Interictal Epileptiform Discharges Research Articles

Synonymous variants in the ATP6AP2 gene may lead to developmental and epileptic encephalopathy.

To the literature, variants in the ATP6AP2 gene may cause abnormal nervous system development and associated neurological symptoms. We report a patient with developmental and epileptic encephalopathy (DEE) carrying an ATP6AP2 c.858G > A (p.Ala286=) synonymous variant. In addition, an overview of reported patients with the same variant were collected and summarized to compare our findings. The patient started experiencing tonic seizures at 3.5 months of age, and magnetic resonance imaging (MRI) indicated impaired brain white matter development and reduced left hippocampal volume. Furthermore, electroencephalography showed multifocal interictal epileptiform discharges. Treatment with various anti-seizure medications yielded unsatisfactory results, and the disorder eventually developed into epileptic spasms. An in vitro splicing assay for the ATP6AP2 gene mRNA revealed that the variant caused a deletion in exon 8 and a corresponding protein truncation. A review of previously reported ATP6AP2-related DEE patients found that synonymous variants in the ATP6AP2 gene can cause early DEE onset, progressive changes in early-life MRI, and exon skipping in all ATP6AP2-related DEE patients. We found that synonymous variants in ATP6AP2 may have significant pathogenicity and are highly correlated with DEE. Due to increased isoform production, ATP6AP2 synonymous variants may cause nervous system developmental disorders by competitively reducing the generation of full-length transcripts, resulting in defects in ATP6AP2-related physiological processes.

Association Between Magnetoencephalography-Localized Epileptogenic Zone, Surgical Resection Volume, and Postsurgical Seizure Outcome.

Surgical resection of magnetoencephalography (MEG) dipole clusters, reconstructed from interictal epileptiform discharges, is associated with favorable seizure outcomes. However, the relation of MEG cluster resection to the surgical resection volume is not known nor is it clear whether this association is direct and causal, or it may be mediated by the resection volume or other predictive factors. This study aims to clarify these open questions and assess the diagnostic accuracy of MEG in our center. We performed a retrospective cohort study of 68 patients with drug-resistant epilepsy who underwent MEG followed by resective epilepsy surgery and had at least 12 months of postsurgical follow-up. Good seizure outcomes were associated with monofocal localization (χ2 = 6.94, P = 0.001; diagnostic odds ratio = 10.2) and complete resection of MEG clusters (χ2 = 22.1, P < 0.001; diagnostic odds ratio = 42.5). Resection volumes in patients with and without removal of MEG clusters were not significantly different (t = 0.18, P = 0.86; removed: M = 20,118 mm3, SD = 10,257; not removed: M = 19,566 mm3, SD = 10,703). Logistic regression showed that removal of MEG clusters predicts seizure-free outcome independent of the resection volume and other prognostic factors (P < 0.001). Complete resection of MEG clusters leads to favorable seizure outcomes without affecting the volume of surgical resection and independent of other prognostic factors. MEG can localize the epileptogenic zone with high accuracy. MEG interictal epileptiform discharges mapping should be used whenever feasible to improve postsurgical seizure outcomes.

Incidence and prognosis of frontal intermittent rhythmic delta activity in King Fahad Hospital-Hofuf intensive care unit

Objective: This study aimed to verify the rate of occurrence of frontal intermittent rhythmic delta activity (FIRDA) in electroencephalograms (EEGs) of adult patients in the intensive care unit (ICU) and its correlation with either neurological or non-neurological etiologies or prognoses. Methods: A retrospective review was performed on 239 EEGs with analysis of their neuroimages and clinical data from an ICU at King Fahad Hospital, Hufof from November 2021 to October 2022. A literature review was also conducted using the PUBMED database. The search scope was covered by the keyword &amp;quot;FIRDA&amp;quot; and was limited to English-language articles. Results: A total of 239 EEGs were conducted in the ICU, 19 (7.9%) had either electrographic or clinical seizures with or without slowing and/or interictal epileptiform discharges, 6 (2.5%) EEGs had FIRDA, and the rest of the EEGs (80.5%) had only generalized slow or rarely other EEG patterns which were noted in coma. Toxic metabolic disturbances and sepsis were the acute diagnoses of all the observed cases. There were no clinical seizures in the patients who had FIRDA and no history of epilepsy. There was no significant association between FIRDA and the seizure occurrence where the p-value was 1 (Confidence interval—0, 10.28). Conclusion: This study provides valuable insights into the incidence, clinical characteristics, and outcomes of FIRDA in critically ill patients admitted to the ICU. While FIRDA remains a relatively uncommon finding, its association with toxic-metabolic disturbances and sepsis underscores the importance of comprehensive neurological monitoring in critically ill patients.

