Termination of seizure clusters is related to the duration of focal seizures

Outpatient management of prolonged seizures and seizure clusters to prevent progression to a higher-level emergency: Consensus recommendations of an expert working group

OBJECTIVE

The management of prolonged seizures (PS) and seizure clusters (SC) is impeded by the lack of international, evidence-based guidance. We aimed to develop expert recommendations regarding consensus definitions of PS, SC, and treatment goals to prevent progression to higher-level emergencies such as status epilepticus (SE).

METHODS

An expert working group, comprising 12 epileptologists, neurologists, and pharmacologists from Europe and North America, used a modified Delphi consensus methodology to develop and anonymously vote on statements. Consensus was defined as ≥75% voting "Agree"/"Strongly agree."

RESULTS

All group members strongly agreed that termination of an ongoing seizure in as short a time as possible is the primary goal of rapid and early seizure termination (REST) and that an ideal medication for REST would start to act within 2 min of administration to terminate ongoing seizure activity. Consensus was reached on the terminology defining PS (with proposed thresholds of 5 min for prolonged focal seizures and 2 min for prolonged absence seizures and the convulsive phase of bilateral tonic-clonic seizures) and SC (an abnormal increase in seizure frequency compared with the individual patient's usual seizure pattern). All group members strongly agreed or agreed that patients who have experienced a PS should be offered a REST medication, and all patients who have experienced a SC should be offered an acute cluster treatment (ACT). Further, when prescribing a REST medication or ACT, a seizure action plan should be agreed upon in consultation with the patient and caregiver.

SIGNIFICANCE

The expert working group had a high level of agreement on the recommendations for defining and managing PS and SC. These recommendations will complement the existing guidance for the management of acute seizures, with the possibility of treating them earlier to potentially avoid progression to more severe seizures, including SE.

Neurological function and drug-refractory epilepsy in Sturge-Weber syndrome children: a retrospective analysis

Epilepsy in Sturge-Weber syndrome (SWS) is common, but drug-refractory epilepsy (DRE) in SWS has rarely been studied in children. We investigated the characteristics of epilepsy and risk factors for DRE in children with SWS. A retrospective study was conducted to analyze the clinical characteristics of children with SWS with epilepsy in our hospital from January 2013 to October 2022. Univariate and multivariate logistic analyses were performed to investigate the factors influencing DRE in children with SWS. A total of 35 SWS children with epilepsy were included (51% male; mean age of presentation 3.6 ± 0.5 years), 71% of children with SWS had their first seizure within the first year of life, and the most common type of seizure was focal seizure (77%). Eleven (31%) patients developed DRE. The median age of onset for the first seizure was 1.0 years and all these cases were of SWS type I. Multivariate logistic analysis revealed that stroke-like episodes and seizure clusters were risk factors for DRE in SWS children. A poor neurological function group was observed in twenty-five children with SWS. Status epilepticus was a risk factor that affected the neurological function of SWS children with epilepsy.  Conclusion: The study explored the epileptic features of children with SWS. The results revealed that stroke-like episodes and seizure clusters are risk factors for DRE in children with SWS. The occurrence of status epilepticus impacts the neurological function of SWS children with epilepsy. Thus, long-term follow-up is necessary to monitor outcomes. What is Known: • Sturge-Weber syndrome (SWS) is a rare neurocutaneous disorder, over 75% of children with SWS experience seizures, and 30-57% develop drug-refractory epilepsy (DRE), which leads to a poor outcome. • Drug-refractory epilepsy in SWS has been rarely studied in children, and the risk factors associated with DRE are unclear. What is New: • Clinical features of SWS children with drug-refractory epilepsy. • In SWS, stroke-like episodes and seizure clusters are risk factors of DRE, the occurrence of status epilepticus impacts the neurological function.

The impact of a history of status epilepticus for epilepsy surgery outcome

OBJECTIVE

Patients with focal drug resistant epilepsy are excellent candidates for epilepsy surgery. Status epilepticus (SE) and seizure clusters (SC), described in a subset of patients, have both been associated with extended epileptogenic cerebral networks within one or both hemispheres. In this retrospective study, we were interested to determine if a history of SE or SC is associated with a worse surgical outcome.

METHODS

Data of 244 patients operated between 2000 to 2018 were reviewed, with a follow-up of at least 2 years. Patients with a previous history of SE or SC were compared to operated patients without these conditions (control group, CG).

RESULTS

We identified 27 (11%) and 38 (15.5%) patients with history of SE or SC, respectively. No difference in post-operative outcome was found for SE and SC patients. Compared to the control group, patients with a history of SE were diagnosed and operated significantly at earlier age(p = 0.01), and after a shorter duration of the disease (p = 0.027), but with a similar age of onset.

SIGNIFICANCE

A history of SE or SC was not associated with a worse post-operative prognosis. Earlier referral of SE patients for surgery suggests a heightened awareness regarding serious complications of recurrent SE by the referring neurologist or neuropediatrician. While the danger of SE is evident, policies to underline the impact for SC or very frequent seizures might be an efficient approach to accelerate patient referral also for this patient group.

