can occur infrequently, ictal recordings are not ideal in terms of time, cost, or risk when, for example, determining the efficacy of existing or new anti-seizure drugs, evaluating potential anti-epileptogenic interventions, or for prolonged intracerebral electrode studies. Thus, there is a need to identify and validate other electrophysiological biomarkers of epilepsy that could be used to diagnose, treat, cure, and prevent epilepsy. Electroencephalography recordings in the epileptic brain contain other interictal electrophysiological disturbances that can occur more frequently than seizures, such as interictal spikes (IIS) and sharp waves, and from invasive studies using wide bandwidth recording and small diameter electrodes, the discovery of pathological high-frequency oscillations (HFOs) and microseizures. Of IIS, HFOs, and microseizures, a significant amount of recent research has focused on HFOs in the pathophysiology of epilepsy. Results from studies in animals with epilepsy and presurgical patients have consistently found a strong association between HFOs and epileptogenic brain tissue that suggest HFOs could be a potential biomarker of epileptogenicity and epileptogenesis. Here, we discuss several aspects of HFOs, as well as IIS and microseizures, and the evidence that supports their role as biomarkers of epilepsy.

MC, Lima FO, Yassuda CL, Cendes F. The impact of EEG in the diagnosis and management of patients with acute impairment of consciousness

OBJECTIVES: To assess the frequency of electroencephalogram (EEG) requests in the emergency room (ER) and intensive care unit (ICU) for patients with impairment of consciousness (IC) and its impact in the diagnosis and management. METHODS: We followed patients who underwent routine EEG from ER and ICU with IC until discharge or death. RESULTS: During the study, 1679 EEGs were performed, with 149 (8.9%) from ER and ICU. We included 65 patients and 94 EEGs to analyze. Epileptiform activity was present in 42 (44.7%). EEG results changed clinical management in 72.2% of patients. The main reason for EEG requisition was unexplained IC, representing 36.3% of all EEGs analyzed. Eleven (33%) of these had epileptiform activity. CONCLUSION: EEG is underused in the acute setting. The frequency of epileptiform activity was high in patients with unexplained IC. EEG was helpful in confirming or ruling out the suspected initial diagnosis and changing medical management in 72% of patients.

Utility of the electroencephalogram in attention deficit hyperactivity disorder

An electroencephalogram (EEG) has not been routinely utilized in the evaluation of children with attention deficit hyperactivity disorder (ADHD). The utility of the EEG in ADHD is unclear. A recent study in our laboratory using sleep and sleep deprivation routinely found one in four non-epileptic children evaluated for attention deficit disorder has epileptiform discharges in the EEG, more than half focal. The majority of abnormalities (97.5%) occur in sleep and sleep-deprived records compared to 7% in prior wake only records. A review of eight publications showed that laboratories using awake only as routine EEG recordings report a relatively low prevalence of epileptiform discharges, whereas the higher prevalence of epileptiform discharges is seen in those with more prolonged sleep recordings. We have determined that sleep deprivation and sleep are essential to rule out an abnormal EEG in attention deficit disorder. In patients with attention deficit disorder complicated by epilepsy, stimulant therapy is generally safe, provided seizures are controlled by antiepileptic medication. Patients with epilepsy or subclinical electrographic abnormalities not treated with anticonvulsants are at increased risk of seizures when stimulant therapy is introduced, especially extended-release methylphenidate. Apart from an increase in risk of seizures and need for caution in use of stimulants, studies show that epileptiform discharges in the electroencephalogram are linked to a better response of attention deficit to methylphenidate and a higher cognitive performance. Transient cognitive impairment related to subclinical electrographic abnormalities responds to antiepileptic medication. An EEG is important in selected cases of attention deficit disorder and is useful in choice of medication, especially in children with lack of awareness and transient cognitive impairment.