Heart rate variability in patients with refractory epilepsy: The influence of generalized convulsive seizures

OBJECTIVE

Patients with epilepsy, mainly drug-resistant, have reduced heart rate variability (HRV), linked to an increased risk of sudden death in various other diseases. In this context, it could play a role in SUDEP. Generalized convulsive seizures (GCS) are one of the most consensual risk factors for SUDEP. Our objective was to assess the influence of GCS in HRV parameters in patients with drug-resistant epilepsy.

METHODS

We prospectively evaluated 121 patients with refractory epilepsy admitted to our Epilepsy Monitoring Unit. All patients underwent a 48-hour Holter recording. Only patients with GCS were included (n = 23), and we selected the first as the index seizure. We evaluated HRV (AVNN, SDNN, RMSSD, pNN50, LF, HF, and LF/HF) in 5-min epochs (diurnal and nocturnal baselines; preictal - 5 min before the seizure; ictal; postictal - 5 min after the seizure; and late postictal - >5 h after the seizure). These data were also compared with normative values from a healthy population (controlling for age and gender).

RESULTS

We included 23 patients, with a median age of 36 (min-max, 16-55) years and 65% were female. Thirty percent had cardiovascular risk factors, but no previously known cardiac disease. HRV parameters AVNN, RMSSD, pNN50, and HF were significantly lower in the diurnal than in the nocturnal baseline, whereas the opposite occurred with LF/HF and HR. Diurnal baseline parameters were inferior to the normative population values (which includes only diurnal values). We found significant differences in HRV parameters between the analyzed periods, especially during the postictal period. All parameters but LF/HF suffered a reduction in that period. LF/HF increased in that period but did not reach statistical significance. Visually, there was a tendency for a global reduction in our patients' HRV parameters, namely AVNN, RMSSD, and pNN50, in each period, comparing with those from a normative healthy population. No significant differences were found in HRV between diurnal and nocturnal seizures, between temporal lobe and extra-temporal-lobe seizures, between seizures with and without postictal generalized EEG suppression, or between seizures of patients with and without cardiovascular risk factors.

SIGNIFICANCE/CONCLUSION

Our work reinforces the evidence of autonomic cardiac dysfunction in patients with refractory epilepsy, at baseline and mainly in the postictal phase of a GCS. Those changes may have a role in some SUDEP cases. By identifying patients with worse autonomic cardiac function, HRV could fill the gap of a lacking SUDEP risk biomarker.

Prolonged post-ictal atrial fibrillation following seizures

It is well known that several types of cardiac arrhythmias can occur after a seizure, with ictal sinus tachycardia being the most common. However, post-ictal atrial fibrillation (PIAF) is a rare phenomenon with significant clinical implications. We describe the case of an epilepsy patient with prolonged PIAF. Our case is that of a 62-year-old female with seizure onset at 51 years of age. She had a left hemispheric meningioma that was resected with ongoing seizures. She described frequent episodes of chest fluttering lasting for several hours post-ictally. During video-EEG monitoring (VEEG), she had a typical seizure with staring and word finding difficulty. This was associated with the occurrence of atrial fibrillation with rapid ventricular rate that lasted 18 hours. We discuss the relation between seizures and prolonged PIAF as it relates to the need for anticoagulation, use of appropriate antiseizure medications, and the possible association with SUDEP.

Digital Semiology: A Prototype for Standardized, Computer-Based Semiologic Encoding of Seizures

Video-EEG monitoring (VEM) is imperative in seizure classification and presurgical assessment of epilepsy patients. Analysis of VEM is currently performed in most institutions using a freeform report, a time-consuming process resulting in a non-standardized report, limiting the use of this essential diagnostic tool. Herein we present a pilot feasibility study of our experience with “Digital Semiology” (DS), a novel seizure encoding software. It allows semiautomated annotation of the videos of suspected events from a predetermined, hierarchal set of options, with highly detailed semiologic descriptions, somatic localization, and timing. In addition, the software's semiologic extrapolation functions identify characteristics of focal seizures and PNES, sequences compatible with a Jacksonian march, and risk factors for SUDEP. Sixty episodes from a mixed adult and pediatric cohort from one level 4 epilepsy center VEM archives were analyzed using DS and the reports were compared with the standard freeform ones, written by the same epileptologists. The behavioral characteristics appearing in the DS and freeform reports overlapped by 78–80%. Encoding of one episode using DS required an average of 18 min 13 s (standard deviation: 14 min and 16 s). The focality function identified 19 out of 43 focal episodes, with a sensitivity of 45.45% (CI 30.39–61.15%) and specificity of 87.50% (CI 61.65–98.45%). The PNES function identified 6 of 12 PNES episodes, with a sensitivity of 50% (95% CI 21.09–78.91%) and specificity of 97.2 (95% CI 88.93–99.95%). Eleven events of GTCS triggered the SUDEP risk alert. Overall, these results show that video recordings of suspected seizures can be encoded using the DS software in a precise manner, offering the added benefit of semiologic alerts. The present study represents an important step toward the formation of an annotated video archive, to be used for machine learning purposes. This will further the goal of automated VEM analysis, ultimately contributing to wider utilization of VEM and therefore to the reduction of the treatment gap in epilepsy.

