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Purpose: The spike-wave index (SWI) is a key feature in the diagnosis of electrical status epilepticus during slow-wave sleep. Estimating the SWI manually is time-consuming and is subject to interrater and intrarater variability. Use of automated detection software would save time. Thereby, this software will consistently detect a certain EEG phenomenon as epileptiform and is not influenced by human factors. To determine noninferiority in calculating the SWI, we compared the performance of a commercially available spike detection algorithm (P13 software, Persyst Development Corporation, San Diego, CA) with human expert consensus., Methods: The authors identified all prolonged EEG recordings for the diagnosis or follow-up of electrical status epilepticus during slow-wave sleep carried out from January to December 2018 at an epilepsy tertiary referral center. The SWI during the first 10 minutes of sleep was estimated by consensus of two human experts. This was compared with the SWI calculated by the automated spike detection algorithm using the three available sensitivity settings: "low," "medium," and "high." In the software, these sensitivity settings are denoted as perception values., Results: Forty-eight EEG recordings from 44 individuals were analyzed. The SWIs estimated by human experts did not differ from the SWIs calculated by the automated spike detection algorithm in the "low" perception mode (P = 0.67). The SWIs calculated in the "medium" and "high" perception settings were, however, significantly higher than the human expert estimated SWIs (both P < 0.001)., Conclusions: Automated spike detection (P13) is a useful tool in determining SWI, especially when using the "low" sensitivity setting. Using such automated detection tools may save time, especially when reviewing larger epochs., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2019 by the American Clinical Neurophysiology Society.)

