Long-term Video-electroencephalography Monitoring Research Articles

Circulating microRNAs and isomiRs as biomarkers for the initial insult and epileptogenesis in four experimental epilepsy models: The EPITARGET study.

Structural epilepsies can manifest months or years after the occurrence of an initial epileptogenic insult, making them amenable for secondary prevention. However, development of preventive treatments has been challenged by a lack of biomarkers for identifying the subset of individuals with the highest risk of epilepsy after the epileptogenic insult. Four different rat models of epileptogenesis were investigated to identify differentially expressed circulating microRNA (miRNA) and isomiR profiles as biomarkers for epileptogenesis. Plasma samples were collected on day 2 and day 9 during the latency period from animals that did or did not develop epilepsy during long-term video-electroencephalographic monitoring. miRNAs and isomiRs were identified and measured in an unsupervised manner, using a genome-wide small RNA sequencing platform. Receiver operating characteristic analysis was performed to determine the performance of putative biomarkers. Two days after an epileptogenic insult, alterations in the levels of several plasma miRNAs and isomiRs predicted epileptogenesis in a model-specific manner. One miRNA, miR-3085, showed good sensitivity (but low specificity) as a prognostic biomarker for epileptogenesis in all four models (area under the curve = .729, sensitivity = 83%, specificity = 64%, p < .05). Identified plasma miRNAs and isomiRs are mostly etiology-specific rather than common prognostic biomarkers of epileptogenesis. These data imply that in preclinical and clinical studies, it may be necessary to identify specific biomarkers for different epilepsy etiologies. Importantly, circulating miRNAs like miR-3085 with high negative predictive value for epileptogenesis in different etiologies could be useful candidates for initial screening purposes of epileptogenesis risk.

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.

Long-Term Video Electroencephalographic Monitoring in

BackgroundDespite recognizing high seizure risk, the current consensus guidelines on evaluating seizures in preterm neonates are based on limited data. We chose to investigate the seizure risk in high-risk preterm (<30 weeks gestation) asymptomatic (without a clinical concern for seizures) infants with high-grade intraventricular hemorrhage who underwent long-term video electroencephalographic monitoring. MethodsWe performed a comprehensive retrospective review on all infants of <30-week gestational age admitted to the University of Alabama at Birmingham Regional Neonatal Intensive Care Unit from June 2018 to October 2022. We selected those patients who underwent electroencephalographic monitoring without a prior clinical concern for seizures. We recorded gender, gestational age, APGAR scores (one and five minutes), intraventricular hemorrhage (grade, age at diagnosis), and electroencephalographic monitoring (timing and duration) data. ResultsAmong 37 premature infants, six had seizures detected on electroencephalographic monitoring. All six infants had subclinical seizures. Only two of six patients had a clinical correlation (although not identified by the providers) with some of their seizures. Patients with seizures were significantly younger in chronological age (median age 6.5 days vs 9 days, P value 0.009) at the time of the electroencephalographic monitoring initiation and were more likely to have subsequent monitoring studies (P value 0.0418). ConclusionsLong-term video electroencephalographic monitoring performed after the diagnosis of high-grade intraventricular hemorrhage captured seizures in ∼16% of asymptomatic premature neonates of <30 weeks’ gestation. Patients identified to have seizures were significantly younger (chronological age) at the time of the electroencephalographic monitoring initiation and were more likely to be remonitored.

Latency of epileptic and psychogenic nonepileptic seizures.

Due to their semiological similarities, psychogenic nonepileptic seizures (PNESs) can occasionally hardly be differentiated from epileptic seizures (ESs), and long-term video-electroencephalographic monitoring (VEM) is needed for the differential diagnosis. To investigate the time of the first clinical event and its distribution on the days of VEM in ES and PNES patients. In total, a consecutive series of 48 PNES and 51 ES patients matched for gender and age were retrospectively and consecutively evaluated. The time distribution of the seizures during the day was noted. Seizure latency was determined as the time in hours from the start of the video-electroencephalographic recording to the first clinical event. The seizure latency was significantly shorter in PNES patients compared to ES patients (p < 0.001). Seventy-two percent of PNES patients and 49.1% of ES patients had their first seizure in the 24 hours of video-EEG recording (p = 0.023). Recording longer than 48 hours was required for 12.5% of PNES patients and 37.3% of ES patients (p = 0.006). While ESs were almost evenly distributed throughout the day, most PNESs occurred during the evening hours (p = 0.011). We observed that the PNESs appeared earlier than the ESs in the VEM and were concentrated during daylight hours. Although not strictly reliable, seizure latency can contribute to the differential diagnosis of ES and PNES.