Fluoxetine as adjunctive therapy in pediatric patients with refractory epilepsy: A retrospective analysis

Approximately 30 % of children with epilepsy develop refractory epilepsy, which has a major impact on neurodevelopmental processes, cognitive functioning, and daily life. Furthermore, children with highly refractory epilepsy are at particular risk of sudden unexpected death. Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), has shown antiseizure action and was associated with a decreased severity of peri-ictal hypoxemia in adult patients with focal epilepsy. However, therapeutic studies on SSRI use in children are scarce - particularly in epileptic patients. We retrospectively recruited 14 pediatric patients; inclusion criteria were i) refractory epilepsy ii) frequent generalized or focal seizures (more than 1/week) iii) treated with fluoxetine as adjunctive therapy for one month at least. We analyzed their clinical outcome (efficacy and tolerance). The median age at fluoxetine initiation was 9.5 years (2-19), and fluoxetine was combined with a median number of 4 (2-6) anti-seizure medications. The median dose of fluoxetine at the last follow-up was 0.4 mg/kg/day (0.2-0.8). Among the 14 patients, we observed 6 (43 %) good responders. Complete freedom from seizures with cyanosis was reached in 3 (21 %) patients, and only one patient with early-onset epilepsy related to an FHF1 mutation was completely seizure-free. None of the recruited patients experienced seizure worsening, and 8 patients showed no effect on seizure frequency. Fluoxetine as adjunctive therapy in refractory epilepsy could be a beneficial therapeutic option. Future prospective, randomized and controlled studies are needed to study the efficacy of fluoxetine better.

Severe autonomic nervous system imbalance in Lennox-Gastaut syndrome patients demonstrated by heart rate variability recordings

OBJECTIVE

Patients diagnosed with Lennox Gastaut syndrome (LGS), an epileptic encephalopathy characterized by usually drug resistant generalized and focal seizures, are often considered as candidates for vagus nerve stimulation (VNS). Recent research shows that heart rate variability (HRV) differs in epilepsy patients and is related to VNS treatment response. This study investigated pre-ictal HRV in generalized onset seizures of patients with LGS in correlation with their VNS response.

METHODS

In drug resistant epilepsy (DRE) patients diagnosed with LGS video-electroencephalography recording was performed during their pre-surgical evaluation. Six HRV parameters (time and-, frequency domain, non-linear parameters) were evaluated for every seizure in epochs of 10 min at baseline (60 to 50 min before seizure onset) and pre-ictally (10 min prior to seizure onset). The results were correlated to VNS response after one year of VNS therapy.

RESULTS

Seven patients and 31 seizures were included, two patients were classified as VNS responders (≥ 50 % seizure reduction). No difference in pre-ictal HRV parameters between VNS responders and VNS non-responders could be found, but high frequency (HF) power, reflecting the parasympathetic tone increased significantly in the pre-ictal epoch in both VNS responders and VNS non-responders (p = 0.017, p = 0.004).

SIGNIFICANCE

In this pilot data pre-ictal HRV did not differ in VNS responders compared to VNS non-responders, but showed a significant increase in HF power - a parasympathetic overdrive - in both VNS responders and VNS non-responders. This sudden autonomic imbalance might have an influence on the cardiovascular system in the ictal period. Generalized tonic-clonic seizures are regarded as the main risk factor for SUDEP and severe seizure-induced autonomic imbalance may play a role in the pathophysiological pathway.

Patients' knowledge about epilepsy-related risks, morbidity, and mortality: A multicenter cohort study from Germany

INTRODUCTION

Patient education is a central component of quality care. Enhancing patient knowledge can improve patients' quality of life and facilitate successful self-management. We sought to identify patients' knowledge levels and knowledge gaps regarding epilepsy-related risks, morbidity, and mortality.

METHODS

Adult patients with epilepsy presenting to the university hospitals in Frankfurt, Greifswald, and Marburg between February 2018 and May 2020 were asked to participate in this questionnaire-based study.

RESULTS

A total of 238 patients (52% women), with a mean age of 39.2 years (range: 18-77 years), participated in this study. Spontaneously, the majority of patients (51.3%) named driving a car, and other traffic-related accidents as possible causes of morbidity and mortality, and 23.9% of patients reported various causes of premature death, such as suffocation, drowning, and respiratory or cardiac arrest due to seizures. Falls due to epilepsy (19.7%) and injuries in general (17.6%) were named as further causes of morbidity and mortality. The vast majority were aware that alcohol (87.4%), sleep deprivation (86.6%), and risky activities in daily life (80.3%) increased the risk of seizure occurrence or increased morbidity and mortality. Regarding overall mortality, 52.1% thought that people with epilepsy were at greater risk of premature death, whereas 46.2% denied this fact to be true. Only 29.4% were aware of status epilepticus, and 27.3% were aware of sudden unexpected death in epilepsy (SUDEP). Driving ability, working ability, and seizure risk were named as major or moderate concerns among patients, but the risk of premature mortality was not a major concern. One-quarter of all patients (26.9%) indicated that they were not counseled about any risk factors or causes of morbidity or mortality by their physicians.

