Sudden unexpected death in epilepsy: ongoing challenges in finding mechanisms and prevention

Sudden unexpected death in epilepsy: A critical view of the literature

Sudden unexpected death in epilepsy (SUDEP) is a sudden, unexpected, witnessed or unwitnessed, non-traumatic and non-drowning death, occurring in benign circumstances, in an individual with epilepsy, with or without evidence for a seizure and excluding documented status epilepticus in which postmortem examination does not reveal other causes of death. Lower diagnostic levels are assigned when cases met most or all of these criteria, but data suggested more than one possible cause of death. The incidence of SUDEP ranged from 0.09 to 2.4 per 1000 person-years. Differences can be attributed to the age of the study populations (with peaks in the 20-40-year age group) and the severity of the disease. Young age, disease severity (in particular, a history of generalized TCS), having symptomatic epilepsy, and the response to antiseizure medications (ASMs) are possible independent predictors of SUDEP. The pathophysiological mechanisms are not fully known due to the limited data available and because SUDEP is not always witnessed and has been electrophysiologically monitored only in a few cases with simultaneous assessment of respiratory, cardiac, and brain activity. The pathophysiological basis of SUDEP may vary according to different circumstances that make that particular seizure, in that specific moment and in that patient, a fatal event. The main hypothesized mechanisms, which could contribute to a cascade of events, are cardiac dysfunction (included potential effects of ASMs, genetically determined channelopathies, acquired heart diseases), respiratory dysfunction (included postictal arousal deficit for the respiratory mechanism, acquired respiratory diseases), neuromodulator dysfunction, postictal EEG depression and genetic factors.

The mechanism of sudden unexpected death in epilepsy: A mini review

Sudden unexpected death in epilepsy (SUDEP) is defined as a sudden, unexpected, non-traumatic, non-drowning death in a person with epilepsy. SUDEP is generally considered to result from seizure-related cardiac dysfunction, respiratory depression, autonomic nervous dysfunction, or brain dysfunction. Frequency of generalized tonic clonic seizures (GTCS), prone posture, and refractory epilepsy are considered risk factors. SUDEP has also been associated with inherited cardiac ion channel disease and severe obstructive sleep apnea. Most previous studies of SUDEP mechanisms have focused on cardiac and respiratory dysfunction and imbalance of the neural regulatory system. Cardiac-related mechanisms include reduction in heart rate variability and prolongation of QT interval, which can lead to arrhythmias. Laryngospasm and amygdala activation may cause obstructive and central apnea, respectively. Neural mechanisms include impairment of 5-HT and adenosine neuromodulation. The research to date regarding molecular mechanisms of SUDEP is relatively limited. Most studies have focused on p-glycoprotein, catecholamines, potassium channels, and the renin-angiotensin system, all of which affect cardiac and respiratory function.

Effects of levetiracetam treatment on autonomic nervous system functions in pediatric epilepsy patients

BACKGROUND

This study investigated the effects of levetiracetam (LEV) treatment on cardiac rhythm and heart rate variability.

METHODS

The study included two groups of patients diagnosed with non-lesional epilepsy who had not yet been treated and who presented to the outpatient pediatric neurology clinic at Van Training and Research Hospital, Van, Turkey, between 2019 and 2020. The heart rate variability (HRV) of 47 patients in the first group, before and at the 3rd month of treatment, and intravenous (IV) LEV loading in 13 patients in the second group was evaluated by Holter electrocardiography (ECG).

RESULTS

It was determined that the values of triangular index, standard deviation of the RR intervals over a 24-hour period (SDNN), standard deviation of all 5-minute mean RR intervals (SDANN), mean of standard deviations of all normal RR intervals (SDNNI), the percentage of RR intervals with >50-millisecond variation (PNN50), and the square root of mean squared differences of successive RR intervals (RMSSD). HRV of 47 patients under LEV treatment significantly increased in the 3rd month of treatment compared to baseline (p < 0.05). No difference was found in HRV between the intravenous loading and the control group (p > 0.05).

CONCLUSIONS

Our study suggests that the sympathovagal balance before treatment in the patient group is in favor of the sympathetic nervous system and that the sympathovagal imbalance improves after treatment. Our results show that LEV monotherapy and loading have no negative effect on HRV and potential cardiac arrhythmia risk in children with epilepsy.