Safety and efficacy of rapid withdrawal of antiseizure medications during long-term video-electroencephalogram monitoring in children with drug-resistant epilepsy: Aretrospective study.

Performing long-term video-electroencephalographic monitoring (LTVEM) to obtain the ictal electroencephalogram (EEG) is important for presurgical evaluation. This study aimed at investigating the safety and efficacy of our protocol developed at Peking University First Hospital (PUFH) for rapid withdrawal of antiseizure medications (ASMs) during LTVEM to induce seizures in children with drug-resistant epilepsy (DRE) exhibiting nondaily seizures. Children with DRE who followed the PUFH protocol for rapid withdrawal of ASMs during LTVEM between 2018 and 2021 were enrolled. The occurrence of seizures, number of ASMs withdrawn, seizure onset time after ASM tapering initiation, changes in interictal epileptiform discharge (IED), and adverse events were evaluated during LTVEM. Among 80 children evaluated in this study, seizures were induced successfully in 72 (90%) children. Furthermore, no change in IED sites was observed in these 72 children following the initiation of ASM tapering while 2 children exhibited secondary bilateral tonic-clonic seizures. The median time from ASM tapering initiation to the onset of the first seizure was found to be 3 days (2-4), while the median number of ASMs withdrawn was 2 (1-2). Finally, 66 children (91.7%) had habitual seizures while 6 children had nonhabitual seizure semiology. The PUFH protocol can be used for the rapid withdrawal of ASMs during LTVEM in children with DRE. Using this protocol, ictal EEG patterns can be obtained in a relatively short time for most patients with fewer adverse effects during LTVEM, which may provide meaningful electro-clinical information for presurgical evaluation.

Inpatient long-term video-electroencephalographic monitoring event capture audiovisual diagnostic quality

ObjectivesLong-term video-electroencephalographic monitoring (LTVEM) represents the gold-standard method to evaluate whether events represent electrographic seizures, but limited work has evaluated the quality of inpatient event capture. We evaluated the frequency of audiovisual factors impairing the ideal electroclinical correlation of seizure-like episodes during LTVEM. MethodsWe retrospectively reviewed consecutive inpatient LTVEM studies (11/2019–12/2019) from three academic epilepsy centers. We evaluated all pushbutton events for audiovisual characteristics such as whether the event was narrated, whether the patient was blocked on camera, and what diagnostic challenges impaired the electroencephalographer’s ability to understand either the reason the event button was pushed or clinical semiology (“electroclinical correlation”). We determined the percent of events and studies with each outcome. ResultsThere were 154 studies with 520 pushbutton events. The pushbutton was most commonly activated by patients (41%), followed by nurses (31%) or family (17%). Twenty-nine percent of events represented electrographic seizures, and 78% occurred in the Epilepsy Monitoring Unit. The reason for the push was not stated in 45% of events, and inadequate narration impaired electroclinical correlation in 19% of events. At least one relevant part of the patient’s body was blocked during 12% of events, but this impaired electroclinical correlation in only 1% of events. There was at least one factor impairing electroclinical correlation in 21% of events, most commonly due to incomplete narration (N = 99), lights off (N = 15), or blankets covering the patient (N = 15). At least one factor impaired electroclinical correlation for any event in 36% of studies. ConclusionAudiovisual factors impairing the electroencephalographer’s ability to render an electroclinical correlation were common, particularly related to inadequate narration from bedside observers to explain the reason for pushing the button or event semiology. Future efforts to develop targeted countermeasures should address narration challenges and improve inpatient seizure monitoring quality metrics.

Development and validation of the Japanese version of the Epilepsy Stigma Scale in adults with epilepsy