CONCLUSIONS

A lack of knowledge concerning premature mortality, SUDEP, and status epilepticus exists among adult patients with epilepsy. A substantial number of patients indicated that these issues were not discussed adequately by their physicians.

Low-grade tumour over the left temporal neocortex and ictal asystole: network and surgical implications

We describe a patient with focal epilepsy characterized by ictal asystole episodes and low-grade tumour over the left temporal neocortex. Non-invasive pre-surgical evaluation showed an epileptogenic zone extended beyond the low-grade tumour. This extension was confirmed by intraoperative electrocorticography. One-stage surgery with anterior temporal lobe resection was performed. The patient was seizure-free after one year of follow-up. Detailed electroclinical and therapeutic reasoning with hypotheses defining epileptogenic and symptomatogenic networks are discussed.

Impact of the COVID-19 pandemic on people with epilepsy: Findings from the Brazilian arm of the COV-E study

The COVID-19 pandemic has had an unprecedented impact on people and healthcare services. The disruption to chronic illnesses, such as epilepsy, may relate to several factors ranging from direct infection to secondary effects from healthcare reorganization and social distancing measures.

OBJECTIVES

As part of the COVID-19 and Epilepsy (COV-E) global study, we ascertained the effects of COVID-19 on people with epilepsy in Brazil, based on their perspectives and those of their caregivers. We also evaluated the impact of COVID-19 on the care delivered to people with epilepsy by healthcare workers.

METHODS

We designed separate online surveys for people with epilepsy and their caregivers. A further survey for healthcare workers contained additional assessments of changes to working patterns, productivity, and concerns for those with epilepsy under their care. The Brazilian arm of COV-E initially collected data from May to November 2020 during the country's first wave. We also examined national data to identify the Brazilian states with the highest COVID-19 incidence and related mortality. Lastly, we applied this geographic grouping to our data to explore whether local disease burden played a direct role in difficulties faced by people with epilepsy.

RESULTS

Two hundred and forty-one people returned the survey, 20% were individuals with epilepsy (n = 48); 22% were caregivers (n = 53), and 58% were healthcare workers (n = 140). Just under half (43%) of people with epilepsy reported health changes during the pandemic, including worsening seizure control, with specific issues related to stress and impaired mental health. Of respondents prescribed antiseizure medication, 11% reported difficulty taking medication on time due to problems acquiring prescriptions and delayed or canceled medical appointments. Only a small proportion of respondents reported discussing significant epilepsy-related risks in the previous 12 months. Analysis of national COVID-19 data showed a higher disease burden in the states of Sao Paulo and Rio de Janeiro compared to Brazil as a whole. There were, however, no geographic differences observed in survey responses despite variability in the incidence of COVID-19.

CONCLUSION

Our findings suggest that Brazilians with epilepsy have been adversely affected by COVID-19 by factors beyond infection or mortality. Mental health issues and the importance of optimal communication are critical during these difficult times. Healthcare services need to find nuanced approaches and learn from shared international experiences to provide optimal care for people with epilepsy as the direct burden of COVID-19 improves in some countries. In contrast, others face resurgent waves of the pandemic.

A ketogenic diet protects DBA/1 and Scn1aR1407X/+ mice against seizure-induced respiratory arrest independent of ketosis

Patients with uncontrolled epilepsy have a high risk of sudden unexpected death in epilepsy (SUDEP). Seizure-induced respiratory arrest (S-IRA) is thought to be the determining cause of death in many cases of SUDEP. The goal of the present study was to use Scn1aR1407X/+ (Dravet Syndrome, DS) and DBA/1 mice to determine: (1) the effect of a ketogenic diet (KD) on S-IRA and (2) the relationship between serum ketones and the protective effect of a KD. Ketogenic diet treatment significantly decreased spontaneous seizure-induced mortality in DS mice compared to control (8% vs 39%, p = 0.0021). This protective effect was not abolished when ketosis was prevented by supplementing the KD with glucose (10% mortality, p = 0.0007). In DBA/1 mice, the latency to onset of S-IRA due to audiogenic seizures was delayed from 7.6 to 20.8 seconds by a KD on treatment day (TD) 7 compared to control (p < 0.0001), an effect that was reversed on TD14 when mice were crossed over to a control diet on TD7. β-Hydroxybutyrate (BHB) levels were significantly decreased in DBA/1 mice on a KD supplemented with glucose (p = 0.0038), but the protective effect was maintained. Our findings show that a KD decreases SUDEP in DS mice and increases the latency to audiogenic S-IRA in DBA/1 mice. In both mouse models, a KD was protective against S-IRA. This effect may be due in part to specific dietary components rather than generation of ketone bodies.

The effect of lamotrigine and other antiepileptic drugs on respiratory rhythm generation in the pre-Bötzinger complex

OBJECTIVE

Lamotrigine and other sodium-channel blocking agents are among the most commonly used antiepileptic drugs (AEDs). Because other sodium channel blockers, such as riluzole, can severely alter respiratory rhythm generation during hypoxia, we wanted to investigate if AEDs can have similar effects. This is especially important in the context of sudden unexpected death in epilepsy (SUDEP), the major cause of death in patients suffering from therapy-resistant epilepsy. Although the mechanism of action is not entirely understood, respiratory dysfunction after generalized tonic-clonic seizures seems to play a major role.

