Risk of a seizure recurrence after a breakthrough seizure and the implications for driving: further analysis of the standard versus new antiepileptic drugs (SANAD) randomised controlled trial

Risk of breakthrough seizures depends on type and etiology of epilepsy

OBJECTIVE

This study was undertaken to analyze whether the rate of breakthrough seizures in patients taking antiseizure medication (ASM) who have been seizure-free for at least 12 months varies among different types and etiologies of epilepsy. Given the relative ease of achieving seizure freedom with ASM in patients with post-ischemic stroke epilepsy, we hypothesized that this etiology is associated with a reduced risk of breakthrough seizures.

METHODS

We defined a breakthrough seizure as an unprovoked seizure occurring while the patient was taking ASM after a period of at least 12 months without seizures. Data were analyzed retrospectively from a tertiary epilepsy outpatient clinic. Patients were eligible for inclusion if they either had a breakthrough seizure at any time or a seizure-free interval of at least 2 years. Our primary endpoint was rate of breakthrough seizures. We conducted univariable and multivariable analyses to identify variables associated with breakthrough seizures.

RESULTS

Of 521 patients (53% females, median age = 49 years) included, 29% had a breakthrough seizure, which occurred after a median seizure-free interval of 34 months (quartiles = 22, 62). When controlling for clinically relevant covariates, breakthrough seizures were associated with post-ischemic stroke epilepsy (odds ratio [OR] = .267, 95% confidence interval [CI] = .075-.946), genetic generalized epilepsy (OR = .559; 95% CI = .319-.978), intellectual disability (OR = 2.768, 95% CI = 1.271-6.031), and the number of ASMs previously and currently tried (OR = 1.203, 95% CI = 1.056-1.371). Of the 151 patients with breakthrough seizures, 34.3% did not reachieve terminal 12-month seizure freedom at the last visit.

SIGNIFICANCE

This is the first study to show an association between type and etiology of epilepsy and risk of breakthrough seizures. Our data suggest that epilepsies in which seizure freedom can be obtained more easily also exhibit a lower risk of breakthrough seizures. These findings may help to better counsel seizure-free patients on their further seizure prognosis.

Therapeutic drug monitoring in pregnancy: Levetiracetam

OBJECTIVE

Levetiracetam (LEV) is an antiseizure medication that is mainly excreted by the kidneys. Due to its low teratogenic risk, LEV is frequently prescribed for women with epilepsy (WWE). Physiological changes during gestation affect the pharmacokinetic characteristics of LEV. The goal of our study was to characterize the changes in LEV clearance during pregnancy and the postpartum period, to better plan an LEV dosing paradigm for pregnant women.

METHODS

This retrospective observational study incorporated a cohort of women who were followed up at the epilepsy in pregnancy clinic at Tel Aviv Sourasky Medical Center during the years 2020-2023. Individualized target concentrations of LEV and an empirical postpartum taper were used for seizure control and to reduce toxicity likelihood. Patient visits took place every 1-2 months and included a review of medication dosage, trough LEV blood levels, week of gestation and LEV dose at the time of level measurement, and seizure diaries. Total LEV concentration/dose was calculated based on LEV levels and dose as an estimation of LEV clearance.

RESULTS

A total of 263 samples were collected from 38 pregnant patients. We observed a decrease in LEV concentration/dose (C/D) as the pregnancy progressed, followed by an abrupt postpartum increase. Compared to the 3rd trimester, the most significant C/D decrease was observed at the 1st trimester (slope = .85), with no significant change in the 2nd trimester (slope = .11). A significant increase in C/D occurred postpartum (slope = 5.23). LEV dose was gradually increased by 75% during pregnancy compared to preconception. Average serum levels (μg/mL) decreased during pregnancy. During the postpartum period, serum levels increased, whereas the LEV dose was decreased by 24%, compared to the 3rd trimester.

SIGNIFICANCE

LEV serum level monitoring is essential for WWE prior to and during pregnancy as well as postpartum. Our data contribute to determining a rational treatment and dosing paradigm for LEV use during both pregnancy and the postpartum period.

