International Federation Of Clinical Neurophysiology Research Articles

Teaching the 6 Criteria of the International Federation of Clinical Neurophysiology for Defining Interictal Epileptiform Discharges on EEG Using a Visual Graphic

The 6 operational criteria for defining interictal epileptiform discharges (IEDs) proposed by the International Federation of Clinical Neurophysiology simplify IED identification into a series of systematic feature extraction tasks. The presence of at least 4 criteria defines a sharp transient as

Routine and sleep EEG: Minimum recording standards of the International Federation of Clinical Neurophysiology and the International League Against Epilepsy.

This article provides recommendations on the minimum standards for recording routine ("standard") and sleep electroencephalography (EEG). The joint working group of the International Federation of Clinical Neurophysiology (IFCN) and the International League Against Epilepsy (ILAE) developed the standards according to the methodology suggested for epilepsy-related clinical practice guidelines by the Epilepsy Guidelines Working Group. We reviewed the published evidence using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The quality of evidence for sleep induction methods was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. A tool for Quality Assessment of Diagnostic Studies (QUADAS-2) was used to assess the risk of bias in technical and methodological studies. Where high-quality published evidence was lacking, we used modified Delphi technique to reach expert consensus. The GRADE system was used to formulate the recommendations. The quality of evidence was low or moderate. We formulated 16 consensus-based recommendations for minimum standards for recording routine and sleep EEG. The recommendations comprise the following aspects: indications, technical standards, recording duration, sleep induction, and provocative methods.

[Basic Principles of Electroencephalogram].

Electroencephalogram(EEG)signals are mainly generated by postsynaptic potentials(EPSP)in the apical dendrites of pyramidal cells in the cortex. The mechanism of generation of interictal epileptiform discharges(IED)is paroxysmal depolarization shift(PDS). IEDs are negative towards the cortical surface and positive towards the white matter. To interpret EEG, readers should know normal EEG waveforms of wakefulness and sleep, normal variants such as wicket spikes or small sharp spikes, and artifacts such as eye movements or electromyography. Overinterpretation of EEG is a major cause of misdiagnosis; therefore, the accurate identification of IED is essential. The International Federation of Clinical Neurophysiology has proposed a criteria for the identification of IED. Long-term video-EEG is useful for correct diagnosis and localization of the epileptogenic zone in the setting of presurgical evaluation of intractable epilepsy and is also useful for the differential diagnosis of epileptic seizures and non-epileptic events. Clinical history and symptomatology are of utmost importance for correct diagnosis. Diagnosis should not be made using only EEG findings.

A quantitative approach to evaluating interictal epileptiform discharges based on interpretable quantitative criteria

ObjectiveTo provide quantitative measures of the six International Federation of Clinical Neurophysiology (IFCN) criteria for interictal epileptiform discharge (IED) identification and estimate the likelihood of a candidate IED being epileptiform. MethodsWe designed an algorithm to identify five fiducial landmarks (onset, peak, trough, slow-wave peak, offset) of a candidate IED, and from these to quantify the six IFCN features of IEDs. Another model was trained with these features to quantify the probability that the waveform is epileptiform and incorporated into a user-friendly interface. ResultsThe model’s performance is excellent (area under the receiver operating characteristic curve (AUROC) = 0.88; calibration error 0.03) but lower than human experts (receiver operating characteristic (ROC) curve is below experts’ operating points) or a deep neural-network model (SpikeNet; AUCROC = 0.97; calibration error 0.04). The six features were all significant (p<0.001), but not equally important when determining potential epileptiform nature of candidate IEDs: waveform asymmetry was the most (coefficient 0.64) and duration the least discriminative (coefficient 0.09). ConclusionsOur approach quantifies the six IFCN criteria for IED identification and combines them in an easily interpretable, accessible fashion that accurately captures the likelihood that a candidate waveform is epileptiform. SignificanceThis model may assist clinical electroencephalographers decide whether candidate waveforms are epileptiform and may assist trainees learn to identify IEDs.

Journal Club: Criteria for Defining Interictal Epileptiform Discharges in EEG.