BackgroundSelf-stigma is considered to have immensely negative influences on the living and psychological states in patients with epilepsy. Understanding the stigma experienced by patients with epilepsy is essential considering its negative impact on their treatment and quality of life (QOL). However, few sufficiently validated self-report instruments are available to evaluate self-stigma in patients with epilepsy. The Epilepsy Stigma Scale (ESS) is one of the most commonly used self-reported questionnaires available to evaluate self-stigma in patients with epilepsy. The present study translated the ESS into Japanese to validate the Japanese version of the ESS (ESS-J) in Japanese adults with epilepsy. MethodsThe study included 338 patients with epilepsy (166 men, aged 18–75 years) who underwent comprehensive assessment including long-term video-electroencephalography monitoring, neuroimaging studies, and neuropsychological and psychosocial assessments in the Tohoku University Hospital Epilepsy Monitoring Unit. This study consisted of two phases: (1) translation of the ESS into Japanese using the back-translation technique; and (2) statistical analysis of the ESS-J to evaluate the factor structure, reliability, and validity. ResultsThe 2-factor model achieved acceptable fit to the data: χ2 = 161.27, df = 34, p < 0.01, comparative fit index = 0.929, root mean square error of approximation = 0.105, standardized root mean squared residual = 0.047, Akaike’s information criterion = 203.27 and, Bayesian information criterion = 283.56. These two subscales were named enacted stigma and felt stigma based on the theoretical model of self-stigma. We found the ESS-J to have acceptable internal consistency as follows: enacted (7 items; α = 0.88) and felt stigma subscale (3 items; α = 0.82). The concurrent validity was confirmed by adequate correlation with other related instruments. Both enacted and felt stigma had positive and moderate correlations with depression as measured by the Neurological Disorders Depression Inventory for Epilepsy (r = 0.44, p < 0.01; r = 0.41, p < 0.01, respectively) and with anxiety as measured by the Generalized Anxiety Disorder -7 (r = 0.48, p < 0.01; r = 0.38, p < 0.01, respectively). ConclusionThe ESS-J demonstrated acceptable validity and reliability. The present study provided preliminary evidence about the psychometric properties of the ESS-J, indicating the reliable factorial structure, adequate internal consistency, and satisfactory construct and concurrent validity. Measurement of the two types of self-stigma may offer a useful tool for clinical interpretation of patients’ psychological state throughout epilepsy care, and as one of the patient-reported outcomes in QOL research.

The Importance of Long-Term Video Electroencephalography Monitoring in the Differential Diagnosis of Epilepsy in Children.

Objective: Epilepsy is a condition in which abnormal, recurring, and excessive neuronal discharges caused by many different disorders in the central nervous system are observed. The rate of detecting epileptiform activity in the first interictal electroencephalography (EEG) of patients with epilepsy is around 40%, even when routine activation methods are applied. Video recordings simultaneously with EEG recordings enable the establishment of correlations between abnormalities.Patients and methods: The long-term video-EEG monitoring (VEM) reports and images of 87 patients hospitalized in the video EEG service in the Pediatric Neurology Clinic of İnönü University between 2016 and 2020 were retrospectively analyzed in this study. Demographic information of the patients, such as age, gender, diagnosis/history, and length of hospital stay, was analyzed.Results: A total of 87 patients were included in the study. Of the patients, 54 (62.1%) were male and 33 (37.9%) were female. The mean age was 107.57 ± 64.40 months. While 10 (11.5%) patients followed up with non-epileptic paroxysmal events (NEPE) were taking antiepileptic drugs (AEDs), AED treatments were discontinued after VEM. The diagnosis of 18 (20.69%) patients changed after VEM. The medications of 27 (31%) patients who took AEDs before VEM were discontinued after VEM. During VEM, sleep movement, psychogenic seizures, infantile masturbation, and tic disorder were observed in 19 (41.3%), 17 (36.9%), three (6.5%), and three (6.5%) patients, respectively.Conclusion: In conclusion, VEM is the gold standard diagnostic method used to distinguish between epilepsy and NEPEs. After VEM, the clinical diagnosis of patients can change, and unnecessary drug administration may be prevented. Psychogenic nonepileptic seizures and NEPEs are common in the pediatric population; however, they are often overlooked.

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.

Long-Term V-EEG in Epilepsy: Chronological Distribution of Recorded Events Focused on the Differential Diagnosis of Epileptic Seizures and Psychogenic Non-Epileptic Seizures.

Differential diagnosis in epilepsy is sometimes challenging. Video-electroencephalography (V-EEG) is an essential tool in the diagnosis and management of epilepsy. The prolonged duration of V-EEG recording increases the diagnostic yield of a conventional V-EEG. The right length of monitoring for different indications is still to be established. We present a retrospective descriptive study with a sample of 50 patients with long-term V-EEG monitoring, with a mean age of 36.1 years, monitored from 2013 to 2019 at the Burgos University Hospital. The mean monitoring time was 3.6 days. Events were obtained in 76% of the patients, corresponding to epileptic seizures (ES) in 57.9% of them, with psychogenic non-epileptic seizures (PNES) in 39.5%, and with episodes of both pathologies in 2.6% of the patients. We found that the first event was highly representative, and it correlated with the rest of the events that would be recorded. Moreover, 92% of the first PNES had been captured at the end of the second day, and 89% of the first ES by the end of the third day. V-EEG for differential diagnosis between ES and PNES can be performed in hospitals without specialized epilepsy surgery units. For this indication, the duration of long-term V-EEG can be adjusted individually depending on the nature of the first event.