Individualized Seizure Cluster Prediction Using Machine Learning and Chronic Ambulatory Intracranial EEG

Epilepsy patients often experience acute repetitive seizures, known as seizure clusters, which can progress to prolonged seizures or status epilepticus if left untreated. Predicting the onset of seizure clusters is crucial to enable patients to receive preventative treatments. Additionally, studying the patterns of seizure clusters can help predict the seizure type (isolated or cluster) after observing a just occurred seizure. This paper presents machine learning models that use bivariate intracranial EEG (iEEG) features to predict seizure clustering. Specifically, we utilized relative entropy (REN) as a bivariate feature to capture potential differences in brain region interactions underlying isolated and cluster seizures. We analyzed a large ambulatory iEEG dataset collected from 15 patients and spanned up to 2 years of recordings for each patient, consisting of 3341 cluster seizures (from 427 clusters) and 369 isolated seizures. The dataset's substantial number of seizures per patient enabled individualized analyses and predictions. We observed that REN was significantly different between isolated and cluster seizures in majority of the patients. Machine learning models based on REN: 1) predicted whether a seizure will occur soon after a given seizure with up to 69.5% Area under the ROC Curve (AUC), 2) predicted if a seizure is the first one in a cluster with up to 55.3% AUC, outperforming baseline techniques. Overall, our findings could be beneficial in addressing the clinical burden associated with seizure clusters, enabling patients to receive timely treatments and improving their quality of life.

A retrospective multicentric study on the effectiveness of intravenous brivaracetam in seizure clusters: Data from the Italian experience

OBJECTIVE

Nearly half of people with epilepsy (PWE) are expected to develop seizure clusters (SC), with the subsequent risk of hospitalization. The aim of the present study was to evaluate the use, effectiveness and safety of intravenous (IV) brivaracetam (BRV) in the treatment of SC.

METHODS

Retrospective multicentric study of patients with SC (≥ 2 seizures/24 h) who received IV BRV. Data collection occurred from January 2019 to April 2022 in 25 Italian neurology units. Primary efficacy outcome was seizure freedom up to 24 h from BRV administration. We also evaluated the risk of evolution into Status Epilepticus (SE) at 6, 12 and 24 h after treatment initiation. A Cox regression model was used to identify outcome predictors.

RESULTS

97 patients were included (mean age 62 years), 74 (76%) of whom had a history of epilepsy (with drug resistant seizures in 49% of cases). BRV was administered as first line treatment in 16% of the episodes, while it was used as first or second drug after benzodiazepines failure in 49% and 35% of episodes, respectively. On the one hand, 58% patients were seizure free at 24 h after BRV administration and no other rescue medications were used in 75 out of 97 cases (77%) On the other hand, SC evolved into SE in 17% of cases. A higher probability of seizure relapse and/or evolution into SE was observed in patients without a prior history of epilepsy (HR 2.0; 95% CI 1.03 - 4.1) and in case of BRV administration as second/third line drug (HR 3.2; 95% CI 1.1 - 9.7). No severe treatment emergent adverse events were observed.

SIGNIFICANCE

In our cohort, IV BRV resulted to be well tolerated for the treatment of SC and it could be considered as a treatment option, particularly in case of in-hospital onset. However, the underlying etiology seems to be the main outcome predictor.

Periodic cycles of seizure clustering and suppression in children with epilepsy strongly suggest focal cortical dysplasia

AIM

We investigated characteristic seizure patterns in epilepsy caused by focal cortical dysplasia (FCD), which differ from epilepsy by other aetiologies in surgical cases with lesions on magnetic resonance imaging (MRI), then examined if these features were applicable to patients with epilepsy without any lesions on MRI.

METHOD

We retrospectively studied clinicopathological features in 291 (143 females) children with epilepsy who had undergone resective surgery after comprehensive evaluation, including 277 cases with lesions on MRI (136 females, age at resection 0-17 years [mean 6 years 10 months, SD 5 years 7 months]) and 14 cases without any lesions on MRI (seven females, age 0-16 years [mean 7 years 8 months, SD 4 years 8 months]).

RESULTS

Among 277 patients with lesions on MRI, 87 cases exhibited recurrent periodic cycles of seizure clustering (≥5 seizures/day for ≥1 week) and suppression (no seizures for ≥1 week); of these, 80 cases (92%) were pathologically diagnosed with FCD. Other pathologies included glial scar, hippocampal sclerosis, hemimegalencephaly, and cortical tuber in three, two, one, and one case respectively. All 14 patients without any lesions on MRI had significant recurrent periodic seizure cycles and FCD histopathologically.

INTERPRETATION

Periodic seizure cycles characterized by clustering and suppression in patients with epilepsy strongly suggest the presence of FCD regardless of MRI findings, and comprehensive evaluations for epilepsy surgery should be proceeded.