EEG misinterpretation is a major contributor to epilepsy misdiagnosis.1,2 To help improve interictal epileptiform discharge (IED) identification, the International Federation of Clinical Neurophysiology (IFCN) proposed a set of 6 operational criteria3 (Table 1) that was subsequently validated with Class III evidence demonstrating IFCN criteria in sensor space (visual analysis) and analysis in source space (spatial filtering method applied to transform scalp signals into regions of interest) have high specificity (>95%) and sensitivity (81%–85%) for IED identification, similar to expert scorings.4

Acceptability by End-users of a Standardized Structured Format for Reporting EEG.

The report of the electroencephalogram (EEG) results has traditionally been made using free-text formats with a huge variation in descriptions due to several factors. Recently, the International Federation of Clinical Neurophysiology (IFCN) endorsed the use of the Standardized Computer-based Organized Reporting of EEG (SCORE). This system has many advantages, but only some concerns have been investigated so far. This study aimed to assess the end-users acceptability of this proposed EEG report format. A 16-item electronic survey was sent to physicians who use EEG services of a medical diagnosis clinic. Physicians had been receiving the EEG reports in free-text formats from the same three board-certified electroencephalographers for the past three years. In January 2019, the report changed to the SCORE format. The survey assessed five main topics: physician information and historical use of EEG; personal preferences; comparative aspects of the formats; impact of the new format on clinical decision-making; and satisfaction. Thirty-two of 52 have responded to the survey (61%). On average, 81% of the responders have received enough reports with the new format to reliably complete the survey. Every responder prefers the standardized compared to the free-text format. Twenty-five responders like the inclusion of the head model, and interestingly, five suggest including another legend to differentiate "slow activity" from "other abnormal activity". Virtually all responders would recommend the new format, but one-third read only the conclusion. Our findings suggest high acceptability of this standardized report format. Despite the limitations of this study, we hope these findings contribute to the improvement and expansion of standardized EEG reporting systems.

The operational definition of epileptiform discharges significantly improves diagnostic accuracy and inter-rater agreement of trainees in EEG reading.

To assess whether trainees can learn and implement the operational definition of interictal epileptiform discharges (IEDs) of the International Federation of Clinical Neurophysiology (IFCN), based on six morphological criteria, and whether its implementation improves their diagnostic performance and inter-rater agreement (IRA). Seven trainees evaluated a balanced dataset of 70 EEG samples containing sharp transients (35 from patients with epilepsy and 35 from patients with non-epileptic paroxysmal events). The gold standard was derived from video-EEG recordings of the habitual clinical episodes. The trainees individually reviewed the EEGs, blinded to all other data, in two successive training sessions, three months apart. The second session was preceded by a teaching module about the IFCN criteria, and the trainees implemented them during the second reading session. By implementing the IFCN criteria, trainees significantly improved their specificity (94.29% vs. 77.14%; p=0.01) and overall accuracy (81.43% vs. 64.29%; p=0.01) for identifying IEDs. Sensitivity also improved but did not reach the level of statistical significance (77.14% vs. 60%; p=0.07). IRA improved significantly from fair (k=0.31; 95%CI: 0.22-0.40) to high-moderate (k=0.56; 95%CI:0.46-0.67) beyond-chance agreement. Implementing the IFCN criteria significantly improves the diagnostic performance and IRA of trainees in identifying IEDs. Teaching the IFCN criteria for IEDs will increase specificity in clinical EEG and avoid over-reading, the most common cause of misdiagnosing epilepsy.

The changes in electroencephalogram parameters in patients in the somatogenic phase of acute poisoning with opioid receptor agonists