METHODS

We used transverse brainstem slice preparations from neonatal and juvenile mice containing the pre-Bötzinger complex (PreBötC) and measured population as well as intracellular activity of the rhythm-generating network under normoxia and hypoxia in the presence or absence of AEDs.

RESULTS

We found a substantial inhibition of the gasping response induced by the application of sodium channel blockers (lamotrigine and carbamazepine). In contrast, levetiracetam, an AED-modulating synaptic function, had a much smaller effect. The inhibition of gasping by lamotrigine was accompanied by a significant reduction of the persistent sodium current (INap) in PreBötC neurons. Surprisingly, the suppression of persistent sodium currents by lamotrigine did not affect the voltage-dependent bursting activity in PreBötC pacemaker neurons, but led to a hypoxia-dependent shift of the action potential rheobase in all measured PreBötC neurons.

SIGNIFICANCE

Our results contribute to the understanding of the effects of AEDs on the vital respiratory functions of the central nervous system. Moreover, our study adds further insight into sodium-dependent changes occurring during hypoxia and the contribution of cellular properties to the respiratory rhythm generation in the pre-Bötzinger complex. It raises the question of whether sodium channel blocking AEDs could, in conditions of extreme hypoxia, contribute to SUDEP, an important issue that warrants further studies.

Frontal lobe hypometabolism associated with Sudden Unexpected Death in Epilepsy (SUDEP) risk: An objective PET study

OBJECTIVE

Abnormalities of brain structures and neuronal networks have been identified in MRI studies of patients with Sudden Unexpected Death in Epilepsy (SUDEP) as well as in those at elevated risk. The goal of this study was to identify common patterns of objectively detected brain glucose metabolic abnormalities associated with SUDEP patients and those at high SUDEP risk.

METHODS

Patients with refractory epilepsy (n = 78, age: 16-61 years, 44 females), who underwent comprehensive presurgical evaluation, were assessed for their risk of SUDEP using the revised SUDEP-7 inventory. From the 57 patients with low SUDEP risk, 35 were selected to match their demographic and clinical characteristics to those with high SUDEP risk (n = 21). [¹⁸F]fluoro-deoxy-glucose positron emission tomography (FDG-PET) abnormalities were evaluated in the high- and low-SUDEP risk subgroups compared to FDG-PET scans of a healthy adult control group using statistical parametric mapping (SPM). Individual FDG-PET scans of 4 additional patients, who died from SUDEP, were also analyzed by SPM.

RESULTS

Mean SUDEP-7 score was 6.1 in the high and 2.7 in the low SUDEP risk group. MRI showed no lesion in 36 patients (64%). Statistical parametric mapping analysis of the high SUDEP risk subgroup showed bilateral medial frontal and inferior frontal hypometabolism as a common pattern. The low-risk group showed no specific common metabolic abnormalities on SPM group analysis. Individual PET scans of all 4 patients who died from SUDEP also showed bilateral frontal lobe hypometabolism.

CONCLUSIONS

These data show that bilateral frontal lobe involvement on FDG-PET, especially the medial and inferior frontal cortex, may be a common metabolic pattern associated with high SUDEP risk and SUDEP itself, in patients with refractory focal epilepsy.

Utilizing multimodal imaging to visualize potential mechanism for sudden death in epilepsy

Sudden death in epilepsy or SUDEP is a fatal condition that accounts for more than 4000 deaths each year. Limited clinical and preclinical data on sudden death suggest critical contributions from autonomic, cardiac, and respiratory pathways. A potential mechanism for such sudden and severe cardiorespiratory dysregulation may be linked to acid reflux-induced laryngospasm. Here, we expand on our previous investigations and utilize a novel multimodal approach to provide visual evidence of acid reflux-initiated cardiorespiratory distress and subsequent sudden death in seizing rats. We used systemic kainic acid to acutely induce seizure activity in Long Evans rats, under urethane anesthesia. We recorded electroencephalography (EEG), electrocardiography (ECG), chest plethysmography, and esophageal pH signals through a multimodal recording platform, during simultaneous fast MRI scans of the rat stomach and esophagus. MRI images, in correlation with electrophysiology data were used to identify seizure progression, stomach acid movement up the esophagus, cardiorespiratory changes, and sudden death. In all cases of sudden death, esophageal pH recordings alongside MRI images visualized stomach acid movement up the esophagus. Severe cardiac (ST segment elevation), respiratory (intermittent apnea) and brain activity (EEG narrowing due to hypoxia) changes were observed only after acid reached larynx, which strongly suggested onset of laryngospasm following acid reflux. The complementary information coming from electrophysiology and fast MRI scans provided insight into the mechanism of esophageal reflux, laryngospasm, obstructive apnea, and subsequent sudden death in seizing animals. The results carry clinical significance as it outlines a potential mechanism that may be relevant to SUDEP in humans.