Current Status and Future Objectives of Surgical Therapies for Epilepsy in Japan.

This study investigated the number of epilepsy surgeries performed over time in Japan, and conducted a questionnaire survey of the Japan Neurosurgical Society (JNS) training program core hospitals to determine the current status and future objectives of surgical therapies and epilepsy training programs for physicians in Japan. This article presents part of a presentation delivered as a presidential address at the 44th Annual Meeting of the Epilepsy Surgery Society of Japan held in January 2021. The number of epilepsy surgeries performed per year has increased in Japan since 2011 to around 1,200 annually between 2015 and 2018. The questionnaire survey showed that 50% of the responding hospitals performed epilepsy surgery and 29% had an epilepsy center, and that these hospitals provided senior residents with education regarding epilepsy surgery. The presence of an epilepsy center in a hospital was positively correlated with the availability of long-term video electroencephalography monitoring beds as well as the number of epilepsy surgeries performed at the hospital. In regions with no medical facilities offering specialized surgical therapies for epilepsy, the JNS training program core hospitals may help improve epilepsy diagnosis and treatment. They may also increase the number of safe and effective surgeries by establishing epilepsy centers that can perform long-term video electroencephalography monitoring, providing junior neurosurgeons with training regarding epilepsy, and playing a core role in surgical therapies for epilepsy in tertiary medical areas in close cooperation with neighboring medical facilities.

Usefulness of long-term video-electroencephalography monitoring for identifying the seizure type in patients with epilepsy

Usefulness of long-term video-electroencephalography monitoring for identifying the seizure type in patients with epilepsy

Photoplethysmography: A measure for the function of the autonomic nervous system in focal impaired awareness seizures.

Photoplethysmography (PPG) reflects variations of blood perfusion in tissues, which may signify seizure-related autonomic changes. The aim of this study is to assess the variability of PPG signals and their value in detecting peri-ictal changes in patients with focal impaired awareness seizures (FIASs). PPG data were recorded using a wearable sensor placed on the wrist or ankle of children with epilepsy admitted for long-term video-electroencephalographic monitoring. We analyzed PPG data in four different periods: seizure-free, preictal, ictal, and postictal. Multiple features were automatically extracted from the PPG signal-frequency, duration, amplitude, increasing and decreasing slopes, smoothness, and area under the curve (AUC)-and were used to identify preictal, ictal, or postictal changes by comparing them with seizure-free periods and with each other using a linear mixed-effects model. We studied PPG in 11 patients (18 FIASs), including seizure-free, preictal, and postictal periods, and a subset of eight patients (12 FIASs) including the ictal period. Compared to the seizure-free period, we found significant changes in PPG (1) during the ictal period across all features; (2) during the preictal period in amplitude, duration, increasing slope, and AUC; and (3) during the postictal period in decreasing slope. Specific PPG changes can be seen before, during, and after FIASs. The peri-ictal changes in the PPG features of patients with FIASs suggest potential applications of PPG monitoring for seizure detection.

Latencies to first interictal epileptiform discharges in different seizure types during video-EEG monitoring

PurposeInterictal epileptiform discharges (IEDs) have high diagnostic value concerning patients with epilepsy and the instances of obtaining IEDs increase with longer recording times. However, the merit of a single, extended electroencephalography (EEG) recording in detecting IEDs has not been substantiated. We aimed to determine the optimal duration of an EEG required to diagnose epilepsy in different seizure types. MethodsOverall, 84 patients—29 with generalised onset epilepsy and 55 with focal onset epilepsy—were evaluated. Long-term video electroencephalographic monitoring (VEM) was analysed to find the first definite IED besides assessing the first seizure and latency. ResultsThe median latency of the first IED (12 min, ranging from 1 to 440 min vs. 55 min, ranging from 2 to 7500 min; p = 0.014) and the median duration of a VEM recording (2 d, ranging from 1 to 10 d vs. 3 d, ranging from 1 to 10 d; p = 0.012) were found significantly lower in the generalised epilepsy group compared with that in the focal epilepsy group. ConclusionsGeneralised onset epilepsy showed a significantly shorter latency to IED and VEM duration compared with focal onset epilepsy. In our data set, all the patients with generalised onset epilepsy had interictal IED within 10 h, but the patients with focal onset epilepsy required monitoring for three days to obtain IED.