Association of Epileptiform Discharge and Autism Spectrum Disorder Severity in Children Attending the Outpatient Clinics, Child Welfare Teaching Hospital, Baghdad

Background: Subjects with Autism Spectrum Disorder (ASD) have a higher prevalence of seizures than the general population, according to a significant body of research. Also, seizure-free patients with ASD have been found to have a higher prevalence of epileptiform discharge abnormalities compared to healthy controls across investigations. Changes in the electroencephalogram (EEG) can manifest as sharp waves or spikes, sharp and slow waves, generally distributed or general area, or focused, and can manifest in various brain regions. There is a necessity to search for a distinctive EEG characteristic in ASD patients. Objectives: This study used electroencephalography to investigate the relationship between interictal epileptiform discharges and the severity of ASD in children. Patient and methods: The study involved a total of 65 children. The first group consisted of 30 children (seven females and 23 males, 2-12 years of age) recruited from the autism center and the pediatric neurology consultancy clinic in the Child Welfare Teaching Hospital / Medical City. The second group consisted of 35 age- and gender-matched normally-developed children (10 females 25 males, 2-12 years of age) recruited from the Pediatrics Consultation Clinics in the Child Welfare Teaching Hospital. The ASD children met the DSM-5 criteria for autism and the Childhood Autism Rating Scale was utilized to determine the severity of autism. The electroencephalography signals were recorded to detect epileptiform discharge. The data was collected during the period from 5th October 2022 to 1st April 2023. Result: A statistically significant association was found between the epileptiform discharges and the study group (ASD Vs normally developed children). The EEG records were normal in 20 (66.7%), abnormal in the form of focal epileptiform discharge in 5 (16.7%), and in the form of generalized epileptiform discharge in 5 (16.7%) of ASD children. The EEG findings and the CARS-measured autism severity showed a statistically significant association (P=0.05), as the EEG abnormalities increased with the severity of autism. Conclusion: The degree of autism was found to be associated with the abnormalities of the electroencephalogram and the degree of autism. Received: May,, 2023 Accepted: Sept, 2023 Published: Jan. 2024

Role of short term Video EEG monitoring and MRI in refractory Epilepsy

Introduction: Inpatient video EEG monitoring is widely used for the diagnosis, seizure classification and pre surgical evaluation of patients with epilepsy. Only few studies have highlighted the role of short term video EEG in the diagnosis of paroxysmal events. The present study was undertaken to identify the role of short term video EEG in refractory epilepsy. Materials &amp; Methods: Forty patients, attending neurology outpatient department in our institution, during the study period, fulfilling the criteria for refractory epilepsy were included. Short term video EEG and MRI Brain were done for all of them. Outcomes measured were 1) Video recording of epileptic seizures with concurrent ictal pattern or psychogenic non epileptic seizure. 2) Identification of new interictal epileptiform discharges, which were not there in the previous routine EEG. 3) Observation of congruency between EEG and MRI Brain. Results: Clinical events were recorded in 12.5% of patients - 7.5% had epileptic seizures and 5% had psychogenic non epileptic seizures recorded. Short term video EEG was abnormal in 70% of the patients, whereas previous routine EEG was abnormal in only 30% and these observations were statistically significant. Short term video EEG was useful in diagnostic classification in 70% of the cases. MRI Brain was abnormal in 35% and among them, 30% had lateralized epiletiform discharges and the congruency between them is not statistically significant. Conclusions: Short term video EEG monitoring could be an initial investigation to sort our more frequent seizure group and proceed to long term VEEG if short term VEEG is inconclusive.