Using an animated video to promote an informed discussion on SUDEP with adolescents

PURPOSE

The purpose of this study was to create and test an animated video to teach adolescent patients about Sudden Unexpected Death in Epilepsy (SUDEP).

METHOD

Thirty-nine patients and thirteen parents watched the SUDEP video and completed at least one survey. Patients with epilepsy aged 14+ and their parents were recruited to watch the video during neurology clinic visits. Parents of minors provided verbal permission for their child to view the video. Participants were asked to complete pre- and post-video surveys. Data analysis included Fischer's exact tests for comparative data and percentages for categorical variables.

RESULTS

After watching the SUDEP video, 100% of parents and patients agreed that the video provided helpful knowledge, and 100% of parents and 96% of patients agreed that patients with epilepsy should know about SUDEP. Half of the parents surveyed, and 20% of patients, felt increased concerns after watching the video. Patients rated their understanding of SUDEP significantly higher after watching the video (p < 0.001).

CONCLUSION

Participants in this study thought that it was important for patients with epilepsy to know about SUDEP, and all agreed that the animated SUDEP video provided helpful knowledge. While some parents endorsed increased concerns after watching the video, the majority of parents still agreed to allow their child to watch the video. Adolescent education on SUDEP using a family-centered approach may be an important method of encouraging harm-reducing behaviors that can be lifesaving for patients with epilepsy. The standard of practice for SUDEP disclosure should continue to be face-to-face discussion with providers, and we propose this video as a tool to elevate and inform those discussions.

Association between semiologic, autonomic, and electrographic seizure characteristics in children with generalized tonic-clonic seizures

INTRODUCTION

Generalized tonic-clonic seizures (GTCS) are associated with elevated electrodermal activity (EDA) and postictal generalized electroencephalographic suppression (PGES), markers that may indicate sudden unexpected death in epilepsy (SUDEP) risk. This study investigated the association of GTCS semiology, EDA, and PGES in children with epilepsy.

METHODS

Patients admitted to the Boston Children's Hospital long-term video-EEG monitoring unit wore a sensor that records EDA. We selected patients with at least one GTCS and reviewed video-EEGs for semiology, tonic and clonic phase duration, total clinical seizure duration, electrographic onset, offset, and PGES. We grouped patients into three semiology classes: GTCS 1: bilateral symmetric tonic arm extension, GTCS 2: no specific tonic arm extension or flexion, GTCS 3: unilateral or asymmetrical arm extension, tonic arm flexion or posturing that does not fit into GTCS 1 or 2. We analyzed the correlation between semiology, EDA, and PGES, and measured the area under the curve (AUC) of the ictal EDA (seizure onset to one hour after), subtracting baseline EDA (one-hour seizure-free before seizure onset). Using generalized estimating equation (GEE) and linear regression, we analyzed all seizures and single episodes per patient.

RESULTS

We included 30 patients (median age 13.8 ± 3.6 years, 46.7% females) and 53 seizures. With GEE, GTCS 1 was associated with longer PGES duration compared to GTCS 2 (Estimate (β) = -26.32 s, 95% Confidence Interval (CI): -36.46 to -16.18, p < 0.001), and the presence of PGES was associated with greater EDA change (β = 429604 μS, 95% CI: 3550.96 to 855657.04, p = 0.048). With single-episode analysis, GTCS 1 had greater EDA change than GTCS 2 ((β = -601339 μS, 95% CI: -1167016.56 to -35661.44, p = 0.047). EDA increased with PGES presence (β = 637500 μS, 95% CI: 183571.84 to 1091428.16, p = 0.01) and duration (β = 16794 μS, 95% CI: 5729.8 to 27858.2, p = 0.006). Patients with GTCS 1 had longer PGES duration compared to GTCS 2 (β = -30.53 s, 95% CI: -44.6 to -16.46, p < 0.001) and GTCS 3 (β = -22.07 s, 95% CI: -38.95 to -5.19, p = 0.016).

CONCLUSION

In children with epilepsy, PGES correlates with greater ictal EDA. GTCS 1 correlated with longer PGES duration and may indirectly correlate with greater ictal EDA. Our study suggests potential applications in monitoring and preventing SUDEP in these patients.

Cardiology perspective on seizure-related bradyarrhythmias and SUDEP: A survey study

OBJECTIVE

To determine cardiologist knowledge of and experience with seizure-related bradyarrhythmias and sudden unexpected death in epilepsy (SUDEP).

BACKGROUND

Autonomic changes related to acute seizures are common and can occur during the ictal or postictal period. Two concerning changes in these periods are significant bradycardia and asystole. Postictal asystole has been investigated as a potential mechanism for SUDEP.

METHODS

A 27-question survey delivered to cardiologists and cardiology fellows assessed demographics, personal experience, and training involving SUDEP and seizure-related bradycardia and asystole. Following IRB approval, a list of US cardiology fellowships was constructed using the AAMC public website. Surveys were distributed by email to all programs whose program director or coordinator's email was readily available on their website. They were asked to forward the survey to both cardiology fellows and practicing cardiologists.