Background: Epilepsy and migraine are paroxysmal neurological conditions associated with disturbances of cortical excitability. No useful biomarkers to monitor disease activity in these conditions are available. Phase clustering was previously described in electroencephalographic (EEG) responses to photic stimulation and may be a potential epilepsy biomarker., Objective: The objective of this study was to investigate EEG phase clustering in response to transcranial magnetic stimulation (TMS), compare it with photic stimulation in controls, and explore its potential as a biomarker of genetic generalized epilepsy or migraine with aura., Methods: People with (possible) juvenile myoclonic epilepsy (JME), migraine with aura, and healthy controls underwent single-pulse TMS with concomitant EEG recording during the interictal period. We compared phase clustering after TMS with photic stimulation across the groups using permutation-based testing., Results: We included eight people with (possible) JME (five off medication, three on), 10 with migraine with aura, and 37 controls. The TMS and photic phase clustering spectra showed significant differences between those with epilepsy without medication and controls. Two phase clustering-based indices successfully captured these differences between groups. One participant was tested multiple times. In this case, the phase clustering-based indices were inversely correlated with the dose of antiepileptic medication. Phase clustering did not differ between people with migraine and controls., Conclusion: We present methods to quantify phase clustering using TMS-EEG and show its potential value as a measure of brain network activity in genetic generalized epilepsy. Our results suggest that the higher propensity to phase clustering is not shared between genetic generalized epilepsy and migraine., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: User safety and the quality of diagnostics on the epilepsy monitoring unit (EMU) depend on reaction to seizures. Online seizure detection might improve this. While good sensitivity and specificity is reported, the added value above staff response is unclear. We ascertained the added value of two electroencephalograph (EEG) seizure detection algorithms in terms of additional detected seizures or faster detection time., Methods: EEG-video seizure recordings of people admitted to an EMU over one year were included, with a maximum of two seizures per subject. All recordings were retrospectively analyzed using Encevis EpiScan and BESA Epilepsy. Detection sensitivity and latency of the algorithms were compared to staff responses. False positive rates were estimated on 30 uninterrupted recordings (roughly 24 h per subject) of consecutive subjects admitted to the EMU., Results: EEG-video recordings used included 188 seizures. The response rate of staff was 67%, of Encevis 67%, and of BESA Epilepsy 65%. Of the 62 seizures missed by staff, 66% were recognized by Encevis and 39% by BESA Epilepsy. The median latency was 31 s (staff), 10 s (Encevis), and 14 s (BESA Epilepsy). After correcting for walking time from the observation room to the subject, both algorithms detected faster than staff in 65% of detected seizures. The full recordings included 617 h of EEG. Encevis had a median false positive rate of 4.9 per 24 h and BESA Epilepsy of 2.1 per 24 h., Conclusions: EEG-video seizure detection algorithms may improve reaction to seizures by improving the total number of seizures detected and the speed of detection. The false positive rate is feasible for use in a clinical situation. Implementation of these algorithms might result in faster diagnostic testing and better observation during seizures., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Standardized terminology for computer-based assessment and reporting of EEG has been previously developed in Europe. The International Federation of Clinical Neurophysiology established a taskforce in 2013 to develop this further, and to reach international consensus. This work resulted in the second, revised version of SCORE (Standardized Computer-based Organized Reporting of EEG), which is presented in this paper. The revised terminology was implemented in a software package (SCORE EEG), which was tested in clinical practice on 12,160 EEG recordings. Standardized terms implemented in SCORE are used to report the features of clinical relevance, extracted while assessing the EEGs. Selection of the terms is context sensitive: initial choices determine the subsequently presented sets of additional choices. This process automatically generates a report and feeds these features into a database. In the end, the diagnostic significance is scored, using a standardized list of terms. SCORE has specific modules for scoring seizures (including seizure semiology and ictal EEG patterns), neonatal recordings (including features specific for this age group), and for Critical Care EEG Terminology. SCORE is a useful clinical tool, with potential impact on clinical care, quality assurance, data-sharing, research and education., (Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Epilepsy is difficult to diagnose using routine EEG recordings of short duration in patients who have low seizure frequency. Long-term EEG may be useful but is impractical in an out-of-hospital setting. We investigated whether single-channel scalp EEG placed behind the earlobe is suitable for seizure identification during prolonged EEG monitoring. Scalp EEG samples were selected from subjects over 15 years of age, and comprised two segments of either background followed by seizure or background followed by background. Bipolar EEG derivations in three directions (F8-T8, C4-T8 and T8-P8) were evaluated for the presence of a seizure by two experienced reviewers. For each EEG segment containing a seizure, one pair of electrodes was oriented towards the suspected region of seizure onset, while two pairs of electrodes were oriented elsewhere. The EEG data contained five frontally localized seizures, five parietal, five temporal, two occipital, and four primary or secondary generalized seizures. The sensitivity and specificity for recognition of seizures was 86% and 95% for Reviewer 1, and 79% and 99% for Reviewer 2, respectively. When identifying a seizure with the lead orientation towards the region of seizure onset, both reviewers identified 20 out of 21 seizures (95%). When the lead was not oriented towards the region of seizure onset, the reviewers identified 34 and 30 out of 42 ictal records correctly, respectively. These results suggest that it is possible to identify epileptic seizures by bipolar EEG derivation using only two scalp electrodes. Lead orientation towards the suspected region of seizure onset is important for optimal detection sensitivity.

