Neurogenic pulmonary edema in unexpected, unexplained death of epileptic patients

Sudden Unexpected Death in Epilepsy: A Narrative Review of Mechanism, Risks, and Prevention

Sudden unexpected death in epilepsy (SUDEP) is sudden, unexpected, witnessed or unwitnessed, nontraumatic, non-drowning death that occurs in a person with epilepsy. SUDEP is the leading cause of epilepsy-related death in adults with epilepsy, with an incidence of about 1.2 per 1000 person-years in the general epilepsy population. Recent studies have shown similar prevalence in the pediatric population too. Although the precise mechanism remains unclear, well-documented cases of SUDEP suggest that a generalized tonic clonic seizure-induced, centrally mediated change in cardiorespiratory function leads to terminal apnea and cardiac arrest. Risk factors include generalized tonic clonic seizure frequency, duration of epilepsy, nocturnal seizure, and certain genetic syndromes. Orexin, adenosine, and serotonin neurotransmission have been explored as novel drug targets to mitigate SUDEP risk. Neurostimulation and resective epilepsy surgery have been reported to have beneficial effects on long-term SUDEP risk as well. Future studies may aim to clarify the role of sleep and other comorbidities in SUDEP pathophysiology.

Sudden unexpected death in epilepsy: Investigation of autopsy-based studies

Epilepsy is a common neurological disorder that is associated with increased morbidity and mortality. Sudden unexpected death in epilepsy (SUDEP) is one of the most common causes for epilepsy-related deaths and its characteristics remain largely unknown, particularly from a forensic autopsy perspective. The present study aimed to investigate the neurological, cardiac, and pulmonary findings for a total of 388 SUDEP decedents, encompassing three cases from our forensic center during 2011-2020 and 385 literature-reported autopsy cases. In the cases mentioned in this study, two of them presented with only mild cardiac abnormalities, such as focal myocarditis and mild coronary atherosclerosis of the left anterior coronary artery. The third one was negative of any pathological findings. After pooling together these SUDEP cases, we found that neurological changes (n = 218 cases, 56.2%) were the most common postmortem findings associated with SUDEP, with cerebral edema/congestion (n = 60 cases, 15.5%) and old traumatic brain injury (n = 58 cases, 14.9%) being the major findings. Interstitial fibrosis, myocyte disarray/hypertrophy, and mild coronary artery atherosclerosis were the most common findings related to primary cardiac pathology, documented in 49 (12.6%), 18 (4.6%), and 15 (3.9%) cases, respectively. Non-specific pulmonary edema was the major finding in the lungs. This is an autopsy-based study that reports the scenario of postmortem findings for SUDEP cases. Our study paves the way for understanding the pathogenesis of SUDEP and the interpretation of death.

Hiding in plain sight? A review of post-convulsive leukocyte elevations

During physiological stress responses such as vigorous exercise, emotional states of fear and rage, and asphyxia, the nervous system induces a massive release of systemic catecholamines that prepares the body for survival by increasing cardiac output and redirecting blood flow from non-essential organs into the cardiopulmonary circulation. A curious byproduct of this vital response is a sudden, transient, and redistributive leukocytosis provoked mostly by the resultant shear forces exerted by rapid blood flow on marginated leukocytes. Generalized convulsive seizures, too, result in catecholamine surges accompanied by similar leukocytoses, the magnitude of which appears to be rooted in semiological factors such as convulsive duration and intensity. This manuscript reviews the history, kinetics, physiology, and clinical significance of post-convulsive leukocyte elevations and discusses their clinical utility, including a proposed role in the scientific investigation of sudden unexpected death in epilepsy (SUDEP).

Definite SUDEP population in Bexar County, Texas: A 36-year data registry

OBJECTIVE

Sudden unexplained death in epilepsy (SUDEP) is one of the leading causes of mortality in epilepsy. In this study, cases of definite SUDEP are reported for Bexar County from a 36-year period.