Routine Interictal EEG Recording Should be Performed Together with Simultaneous Two-Lead ECG Recording

We aimed to evaluate the contribution of simultaneous electrocardiography (ECG) recording during routine interictal electroencephalography (EEG) recording in patients with seizures or epilepsy and therefore to provide evidence-based data on this subject. Patients with interictal cardiac arrhythmia on routine EEG-ECG recordings were determined and evaluated based on cardiologic and neurologic findings. Out of 1,078 patients aged between 5 and 16 years (mean: 10.2 ± 3.2), 9 (0.08%) patients were found to have an arrhythmia. Six patients had both epilepsy and cardiac arrhythmia (premature ventricular contractions [PVCs] in 5; Wolff-Parkinson-White [WPW] in 1 patient) and the remaining three patients had nonepileptic paroxysmal events (NPEs) and arrhythmia (PVC in 2; WPW in 1). Three patients had other diseases (neurofibromatosis type 1, tuberous sclerosis, and congenital heart disease status postsurgery). Cardiac arrhythmia required radiofrequency ablation or antiarrhythmic drug treatment in two patients with epilepsy and also two patients with NPE; however, it improved with no specific treatment in the remaining five patients. NPE was not related to arrhythmia in one of three patients with NPE. Our study suggests that routine interictal EEG-ECG recording provides a valuable and feasible opportunity to reveal unnoticed or new-onset cardiac arrhythmias. Therefore, ECG should be recorded simultaneously during routine interictal EEG recordings. Cardiac arrhythmias detected by routine interictal EEG-ECG recordings would require arrhythmia treatment in nearly half of the patients.

Blood pressure, body mass index lowering and ketogenesis in Qigong Bigu

Background

Hypertension is one of the most common comorbid conditions of epilepsy. Hypertension and epilepsy may be related to each other. Qigong Bigu practice induces a similar effect as fasting in the first week. As ketogenesis is induced during ketogenic diet therapy, we hypothesize that ketogenesis is detectable and related body weight loss would occur during the first week of Qigong Bigu practice.

Methods

During the prospective observational study, 34 healthy adult participants attended the Qigong Bigu practice for one week. The blood pressure, body weight, calorie consumption, blood glucose and beta-hydroxybutyrate level were measured.

Results

The body weight and body mass index decreased by 2.39 ± 1.34 kg (95%CI 1.92–2.85) and 0.94 ± 0.57 (95%CI 0.73–1.15), respectively, after five days of practice (P < 0.001). The systolic and diastolic blood pressure decreased by 17.86 ± 14.17 mmHg (95%CI 12.36–23.35) and 9.75 ± 7.45 mmHg (95%CI 6.86–12.64), respectively (P < 0.001). The average five-day calorie consumption was 1197.47 ± 569.97 kcal (95%CI 998.60–1396.35). Meanwhile, no symptomatic hypoglycemia or other significant side effects were observed. The blood beta-hydroxybutyrate level increased to a nutritional level of 1.15 ± 1.12 mmol/L (95%CI 0.76–1.62). The calorie consumption negatively correlated to the beta-hydroxybutyrate level in the blood. The loss of body weight and the decrease of body mass index were positively correlated to the blood beta-hydroxybutyrate level.

Conclusions

Qigong Bigu can decrease the blood pressure, the body weight and the body mass index in healthy adult participants. The fasting stage of Qigong Bigu is accompanied by ketogenesis. Clinical trial of Qigong Bigu in hypertension and epilepsy patients might be worthwhile. The blood beta-hydroxybutyrate might be used as a biomarker to evaluate the effect of Qigong Bigu practice during fasting.

Trial registration

ChiCTR1800016923.

The role of P-glycoprotein (P-gp) and inwardly rectifying potassium (Kir) channels in sudden unexpected death in epilepsy (SUDEP)

Sudden unexpected death in epilepsy (SUDEP) is the major cause of death that affects patients with epilepsy. The risk of SUDEP increases according to the frequency and severity of uncontrolled seizures; therefore, SUDEP risk is higher in patients with refractory epilepsy (RE), in whom most antiepileptic drugs (AEDs) are ineffective for both seizure control and SUDEP prevention. Consequently, RE and SUDEP share a multidrug resistance (MDR) phenotype, which is mainly associated with brain overexpression of ABC-transporters such as P-glycoprotein (P-gp). The activity of P-gp can also contribute to membrane depolarization and affect the normal function of neurons and cardiomyocytes. Other molecular regulators of membrane potential are the inwardly rectifying potassium channels (Kir), whose genetic variants have been related to both epilepsy and heart dysfunctions. Although it has been suggested that dysfunctions of the cardiac, respiratory, and brainstem arousal systems are the causes of SUDEP, the molecular basis for explaining its dysfunctions remain unknown. In rats, repetitive seizures or status epilepticus induced high expression of P-gp and loss Kir expression in the brain and heart, and promoted membrane depolarization, malignant bradycardia, and the high rate of mortality. Here we reviewed clinical and experimental evidences suggesting that abnormal expression of depolarizing/repolarizing factors as P-gp and Kir could favor persistent depolarization of membranes without any rapid functional recovery capacity. This condition induced by convulsive stress could be the molecular mechanism leading to acquired severe bradycardia, as an ineffective heart response generating the appropriate scenario for SUDEP development. This article is part of the Special Issue "NEWroscience 2018".