Background: Long-term video-EEG monitoring (LTM) aims to record the habitual event and is a useful diagnostic tool for neurological paroxysmal clinical events. In our epilepsy monitoring unit (EMU) setting, admissions are usually planned to last up to five days. We ascertained time taken for the recording of a first event and determined correlations between different clinical characteristics and timings., Methods: We retrospectively reviewed diagnostic and classification LTM recording performed at a tertiary epilepsy centre., Results: Sixty-three recordings were reviewed. Most subjects (89%) had events at least once a week prior to admission. In 40 (63%) a habitual event was recorded, mostly (93%) within the first two days. No events were recorded on day four or five. A few characteristics were associated with a trend for events occurring earlier (events more than once a week vs less than once a week, motor symptoms compared with aura or dyscognitive events, and reduction of antiepileptic drugs versus no reduction)., Conclusions: Our finding suggests that, for diagnostic event recording in people with epilepsy or PNEA, a maximum recording time of three days is sufficient in two thirds of them, if event frequency is at least once a week. In the remaining third, prolonged recording up to five days did not result in capturing a clinical event. For these individuals, shorter admission could be planned, for example for 2days rather than 5days., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Even though it is known that neonatal seizures are associated with acute brain lesions, the relationship of electroencephalographic (EEG) seizures to acute perinatal brain lesions visible on magnetic resonance imaging (MRI) has not been objectively studied. EEG source localization is successfully used for this purpose in adults, but it has not been sufficiently explored in neonates. Therefore, we developed an integrated method for ictal EEG dipole source localization based on a realistic head model to investigate the utility of EEG source imaging in neonates with postasphyxial seizures. We describe here our method and compare the dipole seizure localization results with acute perinatal lesions seen on brain MRI in 10 full-term infants with neonatal encephalopathy. Through experimental studies, we also explore the sensitivity of our method to the electrode positioning errors and the variations in neonatal skull geometry and conductivity. The localization results of 45 focal seizures from 10 neonates are compared with the visual analysis of EEG and MRI data, scored by expert physicians. In 9 of 10 neonates, dipole locations showed good relationship with MRI lesions and clinical data. Our experimental results also suggest that the variations in the used values for skull conductivity or thickness have little effect on the dipole localization, whereas inaccurate electrode positioning can reduce the accuracy of source estimates. The performance of our fused method indicates that ictal EEG source imaging is feasible in neonates and with further validation studies, this technique can become a useful diagnostic tool., (Copyright © 2012 Wiley Periodicals, Inc.)

The electroencephalography (EEG) signal has a high complexity, and the process of extracting clinically relevant features is achieved by visual analysis of the recordings. The interobserver agreement in EEG interpretation is only moderate. This is partly due to the method of reporting the findings in free-text format. The purpose of our endeavor was to create a computer-based system for EEG assessment and reporting, where the physicians would construct the reports by choosing from predefined elements for each relevant EEG feature, as well as the clinical phenomena (for video-EEG recordings). A working group of EEG experts took part in consensus workshops in Dianalund, Denmark, in 2010 and 2011. The faculty was approved by the Commission on European Affairs of the International League Against Epilepsy (ILAE). The working group produced a consensus proposal that went through a pan-European review process, organized by the European Chapter of the International Federation of Clinical Neurophysiology. The Standardised Computer-based Organised Reporting of EEG (SCORE) software was constructed based on the terms and features of the consensus statement and it was tested in the clinical practice. The main elements of SCORE are the following: personal data of the patient, referral data, recording conditions, modulators, background activity, drowsiness and sleep, interictal findings, "episodes" (clinical or subclinical events), physiologic patterns, patterns of uncertain significance, artifacts, polygraphic channels, and diagnostic significance. The following specific aspects of the neonatal EEGs are scored: alertness, temporal organization, and spatial organization. For each EEG finding, relevant features are scored using predefined terms. Definitions are provided for all EEG terms and features. SCORE can potentially improve the quality of EEG assessment and reporting; it will help incorporate the results of computer-assisted analysis into the report, it will make possible the build-up of a multinational database, and it will help in training young neurophysiologists., (Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.)

EEG inter-burst interval (IBI) and its evolution is a robust parameter for grading hypoxic encephalopathy and prognostication in newborns with perinatal asphyxia. We present a reliable algorithm for the automatic detection of IBIs. This automated approach is based on adaptive segmentation of EEG, classification of segments and use of temporal profiles to describe the global distribution of EEG activity. A pediatric neurologist has blindly scored data from 8 newborns with perinatal postasphyxial encephalopathy varying from mild to severe. 15 minutes of EEG have been scored per patient, thus totaling 2 hours of EEG that was used for validation. The algorithm shows good detection accuracy and provides insight into challenging cases that are difficult to detect.