Towards the automated detection of interictal epileptiform discharges with magnetoencephalography

BackgroundThe analysis of clinical magnetoencephalography (MEG) in patients with epilepsy traditionally relies on visual identification of interictal epileptiform discharges (IEDs), which is time consuming and dependent on subjective criteria. New MethodHere, we explore the ability of Independent Components Analysis (ICA) and Hidden Markov Modeling (HMM) to automatically detect and localize IEDs. We tested our pipelines on resting-state MEG recordings from 10 school-aged children with (multi)focal epilepsy. ResultsIn focal epilepsy patients, both pipelines successfully detected visually identified IEDs, but also revealed unidentified low-amplitude IEDs. Success was more mitigated in patients with multifocal epilepsy, as our automated pipeline missed IED activity associated with some foci—an issue that could be alleviated by post-hoc manual selection of epileptiform ICs or HMM states. Comparison with existing methodsWe compared our results with visual IED detection by an experienced clinical magnetoencephalographer, getting heightened sensitivity and requiring minimal input from clinical practitioners. ConclusionsIED detection based on ICA or HMM represents an efficient way to identify IED localization and timing. The development of these automatic IED detection algorithms provide a step forward in clinical MEG practice by decreasing the duration of MEG analysis and enhancing its sensitivity.

Epilepsy is more than a simple seizure disorder: Causal relationships between epilepsy and its comorbidities

This review draws connections between the pathogenesis of canine epilepsy and its most commonly recognised comorbidities: cognitive impairment (CI), attention deficit hyperactivity disorder (ADHD)-like behaviour, fear and anxiety. Uni/bidirectional causalities and the possibility of a common aetiology triggering both epilepsy and the associated diseases are considered. Research on this topic is sparse in dogs, so information has been gathered and assessed from human and laboratory animal studies. Anatomical structures, functional connections, disrupted neurotransmission and neuroinflammatory processes collectively serve as a common foundation for epilepsy and its comorbidities. Specific anatomical structures, especially parts of the limbic system, such as the amygdala and the hippocampus, are involved in generating seizures, as well as cognitive- and behavioural disorders. Furthermore, disturbances in inhibitory and excitatory neurotransmission influence neuronal excitability and networks, leading to underlying brain dysfunction. Functional magnetic resonance imaging (fMRI), interictal epileptiform discharges (IEDs), and electroencephalography (EEG) have demonstrated functional brain connections that are related to the emergence of both epilepsy and its various comorbidities. Neuroinflammatory processes can either cause or be a consequence of seizures, and inflammatory mediators, oxidative stress and mitochondrial dysfunction, can equally evoke mood disorders. The extensive relationships contributing to the development and progression of seizures and comorbid cognitive and behavioural conditions illustrate the complexity of the disease that is epilepsy.

Surgical treatment for drug-resistant epilepsy due to early brain injury in children