Causes and Effects Contributing to Sudden Death in Epilepsy and the Rationale for Prevention and Intervention

Sudden unexpected death in epilepsy (SUDEP) claims the lives of one in every thousand epileptic patients each year. Autonomic, cardiac, and respiratory pieces to a mechanistic puzzle have not yet been completely assembled. We propose a single sequence of causes and effects that unifies disparate and competitive concepts into a single algorithm centered on ictal obstructive apnea. Based on detailed animal studies that are sometimes impossible in humans, and striking parallels with a growing body of clinical examples, this framework (1) accounts for the autonomic, cardiac, and respiratory data to date by showing the causal relationships between specific elements, and (2) highlights specific kinds of data that can be used to precisely classify various patient outcomes. The framework also justifies a “near miss” designation to be applied to any cases with evidence of obstructive apnea even, and perhaps especially, in individuals that do not require resuscitation. Lastly, the rationale for preventative oxygen therapy is demonstrated. With better mechanistic understanding of SUDEP, we suggest changes for detection and classification to increase survival rates and improve risk stratification.

Epilepsy and hypertension: The possible link for sudden unexpected death in epilepsy?

Epilepsy affects about 50 million people worldwide. Sudden unexpected death in epilepsy (SUDEP) is the main cause of death in epilepsy accounting for up to 17% of all deaths in epileptic patients, and therefore remains a major public health problem. SUDEP likely arises from a combination and interaction of multiple risk factors (such as being male, drug resistance, frequent generalized tonic-clonic seizures) making risk prediction and mitigation challenging. While there is a general understanding of the physiopathology of SUDEP, mechanistic hypotheses linking risk factors with a risk of SUDEP are still lacking. Identifying cross-talk between biological systems implicated in SUDEP may facilitate the development of improved models for SUDEP risk assessment, treatment and clinical management. In this review, the aim was to explore an overlap between the pathophysiology of hypertension, cardiovascular disease and epilepsy, and discuss its implication for SUDEP. Presented herein, evidence in literature in support of a cross-talk between the renin-angiotensin system (RAS) and sympathetic nervous system, both known to be involved in the development of hypertension and cardiovascular disease, and as one of the underlying mechanisms of SUDEP. This article also provides a brief description of local RAS in brain neuroinflammation and the role of centrally acting RAS inhibitors in epileptic seizure alleviation.

Let's talk SUDEP

Sudden unexplained death in epilepsy (SUDEP) is a devastating complication of epilepsy which was under-recognized in the recent past despite its clear importance. In this review, we examine the definition of SUDEP, revise current pathophysiological theories, discuss risk factors and preventative measures, disclose tools for appraising the SUDEP risk, and last but not least dwell upon announcing and explaining the SUDEP risk to the patients and their caretakers. We aim to aid the clinicians in their responsibility of knowing SUDEP, explaining the SUDEP risk to their patients in a reasonable and sensible way and whenever possible, preventing SUDEP. Future studies are definitely needed to increase scientific knowledge and awareness related to this prioritized topic with malign consequences.

Update on the Genetic Basis of Sudden Unexpected Death in Epilepsy

Epilepsy is a common neurological disorder associated with increased morbidity and mortality. Sudden unexpected death in epilepsy, also known as SUDEP, is the main cause of death in patients with epilepsy. SUDEP has an incidence of 1.2 per 1000 person-years in adults and 0.2 per 1000 person-years in children. SUDEP accounts for 8-17% of deaths in patients with epilepsy. It is commonly associated with a history of generalized tonic-clonic seizures, and its risk may be increased by other factors such as postictal electroencephalographic suppression, prone sleeping position, altered heart rate variability, conduction abnormalities, gender, or antiepileptic medications. Recently, electrocardiograms, electroencephalograms, and imaging markers have helped clinicians stratify SUDEP risk and identify patients in need of close monitoring. However, the pathophysiology of SUDEP is likely multifactorial and still unknown. Improving the knowledge of SUDEP incidence, risk factors, and biomarkers can help design and implement effective prevention strategies.