Unlabelled: The objective of this review was to evaluate the available medical literature concerning the electroencephalogram (EEG) during hypertensive disorders of pregnancy. All articles found during a MEDLINE and Embase database search on the subject of EEG differences associated with hypertensive disorders in pregnancy were screened for eligibility. In all, 22 articles which describe the EEG during preeclampsia (PE)/eclampsia were retrieved. Abnormal EEG findings were observed in the majority of the preeclamptic/eclamptic patients, consisting of slow waves most frequently localized in the occipital lobe, as well as spike discharges. The EEG abnormalities in PE/eclampsia were reversible in the majority of the cases. We conclude that these described abnormalities may be interpreted as a warning sign of deterioration of brain function in PE/eclampsia. However, some caution regarding this conclusion is advised because most of the retrieved articles were published in the 1950s and 1960s, and were not consistent with current clinical guidelines or medical terminology. Further research is needed to establish the clinical value of implementing EEGs in the assessment of the preeclamptic/eclamptic patient., Target Audience: Obstetricians & Gynecologists, Neurologists, Family Physicians., Learning Objectives: After completion of this educational activity, the obstetrician, gynecologist and neurologist should be better able to evaluate whether the EEG is normal for pregnancy; distinguish EEG abnormalities in hypertensive disorders in pregnancy, and assess the value of EEG abnormalities in preeclampsia (PE)/eclampsia for the detection of early signs of ischemia.

Ictal nystagmus (IN) is an uncommon phenomenon characterized by rhythmic saccadic eye movements occurring during epileptic seizures. We report a newborn baby with severe birth asphyxia, undergoing long-term video EEG monitoring with electro-oculogram (EOG), who showed irregular IN when eye movements crossed the midline from left to right and vice versa, resulting in large amplitude of the nystagmoid movements. The nystagmus was followed 15 to 29 seconds later by ictal discharges in the occipital regions. MRI of the brain showed features suggestive of periventricular leukomalacia. This interesting combination of findings suggests a complex mechanism for IN of cortical or subcortical ictal rhythms, which results in (a) the generation of subcortical electrical discharges in the pons and midbrain, causing nystagmoid eye movements, and (b) subsequent occipital spiking. We conclude that this clinical manifestation supports the existence of functioning cortical-subcortical connections between the brainstem ocular motor centers and the occipital cortex at birth.

The purpose of this study was to evaluate the contribution of quantitative EEG (qEEG) to an animal model of cerebral air embolism (CAE). In 12 anesthetized pigs, air was injected into the internal carotid artery, and hyperbaric oxygen (HBO) treatment was started either after 3 minutes or after 60 minutes (United States Navy Treatment Table 6). Off-line spectral analysis was used to determine the frequency content of the EEG signal, and factor analysis was performed to determine the frequency ranges that optimally showed the changes in the power spectrum. Factor analysis revealed two factors that represented different and independent spectral changes during embolization: 0.5 to 7.3 Hz (band 1) and 26.4 to 30.3 Hz (band 2). Shortly after embolization, the power in both bands decreased to a minimum, representing an isoelectric EEG in 11 out of the 12 animals. EEG differences between animals were considerable, despite standardized doses of injected air, and qEEG can objectively assess and quantify these differences in immediate impact of air embolism on brain function. Also, qEEG enabled monitoring of the recovery from the initial embolic event and of the response on treatment. The initial recovery was much more protracted in band 2 than in band 1, but even after completing HBO treatment, qEEG values did not return to baseline values in all animals. In addition, two animals did not survive until the end of the HBO treatment, and qEEG proved to be superior to the other measured hemodynamic variables to detect and ensure a deterioration of brain function. This study showed that qEEG monitoring has significant additional value to monitoring HBO treatment.

