Sudden unexpected death in epilepsy

Mortality of Epilepsy in Chinese Populations: A Comprehensive Review

BACKGROUND

Premature mortality is a significant part of the epilepsy burden and may vary across populations, especially between high-income and lower- and middle-income countries. People with epilepsy in China are approximately a fifth of the global population with epilepsy. Previous studies were unlikely to represent the situation in China due to limitations in design, methods, sample size, follow-up time, and other inherent population heterogeneity.

SUMMARY

By summarising the evidence on the mortality characteristics in Chinese populations with epilepsy in the last 6 decades, we found a median mortality rate of 14.7 (6.8-74.4)/1,000 person-years and a median standardised mortality ratio (SMR) of 4.4 (2.6-12.9) in population-based studies, and a median mortality rate of 12.3 (9.5-101.5)/1,000 person-years and a median SMR of 3.0 (1.5-5.1) in hospital-based studies. Vascular diseases, complications of diabetes, and accidental injuries were the leading causes of death. Risk factors for mortality were reported as older age, male, longer duration, and higher frequency of seizures. Case fatality ratios of status epilepticus in adults were higher than in children, and both increased with follow-up time. Mortality in people with symptomatic epilepsy was high and varied across different primary diseases.

KEY MESSAGES

The highest mortality rate and sudden unexpected death in epilepsy (SUDEP) incidence were reported from the least developed areas in China. Accidental injuries were the most common causes of epilepsy-related deaths, while the incidence of SUDEP may be underestimated in Chinese populations. Further research is warranted to improve the understanding of premature mortality risk so that preventative measures can be introduced to improve the situation.

A novel wearable device for automated real-time detection of epileptic seizures

BACKGROUND

Epilepsy is a neurological disorder that has a variety of origins. It is caused by hyperexcitability and an imbalance between excitation and inhibition, which results in seizures. The World Health Organization (WHO) and its partners have classified epilepsy as a major public health concern. Over 50 million individuals globally are affected by epilepsy which shows that the patient's family, social, educational, and vocational activities are severely limited if seizures are not controlled. Patients who suffer from epileptic seizures have emotional, behavioral, and neurological issues. Alerting systems using a wearable sensor are commonly used to detect epileptic seizures. However, most of the devices have no multimodal systems that increase sensitivity and lower the false discovery rate for screening and intervention of epileptic seizures. Therefore, the objective of this project was, to design and develop an efficient, economical, and automatically detecting epileptic seizure device in real-time.

METHODS

Our design incorporates different sensors to assess the patient's condition such as an accelerometer, pulsoxymeter and vibration sensor which process body movement, heart rate variability, oxygen denaturation, and jerky movement respectively. The algorithm for real-time detection of epileptic seizures is based on the following: acceleration increases to a higher value of 23.4 m/s² or decreases to a lower value of 10 m/s² as energy is absorbed by the body, the heart rate increases by 10 bpm from the normal heart rate, oxygen denaturation is below 90% and vibration should be out of the range of 3 Hz -17 Hz. Then, a pulsoxymeter device was used as a gold standard to compare the heart rate variability and oxygen saturation sensor readings. The accuracy of the accelerometer and vibration sensor was also tested by a fast-moving and vibrating normal person's hand.

RESULTS

The prototype was built and subjected to different tests and iterations. The proposed device was tested for accuracy, cost-effectiveness and ease of use. An acceptable accuracy was achieved for the accelerometer, pulsoxymeter, and vibration sensor measurements, and the prototype was built only with a component cost of less than 40 USD excluding design, manufacturing, and other costs. The design is tested to see if it fits the design criteria; the results of the tests reveal that a large portion of the scientific procedures utilized in this study to identify epileptic seizures is effective.

CONCLUSION

This project is objectively targeted to design a medical device with multimodal systems that enable us to accurately detect epileptic seizures by detecting symptoms commonly associated with an episode of epileptic seizure and notifying a caregiver for immediate assistance. The proposed device has a great impact on reducing epileptic seizer mortality, especially in low-resource settings where both expertise and treatment are scarce.

SCN5A channelopathy: arrhythmia, cardiomyopathy, epilepsy and beyond

Influx of sodium ions through voltage-gated sodium channels in cardiomyocytes is essential for proper electrical conduction within the heart. Both acquired conditions associated with sodium channel dysfunction (myocardial ischaemia, heart failure) as well as inherited disorders secondary to mutations in the gene SCN5A encoding for the cardiac sodium channel Nav1.5 are associated with life-threatening arrhythmias. Research in the last decade has uncovered the complex nature of Nav1.5 distribution, function, in particular within distinct subcellular subdomains of cardiomyocytes. Nav1.5-based channels furthermore display previously unrecognized non-electrogenic actions and may impact on cardiac structural integrity, leading to cardiomyopathy. Moreover, SCN5A and Nav1.5 are expressed in cell types other than cardiomyocytes as well as various extracardiac tissues, where their functional role in, e.g. epilepsy, gastrointestinal motility, cancer and the innate immune response is increasingly investigated and recognized. This review provides an overview of these novel insights and how they deepen our mechanistic knowledge on SCN5A channelopathies and Nav1.5 (dys)function. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.