Automated subcortical volume estimation from 2D MRI in epilepsy and implications for clinical trials

Purpose

Most techniques used for automatic segmentation of subcortical brain regions are developed for three-dimensional (3D) MR images. MRIs obtained in non-specialist hospitals may be non-isotropic and two-dimensional (2D). Automatic segmentation of 2D images may be challenging and represents a lost opportunity to perform quantitative image analysis. We determine the performance of a modified subcortical segmentation technique applied to 2D images in patients with idiopathic generalised epilepsy (IGE).

Methods

Volume estimates were derived from 2D (0.4 × 0.4 × 3 mm) and 3D (1 × 1x1mm) T1-weighted acquisitions in 31 patients with IGE and 39 healthy controls. 2D image segmentation was performed using a modified FSL FIRST (FMRIB Integrated Registration and Segmentation Tool) pipeline requiring additional image reorientation, cropping, interpolation and brain extraction prior to conventional FIRST segmentation. Consistency between segmentations was assessed using Dice coefficients and volumes across both approaches were compared between patients and controls. The influence of slice thickness on consistency was further assessed using 2D images with slice thickness increased to 6 mm.

Results

All average Dice coefficients showed excellent agreement between 2 and 3D images across subcortical structures (0.86–0.96). Most 2D volumes were consistently slightly lower compared to 3D volumes. 2D images with increased slice thickness showed lower agreement with 3D images with lower Dice coefficients (0.55–0.83). Significant volume reduction of the left and right thalamus and putamen was observed in patients relative to controls across 2D and 3D images.

Conclusion

Automated subcortical volume estimation of 2D images with a resolution of 0.4 × 0.4x3mm using a modified FIRST pipeline is consistent with volumes derived from 3D images, although this consistency decreases with an increased slice thickness. Thalamic and putamen atrophy has previously been reported in patients with IGE. Automated subcortical volume estimation from 2D images is feasible and most reliable at using in-plane acquisitions greater than 1 mm x 1 mm and provides an opportunity to perform quantitative image analysis studies in clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00234-021-02811-x.

Functional network topology in drug resistant and well-controlled idiopathic generalized epilepsy: a resting state functional MRI study

Despite an increasing number of drug treatment options for people with idiopathic generalized epilepsy (IGE), drug resistance remains a significant issue and the mechanisms underlying it remain poorly understood. Previous studies have largely focused on potential cellular or genetic explanations for drug resistance. However, epilepsy is understood to be a network disorder and there is a growing body of literature suggesting altered topology of large-scale resting networks in people with epilepsy compared with controls. We hypothesize that network alterations may also play a role in seizure control. The aim of this study was to compare resting state functional network structure between well-controlled IGE (WC-IGE), drug resistant IGE (DR-IGE) and healthy controls. Thirty-three participants with IGE (10 with WC-IGE and 23 with DR-IGE) and 34 controls were included. Resting state functional MRI networks were constructed using the Functional Connectivity Toolbox (CONN). Global graph theoretic network measures of average node strength (an equivalent measure to mean degree in a network that is fully connected), node strength distribution variance, characteristic path length, average clustering coefficient, small-world index and average betweenness centrality were computed. Graphs were constructed separately for positively weighted connections and for absolute values. Individual nodal values of strength and betweenness centrality were also measured and ‘hub nodes’ were compared between groups. Outcome measures were assessed across the three groups and between both groups with IGE and controls. The IGE group as a whole had a higher average node strength, characteristic path length and average betweenness centrality. There were no clear differences between groups according to seizure control. Outcome metrics were sensitive to whether negatively correlated connections were included in network construction. There were no clear differences in the location of ‘hub nodes’ between groups. The results suggest that, irrespective of seizure control, IGE interictal network topology is more regular and has a higher global connectivity compared to controls, with no alteration in hub node locations. These alterations may produce a resting state network that is more vulnerable to transitioning to the seizure state. It is possible that the lack of apparent influence of seizure control on network topology is limited by challenges in classifying drug response. It is also demonstrated that network topological features are influenced by the sign of connectivity weights and therefore future methodological work is warranted to account for anticorrelations in graph theoretic studies.