Transcranial magnetic stimulation (TMS) with electroencephalography (EEG), that is TMS‐EEG, may assist in managing epilepsy. We systematically reviewed the quality of reporting and findings in TMS‐EEG studies on people with epilepsy and healthy controls, and on healthy individuals taking anti‐seizure medication. We searched the Cochrane Library, Embase, PubMed and Web of Science databases for original TMS‐EEG studies comparing people with epilepsy and healthy controls, and healthy subjects before and after taking anti‐seizure medication. Studies should involve quantitative analyses of TMS‐evoked EEG responses. We evaluated the reporting of study population characteristics and TMS‐EEG protocols (TMS sessions and equipment, TMS trials and EEG protocol), assessed the variation between protocols, and recorded the main TMS‐EEG findings. We identified 20 articles reporting 14 unique study populations and TMS methodologies. The median reporting rate for the group of people with epilepsy parameters was 3.5/7 studies and for the TMS parameters was 13/14 studies. TMS protocols varied between studies. Fifteen out of 28 anti‐seizure medication trials in total were evaluated with time‐domain analyses of single‐pulse TMS‐EEG data. Anti‐seizure medication significantly increased N45, and decreased N100 and P180 component amplitudes but in marginal numbers (N45: 8/15, N100: 7/15, P180: 6/15). Eight articles compared people with epilepsy and controls using different analyses, thus limiting comparability. The reporting quality and methodological uniformity between studies evaluating TMS‐EEG as an epilepsy biomarker is poor. The inconsistent findings question the validity of TMS‐EEG as an epilepsy biomarker. To demonstrate TMS‐EEG clinical applicability, methodology and reporting standards are required. [ABSTRACT FROM AUTHOR]

It is not fully understood how seizures terminate and why some seizures are followed by a period of complete brain activity suppression, postictal generalized EEG suppression. This is clinically relevant as there is a potential association between postictal generalized EEG suppression, cardiorespiratory arrest and sudden death following a seizure. We combined human encephalographic seizure data with data of a computational model of seizures to elucidate the neuronal network dynamics underlying seizure termination and the postictal generalized EEG suppression state. A multi-unit computational neural mass model of epileptic seizure termination and postictal recovery was developed. The model provided three predictions that were validated in EEG recordings of 48 convulsive seizures from 48 subjects with refractory focal epilepsy (20 females, age range 15-61 years). The duration of ictal and postictal generalized EEG suppression periods in human EEG followed a gamma probability distribution indicative of a deterministic process (shape parameter 2.6 and 1.5, respectively) as predicted by the model. In the model and in humans, the time between two clonic bursts increased exponentially from the start of the clonic phase of the seizure. The terminal interclonic interval, calculated using the projected terminal value of the log-linear fit of the clonic frequency decrease was correlated with the presence and duration of postictal suppression. The projected terminal interclonic interval explained 41% of the variation in postictal generalized EEG suppression duration (P < 0.02). Conversely, postictal generalized EEG suppression duration explained 34% of the variation in the last interclonic interval duration. Our findings suggest that postictal generalized EEG suppression is a separate brain state and that seizure termination is a plastic and autonomous process, reflected in increased duration of interclonic intervals that determine the duration of postictal generalized EEG suppression. [ABSTRACT FROM AUTHOR]

People with epilepsy often report seizures precipitated by stress. This is believed to be due to effects of stress hormones, such as cortisol, on neuronal excitability. Cortisol, regardless of stress, is released in hourly pulses, whose effect on epileptic activity is unknown. We tested the relation between cortisol levels and the incidence of epileptiform abnormalities in the electroencephalogram of people with focal epilepsy. Morning cortisol levels were measured in saliva samples obtained every 15 min. Interictal epileptiform discharges were determined in the same time periods. We investigated the relationship between cortisol levels and the epileptiform discharges distinguishing persons with from those without stress-precipitated seizures (linear mixed model), and analysed the contribution of individual, epilepsy and recording characteristics with multivariable analysis. Twenty-nine recordings were performed in 21 individuals. Cortisol was positively related to incidence of epileptiform discharges (β = 0.26, P = 0.002) in people reporting stress-sensitive seizures, but not those who did not report stress sensitivity (β = -0.07, P = 0.64). The relationship between cortisol and epileptiform discharges was positively associated only with stress sensitivity of seizures (β = 0.31, P = 0.005). The relationship between cortisol levels and incidence of interictal epileptiform discharges in people with stress-sensitive seizures suggests that stress hormones influence disease activity in epilepsy, also under basal conditions. [ABSTRACT FROM AUTHOR]