BackgroundThe study aimed to summarize the indications and clinical features of pediatric drug-resistant epilepsy associated with early brain injury, surgical outcomes, and prognostic factors. MethodsWe retrospectively analyzed children diagnosed with drug-resistant epilepsy due to early brain injury, who had undergone surgery at the Pediatric Epilepsy Center of Peking University First Hospital from May 2014 to May 2021. Clinical data of vasculogenic and non-vasculogenic injuries from early brain damage were compared and analyzed. The surgical outcomes were assessed using the Engel grading system. ResultsThe median ages at acquiring injury, seizure onset, and surgery among 65 children were 19.0 (0–120) days, 8.6 (0–136.5) months, and 62.9 (13.5–234) months, respectively. Of the 14 children with non-vasculogenic injuries, 12 had posterior ulegyria. Unilateral or bilateral synchronous interictal epileptiform discharges were located mainly in the posterior quadrant in 10 children (71 %), and unilateral posterior quadrant or non-lateralized ictal region in eight children (57 %). The surgical approach was mainly temporo-parieto-occipital or parieto-occipital disconnection in nine children. Of 49 children with vasculogenic injuries, magnetic resonance imaging revealed hemispheric abnormalities in 38. Unilaterally hemispheric or bilateral interictal epileptiform discharges were observed in 36 children (73 %), whereas 42 (86 %) had unilateral hemispheric or non-lateralized ictal onset. The surgical procedure involved hemispherotomy in 38 children (78 %) and lobectomy or disconnection, multilobectomy or disconnection and hemispherotomy in 5, 20, and 40 children, respectively. Fifty-five patients (84.6 %) achieved remission from seizure during follow-up at 5.4 years. Age at surgery (odds ratio = 1.022, 95 % confidence interval = 1.003–1.042, P = 0.023) and etiology (odds ratio = 17.25, 95 % confidence interval = 2.778–107.108, P = 0.002) affected the seizure outcomes. ConclusionChildren with drug-resistant epilepsy due to early brain injury can successfully be treated with surgery after rigorous preoperative screening. Good surgical outcomes are associated with an early age at surgery and an etiology of vasculogenic injury.

Alcohol for seizure induction in the epilepsy monitoring unit

Rationale: Seizure induction techniques are used in the epilepsy monitoring unit (EMU) to increase diagnostic yield and reduce length of stay. There are insufficient data on the efficacy of alcohol as an induction technique. MethodsWe performed a retrospective cohort study using six years of EMU data at our institution. We compared cases who received alcohol for seizure induction to matched controls who did not. The groups were matched on the following variables: age, reason for admission, length of stay, number of antiseizure medications (ASM) at admission, whether ASMs were tapered during admission, and presence of interictal epileptiform discharges. We used both propensity score and exact matching strategies. We compared the likelihood of epileptic seizures and nonepileptic events in cases versus controls using Kaplan-Meier time-to-event analysis, as well as odds ratios for these outcomes occurring at any time during the admission. ResultsWe analyzed 256 cases who received alcohol (median dose 2.5 standard drinks) and 256 propensity score-matched controls. Cases who received alcohol were no more likely than controls to have an epileptic seizure (X2(1) = 0.01, p = 0.93) or nonepileptic event (X2(1) = 2.1, p = 0.14) in the first 48 h after alcohol administration. For the admission overall, cases were no more likely to have an epileptic seizure (OR 0.89, 95 % CI 0.61–1.28, p = 0.58), nonepileptic event (OR 0.97, CI 0.62–1.53, p = 1.00), nor require rescue benzodiazepine (OR 0.63, CI 0.35–1.12, p = 0.15). Stratified analyses revealed no increased risk of epileptic seizure in any subgroups. Sensitivity analysis using exact matching showed that results were robust to matching strategy. ConclusionsAlcohol was not an effective induction technique in the EMU. This finding has implications for counseling patients with epilepsy about the risks of drinking alcohol in moderation in their daily lives.

Seizures and electrophysiological features in familial cortical myoclonic tremor with epilepsy 1.

To investigate and characterize epileptic seizures and electrophysiological features of familial cortical myoclonic tremor with epilepsy (FCMTE) type 1 patients in a large Chinese cohort. We systematically evaluated 125 FCMTEtype 1 patients carrying the pentanucleotide (TTTCA) repeat expansion in the SAMD12 gene in China. Among the 28 probands, epileptic seizures (96.4%, 27/28) were the most common reason for an initial clinic visit. Ninety-seven (77.6%, 97/125) patients had experienced seizures. The seizures onset age was 36.5 ± 9.0 years, which was 6.9 years later than cortical tremors. The seizures were largely rare (<1/year, 58.8%) and occasional (1-6/year, 37.1%). Prolonged prodromes were reported in 57.7% (56/97). Thirty-one patients (24.8%, 31/125) reported photosensitivity history, and 79.5% (31/39) had a photoparoxysmal response. Interictal epileptiform discharges (IEDs) were recorded in 69.1% (56/81) of patients. Thirty-three patients showed generalized IEDs and 72.7% (24/33) were occipitally dominant, while 23 patients presented with focal IEDs with 65.2% (15/23) taking place over the occipital lobe. Overnight EEG of FCMTE patients displayed paradoxical sleep-wake fluctuation, with a higher average IED index of 0.82 ± 0.88/min during wakefulness and a lower IED index of 0.04 ± 0.06/min during non-rapid eye movement sleep stages I-II. FCMTE type 1 has a benign course of epilepsy and distinct clinical and electrophysiological features. In addition to a positive family history and cortical myoclonus tremor, the seizure prodromes, specific seizure triggers, photosensitivity, distribution of IEDs, and unique fluctuations during sleep-wake cycle are cues for proper genetic testing and an early diagnosis of FCMTE.