Prevalence and Predictors of Seizure Clusters in Pediatric Patients With Epilepsy: The Harvard-Yale Pediatric Seizure Cluster Study

BACKGROUND

Determine the prevalence of seizure clusters (two or more seizures in six hours), use of rescue medications, and adverse outcomes associated with seizure clusters in pediatric patients with a range of epilepsy severities, and identify risk factors predictive of seizure clusters.

METHODS

Prospective observational two-center study, including phone call and seizure diary follow-up for 12 months in patients with epilepsy aged one month to 18 years. We classified patients into three risk groups based on seizures within the prior year: high, seizure cluster (two or more seizures within one day); intermediate, at least one seizure but no days with two or more seizures; low, no seizures.

RESULTS

One-third (32.3%; high risk, 72.4%; intermediate risk, 30.4%; low risk, 3.1%) of 297 patients had a seizure cluster during the study, including half (46.2%) of the patients with active seizures at baseline (intermediate- and high-risk groups combined). Emergency room visits or injuries were no more likely due to a seizure cluster than an isolated seizure. Rescue medications were utilized in 15.8% of patients in the high-risk group and 19.2% in the intermediate-risk group. History of status epilepticus (adjusted odds ratio [aOR], 2.13; confidence interval [CI], 1.09 to 4.16]), seizure frequency greater than four per month (aOR, 4.27; CI, 1.92 to 9.50), and high-risk group status (aOR, 6.42; CI, 2.97 to 13.87) were associated with greater odds of seizure cluster.

CONCLUSIONS

Seizure clusters are common in pediatric patients with epilepsy. High seizure frequency was the strongest predictor of clusters. Rescue medications were underutilized. Future studies should evaluate the applicability and effectiveness of these medications for optimization of pediatric seizure cluster treatment and reduction of seizure-related emergency department visits, injuries, and mortality.

Significant improvements in SEIzure interVAL (time between seizure clusters) across time in patients treated with diazepam nasal spray as intermittent rescue therapy for seizure clusters

OBJECTIVE

Intermittent rescue therapy may be used for seizure clusters, which are clinical emergencies that may persist ≥24 h and increase risk of status epilepticus, emergency room visits, and reduced quality of life for patients with epilepsy. Beyond effectiveness for aborting seizure clusters, no data exist on how intermittent rescue therapy may impact the long-term natural course of seizure clusters. This novel analysis explores SEIzure interVAL (SEIVAL; time between seizure clusters) in patients from a long-term safety study of diazepam nasal spray (Valtoco) to assess SEIVAL changes with intermittent rescue therapy across time.

METHODS

Patients were aged 6-65 years. Age- and weight-based doses of diazepam nasal spray were administered during a 12-month treatment period with an optional follow-up period. SEIVAL was evaluated in patients receiving two or more doses of diazepam nasal spray using 90-day periods.

RESULTS

Of 163 treated patients, 151 had one or more SEIVALs. One hundred twenty had SEIVALs in Period 1 and one or more other periods. An increase in SEIVAL was noted from Period 1 compared with all subsequent periods (p ≤ .001). A consistent cohort (n = 76) had one or more SEIVALs in each of Periods 1-4 (360 days); mean SEIVALs increased significantly (p < .01) from 12.2 days (Period 1) to 25.7 days (Period 4). Similar SEIVAL patterns occurred when repeat doses within a seizure cluster were eliminated and irrespective of age group, treatment duration, and change to concomitant medications. In adults, Quality of Life in Epilepsy scores were maintained with increased SEIVALs.

SIGNIFICANCE

Across 12 months, increases in SEIVAL were demonstrated in patients using diazepam nasal spray for seizure cluster treatment in a phase 3 safety study. Increased time between seizure clusters may reflect a previously unrecognized beneficial effect of intermittent rescue therapy. These results generate a range of biological and behavioral hypotheses and warrant exploration of the impact of intermittent rescue therapy.

Future Opportunities for Research in Rescue Treatments

Clinical studies of rescue medications for seizure clusters are limited and are designed to satisfy regulatory requirements, which may not fully consider the needs of the diverse patient population that experiences seizure clusters or utilize rescue medication. The purpose of this narrative review is to examine the factors that contribute to, or may influence the quality of, seizure cluster research with a goal of improving clinical practice. We address five areas of unmet needs and provide advice for how they could enhance future trials of seizure cluster treatments. The topics addressed in this article are: (1) unaddressed end points to pursue in future studies, (2) roles for devices to enhance rescue medication clinical development programs, (3) tools to study seizure cluster prediction and prevention, (4) the value of other designs for seizure cluster studies, and (5) unique challenges of future trial paradigms for seizure clusters. By focusing on novel end points and technologies with value to patients, caregivers, and clinicians, data obtained from future studies can benefit the diverse patient population that experiences seizure clusters, providing more effective, appropriate care as well as alleviating demands on health care resources.

Rescue therapies in epilepsy

PURPOSE OF REVIEW

The purpose of this review is to provide a succinct evaluation of the current rescue medications and action plans available to our patients with seizure clusters in the outpatient setting.