A unified hypothesis of SUDEP: Seizure-induced respiratory depression induced by adenosine may lead to SUDEP but can be prevented by autoresuscitation and other restorative respiratory response mechanisms mediated by the action of serotonin on the periaqueductal gray

Sudden unexpected death in epilepsy (SUDEP) is a major cause of death in people with epilepsy (PWE). Postictal apnea leading to cardiac arrest is the most common sequence of terminal events in witnessed cases of SUDEP, and postconvulsive central apnea has been proposed as a potential biomarker of SUDEP susceptibility. Research in SUDEP animal models has led to the serotonin and adenosine hypotheses of SUDEP. These neurotransmitters influence respiration, seizures, and lethality in animal models of SUDEP, and are implicated in human SUDEP cases. Adenosine released during seizures is proposed to be an important seizure termination mechanism. However, adenosine also depresses respiration, and this effect is mediated, in part, by inhibition of neuronal activity in subcortical structures that modulate respiration, including the periaqueductal gray (PAG). Drugs that enhance the action of adenosine increase postictal death in SUDEP models. Serotonin is also released during seizures, but enhances respiration in response to an elevated carbon dioxide level, which often occurs postictally. This effect of serotonin can potentially compensate, in part, for the adenosine-mediated respiratory depression, acting to facilitate autoresuscitation and other restorative respiratory response mechanisms. A number of drugs that enhance the action of serotonin prevent postictal death in several SUDEP models and reduce postictal respiratory depression in PWE. This effect of serotonergic drugs may be mediated, in part, by actions on brainstem sites that modulate respiration, including the PAG. Enhanced activity in the PAG increases respiration in response to hypoxia and other exigent conditions and can be activated by electrical stimulation. Thus, we propose the unifying hypothesis that seizure-induced adenosine release leads to respiratory depression. This can be reversed by serotonergic action on autoresuscitation and other restorative respiratory responses acting, in part, via the PAG. Therefore, we hypothesize that serotonergic or direct activation of this brainstem site may be a useful approach for SUDEP prevention.

More than a drug target: Purinergic signalling as a source for diagnostic tools in epilepsy

Epilepsy is one of the most common and disabling chronic neurological diseases affecting people of all ages. Major challenges of epilepsy management include the persistently high percentage of drug-refractoriness among patients, the absence of disease-modifying treatments, and its diagnosis and prognosis. To date, long-term video-electroencephalogram (EEG) recordings remain the gold standard for an epilepsy diagnosis. However, this is very costly, has low throughput, and in some instances has very limited availability. Therefore, much effort is put into the search for non-invasive diagnostic tests. Purinergic signalling, via extracellularly released adenosine triphosphate (ATP), is gaining increasing traction as a therapeutic strategy for epilepsy treatment which is supported by evidence from both experimental models and patients. This includes in particular the ionotropic P2X7 receptor. Besides that, other components from the ATPergic signalling cascade such as the metabotropic P2Y receptors (e.g., P2Y₁ receptor) and ATP-release channels (e.g., pannexin-1), have also been shown to contribute to seizures and epilepsy. In addition to the therapeutic potential of purinergic signalling, emerging evidence has also shown its potential as a diagnostic tool. Following seizures and epilepsy, the concentration of purines in the blood and the expression of different compounds of the purinergic signalling cascade are significantly altered. Herein, this review will provide a detailed discussion of recent findings on the diagnostic potential of purinergic signalling for epilepsy management and the prospect of translating it for clinical application. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.

ABCDEF…SUDEP: Action Potential Barrage in (Superior) Colliculus Causes (Spreading) Depolarization Leading to Epilepsy Fatality

Hyperexcitable Superior Colliculus and Fatal Brainstem Spreading Depolarization in a Model of Sudden Unexpected Death in Epilepsy

Cain SM, Bernier LP, Zhang Y, Yung AC, Kass J, Bohnet B, Yang Y, Gopaul R, Kozlowski P, MacVicar BA, Snutch TP. Brain Commun. 2022;4(2):fcac006. doi:10.1093/braincomms/fcac006