Latencies to the first interictal epileptiform discharges recorded by the electroencephalography in different epileptic patients

PurposeInterictal epileptiform discharges (IEDs) captured in electroencephalography (EEG) have a high diagnostic value for epileptic patients. Extending the recording time may increase the possibility of obtaining IEDs. The purpose of our research was to determine how long it took for various epileptic individuals to receive their first IEDs.MethodsWe retrospectively analyzed patients who were diagnosed with epilepsy and had no anti-seizure medications (ASMs) between September 2018 and March 2019 in the neurology department of the First Affiliated Hospital of Xi'an Jiaotong University. Each individual underwent a 24-h long-term video electroencephalographic monitoring (VEM) procedure. Clinical information including age, gender, age of seizure onset, frequency of seizures, the interval between last seizure and VEM, and results of neuroimaging were gathered. We also calculated the times from the start of the VEM to the first definite IEDs.ResultsA total of 241 patients were examined, including 191 with focal-onset epilepsy and 50 with generalized epilepsy. In individuals with focal-onset epilepsy, the median latency to the first IED was 63.0 min (IQR 19.0–299.0 min), as compared to 30.0 min (IQR 12.5–62.0 min) in patients with generalized epilepsy (p < 0.001). The latency to the first IED is significantly related to the age of seizure onset (HR = 0.988, p = 0.049), the interval between last seizure and VEM (HR = 0.998, p = 0.013). But it is not correlated with seizure frequency, gender and age.ConclusionsIEDs were discovered during 24-h EEG monitoring in 222/241(92.1%) of the epilepsy patients that were included. Compared to focal-onset epilepsy, generalized epilepsy demonstrated a much shorter latency to IED. Patients with late-onset epilepsy or those without recent episodes may require longer EEG monitoring periods.

Wake slow waves in focal human epilepsy impact network activity and cognition

Slow waves of neuronal activity are a fundamental component of sleep that are proposed to have homeostatic and restorative functions. Despite this, their interaction with pathology is unclear and there is only indirect evidence of their presence during wakefulness. Using intracortical recordings from the temporal lobe of 25 patients with epilepsy, we demonstrate the existence of local wake slow waves (LoWS) with key features of sleep slow waves, including a down-state of neuronal firing. Consistent with a reduction in neuronal activity, LoWS were associated with slowed cognitive processing. However, we also found that LoWS showed signatures of a homeostatic relationship with interictal epileptiform discharges (IEDs): exhibiting progressive adaptation during the build-up of network excitability before an IED and reducing the impact of subsequent IEDs on network excitability. We therefore propose an epilepsy homeostasis hypothesis: that slow waves in epilepsy reduce aberrant activity at the price of transient cognitive impairment.

Cathodal HD-tDCS and attention: A study on patients with intractable left lateral frontal lobe epilepsy