Referral trends for temporal lobe epilepsy surgery between 2000 and 2014 in India.

We conducted a retrospective study examining the trends in referral to a tertiary epilepsy surgery center in India over 2 decades. Data of patients who underwent long-term video electro encephalography monitoring for presurgical evaluation were retrospectively analyzed. Patients aged >16 years and diagnosed to have drug-resistant temporal lobe epilepsy (TLE) were included. They were divided into 3 groups comprising 5-year periods each during which they underwent presurgical evaluation, group 1: year 2000-2004; group 2: year 2005-2009; and group 3: year 2010-2014. Referral data with particular reference to duration of epilepsy before referral, age at onset of seizures, and number of antiepileptic drugs tried before referral were analyzed. A total of 1362 patients fulfilled the inclusion criteria. There were 385 referrals in group 1, 488 in group 2, and 489 in group 3. The mean duration of epilepsy before referral was 18.10 ± 9.44 years; there was no change in the duration of epilepsy before referral (p = 0.638). A significant increase in the age at onset of seizures and age at presurgical evaluation was noted over time. There is evidence for delayed referral of patients with refractory TLE to a surgical epilepsy center in this study. Renewed efforts to confront challenges beholding epilepsy surgery and steps to ensure timely referral are desirable.

Diagnostic and prognostic value of noninvasive long-term video-electroencephalographic monitoring in epilepsy surgery: A systematic review and meta-analysis from the E-PILEPSY consortium.

The European Union-funded E-PILEPSY network (now continuing within the European Reference Network for rare and complex epilepsies [EpiCARE]) aims to harmonize and optimize presurgical diagnostic procedures by creating and implementing evidence-based guidelines across Europe. The present study evaluates the current evidence on the diagnostic accuracy of long-term video-electroencephalographic monitoring (LTM) in identifying the epileptogenic zone in epilepsy surgery candidates. MEDLINE, Embase, CENTRAL, and ClinicalTrials.gov were searched for relevant articles. First, we used random-effects meta-analytical models to calculate pooled estimates of sensitivity and specificity with respect to postsurgical seizure freedom. In a second phase, we analyzed individual patient data in an exploratory fashion, assessing diagnostic accuracy within lesional and nonlesional temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE) patients. We also evaluated seizure freedom rate in the presence of "localizing" or "nonlocalizing" LTM within each group. The quality of evidence was assessed using the QUADAS-2 tool and the GRADE approach. Ninety-four studies were eligible. Forty-four were included in sensitivity meta-analysis and 34 in specificity meta-analysis. Pooled sensitivity was 0.70 (95% confidence interval [CI] = 0.60-0.80) and specificity was 0.40 (95% CI = 0.27-0.54). Subgroup analysis was based on individual data of 534 patients (41% men). In lesional TLE patients, sensitivity was 0.85 (95% CI = 0.81-0.89) and specificity was -0.19 (95% CI = 0.13-0.28). In lesional ETLE patients, a sensitivity of 0.47 (95% CI = 0.36-0.58) and specificity of 0.35 (95% CI = 0.21-0.53) were observed. In lesional TLE, if LTM was localizing and concordant with resection site, the seizure freedom rate was 247 of 333 (74%), whereas in lesional ETLE it was 34 of 56 (61%). The quality of evidence was assigned as "very low." Long-term video-electroencephalographic monitoring is associated with moderate sensitivity and low specificity in identification of the epileptogenic zone. Sensitivity is remarkably higher in lesional TLE compared to lesional ETLE. Substantial heterogeneity across the studies indicates the need for improved design and quality of reporting.

S10-4. Role of the medical doctors in longterm VIDO-EEG monitoring

Long-term video-electroencephalography monitoring (LTM) in epilepsy monitoring units (EMUs) is an essential and most meaningful investigation for diagnosis of epilepsy, classification of epileptic seizures and pre-surgical evaluation of patients with intractable localization-related epilepsy. The tapering of antiepileptic drugs is commonly used to record seizures efficiently. However, this practice may expose patients to serious adverse events, such as falls, status epilepticus, psychiatric complication, cardiac events and pulmonary complications. The issue of patients’ safety during LTM is one of the most important tasks. Before the starting of the LTM, the patients’ information (seizure type and frequency, history of seizure clusters, status epilepticus, and postictalpsychosis, number, dosage, and type of AEDs) must be shared in multidisciplinary conference, Based on these information, the AED tapering and safety plan should be developed for each patient. Furthermore, staff education improve patients’ supervision by nurses and EEG technicians, and immediate review of adverse events. The information and knowledge sharing by all the EMU staff might be most important for the patients‘ safety and efficient seizure recording.