To evaluate the parameters of the electroencephalogram (EEG) using the methods of computer processing of EEG data for an approach to the analysis of possible neurophysiological mechanisms underlying the fluctuations detected in the EEG in patients in the somatogenic phase of acute poisoning with opioid receptor agonists. Thirty-one patients were examined in the somatogenic phase of acute poisoning with opioid receptor agonists with a wakefulness level 3 to 15 points on the Glasgow Coma Scale. The EEG was recorded in accordance with the recommendations of the International Federation of Clinical Neurophysiology. The indicators of electrical activity of the brain were analyzed; computer processing of EEG data, including spectral analysis, localization of equivalent dipole sources of pathological electrical activity of the brain localization of the maximum of the equivalent density of EEG oscillation currents in the neocortex, was performed. Delta-band oscillations dominated in the majority of patients (65%, 20 patients). EEG delta waves were localized mainly at the level of the thalamus; using the method of low-resolution electromagnetic tomography, the localization of the maximum of the equivalent current density of delta oscillations in the projection of the neocortex was noted. Possible neurophysiological mechanisms of «pathological» delta waves recorded in the EEG of these patients are discussed. The changes on the EEG in these patients arise as a result of a disturbance of the function of the generator mechanisms of both cortical and activating structures of the brain, while the recorded slow-wave, mainly delta activity, taking into account the recording time (somatogenic phase), may be due to the action of secondary alternating factors (hypoxia and cerebral edema).

Minimum standards for inpatient long-term video-electroencephalographic monitoring: A clinical practice guideline of the International League Against Epilepsy and International Federation of Clinical Neurophysiology.

The objective of this clinical practice guideline is to provide recommendations on the indications and minimum standards for inpatient long-term video-electroencephalographic monitoring (LTVEM). The Working Group of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology develop guidelines aligned with the Epilepsy Guidelines Task Force. We reviewed published evidence using the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) statement. We found limited high-level evidence aimed at specific aspects of diagnosis for LTVEM performed to evaluate patients with seizures and nonepileptic events. For classification of evidence, we used the Clinical Practice Guideline Process Manual of the American Academy of Neurology. We formulated recommendations for the indications, technical requirements, and essential practice elements of LTVEM to derive minimum standards used in the evaluation of patients with suspected epilepsy using GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Further research is needed to obtain evidence about long-term outcome effects of LTVEM and to establish its clinical utility.

Gold Coast diagnostic criteria: Implications for ALS diagnosis and clinical trial enrollment.

Diagnostic criteria for amyotrophic lateral sclerosis (ALS) are complex, incorporating multiple levels of certainty from possible through to definite, and are thereby prone to error. Specifically, interrater variability was previously established to be poor, thereby limiting utility as diagnostic enrollment criteria for clinical trials. In addition, the different levels of diagnostic certainty do not necessarily reflect disease progression, adding confusion to the diagnostic algorithm. Realizing these inherent limitations, the World Federation of Neurology, the International Federation of Clinical Neurophysiology, the International Alliance of ALS/MND Associations, the ALS Association (United States), and the Motor Neuron Disease Association convened a consensus meeting (Gold Coast, Australia, 2019) to consider the development of simpler criteria that better reflect clinical practice, and that could merge diagnostic categories into a single entity. The diagnostic accuracy of the novel Gold Coast criteria was subsequently interrogated through a large cross-sectional study, which established an increased sensitivity for ALS diagnosis when compared with previous criteria. Diagnostic accuracy was maintained irrespective of disease duration, functional status, or site of disease onset. Importantly, the Gold Coast criteria differentiated atypical phenotypes, such as primary lateral sclerosis, from the more typical ALS phenotype. It is proposed that the Gold Coast criteria should be incorporated into routine practice and clinical trial settings.

Importance of access to epilepsy monitoring units during the COVID-19 pandemic: consensus statement of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology.

Restructuring of healthcare services during the COVID‐19 pandemic has led to lockdown of epilepsy monitoring units (EMUs) in many hospitals. The ad‐hoc taskforce of the International League Against Epilepsy (ILAE) and the International Federation of Clinical Neurophysiology (IFCN) highlights the detrimental effect of postponing video‐EEG monitoring of patients with epilepsy and other paroxysmal events. The taskforce calls for action for continued functioning of EMUs during emergency situations, such as the COVID‐19 pandemic. Long‐term video‐EEG monitoring is an essential diagnostic service. Access to video‐EEG monitoring of the patients in the EMUs must be given high priority. Patients should be screened for COVID‐19, before admission, according to the local regulations. Local policies for COVID‐19 infection control should be adhered to during the video‐EEG monitoring. In cases of differential diagnosis in which reduction of antiseizure medication is not required, home video‐EEG monitoring should be considered as an alternative in selected patients.