Optimizing Management of Medically Responsive Epilepsy

PURPOSE OF REVIEW

This article reviews the management of patients with medically responsive epilepsy, including discussion of factors that may lead to transient breakthrough seizures and patient and physician strategies to maintain freedom from seizures.

RECENT FINDINGS

Imperfect adherence, unanticipated changes in ongoing medical therapy, inadvertent use of proconvulsants or concurrent medications that alter epilepsy medication kinetics, and a variety of seizure precipitants such as stress or sleep deprivation may alter long-term seizure control.

SUMMARY

The majority of patients with epilepsy are medically responsive. Many potential factors may lead to breakthrough seizures in these patients. Identification of these factors, patient education, and use of self-management techniques including mindfulness therapy and cognitive-behavioral therapy may play a role in protecting patients with epilepsy against breakthrough seizures.

General health complaints and sleep associated with new injury within an endurance sporting population: A prospective study

OBJECTIVES

To examine the association between subjective health complaints, sleep quantity and new injury within an endurance sport population.

DESIGN

Prospective cohort study.

METHODS

Ninety-five endurance sporting participants were recruited from running, triathlon, swimming, cycling and rowing disciplines. Over 52-week period participants submitted weekly data regarding subjective health complaints (SHCs) (cardiorespiratory, gastrointestinal and psychological/lifestyle), sleep quantity, training load and new injury episodes. Applying a 7- and 14-day lag period, a shared frailty model was used to explore new injury risk associations with total SHCs and sleep quantity.

RESULTS

92.6% of 95 participants completed all 52 weeks of data submission and the remainder of the participants completed ≥30 weeks. Seven-day lag psychological/lifestyle SHCs were significantly associated with new injury risk (Hazard ratio (HR)=1.32; CI 95%=1.01-1.72, p<0.04). In contrast, cardiorespiratory (HR=1.15; CI 95%=0.99-1.36, p=0.07) and gastrointestinal (HR=0.77; CI 95%=0.56-1.05, p=0.09) SHCs were not significantly associated with new injury risk. New injury risk had a significant increased association with 14-day lag <7h/day sleep quantity (HR=1.51; CI 95%=2.02-1.13, p<0.01) and a significant decreased association with >7h/day sleep quantity (HR=0.63, CI 95%=0.45-0.87, p<0.01. A secondary regression analysis demonstrated no significant association with total SHCs and training load factors (Relative Risk (RR)=0.08, CI 95%=0.04-0.21, p=0.20).

CONCLUSIONS

To minimise an increased risk of new injuries within an endurance sporting population, this study demonstrates that psychological/lifestyle subjective health complaints and sleep quantity should be considered. The study also highlights a lag period between low sleep quantity and its subsequent impact on new injury risk. No association was demonstrated between subjective health complaints, sleep quantity and training load factors.

Investigating imaging network markers of cognitive dysfunction and pharmacoresistance in newly diagnosed epilepsy: a protocol for an observational cohort study in the UK

INTRODUCTION

Epilepsy is one of the most common serious brain disorders, characterised by seizures that severely affect a person's quality of life and, frequently, their cognitive and mental health. Although most existing work has examined chronic epilepsy, newly diagnosed patients present a unique opportunity to understand the underlying biology of epilepsy and predict effective treatment pathways. The objective of this prospective cohort study is to examine whether cognitive dysfunction is associated with measurable brain architectural and connectivity impairments at diagnosis and whether the outcome of antiepileptic drug treatment can be predicted using these measures.

METHODS AND ANALYSIS

107 patients with newly diagnosed focal epilepsy from two National Health Service Trusts and 48 healthy controls (aged 16-65 years) will be recruited over a period of 30 months. Baseline assessments will include neuropsychological evaluation, structural and functional Magnetic Resonance Imaging (MRI), Electroencephalography (EEG), and a blood and saliva sample. Patients will be followed up every 6 months for a 24-month period to assess treatment outcomes. Connectivity- and network-based analyses of EEG and MRI data will be carried out and examined in relation to neuropsychological evaluation and patient treatment outcomes. Patient outcomes will also be investigated with respect to analysis of molecular isoforms of high mobility group box-1 from blood and saliva samples.