RECENT FINDINGS

The main themes of the recent findings are that rescue medications and seizure action plans (SAPs) are underutilized, particularly in the adult population. The safety and efficacy of intranasal midazolam and intranasal diazepam is comparable with rectal diazepam for the treatment of seizure clusters. Additionally, this intranasal formulation has the benefit of a more socially acceptable route of administration and ease of use.

SUMMARY

The implication of these findings is a greater variety and awareness in the rescue medications available to our patients suffering from seizure clusters.

The Occurrence of Seizure Clusters in Patients With Epilepsy Is Partly Determined by Epilepsy Severity: A Single-Center Retrospective Observational Study

Purpose: This retrospective observational study aimed to investigate the self-reported prevalence of seizure clusters (SCs) in patients with epilepsy (PWE) and its relationship with clinical characteristics.

Methods: We retrospectively analyzed data from consecutive PWE from our hospital in northeastern China. Data were collected from the databank of a tertiary epilepsy center. Logistic regression models were employed to investigate the relationships between the individual patient demographic/clinical variables and the occurrence of SC.

Results: In total, 606 consecutive PWE were included in the final analysis, and 268 (44.2%) patients experienced at least one seizure cluster. In multivariate logistic regression models, age (OR: 1.014; 95% CI: 1.002–1.027; p = 0.02), seizure frequency (OR: 2.08; 95% CI: 1.555–2.783; p < 0.001), multiple seizure types (OR: 5.111; 95% CI: 1.737–15.043; p = 0.003), number of current anti-seizure medications (ASM) (OR: 1.533; 95% CI: 1.15–2.042; p = 0.004), drug-resistant epilepsy (OR: 1.987; 95% CI: 1.159–3.407; p = 0.013), and a history of status epilepticus (OR: 1.903; 95% CI: 1.24–2.922; p = 0.003) were independent variables associated with a history of SC in PWE.

Conclusion: Seizure clusters (SCs) are common occurrences at our study center. The occurrence of SC in individuals with epilepsy, to some extent, is determined by the epilepsy severity.

Evidence for long memory in focal seizure duration

Objective

A major source of disability for people with epilepsy involves uncertainty surrounding seizure timing and severity. Although patients often report that long seizure-free intervals are followed by more severe seizures, there is little experimental evidence supporting this observation. Optimal characterization of seizure severity is debated; however, seizure duration is associated with seizure type and can be quantified in electrographic recordings as a limited proxy of clinical seizure severity. Here, using chronic intracranial electroencephalography (cEEG), we investigate the relationship between interseizure interval (ISI) and duration of the subsequent seizure.

Methods

We performed a retrospective analysis of 14 subjects implanted with a responsive neurostimulation device (RNS System) that provides cEEG, including timestamps of electrographic seizures. We determined seizure durations for isolated seizures and for representative seizures from clusters determined through unsupervised methods. For each subject, the median ISI preceding long-duration seizures, defined as the top quintile of seizure durations, was compared with the median ISI preceding seizures with durations in the residual quintiles. In a group analysis, the mean seizure duration and the proportion of long-duration seizures were compared across ISI categories representing different lengths.

Results

For 5 out of 14 subjects (36%), the median ISI preceding long-duration seizures was significantly greater than the median ISI preceding shorter-duration seizures. In the group analysis, when ISI was categorized by length, the proportion of long-duration seizures within the high ISI category was significantly higher than that of the low ISI category (P < 0.001).

Significance

By leveraging cEEG and accounting for seizure clusters, we found that the likelihood of long-duration seizures positively correlates with ISI length, in a subset of individuals. These findings corroborate anecdotal clinical observations and support the existence of capacitor-like long memory processes governing the dynamics of focal seizures.

Intravenous Ketamine Bolus(es) for the Treatment of Status Epilepticus, Refractory Status Epilepticus, and Cluster Seizures: A Retrospective Study of 15 Dogs

Status epilepticus (SE) and cluster seizures (CS) are common occurrences in veterinary neurology and frequent reasons of admission to veterinary hospitals. With prolonged seizure activity, gamma amino-butyric acid (GABA) receptors (GABAa receptors) become inactive, leading to a state of pharmacoresistance to benzodiazepines and other GABAergic medications, which is called refractory status epilepticus (RSE). Prolonged seizure activity is also associated with overexpression of N-methyl-D-aspartic (NMDA) receptors. Rodent models have shown the efficacy of ketamine (KET) in treating RSE, and its use has been reported in one canine case of RSE. Boluses of KET 5 mg/kg IV have become the preferred treatment for RSE in our hospital. A retrospective study was performed to evaluate and report our experience with KET IV bolus to treat prolonged and/or repeated seizure activity in cases of canine CS, SE, and RSE. A total of 15 dogs were retrieved, for 20 hospitalizations and 28 KET IV injections over 3 years. KET IV boluses were used 12 times for RSE (9 generalized seizures, 3 focal seizures) and KET terminated the episode of RSE 12/12 times (100%); however, seizures recurred 4/12 times (33%) within ≤6 h of KET IV bolus. When used for CS apart from episodes of RSE, KET IV bolus was associated with termination of the CS episode only 4/14 times (29%). Only 4/28 (14%) KET IV boluses were associated with adverse effects imputable only to the use of KET. One dog experienced a short, self-limited seizure activity during administration of KET IV, which was most likely related to a pre-mature use of KET IV (i.e., before GABAergic resistance and NMDA receptor overexpression had taken place). This study indicates that KET 5 mg/kg IV bolus may be successful for the treatment of RSE in dogs.