P-EV002. Visual evoked potentials in neuromyelitis optica spectrum disorders

Introduction. Neuromyelitis optica spectrum disorders (NMOSD) are rare antibody-mediated disorders of the central nervous system with a predilection for the spinal cord and optic nerves. The clinical utility of evoked potential recordings (EPs) has already been established for multiple sclerosis, in particular, the abnormal visual evoked potentials (VEP) a key criterion in the McDonald diagnostic criteria for MS. On the other hand, there have been few reports on EPs in patients with NMOSD. Methods. The VEP were prospectively performed in 13 patients with NMOSD. All the patients were recruited from the outpatient clinic of a demyelinating diseases center. The recorded was done as recommended by the International Federation of Clinical Neurophysiology. All studies were conducted in accordance with ethical principles after obtaining patient informed consent. Results. We evaluated 12 women with mean age of 42 years old and one man of 25 years old. In 6 the examined eye, a response was not obtained. In the remaining 20, we found a significant increase in P100 latency without amplitude change. The relation to the VEP variable (Normal vs Abnormal), there was a statistical difference in relation to P100 Oc latencies. Conclusion. VEP is a well-known noninvasive tool for investigating the function of the visual system. Decreased amplitude and prolonged latency of VEP recording is believed to reflect the damage of axon and demyelination in the optic nerve. VEP showed a significant increase in P100 latency. VEP is a non-invasive, painless, fast and low-cost exam which provides neurophysiological data for diagnosis of NMOSD. Our results reinforce the concept of VEP evaluation is currently the standard method used to confirm the presence of clinical and subclinical Optic Neuritis.

P-OT029. Clinical neurophysiology social media engagement differs between facebook and twitter users

Introduction . In an age where social media is prevalent and long hours are spent browsing through the internet, it is crucial to understand audience engagement. Two of the most common platforms used worldwide are Twitter and Facebook. Both have provided a unique opportunity for the science world; it broadened the horizons for spreading information on current endeavors in the research world. Clinical Neurophysiology and Clinical Neurophysiology Practice, the Official Journals of the International Federation of Clinical Neurophysiology, opened the Twitter and Facebook pages on April 1, 2020. We determined what factors would alter users’ engagement. Methods . We employed a multivariate regression analysis. The tested predictor variables included ‘days elapsed since the opening (range: 1–100)’, ‘posting during weekend’, ‘introduction of a 2020 article’, ‘author interview’, ‘inclusion of guidelines or review article’, ‘COVID19-related information’, ‘number of hashtags’, ‘number of attachments’, ‘presence of colored attachment’, and ‘attachment of movie’. The dependent variable was the proportion of engaged users, defined as the number of link clicks divided by users who saw the post. Results . Posts including author interviews (p < 0.001) and those introducing guidelines/review articles (p = 0.005) independently increased the proportion of engaged Facebook users. Conversely, posts including a larger number of colored attachments (p < 0.001) and those introducing COVID19-related articles (p = 0.007) independently increased the proportion of engaged Twitter users. Conclusion . Different types of posts attracted Facebook and Twitter users. Facebook users were specifically engaged with interview-based posts. Facebook users might be willing to read through lengthy posts to understand the authors’ stories behind the study. In contrast, Twitter users might want to absorb essential information with a glance.

The influence of the abundance and morphology of epileptiform discharges on diagnostic accuracy: How many spikes you need to spot in an EEG

ObjectiveThe operational definition of interictal epileptiform discharges (IEDs) of the International Federation of Clinical Neurophysiology (IFCN) described six morphological criteria. Our objective was to assess the impact of pattern-repetition in the EEG-recording, on the diagnostic accuracy of using the IFCN criteria. For clinical implementation, specificity over 95% was set as target. MethodsInterictal EEG-recordings of 20-minutes, containing sharp-transients, from 60 patients (30 with epilepsy and 30 with non-epileptic paroxysmal events) were evaluated by three experts, who first marked IEDs solely based on expert opinion, and then, independently from the first session evaluated the presence of the IFCN criteria for each sharp-transient. The gold standard was derived from long-term video-EEG recordings of the patientś habitual paroxysmal episodes. ResultsPresence of at least one discharge fulfilling five criteria provided a specificity of 100% (sensitivity: 70%). For discharges fulfilling fewer criteria, a higher number of discharges was needed to keep the specificity over 95% (5 discharges, when only 3 criteria were fulfilled). A sequential combination of these sets of criteria and thresholds provided a specificity of 97% and sensitivity of 80%. ConclusionsPattern-repetition and IED morphology influence diagnostic accuracy. SignificanceSystematic application of these criteria will improve quality of clinical EEG interpretation.