ObjectiveDefects in the attentional network in patients with epilepsy are influenced by factors such as the location of epileptic foci. Examining the impact of cathodal high-definition transcranial direct current stimulation (HD-tDCS) on attention components could provide insights into potential attention-related side effects of tDCS. This study aimed to investigate the effect of cathodal HD-tDCS on interictal epileptiform discharges (IEDs), auditory/visual (A/V) attention components, and reaction time (RT) in patients with intractable focal left lateral frontal lobe epilepsy (LFLE). MethodsTo control for variations in individual epilepsy syndrome, 12 adult participants diagnosed with drug-resistant left LFLE with focal cortical IEDs on C3 underwent repeated measurements at pretest, posttest, and follow-up steps. 4 × 1 ring electrodes (cathode on C3 and four anodes on F3, P3, T3, and Cz) delivered 2 mA DC for 20 min per session for 10 consecutive days. The integrated visual and auditory continuous performance test (IVA+) assessed the A/V attention components and RT. One-way repeated-measure ANOVA was used. ResultsThe findings suggest a significant effect in reducing IEDs. The IVA+ results showed a significant improvement in auditory divided attention and visual selective and focused attention (p < 0.05). In the follow-up, these changes demonstrated lasting efficacy. A/V speed scales increased (p < 0.05), showing a significant decrease in reaction time. ConclusionsCathodal HD-tDCS significantly reduced IEDs and improved the components of auditory divided attention, visual focused attention, and visual selective attention, with a reduction in patient reaction time. A significant lasting, side-effect-free positive effect was observed for up to one month after the intervention.

Early antiseizure medication withdrawal and risk of seizure recurrence in children after epilepsy surgery: A retrospective study

ObjectiveThe timing of antiseizure medication (ASM) withdrawal in children after epilepsy surgery remains controversial and lacks recognized standards. Given the various negative effects of ASM on development in children, this study aimed to evaluate the safety and feasibility of early ASM withdrawal after epileptic resection surgery. MethodsWe retrospectively assessed the seizure outcomes and ASM profiles of children who had undergone epileptic resection surgery between August 2015 and August 2020 and attempted ASM reduction in the early postoperative phase. Tapering the dose of ASM was attempted when children were seizure-free with no interictal epileptiform discharges (IEDs) on electroencephalogram (EEG) for at least 6 months postoperatively. ResultsThis study included 145 children with a median follow-up duration of 40 months. Early ASM tapering was attempted postoperatively in 99 (68.3 %) children. Postoperative ASM discontinuation was attempted in 87 (60.0 %) children. Nine (9.1 %) children experienced seizure recurrence during the ASM reduction stage, and 10 (11.5 %) experienced recurrence after ASM discontinuation. Incomplete resection (P = 0.003) and postoperative seizures before ASM tapering (P = 0.003) were independent predictors of seizure recurrence during and after early ASM withdrawal. SignificanceASM withdrawal is viable and safe to be initiated in children who are seizure-free postoperatively and have no IEDs on the scalp EEG for at least 6 months. Children with incomplete resection and postoperative seizures before ASM withdrawal are at a higher risk of seizure recurrence and may need to continue ASM for a longer period.

Tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges: a case study

Cryogenic magnetoencephalography (MEG) enhances the presurgical assessment of refractory focal epilepsy (RFE). Optically pumped magnetometers (OPMs) are cryogen-free sensors that enable on-scalp MEG recordings. Here, we investigate the application of tri-axial OPMs [87Rb (Rb-OPM) and 4He gas (He-OPM)] for the detection of interictal epileptiform discharges (IEDs). IEDs were recorded simultaneously with 4 tri-axial Rb- and 4 tri-axial He-OPMs in a child with RFE. IEDs were identified visually, isolated from magnetic background noise using independent component analysis (ICA) and were studied following their optimal magnetic field orientation thanks to virtual sensors. Most IEDs (&amp;gt;1,000) were detectable by both He- and Rb-OPM recordings. IEDs were isolated by ICA and the resulting magnetic field oriented mostly tangential to the scalp in Rb-OPMs and radial in He-OPMs. Likely due to differences in sensor locations, the IED amplitude was higher with Rb-OPMs. This case study shows comparable ability of Rb-OPMs and He-OPMs to detect IEDs and the substantial benefits of triaxial OPMs to detect IEDs from different sensor locations. Tri-axial OPMs allow to maximize spatial brain sampling for IEDs detection with a limited number of sensors.

Interaction of interictal epileptiform activity with sleep spindles is associated with cognitive deficits and adverse surgical outcome in pediatric focal epilepsy.