Objectives: To compare electroencephalography (EEG) findings during pregnancy and postpartum in women with normotensive pregnancies and pregnancies complicated by hypertensive disorders. Also the health related quality of life postpartum was related to these EEG findings. Materials and Methods: An observational case-control study in a university hospital in the Netherlands. Twenty-nine normotensive and 58 hypertensive pregnant women were included. EEG’s were recorded on several occasions during pregnancy and 6–8 weeks postpartum. Postpartum, the women filled out health related quality of life questionnaires. Main outcome measures were qualitative and quantitative assessments on EEG, multidimensional fatigue inventory, Short Form (36) Health Survey and EuroQoL visual analogue scale. Results: In women with severe preeclampsia significantly lower alpha peak frequency, more delta and theta activity bilaterally and a higher EEG Sum Score were seen. Postpartum, these women showed impaired mental health, mental fatigue and social functioning, which could not be related to the EEG findings. Conclusions: Severe preeclamptic patients show more EEG abnormalities and have impaired mental wellbeing postpartum, but these findings are not correlated. [ABSTRACT FROM AUTHOR]

A novel automated algorithm is proposed to approximate the seizure onset zone (SOZ), while providing reproducible output. The SOZ, a surrogate marker for the epileptogenic zone (EZ), was approximated from intracranial electroencephalograms (iEEG) of nine people with temporal lobe epilepsy (TLE), using three methods: (1) Total ripple length (TRL): Manually segmented high-frequency oscillations, (2) Rippleness (R): Area under the curve (AUC) of the autocorrelation functions envelope, and (3) Autoregressive model residual variation (ARR, novel algorithm): Time-variation of residuals from autoregressive models of iEEG windows. TRL, R, and ARR results were compared in terms of separability, using Kolmogorov-Smirnov tests, and performance, using receiver operating characteristic (ROC) curves, to the gold standard for SOZ delineation: visual observation of ictal video-iEEGs. TRL, R, and ARR can distinguish signals from iEEG channels located within the SOZ from those outside it (p < 0.01). The ROC AUC was 0.82 for ARR, while it was 0.79 for TRL, and 0.64 for R. ARR outperforms TRL and R, and may be applied to identify channels in the SOZ automatically in interictal iEEGs of people with TLE. ARR, interpreted as evidence for nonharmonicity of high-frequency EEG components, could provide a new way to delineate the EZ, thus contributing to presurgical workup. [ABSTRACT FROM AUTHOR]

Neonatal electroencephalogram (EEG), though often perceived as being difficult to record and interpret, is relatively easy to study due to the immature nature of the brain, which expresses only a few well-defined set of patterns. The EEG interpreter needs to be aware of the maturational changes as well as the effect of pathological processes and medication on brain activity. It gives valuable information for the treatment and prognostication in encephalopathic neonates. In this group, serial EEGs or EEG monitoring often gives additional information regarding deterioration/improvement of the brain function or occurrence of seizures. [ABSTRACT FROM AUTHOR]

Abstract: Objective: (a) To relate MRI patterns of brain injury to somatosensory evoked potentials (SEPs), and (b) to determine the prognostic value of SEPs in addition to continuous EEG monitoring (cEEG) and cerebral imaging, in term asphyxiated newborns. Methods: Fifty one consecutive neonates were studied. Survivors were followed for at least 2years. cEEG, started within 24h, was done for ⩾24h and scored. SEPs and MRIs were performed in the first week. Brain injury patterns were classified. Results: Bilaterally abnormal SEPs had a sensitivity of 90% (28/31) and specificity of 85% (17/20) in predicting a poor outcome, defined as death or severe handicap. SEPs were of particular value in predicting outcome in isolated symmetrical white matter injury and predicting the development of hemiparesis in isolated asymmetrical watershed injury. Binary logistic regression analysis revealed a significant relation to outcome separately for cEEG, deep grey matter injury on MRI and SEPs. SEPs provided additional value when added to cEEG and MRI in the model (p =0.034). Conclusions: SEPs are of additional prognostic value after term birth asphyxia. Significance: In certain patterns of postasphyxial neonatal brain injury like asymmetrical watershed lesions and symmetrical white matter injury, EPs are complementary to information obtained from cEEG and MRI for prognostication. [Copyright &y& Elsevier]