RESULTS

Fifty one surveys were completed: 23 from fellows and 28 from practicing cardiologists. Forty nine were from academic centers. Twenty four respondents (47%) reported being consulted for ictal bradycardia or asystole. Nine and 13 recommended treatment for ictal bradycardia or ictal asystole, respectively. Nineteen respondents (37%) reported being consulted for postictal bradycardia or asystole. Eight recommended treatment for postictal bradycardia or asystole, respectively. Treatment recommendations included medical management and/or pacemaker. None reported a substantial knowledge of SUDEP. The most common response interrogating SUDEP awareness (63%) was "no knowledge of SUDEP". Formal SUDEP education was not reported by any participant with only one reporting formal didactics regarding seizure-related arrhythmias.

DISCUSSION

Our results suggest ictal bradyarrhythmias are less commonly known to cardiologists, with SUDEP awareness being far less. Formal education to cardiologists on these two topics could prove beneficial at the intersection of cardiology and care for patients with epilepsy.

Hypercapnic ventilatory response in epilepsy patients treated with VNS: A case-control study

OBJECTIVE

Central CO2 chemoreception (CCR), a major chemical drive for breathing, can be quantified with a CO2 re-breathing test to measure the hypercapnic ventilatory response (HCVR). An attenuated HCVR correlates with the severity of respiratory dysfunction after generalized convulsive seizures and is a potential biomarker for sudden unexpected death in epilepsy (SUDEP) risk. Vagus nerve stimulation (VNS) may reduce SUDEP risk, but for unclear reasons the risk remains higher during the first 2 years after implantation. The vagus nerve has widespread connections in the brainstem, including key areas related to CCR. Here we examined whether chronic electrical stimulation of the vagus nerve induces changes in CCR.

METHODS

We compared the HCVR in epilepsy patients with or without an active VNS in a sex- and age-matched case-control study. Eligible subjects were selected from a cohort of patients who previously underwent HCVR testing. The HCVR slope, change in minute ventilation (VE) with respect to change in end tidal (ET) CO2 (∆ VE/ ∆ ETCO2) during the test was calculated for each subject. Key variables were compared between the two groups. Univariate and multivariate analyses were carried out for HCVR slope as dependent variable.

RESULTS

A total of 86 subjects were in the study. HCVR slope was significantly lower in the cases compared to the controls. Cases had longer duration of epilepsy and higher number of anti-epileptic drugs (AEDs) tried during lifetime. Having active VNS and ETCO2 were associated with a low HCVR slope while high BMI was associated with high HCVR slope in both univariate and multivariate analyses.

DISCUSSION

We found having an active VNS was associated with relatively attenuated HCVR slope. Although duration of epilepsy and number of AEDs tried during lifetime was significantly different between the groups, they were not predictors of HCVR slope in subsequent analysis.

CONCLUSION

Chronic electrical stimulation of the vagus nerve by VNS may be associated with an attenuated CCR [Correction added on 24 November 2021, after first online publication: The preceding sentence has been revised from “Chronic electrical stimulation of VNS nerve by VNS…”]. A larger prospective study may help to establish the time course of this effect in relation to the time of VNS implantation, whether there is a causal relationship, and determine how it affects SUDEP risk.

Acute and chronic cardiorespiratory consequences of focal intrahippocampal administration of seizure-inducing agents. Implications for SUDEP

The risk factors for SUDEP are undoubtedly heterogenous but the main factor is the frequency of generalized tonic-clonic seizures with apnoea and/or cardiac abnormalities likely precipitating the lethal event. By its very nature modelling SUDEP experimentally is challenging, yet insights into the nature of the lethal event and precipitating factors are vital in order to understand and prevent fatalities. Acute animal models, which induce status epilepticus (SE), can be used to help understand pathophysiological processes during and following seizures, which sometimes lead to death. The most commonly used method to induce seizures and status epilepticus is systemic administration of an ictogenic agent. Microinjection of such agents into restricted regions within the brain induces a more localised epileptic focus and circumvents the risk of direct actions on cardiorespiratory control centres. Both approaches have revealed substantial cardiovascular and respiratory consequences, including death as a result of apnoea, which may be of central origin, obstructive due to laryngospasm or, at least in genetically modified mice, a result of spreading depolarisation to medullary respiratory control centres. SUDEP is by definition a result of epilepsy, which in turn is diagnosed on the basis of two or more unprovoked seizures. The incidence of tonic-clonic seizures is the main risk factor, raising the possibility that repeated seizures cause cumulative pathological and/or pathophysiological changes that contribute to the risk of SUDEP. Chronic experimental models, which induce repeated seizures that in some cases lead to death, do show progressive development of pathophysiological changes in the myocardium, e.g. prolongation of QT the interval of the ECG or, over longer periods, ventricular hypertrophy. However, the currently available evidence indicates that seizure-related deaths are primarily due to apnoeas, but cardiac factors, particularly cumulative cardiac pathophysiologies due to repeated seizures, are potential contributing factors.