METHODS

Death reports by Bexar County Medical Examiner (BCME) from 1983 to 2018 were reviewed to identify cases with definite SUDEP. The findings were based upon investigators' reports, which included medical history, medication list, sleep position, time of death, and pathology reports. In addition to these potential risk factors, body mass indices (BMI), as well as heart, lung, and brain weights were compared between SUDEP victims with therapeutic vs subtherapeutic anti-seizure medication (ASM) levels.

RESULTS

Definite SUDEP was identified in 286 cases. The incidence of definite SUDEP was 0.51 ± 0.26/1000 person-years among PWE and 0.56 ± 0.29 per 100,000 person-years among the general population in Bexar County. The median age was 37 years old (interquartile range 27-48), and the majority were male (65%). While 171 (60%) people were prescribed at least one ASM, ASM levels were subtherapeutic in 239 cases (83.6%). Risk factors for SUDEP did not differ between SUDEP victims with therapeutic vs subtherapeutic ASM levels. While BMIs were only slightly increased in adherent vs nonadherent SUDEP victims, they were significantly associated with subtherapeutic ASM levels. Abnormal lung, heart, and brain weights were reported in 48 (16.8%), 67 (23.4%), and 43 (15.0%) SUDEP cases, respectively.

SIGNIFICANCE

This study is one of the largest autopsy-based registries of definite SUDEP. Subtherapeutic ASM levels measured in post-mortem blood samples suggest that nonadherence to ASM therapy was a leading risk factor for SUDEP. As BMI was elevated in this cohort, and obesity was significantly associated with subtherapeutic ASM levels, it may also be a risk factor for SUDEP. Case-controlled studies are needed to validate the specific role of obesity and related comorbidities in this population.

Autonomic Dysfunction Contributes to Impairment of Cerebral Autoregulation in Patients with Epilepsy

Patients with epilepsy frequently experience autonomic dysfunction and impaired cerebral autoregulation. The present study investigates autonomic function and cerebral autoregulation in patients with epilepsy to determine whether these factors contribute to impaired autoregulation. A total of 81 patients with epilepsy and 45 healthy controls were evaluated, assessing their sudomotor, cardiovagal, and adrenergic functions using a battery of autonomic nervous system (ANS) function tests, including the deep breathing, Valsalva maneuver, head-up tilting, and Q-sweat tests. Cerebral autoregulation was measured by transcranial Doppler examination during the breath-holding test, the Valsalva maneuver, and the head-up tilting test. Autonomic functions were impaired during the interictal period in patients with epilepsy compared to healthy controls. The three indices of cerebral autoregulation—the breath-holding index (BHI), an autoregulation index calculated in phase II of the Valsalva maneuver (ASI), and cerebrovascular resistance measured in the second minute during the head-up tilting test (CVR_2-min)—all decreased in patients with epilepsy. ANS dysfunction correlated significantly with impairment of cerebral autoregulation (measured by BHI, ASI, and CVR_2-min), suggesting that the increased autonomic dysfunction in patients with epilepsy may augment the dysregulation of cerebral blood flow. Long-term epilepsy, a high frequency of seizures, and refractory epilepsy, particularly temporal lobe epilepsy, may contribute to advanced autonomic dysfunction and impaired cerebral autoregulation. These results have implications for therapeutic interventions that aim to correct central autonomic dysfunction and impairment of cerebral autoregulation, particularly in patients at high risk for sudden, unexplained death in epilepsy.

Neurogenic pulmonary edema secondary to epileptic seizure

Neurogenic pulmonary edema (NPE) is a non-cardiogenic pulmonary edema that is caused by an acute central nervous system injury and usually develops rapidly after an injury. Although several episodes of NPE resolve spontaneously, the condition may cause unexpected death among patients with epilepsy.

Sudden death in epilepsy: There is room for intracranial pressure

INTRODUCTION

Sudden unexpected death in patients with epilepsy (SUDEP) remains a poorly understood entity, and it is unclear whether the same pathomechanisms underlie all sudden deaths occurring in patients with epilepsy. One aspect not included in current models of SUDEP is the role of increased intracranial pressure (ICP) which can be observed immediately upon seizure activity in neurosurgical practice.