Seizure Clusters, Seizure Severity Markers, and SUDEP Risk

Rationale: Seizure clusters may be related to Sudden Unexpected Death in Epilepsy (SUDEP). Two or more generalized convulsive seizures (GCS) were captured during video electroencephalography in 7/11 (64%) patients with monitored SUDEP in the MORTEMUS study. It follows that seizure clusters may be associated with epilepsy severity and possibly with SUDEP risk. We aimed to determine if electroclinical seizure features worsen from seizure to seizure within a cluster and possible associations between GCS clusters, markers of seizure severity, and SUDEP risk. Methods: Patients were consecutive, prospectively consented participants with drug-resistant epilepsy from a multi-center study. Seizure clusters were defined as two or more GCS in a 24-h period during the recording of prolonged video-electroencephalography in the Epilepsy monitoring unit (EMU). We measured heart rate variability (HRV), pulse oximetry, plethysmography, postictal generalized electroencephalographic suppression (PGES), and electroencephalography (EEG) recovery duration. A linear mixed effects model was used to study the difference between the first and subsequent seizures, with a level of significance set at p < 0.05. Results: We identified 112 GCS clusters in 105 patients with 285 seizures. GCS lasted on average 48.7 ± 19 s (mean 49, range 2-137). PGES emerged in 184 (64.6%) seizures and postconvulsive central apnea (PCCA) was present in 38 (13.3%) seizures. Changes in seizure features from seizure to seizure such as seizure and convulsive phase durations appeared random. In grouped analysis, some seizure features underwent significant deterioration, whereas others improved. Clonic phase and postconvulsive central apnea (PCCA) were significantly shorter in the fourth seizure compared to the first. By contrast, duration of decerebrate posturing and ictal central apnea were longer. Four SUDEP cases in the cluster cohort were reported on follow-up. Conclusion: Seizure clusters show variable changes from seizure to seizure. Although clusters may reflect epilepsy severity, they alone may be unrelated to SUDEP risk. We suggest a stochastic nature to SUDEP occurrence, where seizure clusters may be more likely to contribute to SUDEP if an underlying progressive tendency toward SUDEP has matured toward a critical SUDEP threshold.

Seizure clusters, rescue treatments, seizure action plans: Unmet needs and emerging formulations

PURPOSE OF REVIEW

The aim of the study was to provide an overview of the prevalence, risk factors, burden, and current and emerging pharmacologic treatments for seizure clusters in patients with epilepsy.

RECENT FINDINGS

Close to half of patients with active epilepsy experience seizure clusters, and the clinical, social, and financial burdens of seizure clusters are high. However, there is no widely accepted definition of seizure clusters; their prevalence is underappreciated, contingencies for addressing them (seizure action plans) are often lacking, and their effects are not well-studied. These issues have resulted in an insufficient number of investigations and approved medications for this condition. Novel formulations are in late-stage development to meet this unmet need.

Placebo in epilepsy

Placebos impact epilepsy in a number of ways. Through randomized clinical trials, explicit clinical use, and also through implicit clinical use, placebos play a role in epilepsy. This chapter will discuss the reasons placebo is used, the determinants of placebo response in epilepsy, observations about placebo specific to epilepsy, and ways in which clinical trial design is impacted by placebo.

Circadian and multiday seizure periodicities, and seizure clusters in canine epilepsy

Advances in ambulatory intracranial EEG devices have enabled objective analyses of circadian and multiday seizure periodicities, and seizure clusters in humans. This study characterizes circadian and multiday seizure periodicities, and seizure clusters in dogs with naturally occurring focal epilepsy, and considers the implications of an animal model for the study of seizure risk patterns, seizure forecasting and personalized treatment protocols. In this retrospective cohort study, 16 dogs were continuously monitored with ambulatory intracranial EEG devices designed for humans. Detailed medication records were kept for all dogs. Seizure periodicity was evaluated with circular statistics methods. Circular non-uniformity was assessed for circadian, 7-day and approximately monthly periods. The Rayleigh test was used to assess statistical significance, with correction for multiple comparisons. Seizure clusters were evaluated with Fano factor (index of dispersion) measurements, and compared to a Poisson distribution. Relationships between interseizure interval (ISI) and seizure duration were evaluated. Six dogs met the inclusion criteria of having at least 30 seizures and were monitored for an average of 65 weeks. Three dogs had seizures with circadian seizure periodicity, one dog had a 7-day periodicity, and two dogs had approximately monthly periodicity. Four dogs had seizure clusters and significantly elevated Fano factor values. There were subject-specific differences in the dynamics of ISI and seizure durations, both within and between lead and clustered seizure categories. Our findings show that seizure timing in dogs with naturally occurring epilepsy is not random, and that circadian and multiday seizure periodicities, and seizure clusters are common. Circadian, 7-day, and monthly seizure periodicities occur independent of antiseizure medication dosing, and these patterns likely reflect endogenous rhythms of seizure risk.