Neuropathology in the North American sudden unexpected death in epilepsy registry

Sudden unexpected death in epilepsy is the leading category of epilepsy-related death and the underlying mechanisms are incompletely understood. Risk factors can include a recent history and high frequency of generalized tonic-clonic seizures, which can depress brain activity postictally, impairing respiration, arousal and protective reflexes. Neuropathological findings in sudden unexpected death in epilepsy cases parallel those in other epilepsy patients, with no implication of novel structures or mechanisms in seizure-related deaths. Few large studies have comprehensively reviewed whole brain examination of such patients. We evaluated 92 North American Sudden unexpected death in epilepsy Registry cases with whole brain neuropathological examination by board-certified neuropathologists blinded to the adjudicated cause of death, with an average of 16 brain regions examined per case. The 92 cases included 61 sudden unexpected death in epilepsy (40 definite, 9 definite plus, 6 probable, 6 possible) and 31 people with epilepsy controls who died from other causes. The mean age at death was 34.4 years and 65.2% (60/92) were male. The average age of death was younger for sudden unexpected death in epilepsy cases than for epilepsy controls (30.0 versus 39.6 years; P = 0.006), and there was no difference in sex distribution respectively (67.3% male versus 64.5%, P = 0.8). Among sudden unexpected death in epilepsy cases, earlier age of epilepsy onset positively correlated with a younger age at death (P = 0.0005) and negatively correlated with epilepsy duration (P = 0.001). Neuropathological findings were identified in 83.7% of the cases in our cohort. The most common findings were dentate gyrus dysgenesis (sudden unexpected death in epilepsy 50.9%, epilepsy controls 54.8%) and focal cortical dysplasia (FCD) (sudden unexpected death in epilepsy 41.8%, epilepsy controls 29.0%). The neuropathological findings in sudden unexpected death in epilepsy paralleled those in epilepsy controls, including the frequency of total neuropathological findings as well as the specific findings in the dentate gyrus, findings pertaining to neurodevelopment (e.g. FCD, heterotopias) and findings in the brainstem (e.g. medullary arcuate or olivary dysgenesis). Thus, like prior studies, we found no neuropathological findings that were more common in sudden unexpected death in epilepsy cases. Future neuropathological studies evaluating larger sudden unexpected death in epilepsy and control cohorts would benefit from inclusion of different epilepsy syndromes with detailed phenotypic information, consensus among pathologists particularly for more subjective findings where observations can be inconsistent, and molecular approaches to identify markers of sudden unexpected death in epilepsy risk or pathogenesis.

Sudden unexpected death in epilepsy in persons younger than 50 years: A retrospective nationwide cohort study in Denmark

OBJECTIVE

Persons with epilepsy have an increased mortality including a high risk of sudden unexplained death (SUD), also referred to as sudden unexpected death in epilepsy (SUDEP). We aimed to evaluate the risk of SUDEP in comparison to other causes of death and the risk of SUD in persons with and without epilepsy.

METHODS

We undertook a retrospective population-based cohort study of all Danish citizens with and without epilepsy aged 1-49 years during 2007-2009. All deaths in the population were evaluated, and all cases of SUD identified. Primary causes of death in persons with epilepsy were evaluated independently by three neurologists and one neuropediatrician, using the unified SUDEP criteria.

RESULTS

The three most frequent causes of death in persons with epilepsy were cancer (2.38 per 1000 person-years), SUDEP (1.65 per 1000 person-years), and pneumonia (1.09 per 1000 person-years) compared with cancer (.17 per 1000 person-years), accident-related deaths (.14 per 1000 person-years), and cardiovascular disease (.09 per 1000 person-years) in persons without epilepsy. Considering definite, definite plus, and probable cases, the SUDEP incidence was .27 per 1000 person-years (95% confidence interval [CI] = .11-.64) in children aged 1-17 years and 1.21 per 1000 person-years (95% CI = .96-1.51) in adults aged 18-49 years. Adjusted for age and sex, persons with epilepsy younger than 50 years had a 10.8-fold (95% CI = 9.97-11.64, p < .0001) increased all-cause mortality and a 34.4-fold (95% CI = 23.57-50.28, p < .0001) increased risk of SUD compared with persons without epilepsy. SUDEP accounted for 23.3% of all SUD.

SIGNIFICANCE

This nationwide study of all deaths in persons with epilepsy younger than 50 years found a lower SUDEP risk in children compared with adults, and that epilepsy was a major risk factor for SUD in the background population. This underlines the importance of addressing risk factors for SUDEP to prevent premature death.

Dysregulated long noncoding RNAs in the brainstem of the DBA/1 mouse model of SUDEP

Background

Long noncoding RNAs (lncRNAs) play an important role in many neurological diseases. This study aimed to investigate differentially expressed lncRNAs and messenger RNAs (mRNAs) in the susceptibility gaining process of primed DBA/1 mice, a sudden unexpected death in epilepsy (SUDEP) model, to illustrate the potential role of lncRNAs in SUDEP.

Methods

The Arraystar mouse lncRNA Microarray V3.0 (Arraystar, Rockville, MD) was applied to identify the aberrantly expressed lncRNAs and mRNAs between primed DBA/1 mice and normal controls. The differences were verified by qRT-PCR. We conducted gene ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and coexpression analyses to explore the possible function of the dysregulated RNAs.