ETHICS AND DISSEMINATION

This study was approved by the North West, Liverpool East Research Ethics Committee (19/NW/0384) through the Integrated Research Application System (Project ID 260623). Health Research Authority (HRA) approval was provided on 22 August 2019. The project is sponsored by the UoL (UoL001449) and funded by a UK Medical Research Council (MRC) research grant (MR/S00355X/1). Findings will be presented at national and international meetings and conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

IRAS Project ID 260623.

Fitness to drive in seizure and epilepsy: A protocol for Iranian clinicians

Driving restriction is a well-known undesirable consequence of epilepsy and causes significant problems regarding independence and employment for epileptic patients. Many countries all over the world have provided comprehensive protocols in this regard with the aim of providing the possibility of less restricted, but safe driving for epileptic patients and also providing the opportunity for uniform decision-making for clinicians. However, the available fitness to drive protocol in Iran still lacks sufficient details and clinicians might encounter serious problems in terms of the driving issue in epileptic patients. In order to provide a uniform protocol containing adequate practical data, a systematic review of literature addressing guidelines about driving and epilepsy and driving laws of different countries for epileptic patients was performed and, after consideration of cultural issues, a practical protocol for Iranian neurologists was suggested.

Identifying patients who will not reachieve remission after breakthrough seizures

Objective

We aim to identify people with epilepsy who are unlikely to reachieve a 12‐month remission within 2 years after experiencing a breakthrough seizure following an initial 12‐month remission.

Methods

We apply a novel longitudinal discriminant approach to data from the Standard and New Antiepileptic Drugs study to dynamically predict the risk of a patient not achieving a second remission after a breakthrough seizure by combining both baseline covariates (collected at the time of breakthrough seizure) and follow‐up data.

Results

The model classifies 83% of patients. Of these, 73% of patients (95% confidence interval [CI] = 58%‐88%) who did not achieve a second remission were correctly identified (sensitivity), and 84% of patients (95% CI = 69%‐96%) who achieved a second remission were correctly identified (specificity). The area under the curve from our model was 87% (95% CI = 80%‐94%). Patients who did not achieve a second remission were correctly identified on average after 10 months of observation postbreakthrough. Occurrence of seizures after breakthrough and the number of seizures experienced were the most informative longitudinal variables. These longitudinal profiles were influenced by the following baseline covariates: age at breakthrough seizure, presence of neurological insult, and number of antiepileptic drugs required to achieve first remission.

Significance

Using longitudinal data gathered during patient follow‐up allows more accurate predictions than using baseline covariates in a standard Cox model. The model developed in this paper is a useful first step in developing a tool for identifying patients who develop drug resistance after an initial remission.

Driving status of patients with generalized spike-wave on EEG but no clinical seizures

Generalized spike-wave discharges (SWDs) are the hallmark of generalized epilepsy on the electroencephalogram (EEG). In clinically obvious cases, generalized SWDs produce myoclonic, atonic/tonic, or absence seizures with brief episodes of staring and behavioral unresponsiveness. However, some generalized SWDs have no obvious behavioral effects. A serious challenge arises when patients with no clinical seizures request driving privileges and licensure, yet their EEG shows generalized SWD. Specialized behavioral testing has demonstrated prolonged reaction times or missed responses during SWD, which may present a driving hazard even when patients or family members do not notice any deficits. On the other hand, some SWDs are truly asymptomatic in which case driving privileges should not be restricted. Clinicians often decide on driving privileges based on SWD duration or other EEG features. However, there are currently no empirically-validated guidelines for distinguishing generalized SWDs that are "safe" versus "unsafe" for driving. Here, we review the clinical presentation of generalized SWD and recent work investigating mechanisms of behavioral impairment during SWD with implications for driving safety. As a future approach, computational analysis of large sets of EEG data during simulated driving utilizing machine learning could lead to powerful methods to classify generalized SWD as safe vs. unsafe. This may ultimately provide more objective EEG criteria to guide decisions on driving safety in people with epilepsy.