Long-term Outcome of Intravenous Lidocaine in Pediatric Cluster Seizures: A Preliminary Study

BACKGROUND

Cluster seizures are life-threatening conditions. They may easily evolve into status epilepticus and are reported in up to 20% to 30% of patients with epilepsy. Sometimes cluster seizures become drug resistant, leading to the use of unconventional therapies. One of these unconventional approaches may be the use of lidocaine, which is a sodium-channel-blocking drug mostly known as a local anesthetic and antiarrhythmic agent.

METHODS

We describe the outcome of four children who were treated with continuous intravenous infusion of 2% lidocaine due to drug-resistant focal cluster seizures. Lidocaine was administered as an initial dose of 1 mg/kg/hour and, subsequently, was increased to 2 to 4 mg/kg/hour. The therapy was continued for five to 10 days. Patients remained under careful cardiological surveillance during the treatment.

RESULTS

Complete seizure remission was achieved in all four children. None of the patients experienced adverse events. Although seizures recurred in all patients within an average time of 2.4 months, they appeared with reduced frequency, and within the follow-up period (mean 7.5 months) no additional cluster seizures occurred.

CONCLUSIONS

Treatment with lidocaine in pediatric cluster seizures may be useful and may be considered as a therapeutic option. Our patients encountered no side effects and experienced prolonged seizure remission, possibly resulting from the effect of lidocaine on sodium channels or from its anti-inflammatory properties. However, more studies are required to confirm the safety and long-term effectiveness of this approach. Clinicians should be aware of possible adverse effects and necessity of sustained cardiological surveillance during the treatment.

Methods for the Detection of Seizure Bursts in Epilepsy

Background: Seizure clusters and “bursts” are of clinical importance. Clusters are reported to be a marker of antiepileptic drug resistance. Additionally, seizure clustering has been found to be associated with increased morbidity and mortality. However, there are no statistical methods described in the literature to delineate bursting phenomenon in epileptic seizures.

Methods: We present three automatic burst detection methods referred to as precision constrained grouping (PCG), burst duration constrained grouping (BCG), and interseizure interval constrained grouping (ICG). Concordance correlation coefficients were used to confirm the pairwise agreement between common bursts isolated using these three automatic burst detection procedures. Additionally, three graphical methods were employed to demonstrate seizure bursts: modified scatter plots, staircase plots, and dropline plots. Burst detection procedures are demonstrated on data from continuous intracranial ambulatory EEG monitoring in a patient diagnosed with drug-refractory focal epilepsy.

Results: We analyzed 1,569 seizures, from our assigned index patient, captured on ambulatory intracranial EEG monitoring. A total of 31, 32, and 32 seizure bursts were detected by the three quantitative methods (BCG, ICG, and PCG), respectively. The concordance correlation coefficient was ≥0.99 signifying considerably stronger than chance burst detector agreements with one another.

Conclusions: Bursting is a quantifiable temporal phenomenon in epilepsy and seizure bursts can be reliably detected using our methodology.

Prevalence and predictors of seizure clusters: A prospective observational study of adult patients with epilepsy

OBJECTIVE

The purpose of this prospective observational study was to describe the prevalence and adverse outcomes associated with seizure clusters (defined as ≥2 seizures in a 6-hour period) in a large sample of adult patients with a range of epilepsy severities and to identify clinical characteristics predictive of clustering.

METHODS

Patients maintained a seizure diary and were contacted monthly to verify compliance and data accuracy. Logistic regression models were utilized to test associations between individual patient demographic/clinical characteristics and seizure clustering. Fisher's exact test was utilized to test associations between rescue medication use and adverse seizure-related outcomes.

RESULTS

A total of 300 patients were followed prospectively for one year; 247 patients qualified for final analysis. Six-hour seizure clusters occurred in 45.8% of patients with active epilepsy at enrollment, including 62.7% of those with prior day-clusters and 30.0% of those without prior day-clusters. The odds of clustering were markedly greater among patients who reported a higher seizure frequency (>4 seizures per year vs. 1-4 seizures per year) (adjusted odds ratio (OR): 8.9; 95% confidence interval (CI): 3.2-24.6; p < 0.0001) and among patients with prior day-clusters (adjusted OR: 11.0; 95% CI: 1.2-104.2; p = 0.036). Rescue medication use was associated with significantly fewer injuries and emergency department visits, but rescue medication was underutilized.