Temporal coordination between oscillations enables intercortical communication and is implicated in cognition. Focal epileptic activity can affect distributed neural networks and interfere with these interactions. Refractory pediatric epilepsies are often accompanied by substantial cognitive comorbidity, but mechanisms and predictors remain mostly unknown. Here, we investigate oscillatory coupling across large-scale networks in the developing brain. We analyzed large-scale intracranial electroencephalographic recordings in children with medically refractory epilepsy undergoing presurgical workup (n = 25, aged 3-21 years). Interictal epileptiform discharges (IEDs), pathologic high-frequency oscillations (HFOs), and sleep spindles were detected. Spatiotemporal metrics of oscillatory coupling were determined and correlated with age, cognitive function, and postsurgical outcome. Children with epilepsy demonstrated significant temporal coupling of both IEDs and HFOs to sleep spindles in discrete brain regions. HFOs were associated with stronger coupling patterns than IEDs. These interactions involved tissue beyond the clinically identified epileptogenic zone and were ubiquitous across cortical regions. Increased spatial extent of coupling was most prominent in older children. Poor neurocognitive function was significantly correlated with high IED-spindle coupling strength and spatial extent; children with strong pathologic interactions additionally had decreased likelihood of postoperative seizure freedom. Our findings identify pathologic large-scale oscillatory coupling patterns in the immature brain. These results suggest that such intercortical interactions could predict risk for adverse neurocognitive and surgical outcomes, with the potential to serve as novel therapeutic targets to restore physiologic development.

Detection of interictal epileptiform discharge in focal seizures

Introduction: Many factors underlying basic epileptic conditions determine the characteristics of epileptic seizures and the therapeutic outcome. Visual obvious abnormalities in resting baseline EEG are cardinal but incompletely understood like feature of seizure onset zone in focal epilepsy and interictal epileptiform discharge. Present study is an attempt to diagnose that evidence of epileptic discharge in temporal lobe epilepsy (TLE), would persist during interictal period in absence of abnormalities in baseline EEG, which could increase the impact of automatic analysis of EEG waves for clinical relevance.&#x0D; Material and Methods: By using 10-20 system, functional connectivity was estimated in the 20 channels of delta, theta, alpha, beta and gamma frequency bands of EEG, from 16 diagnosed focal epileptic seizure patients and 16 age and sex matched controls. To observe the dynamics of the healthy brain, differ from the brain of dynamically focal epileptic patients during interictal period treated with anti-epileptic drugs in the context of resting state during eye close session of EEG. Such differences can be observed by using absolute spectral power from BESS ((Brain Electro Scan Software) of the Axxonet System and statistically measure by applied unpaired student t -test.&#x0D; Result: The high significance results in slow frequency EEG waves (delta and theta) in power spectral analysis were observed that demonstrates the potential epileptic discharge occurring during interictal period without visible pathological activity for helping in the diagnosis and lateralization of TLE.&#x0D; Conclusion: The detailed spectral analysis of EEG waves offers novel insight into focal epileptic patients when visually EEG findings were normal. This linear analysis helpful in extracting information from EEG signals in diagnosing specific neuronal correlates for TLE. Present findings concluded that epileptic discharges occur at different topographical regions of brain during interictal period and power spectral analysis plays a new insight in diagnosis of focal discharge.

Detection of Interictal epileptiform discharges with semi-supervised deep learning