Cardiorespiratory arrest and death in mouse models of sudden unexpected death in epilepsy occur when spreading depolarization (SD) is triggered by cortical seizures and then propagates to the brainstem. However, the critical brain regions and the specific changes required to allow SD to propagate to the brainstem under the relatively rare circumstances leading to a fatal seizure are unknown. We previously found that following cortical seizure-inducing electrical stimulation, SD could occur in both the superior and inferior colliculi in Cacna1a^S218L mice, but was never observed in wild-type animals or following non-seizure-inducing stimuli in Cacna1a^S218L mice. Here, we show that optogenetic stimulation of the superior/inferior colliculi in Cacna1a^S218L mice induces severe seizures, and resulting SD in the superior/inferior colliculi that propagates to the brainstem and correlates with the respiratory arrest followed by cardiac arrest. Further, we show that neurons of the superior colliculus in Cacna1a^S218L mice exhibit hyperexcitable properties that we propose underlie a distinct susceptibility to SD. Our data suggest that the susceptibility of the superior colliculus to elicit fatal SD is a result of either genetic or seizure-related alterations within the superior colliculus that may involve changes to structure, connectivity and/or excitability.

Morbidity and rehospitalization postpartum among women with epilepsy and their infants: A population-based study

OBJECTIVE

We compared the relative occurrence of selected pregnancy outcomes and postpartum rehospitalizations among women with and without epilepsy and their infants. Using linked vital-hospital discharge records of women with deliveries in Washington State 1987-2014, comparisons were made overall, by epilepsy type, and by time periods related to antiepileptic drug (AED) marketing changes.

METHODS

This population-based retrospective cohort study identified women with, and without epilepsy per diagnosis codes in the hospital discharge record from among all deliveries during 1987-2014 to examine maternal and infant outcomes, rehospitalization and mortality <2 years postpartum. Relative risks (RRs) and 95 % confidence intervals (CI) overall, and by epilepsy type were calculated using Poisson regression. We assessed the validity of epilepsy identification based on diagnosis codes by conducting a medical chart review for a sample of women.

RESULTS

Women with epilepsy had increased risks of preeclampsia (RR 1.23; 95 % CI 1.08-1.41) and gestational diabetes (RR 1.18; 95 % CI 1.02-1.36). Their infants had increased malformation (RR 1.23; 95 % C: 1.08-1.42) and small for gestational age (SGA, RR 1.39; 95 % CI 1.25-1.54) risks, and were nearly three times as likely to not be breastfed. Affected mothers (RR 5.25; 95 % CI 2.46-11.23) and their infants (RR 1.64, 95 % CI 1.41-1.89) required more ICU admissions during the delivery hospitalizations, and more postpartum rehospitalization, with greatest risk in the first six months. Maternal mortality < 2 years after delivery was increased (RR 7.11; 95 % CI 2.47-20.49). Increased risks were observed for all epilepsy subtypes for nearly all outcomes examined. Risks of preterm delivery and low birthweight increased over time (p <.05). Suggestive, but not statistically significant temporal decreases in risks of gestational diabetes and malformations and increased risk of preterm labor were noted. We observed high sensitivity of diagnosis codes for identifying pregnant women with epilepsy.

CONCLUSION

These population-based results emphasize the need for frequent postpartum monitoring of women with epilepsy. Increases in risks of low birthweight and preterm delivery over time are of concern. Possible temporal changes in other outcomes warrant further investigation.

Implementation of a Morphological Filter for Removing Spikes from the Epileptic Brain Signals to Improve Identification Ripples

Epilepsy is a very common disease affecting at least 1% of the population, comprising a number of over 50 million people. As many patients suffer from the drug-resistant version, the number of potential treatment methods is very small. However, since not only the treatment of epilepsy, but also its proper diagnosis or observation of brain signals from recordings are important research areas, in this paper, we address this very problem by developing a reliable technique for removing spikes and sharp transients from the baseline of the brain signal using a morphological filter. This allows much more precise identification of the so-called epileptic zone, which can then be resected, which is one of the methods of epilepsy treatment. We used eight patients with 5 KHz data set and depended upon the Staba 2002 algorithm as a reference to detect the ripples. We found that the average sensitivity and false detection rate of our technique are significant, and they are ∼94% and ∼14%, respectively.

The role of monoaminergic neurons in modulating respiration during sleep and the connection with SUDEP

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death among epilepsy patients, occurring even more frequently in cases with anti-epileptic drug resistance. Despite some advancements in characterizing SUDEP, the underlying mechanism remains incompletely understood. This review summarizes the latest advances in our understanding of the pathogenic mechanisms of SUDEP, in order to identify possible targets for the development of new strategies to prevent SUDEP. Based on our previous research along with the current literature, we focus on the role of sleep-disordered breathing (SDB) and its related neural mechanisms to consider the possible roles of monoaminergic neurons in the modulation of respiration during sleep and the occurrence of SUDEP. Overall, this review suggests that targeting the monoaminergic neurons is a promising approach to preventing SUDEP. The proposed roles of SDB and related monoaminergic neural mechanisms in SUDEP provide new insights for explaining the pathogenesis of SUDEP.