CONCLUSIONS

Seizure clusters are common, occurring in nearly half of adult patients with active epilepsy followed prospectively over one year, and are more frequent in those with higher seizure frequencies and prior day-clusters. Although underutilized, rescue medication was associated with fewer injuries and emergency department visit.

Clustering of spontaneous recurrent seizures separated by long seizure-free periods: An extended video-EEG monitoring study of a pilocarpine mouse model

Seizure clustering is a common and significant phenomenon in patients with epilepsy. The clustering of spontaneous recurrent seizures (SRSs) in animal models of epilepsy, including mouse pilocarpine models, has been reported. However, most studies have analyzed seizures for a short duration after the induction of status epilepticus (SE). In this study, we investigated the detailed characteristics of seizure clustering in the chronic stage of a mouse pilocarpine-induced epilepsy model for an extended duration by continuous 24/7 video-EEG monitoring. A seizure cluster was defined as the occurrence of one or more seizures per day for at least three consecutive days and at least five seizures during the cluster period. We analyzed the cluster duration, seizure-free period, cluster interval, and numbers of seizures within and outside the seizure clusters. The video-EEG monitoring began 84.5±33.7 days after the induction of SE and continued for 53.7±20.4 days. Every mouse displayed seizure clusters, and 97.0% of the seizures occurred within a cluster period. The seizure clusters were followed by long seizure-free periods of 16.3±6.8 days, showing a cyclic pattern. The SRSs also occurred in a grouped pattern within a day. We demonstrate that almost all seizures occur in clusters with a cyclic pattern in the chronic stage of a mouse pilocarpine-induced epilepsy model. The seizure-free periods between clusters were long. These findings should be considered when performing in vivo studies using this animal model. Furthermore, this model might be appropriate for studying the unrevealed mechanism of ictogenesis.

Seizure clustering during presurgical electroencephalographic monitoring in children

BACKGROUND

Presurgical evaluation with antiseizure medication tapering in patients with refractory epilepsy places them at risk for seizure clustering or prolonged seizures. We looked at the occurrence of seizure clustering (3 or more seizures within 24h) and prolonged seizures and the factors that influence seizure clustering and affect length of stay (LOS) in pediatric patients during presurgical monitoring.

METHODS

We retrospectively reviewed the medical records of all consecutive admissions to the epilepsy monitoring unit (EMU) and included patients undergoing noninvasive presurgical evaluation. Data were extracted regarding demographics, seizure history, details of the EMU admission including occurrence of seizure clusters, prolonged seizures, status epilepticus, treatment, and LOS.

RESULTS

Sixty-nine patients met our inclusion criteria. Seizure clustering during monitoring was observed in 33 patients (48%). Prolonged seizures lasting >5min was observed in 14 (20%) patients including 2 with status epilepticus (3%). Seizure clusters necessitated rescue treatment in around 30%. History of seizure clustering at home was the only factor associated with the occurrence of seizure clustering during the EMU stay (p<0.0001). The LOS did not differ significantly between patients who had seizure clustering during monitoring versus those who did not (p=0.369).

CONCLUSIONS

Seizure clustering was common in children undergoing presurgical monitoring and seen especially in those with a history of seizure clustering at home. Occurrence of seizure clustering did not prolong the LOS but necessitated the use of rescue medications in about a third of the patients with seizure clusters due to multiple seizures.

SK channels participate in the formation of after burst hyperpolarization and partly inhibit the burst strength of epileptic ictal discharges

Epilepsy is a common disease of the central nervous system. Tetanic spasms and convulsions are the key symptoms exhibited during epileptic seizures. However, the majority of patients have a significant post-seizure silence following a serious seizure; the underlying molecular neural mechanisms in this burst interval are unclear. The aim of the present study was to reveal the effect and role of calcium-activated potassium channels during this seizure interval silence period. Cyclothiazide (CTZ) was used to establish the seizure model in rat hippocampal cultured neurons, then the after-burst hyperpolarization (ABH) activities were recorded using the patch clamp technique. By comparing the amplitude and duration of hyperpolarizations, the present study analyzed the association between epileptiform bursts and ABHs when treated with different concentrations of CTZ. In addition, apamin and iberiotoxin were used for pharmacological tests. An intracranial electroencephalogram (EEG) recording was also performed when the CTZ experiments were repeated on animals. The experimental results revealed that treatment with high levels of CTZ induced larger ABHs and was associated with stronger burst activities, which suggested a positive correlation between ABH and epileptiform burst. Apamin, an antagonist of small conductance calcium-activated potassium (SK) channels, decreased the amplitude of ABH; however, reduced ABH was associated with enhanced burst activity, in burst probability and burst strength. These results revealed an important role of SK channels in the formation of ABH and in the inhibition of burst activity. Iberiotoxin, an antagonist of big conductance calcium-activated potassium (BK) channels, had no significant effect on ABH and burst activity. In addition, a positive correlation was identified between burst duration and ABH parameters. An intracellular calcium chelator impaired the amplitude of ABH; however, it did not affect the burst parameters. The rat cortical EEG recordings also exhibited a similar positive correlation between the duration of epileptic burst and after burst depression. Collectively, the results indicate that ABH may serve in the physiological feedback system to reduce the strength of epileptic hyperexcitation, a process in which SK channels are important.