Results

A total of 502 lncRNAs (126 upregulated and 376 downregulated lncRNAs) and 263 mRNAs (141 upregulated and 122 downregulated mRNAs) were dysregulated with P < 0.05 and a fold change over 1.5, among which Adora3 and Gstt4 were possibly related to SUDEP. GO analysis revealed that chaperone cofactor-dependent protein refolding and misfolded protein binding were among the top ten downregulated terms, which pointed to Hspa1a, Hspa2a and their related lncRNAs. KEGG analysis identified 28 upregulated and 10 downregulated pathways. Coexpression analysis showed fifteen dysregulated long intergenic noncoding RNAs (lincRNAs) and three aberrantly expressed antisense lncRNAs, of which AK012034 and NR_040757 are potentially related to SUDEP by regulating LMNB2 and ITPR1, respectively.

Conclusions

LncRNAs and their coexpression mRNAs are dysregulated in the priming process of DBA/1 in the brainstem. Some of these mRNAs and lncRNAs may be related to SUDEP, including Adora3, Lmnb2, Hspa1a, Hspa1b, Itrp1, Gstt4 and their related lncRNAs. Further study on the mechanism of lncRNAs in SUDEP is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07921-7.

Pilot Safety and Feasibility Study of Non-invasive Limb Proprioceptive Cerebellar Stimulation for Epilepsy

Cerebellar stimulation reduces seizures in animals and in humans with drug-resistant epilepsy. In a pilot safety and feasibility study, we applied continuous cutaneous vibratory stimulation (limb proprioceptive cerebellar stimulation) to foot limb proprioceptive receptors to activate cerebellar, pontine, and thalamic structures in drug-resistant epilepsy patients for 8-h nocturnally up to 6-months after a 4-week pre-treatment control baseline. Seizure frequency was evaluated during the baseline control period, and at 6, 12, and 24 weeks after the control recordings. Five-subjects completed at least the first 6-week treatment. At 12-weeks, the median reduction in seizure frequency was -27.8% (mean reduction = -22.3%). Two subjects continued for 24 weeks, with a decline of -44.1 and -45.4%. This pilot study provides support for further clinical studies into the safety and efficacy of limb proprioceptive cerebellar stimulation for epilepsy.

Syncope, Epilepsy and Ictal Asystole: A Case Series and Narrative Review

IMPORTANCE

Syncope is a common presentation to emergency departments, and cardiac and neurological aetiologies are the predominant causes. Ictal asystole is a rare cardio-neural phenomenon seen in epilepsy syndromes whereby a seizure causes asystole (≥3 s) leading to syncope.

OBSERVATIONS

We present three cases of ictal asystole, together with a narrative review of the literature to assess the prevalence of the condition and review the pathophysiology, diagnosis and management. Our review of the literature has shown that ictal asystole is an unlikely contributor to sudden unexplained death with epilepsy (SUDEP). Pacemaker insertion may limit morbidity from trauma related to syncopal episodes but does not impact mortality.

CONCLUSIONS AND RELEVANCE

Patients with ictal asystole should be diagnosed with concurrent electroencephalogram-electrocardiograph (EEG-ECG) monitoring, have their anti-epileptic drugs optimised and be considered for epilepsy surgery if feasible. The use of longer term ECG monitoring may be used as a diagnostic aid if ictal asystole is suspected. If there are ongoing syncopal episodes with associated ictal asystole ≥6 seconds, particularly despite medical therapy, a permanent pacemaker may be considered to reduce morbidity. Current guidelines should be updated to reflect the increasing knowledge of this condition.

Amygdala lesions reduce seizure-induced respiratory arrest in DBA/1 mice

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of death in patients with refractory epilepsy. Human studies and animal models suggest that respiratory arrest is the initiating event leading to death in many cases of SUDEP. It has previously been reported that the onset of apnea can coincide with the spread of seizures to the amygdala, and apnea can be reproduced by electrical stimulation of the amygdala. The aim of the current work was to determine if the amygdala is required for seizure-induced respiratory arrest (S-IRA) in a mouse model of SUDEP. Experiments were performed on DBA/1 mice that have audiogenic seizures with a high incidence of fatal postictal respiratory arrest. Electrolytic lesions of the amygdala significantly reduced the incidence of S-IRA without altering seizures, baseline breathing, or the hypercapnic ventilatory response. These results indicate that the amygdala is a critical node in a pathway to the lower brainstem that is needed for seizures to cause respiratory arrest. SIGNIFICANCE STATEMENT: Sudden unexpected death in epilepsy is the most common cause of mortality in patients with refractory epilepsy, and S-IRA is thought to be important in the pathophysiology in many cases. In a patient with epilepsy, the onset of apnea has been shown to coincide with spread of seizures to the amygdala, and in multiple patients, apnea was induced by stimulation of the amygdala. Here, we show that lesions of the amygdala reduced the incidence of S-IRA and death in a mouse model of SUDEP. These results provide evidence that the amygdala may be a critical node in the pathway by which seizures influence the brainstem respiratory network to cause apnea. This article is part of the Special Issue NEWroscience 2018.