Automated seizure detection using wearable devices: A clinical practice guideline of the International League Against Epilepsy and the International Federation of Clinical Neurophysiology.

The objective of this clinical practice guideline (CPG) is to provide recommendations for healthcare personnel working with patients with epilepsy on the use of wearable devices for automated seizure detection in patients with epilepsy, in outpatient, ambulatory settings. The Working Group of the International League Against Epilepsy (ILAE) and the International Federation of Clinical Neurophysiology (IFCN) developed the CPG according to the methodology proposed by the ILAE Epilepsy Guidelines Working Group. We reviewed the published evidence using The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and evaluated the evidence and formulated the recommendations following the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. We found high level of evidence for the accuracy of automated detection of generalized tonic-clonic seizures (GTCS) and focal-to-bilateral tonic-clonic seizures (FBTCS) and recommend the use of wearable automated seizure detection devices for selected patients when accurate detection of GTCS and FBTCS is recommended as a clinical adjunct. We also found a moderate level of evidence for seizure types without GTCS or FBTCS. However, it was uncertain whether the detected alarms resulted in meaningful clinical outcomes for the patients. We recommend using clinically validated devices for automated detection of GTCS and FBTCS, especially in unsupervised patients, where alarms can result in rapid intervention (weak/conditional recommendation). At present, we do not recommend clinical use of the currently available devices for other seizure types (weak/conditional recommendation). Further research and development are needed to improve the performance of automated seizure detection and to document their accuracy and clinical utility.

Safety Review for Clinical Application of Repetitive Transcranial Magnetic Stimulation.

Studies using repetitive transcranial magnetic stimulation (rTMS) in healthy individuals and those with neuropsychiatric diseases have rapidly increased since the 1990s, due to the potential of rTMS to modulate the cortical excitability in the brain depending on the stimulation parameters; therefore, the safety considerations for rTMS use are expected to become more important. Wassermann published the first safety guidelines for rTMS from the consensus conference held in 1996, and Rossi and colleague then published the second safety guidelines from the multidisciplinary consensus meeting held in Siena, Italy in 2008, on behalf of the International Federation of Clinical Neurophysiology. More than 10 years after the second guidelines, the updated third safety guidelines were recently published in 2021. The general safety guidelines for conventional rTMS have not substantially changed. Because the most frequently used rTMS protocol is conventional (low- and high-frequency) rTMS in research and clinical settings, we focus on reviewing safety issues when applying conventional rTMS with a focal cortical stimulation coil. The following issues will be covered: 1) possible adverse events induced by rTMS; 2) checklists to screen for any precautions and risks before rTMS; 3) safety considerations for dosing conventional rTMS; and 4) safety considerations for using rTMS in stroke and traumatic brain injury.

Brief Overview and Experience of Visual Evoked Potential of First 67 cases at Referral Neuroscience Hospital in Bangladesh