Identifying seizure onset zone from electrocorticographic recordings: A machine learning approach based on phase locking value

PURPOSE

Using a novel technique based on phase locking value (PLV), we investigated the potential for features extracted from electrocorticographic (ECoG) recordings to serve as biomarkers to identify the seizure onset zone (SOZ).

METHODS

We computed the PLV between the phase of the amplitude of high gamma activity (80-150Hz) and the phase of lower frequency rhythms (4-30Hz) from ECoG recordings obtained from 10 patients with epilepsy (21 seizures). We extracted five features from the PLV and used a machine learning approach based on logistic regression to build a model that classifies electrodes as SOZ or non-SOZ.

RESULTS

More than 96% of electrodes identified as the SOZ by our algorithm were within the resected area in six seizure-free patients. In four non-seizure-free patients, more than 31% of the identified SOZ electrodes by our algorithm were outside the resected area. In addition, we observed that the seizure outcome in non-seizure-free patients correlated with the number of non-resected SOZ electrodes identified by our algorithm.

CONCLUSION

This machine learning approach, based on features extracted from the PLV, effectively identified electrodes within the SOZ. The approach has the potential to assist clinicians in surgical decision-making when pre-surgical intracranial recordings are utilized.

Prevalence and risk factors of seizure clusters in adult patients with epilepsy

PURPOSE

In the current study, we explored the prevalence of physician-confirmed seizure clusters. We also investigated potential clinical factors associated with the occurrence of seizure clusters overall and by epilepsy type.

METHODS

We reviewed medical records of 4116 adult (≥16years old) outpatients with epilepsy at our centers for documentation of seizure clusters. Variables including patient demographics, epilepsy details, medical and psychiatric history, AED history, and epilepsy risk factors were then tested against history of seizure clusters. Patients were then divided into focal epilepsy, idiopathic generalized epilepsy (IGE), or symptomatic generalized epilepsy (SGE), and the same analysis was run.

RESULTS

Overall, seizure clusters were independently associated with earlier age of seizure onset, symptomatic generalized epilepsy (SGE), central nervous system (CNS) infection, cortical dysplasia, status epilepticus, absence of 1-year seizure freedom, and having failed 2 or more AEDs (P<0.0026). Patients with SGE (27.1%) were more likely to develop seizure clusters than patients with focal epilepsy (16.3%) and IGE (7.4%; all P<0.001). Analysis by epilepsy type showed that absence of 1-year seizure freedom since starting treatment at one of our centers was associated with seizure clustering in patients across all 3 epilepsy types. In patients with SGE, clusters were associated with perinatal/congenital brain injury. In patients with focal epilepsy, clusters were associated with younger age of seizure onset, complex partial seizures, cortical dysplasia, status epilepticus, CNS infection, and having failed 2 or more AEDs. In patients with IGE, clusters were associated with presence of an aura. Only 43.5% of patients with seizure clusters were prescribed rescue medications.

CONCLUSION

Patients with intractable epilepsy are at a higher risk of developing seizure clusters. Factors such as having SGE, CNS infection, cortical dysplasia, status epilepticus or an early seizure onset, can also independently increase one's chance of having seizure clusters.

Bursts of seizures in long-term recordings of human focal epilepsy

OBJECTIVE

We report on temporally clustered seizures detected from continuous long-term ambulatory human electroencephalographic data. The objective was to investigate short-term seizure clustering, which we have termed bursting, and consider implications for patient care, seizure prediction, and evaluating therapies.

METHODS

Chronic ambulatory intracranial electroencephalography (EEG) data collected for the purpose of seizure prediction were annotated to identify seizure events. A detection algorithm was used to identify bursts of events. Burst events were compared to nonburst events to evaluate event dispersion, duration and dynamics.

RESULTS

Bursts of seizures were present in 6 of 15 subjects, and detections were consistent over long-term monitoring (>2 years). Subjects with bursts of seizures had highly overdispersed seizure rates, compared to other subjects. There was a complicated relationship between bursts and clinical seizures, although bursts were associated with multimodal distributions of seizure duration, and poorer predictive outcomes. For three subjects, bursts demonstrated distinctive preictal dynamics compared to clinical seizures.

SIGNIFICANCE

We have previously hypothesized that there are distinct physiologic pathways underlying short- and long-duration seizures. Herein we show that burst seizures fall almost exclusively within the short population of seizure durations; however, a short duration event was not sufficient to induce or imply bursting. We can therefore conclude that in addition to distinct mechanisms underlying seizure duration, there are separate factors regulating bursts of seizures. We show that bursts were a robust phenomenon in our patient cohort, which were consistent with overdispersed seizure rates, suggesting long-memory dynamics.