METHODS

We conducted a systematic review of the occurrence of edema in patients with epilepsy reported to have died of sudden death who underwent brain autopsy or postmortem brain imaging and discuss how increased ICP may contribute to clinical features of SUDEP.

RESULTS

19 eligible studies comprising a total of 623 patients were identified. Edema-mostly mild or moderate-was reported in 17% of cases and 74% of studies. 1% (n = 6) of the overall cases were clearly identified as having Dravet syndrome or an SCN1A mutation. In these patients, edema was found in 4 (67%) of cases.

CONCLUSION

Edema is regularly found in patients with epilepsy classified to have died from SUDEP. We argue that seizures preceding SUDEP may in certain cases elicit acute edema which may represent an additional contributing factor in the cascade of events leading to sudden death of patients with epilepsy. Furthermore, we hypothesize that mild edema may especially progress to severe edema in patients with sodium channel mutations which may represent an important mechanism to investigate in the context of understanding the significantly elevated risk of SUDEP in patients with SCN1A mutations.

Considerations around the SARS-CoV-2 Spike Protein with Particular Attention to COVID-19 Brain Infection and Neurological Symptoms

Spike protein (S protein) is the virus "key" to infect cells and is able to strongly bind to the human angiotensin-converting enzyme2 (ACE2), as has been reported. In fact, Spike structure and function is known to be highly important for cell infection as well as for entering the brain. Growing evidence indicates that different types of coronaviruses not only affect the respiratory system, but they might also invade the central nervous system (CNS). However, very little evidence has been so far reported on the presence of COVID-19 in the brain, and the potential exploitation, by this virus, of the lung to brain axis to reach neurons has not been completely understood. In this Article, we assessed the SARS-CoV and SARS-CoV-2 Spike protein sequence, structure, and electrostatic potential using computational approaches. Our results showed that the S proteins of SARS-CoV-2 and SARS-CoV are highly similar, sharing a sequence identity of 77%. In addition, we found that the SARS-CoV-2 S protein is slightly more positively charged than that of SARS-CoV since it contains four more positively charged residues and five less negatively charged residues which may lead to an increased affinity to bind to negatively charged regions of other molecules through nonspecific and specific interactions. Analysis the S protein binding to the host ACE2 receptor showed a 30% higher binding energy for SARS-CoV-2 than for the SARS-CoV S protein. These results might be useful for understanding the mechanism of cell entry, blood-brain barrier crossing, and clinical features related to the CNS infection by SARS-CoV-2.

Cardiorespiratory depression from brainstem seizure activity in freely moving rats

Cardiorespiratory dysfunction during or after seizures may contribute to sudden unexpected death in epilepsy. Disruption of lower brainstem cardiorespiratory systems by seizures is postulated to impair respiratory and cardiac function. Here, we explore the effects of brainstem seizures and stimulation on cardiorespiratory function using a rat model of intrahippocampal 4-aminopyridine (4-AP)-induced acute recurrent seizures. Cardiac and respiratory monitoring together with local field potential recordings from hippocampus, contralateral parietal cortex and caudal dorsomedial brainstem, were conducted in freely moving adult male Wistar rats. Seizures were induced by intrahippocampal injection of 4-AP. Increased respiratory rate but unchanged heart rate occurred during hippocampal and secondarily generalized cortical seizures. Status epilepticus without brainstem seizures increased respiratory and heart rates, whereas status epilepticus with intermittent brainstem seizures induced repeated episodes of cardiorespiratory depression leading to death. Respiratory arrest occurred prior to asystole which was the terminal event. Phenytoin (100 mg/kg, intraperitoneal injection), administered after 4-AP intrahippocampal injection, terminated brainstem seizures and the associated cardiorespiratory depression, preventing death in five of six rats. Focal electrical stimulation of the caudal dorsomedial brainstem also suppressed cardiorespiratory rates. We conclude that in our model, brainstem seizures were associated with respiratory depression followed by cardiac arrest, and then death. We hypothesize this model shares mechanisms in common with the classic sudden unexpected death in epilepsy (SUDEP) syndrome associated with spontaneous seizures.

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.