Interictal discharges (IEDs) in EEG recordings are important signatures of epilepsy as their presence is strongly associated with an increased risk of seizures. IEDs are relatively short-duration events (typically 70–250 ms) that can be viewed as stochastic anomalies in such recordings. Currently, visual analysis of the EEG by clinical experts is the gold standard. This process, however, is time-consuming, error prone, and associated with a long learning period.Automatizing the detection of IEDs has the potential to significantly reduce review time, and may serve to complement the visual analysis. Supervised deep learning methods have shown potential for this purpose, but the scarceness of annotated data has limited their performance, which motivates to explore unsupervised and semi-supervised approaches, that do not require (extensive) expert annotations.We trained different unsupervised deep learning models, Autoencoders (AE) and Variational Autoencoders (VAE) for anomaly (IED) detection in these recordings. These models are dimensionality reduction based approaches, that can compress the data to lower dimensional representations, learning the notion of normality within data and reconstruct samples accordingly. Our data set comprised 203 clinical EEGs, 115 from patients with epilepsy, that contained IEDs, and 88 normal EEGs. Performance was assessed qualitatively through visual analysis of reconstructed samples and quantified as Area Under the Curve (AUC), sensitivity and specificity.The best performance was obtained using a semi-supervised approach, allowing the detection of IEDs with a sensitivity of 81.9% and specificity of 91.7%.Our work shows that unsupervised approaches and other approaches with limited supervision perform satisfactorily and have the potential to assist visual assessment of interictal discharges in epilepsy diagnostics.

A Two-Stage Automatic System for Detection of Interictal Epileptiform Discharges from Scalp Electroencephalograms.

The objective of this work was to develop a deep learning-based automatic system with reliable performance in detecting interictal epileptiform discharges (IEDs) from scalp electroencephalograms (EEGs). For the present study, 484 raw scalp EEG recordings were included, standardized, and split into 406 for training and 78 for testing. Two neurophysiologists individually annotated the recordings for training in channel-wise manner. Annotations were divided into segments, on which nine deep neural networks (DNNs) were trained for the multiclassification of IED, artifact, and background. The fitted IED detectors were then evaluated on 78 EEG recordings with IED events fully annotated by three experts independently (majority agreement). A two montage-based decision mechanism (TMDM) was designed to determine whether an IED event occurred at a single time instant. Area under the precision-recall curve (AUPRC), as well as false-positive rates, F1 scores, and kappa agreement scores for sensitivity = 0.8 were estimated. In multitype classification, five DNNs provided one-versus-rest AUPRC mean value >0.993 using fivefold cross-validation. In IED detection, the system that had integrated the temporal convolutional network (TCN)-based IED detector and the TMDM rule achieved an AUPRC of 0.811. The false positive was 0.194/min (11.64/h), and the F1 score was 0.745. The agreement score between the system and the experts was 0.905. The proposed framework provides a TCN-based IED detector and a novel two montage-based determining mechanism that combined to make an automatic IED detection system. The system would be useful in aiding clinic EEG interpretation.

Yield of non-invasive imaging in MRI-negative focal epilepsy.

The absence of MRI-lesion reduces considerably the probability of having an excellent outcome (International League Against Epilepsies [ILAE] class I-II) after epilepsy surgery. Surgical success in magnetic-resonance imaging (MRI)-negative cases relies therefore mainly on non-invasive techniques such as positron-emission tomography (PET), subtraction ictal/inter-ictal single-photon-emission-computed-tomography co-registered to MRI (SISCOM), electric source imaging (ESI) and morphometric MRI analysis (MAP). We were interested in identifying the optimal imaging technique or combination to achieve post-operative class I-II in patients with MRI-negative focal epilepsy. We identified 168 epileptic patients without MRI lesion. Thirty-three (19.6%) were diagnosed with unifocal epilepsy, underwent surgical resection and follow-up ⩾ 2 years. Sensitivity, specificity, predictive values, and diagnostic odds ratio (OR) were calculated for each technique individually and in combination (after co-registration). 23/33 (70%) were free of disabling seizures (75.0% with temporal and 61.5% extratemporal lobe epilepsy). None of the individual modalities presented an OR > 1.5, except ESI if only patients with interictal epileptiform discharges (IEDs) were considered (OR 3.2). On a dual combination, SISCOM with ESI presented the highest outcome (OR = 6). MAP contributed to detecting indistinguishable focal cortical dysplasia in particular in extratemporal epilepsies with a sensitivity of 75%. Concordance of PET, ESI on interictal epileptic discharges, and SISCOM was associated with the highest chance for post-operative seizure control (OR = 11). If MRI is negative, the chances to benefit from epilepsy surgery are almost as high as in lesional epilepsy, provided that multiple established non-invasive imaging tools are rigorously applied and co-registered together.