Background: The visual evoked potentials (VEP) is a valuable tool to document occult lesions of the central visual channels especially within the optic nerve.&#x0D; Objectives: The purpose of the present study was to observe the findings of first few cases of VEP done in the neurophysiology department of the National Institute of Neurosciences (NINS), Dhaka, Bangladesh.&#x0D; Methodology: This cross-sectional study was conducted in the Department of Neurophysiology at the National Institute of Neurosciences and Hospital, Dhaka, Bangladesh from September 2017 to March 2020. All patients referred to the Neurophysiology Department of NINS for VEP were included. Pattern reversal VEPs were done using standard protocol set by International Federation of Clinical Neurophysiology (IFCN).&#x0D; Results: The mean age of the study population was 30.70 (±12.11) years (6-68 years) with 31 (46.3%) male and 36 (53.7%) female patients. The mean duration of illness was 8.71 (±1.78) months (3 days- 120 months). Most common presenting symptom was blurring of vision (37.3%) and dimness of vision (32.8%). Patterned VEP revealed mixed type (both demyelinating and axonal) of abnormality in most cases [29(43.35)]. The most common clinical diagnosis was multiple sclerosis (29.85%) and optic neuropathy (26.87%). In the clinically suspected cases of multiple sclerosis, optic neuropathy and optic neuritis most of the cases of VEP were abnormal and the p value is 0.04 in optic neuropathy and optic neuritis.&#x0D; Conclusion: The commonest presentation of the patients in this series were blurring of vision and dimness of vision. The most common clinical diagnosis for which VEP was asked for, was optic neuritis and multiple sclerosis. Most abnormalities were of mixed pattern (demyelinating and axonal).&#x0D; Journal of National Institute of Neurosciences Bangladesh, 2020;6(2): 74-77

Optimized set of criteria for defining interictal epileptiform EEG discharges

ObjectiveTo find and validate the optimal combination of criteria that define interictal epileptiform EEG discharges (IEDs). Our target was a specificity over 95%, to avoid over-reading in clinical EEG. MethodsWe constructed 63 combinations of the six criteria from the operational definition of IEDs, recently issued in the EEG-glossary of the International Federation of Clinical Neurophysiology (IFCN). The diagnostic gold standard was derived from video-EEG recordings. In a testing EEG dataset from 100 patients, we selected the best performing combinations of criteria and then we validated them in an independent dataset from 70 patients. We compared their performance with subjective, expert-scorings and we determined inter-rater agreement (IRA). ResultsWithout using criteria, the specificity of expert-scorings was lower than the pre-defined threshold (86%). The best performing combination of criteria was the following: waves with spiky morphology, followed by a slow-afterwave and voltage map suggesting a source in the brain. In the validation dataset this achieved a specificity of 97% and a sensitivity of 89%. IRA was substantial. ConclusionsThe optimized set of criteria for defining IEDs has high accuracy and IRA. SignificanceUsing these criteria will contribute to decreasing over-reading of EEG and avoid misdiagnosis of epilepsy.

Criteria for defining interictal epileptiform discharges in EEG: A clinical validation study.

ObjectiveTo define and validate criteria for accurate identification of EEG interictal epileptiform discharges (IEDs) using (1) the 6 sensor space criteria proposed by the International Federation of Clinical Neurophysiology (IFCN) and (2) a novel source space method. Criteria yielding high specificity are needed because EEG over-reading is a common cause of epilepsy misdiagnosis.MethodsSeven raters reviewed EEG sharp transients from 100 patients with and without epilepsy (diagnosed definitively by video-EEG recording of habitual events). Raters reviewed the transients, randomized, and classified them as epileptiform or nonepileptiform in 3 separate rounds: in 2, EEG was reviewed in sensor space (scoring the presence/absence of each IFCN criterion for each transient or classifying unrestricted by criteria [expert scoring]); in the other, review and classification were performed in source space.ResultsCutoff values of 4 and 5 criteria in sensor space and analysis in source space provided high accuracy (91%, 88%, and 90%, respectively), similar to expert scoring (92%). Two methods had specificity exceeding the desired threshold of 95%: using 5 IFCN criteria as cutoff and analysis in source space (both 95.65%); the sensitivity of these methods was 81.48% and 85.19%, respectively.ConclusionsThe presence of 5 IFCN criteria in sensor space and analysis in source space are optimal for clinical implementation. By extracting these objective features, diagnostic accuracy similar to expert scorings is achieved.Classification of evidenceThis study provides Class III evidence that IFCN criteria in sensor space and analysis in source space have high specificity (>95%) and sensitivity (81%–85%) for identification of IEDs.

A proposal for new diagnostic criteria for ALS

© 2020 The Authors. Published by Elsevier B.V. on behalf of International Federation of Clinical Neurophysiology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).