A 49-Year-Old Woman With Chest Pain, Cough, and Hypoxemia After a Seizure

CASE PRESENTATION

A 49-year-old woman with a medical history of epilepsy presented to the ED 1 h after a single, 15-min, witnessed, tonic-clonic seizure. Over the preceding 6 months, she had experienced five similar seizures of shorter duration. There were no recent changes to her phenytoin dose nor had she started any new medications. The patient had traveled to Jamaica 3 weeks before presentation, where she smoked marijuana once but otherwise had not used illicit substances nor had she used tobacco or alcohol. She states she felt well during and after the trip until this presentation. While being evaluated by the neurology service, the patient complained of sudden-onset chest pain and cough with associated hypoxemia. She denied changes in her sleep habits, she had not experienced any fevers, and she had no changes in her exercise tolerance. The patient was admitted to the general medicine floor for further workup.

Sudden unexpected death in epilepsy: Risk factors, biomarkers, and prevention

Sudden unexpected death in epilepsy (SUDEP) is one of the most important direct epilepsy-related causes of death, with an incidence in adults of 1.2 per 1000 person-years. Generalized tonic-clonic seizures have consistently emerged as the leading risk factor for SUDEP, particularly when such seizures are uncontrolled. High seizure burden, lack of antiepileptic drug (AED) treatment, polytherapy, intellectual disability, and prone position at the time of death are other key risk factors. Unfortunately, despite advances in treatment, overall mortality rates in epilepsy are rising. It is imperative that we learn more about SUDEP so that effective prevention strategies can be implemented. To help identify persons at greater risk of SUDEP and in need of closer monitoring, biomarkers are needed. Candidate biomarkers include electrocardiographic, electroencephalographic, and imaging abnormalities observed more frequently in those who have died suddenly and unexpectedly. As our knowledge of the pathophysiologic mechanisms behind SUDEP has increased, various preventative measures have been proposed. These include lattice pillows, postictal oxygen therapy, selective serotonin reuptake inhibitors, and inhibitors of opiate and adenosine receptors. Unfortunately, no randomized clinical trials are available to definitively conclude these measures are effective. Rather, gaining the best control of seizures possible (with AEDs, devices, and resective surgery) still remains the intervention with the best evidence to reduce the risk of SUDEP. In this evidence-based review, we explore the incidence of SUDEP and review the risk factors, biomarkers, and latest prevention strategies.

Review: The past, present and future challenges in epilepsy-related and sudden deaths and biobanking

Awareness and research on epilepsy-related deaths (ERD), in particular Sudden Unexpected Death in Epilepsy (SUDEP), have exponentially increased over the last two decades. Most publications have focused on guidelines that inform clinicians dealing with these deaths, educating patients, potential risk factors and mechanisms. There is a relative paucity of information available for pathologists who conduct these autopsies regarding appropriate post mortem practice and investigations. As we move from recognizing SUDEP as the most common form of ERD toward in-depth investigations into its causes and prevention, health professionals involved with these autopsies and post mortem procedure must remain fully informed. Systematizing a more comprehensive and consistent practice of examining these cases will facilitate (i) more precise determination of cause of death, (ii) identification of SUDEP for improved epidemiological surveillance (the first step for an intervention study), and (iii) biobanking and cell-based research. This article reviews how pathologists and healthcare professionals have approached ERD, current practices, logistical problems and areas to improve and harmonize. The main neuropathology, cardiac and genetic findings in SUDEP are outlined, providing a framework for best practices, integration of clinical, pathological and molecular genetic investigations in SUDEP, and ultimately prevention.

Collection and Analysis of Multimodal Data for SUDEP Biomarker Discovery

This paper discusses the acquisition and processing of multimodal physiological data from patients with epilepsy in Epilepsy Monitoring Units for the discovery of risk factors for Sudden Expected Death in Epilepsy (SUDEP) that can be combined through integrative analysis for biomarker discovery.