Clinical value and predictors of subclinical seizures in patients with temporal lobe epilepsy undergoing scalp video-EEG monitoring

The aim of this study was to determine the clinical importance and predictors of SCSs in a large population of patients with temporal epilepsy (TLE) undergoing video electroencephalographic (VEEG) monitoring. We reviewed the VEEG data of 327 consecutive patients with TLE admitted to our epilepsy center between August 2012 and January 2017. Demographic, electro-clinical, and neuroimaging data were recorded and re-analyzed. To our knowledge, this is the first study assessing SCSs recorded by long-term VEEG monitoring in patients with TLE. Twenty-seven of 327 (8.3%) patients exhibited SCSs during VEEG monitoring. Of these patients, 24 had both SCSs and clinical seizures. The mean duration of the SCSs was 23.18s (range: 5–1307s). Of the 27 patients with SCSs, 24 (88.9%) showed localizing value during the diagnostic process. Seventeen patients exhibited colocalization with clinical seizures, 4 showed useless localization related to clinical seizures, and 3 did not have clinical seizures. Sixteen patients (59.3%) experienced their first SCSs within the first 24h of monitoring and one had the first SCSs within 20min. Multivariate logistic regression analysis showed that age <18years at VEEG monitoring (OR=3.272, 95% CI=1.283–8.343, p=0.013) and bilateral IEDs (OR=4.558, 95% CI=1.982–10.477, p<0.001) were independently associated with the presence of SCSs. Thus, SCSs are not uncommon in patients with TLE, particularly those with age <18years or bilateral IEDs, and should be considered of significant clinical relevance during the diagnostic process.

Optimal duration of video-electroencephalographic monitoring to capture seizures

We aimed to find the optimal duration of long-term video-electroencephalographic monitoring (VEM) to capture seizures in patients with epileptic seizures (ES) and psychogenic non-epileptic seizures (PNES) by evaluating the time to first clinical event and the diagnostic yield of clinical events and positive cases in each day of VEM. Patients aged ⩾18years who underwent VEM from May 2009 to June 2014 were studied retrospectively. Demographic, clinical and VEM data (including total monitoring length, type and time to first event, total number of ES/PNES) were collected. The difference in time to the first event between ES and PNES was analysed with Mann–Whitney U test. Of 207 VEM studies performed during the 5year period, 108 recordings captured seizures (ES and PNES) (52.2%). Median times to the first ES and PNES were 19.7 and 23.4hours, respectively (p=0.99). A small majority (53.7%) of event-positive patients had their first event on the first day of monitoring. By the end of the fifth day, 98% of all clinical events were captured and 99% of all positive cases were diagnosed. In conclusion, in a patient monitoring program where a diagnosis is reached by capturing seizures, 5days is probably sufficient to capture the greatest number of events and diagnose 99% of those patients.

Non-invasive Evaluation for Epilepsy Surgery.

Epilepsy surgery is aimed to remove the brain tissues that are indispensable for generating patient’s epileptic seizures. There are two purposes in the pre-operative evaluation: localization of the epileptogenic zone and localization of function. Surgery is planned to remove possible epileptogenic zone while preserving functional area. Since no single diagnostic modality is superior to others in identifying and localizing the epileptogenic zone, multiple non-invasive evaluations are performed to estimate the location of the epileptogenic zone after concordance between evaluations. Essential components of non-invasive pre-surgical evaluation of epilepsy include detailed clinical history, long-term video-electroencephalography monitoring, epilepsy-protocol magnetic resonance imaging (MRI), and neuropsychological testing. However, a significant portion of drug-resistant epilepsy is associated with no or subtle MRI lesions or with ambiguous electro-clinical signs. Additional evaluations including fluoro-deoxy glucose positron emission tomography (FDG-PET), magnetoencephalography and ictal single photon emission computed tomography can play critical roles in planning surgery. FDG-PET should be registered on three-dimensional MRI for better detection of focal cortical dysplasia. All diagnostic tools are complementary to each other in defining the epileptogenic zone, so that it is always important to reassess the data based on other results to pick up or confirm subtle abnormalities.