Serum Levels of Brain-Derived Neurotrophic Factor and Insulin-Like Growth Factor 1 Are Associated With Autonomic Dysfunction and Impaired Cerebral Autoregulation in Patients With Epilepsy

Background: Brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF-1) may regulate the autonomic nervous system (ANS) in epilepsy. The present study investigated the role of IGF-1 and BDNF in the regulation of autonomic functions and cerebral autoregulation in patients with epilepsy. Methods: A total of 57 patients with focal epilepsy and 35 healthy controls were evaluated and their sudomotor, cardiovagal, and adrenergic functions were assessed using a battery of ANS function tests, including the deep breathing, Valsalva maneuver, head-up tilting, and Q-sweat tests. Cerebral autoregulation was measured by transcranial doppler during the breath-holding test and the Valsalva maneuver. Interictal serum levels of BDNF and IGF-1 were measured with enzyme-linked immunosorbent assay kits. Results: During interictal period, reduced serum levels of BDNF and IGF-1, impaired autonomic functions, and decreased cerebral autoregulation were noted in patients with epilepsy compared with healthy controls. Reduced serum levels of BDNF correlated with age, adrenergic and sudomotor function, overall autonomic dysfunction, and the autoregulation index calculated in Phase II of the Valsalva maneuver, and showed associations with focal to bilateral tonic-clonic seizures. Reduced serum levels of IGF-1 were found to correlate with age and cardiovagal function, a parameter of cerebral autoregulation (the breath-hold index). Patients with a longer history of epilepsy, higher seizure frequency, and temporal lobe epilepsy had lower serum levels of IGF-1. Conclusions: Long-term epilepsy and severe epilepsy, particularly temporal lobe epilepsy, may perturb BDNF and IGF-1 signaling in the central autonomic system, contributing to the autonomic dysfunction and impaired cerebral autoregulation observed in patients with focal epilepsy.

Ictal Asystole in Temporal Lobe Epilepsy: A Possible Cause of Sudden Unexplained Death - A Case Report

We report a case of a 47-year-old woman who presented with a 3-year history of paroxysmal events after suffering traumatic brain injury in a motor vehicle accident. She had not previously been diagnosed with epilepsy. On video-EEG monitoring, she was found to have a right temporal seizure associated with ictal asystole lasting for 18 seconds. Our case raises the possibility that undiagnosed ictal asystole could be a potential cause of sudden unexplained death.

Ictal Mammalian Dive Response: A Likely Cause of Sudden Unexpected Death in Epilepsy

Even though sudden unexpected death in epilepsy (SUDEP) takes the lives of thousands of otherwise healthy epilepsy patients every year, the physiopathology associated with this condition remains unexplained. This article explores important parallels, which exist between the clinical observations and pathological responses associated with SUDEP, and the pathological responses that can develop when a set of autonomic reflexes known as the mammalian dive response (MDR) is deployed. Mostly unknown to physicians, this evolutionarily conserved physiological response to prolonged apnea economizes oxygen for preferential use by the brain. However, the drastic cardiovascular adjustments required for its execution, which include severe bradycardia and the sequestration of a significant portion of the total blood volume inside the cardiopulmonary vasculature, can result in many of the same pathological responses associated with SUDEP. Thus, this article advances the hypothesis that prolonged apneic generalized tonic clonic seizures induce augmented forms of the MDR, which, in the most severe cases, cause SUDEP.

National Association of Medical Examiners Position Paper: Recommendations for the Investigation and Certification of Deaths in People with Epilepsy

Sudden unexpected death of an individual with epilepsy (SUDEP) can pose a challenge to death investigators, as most deaths are unwitnessed and the individual is commonly found dead in bed. Anatomic findings (e.g., tongue/lip bite) are commonly absent and of varying specificity, limiting the evidence to implicate epilepsy as a cause of or contributor to death. Thus, it is likely that death certificates significantly underrepresent the true number of deaths in which epilepsy was a factor. To address this, members of the National Association of Medical Examiners, North American SUDEP Registry, Epilepsy Foundation SUDEP Institute, American Epilepsy Society, and the Centers for Disease Control and Prevention convened an expert panel to generate evidence-based recommendations for the practice of death investigation and autopsy, toxicological analysis, interpretation of autopsy and toxicology findings, and death certification to improve the precision of death certificate data available for public health surveillance of epilepsy-related deaths. The recommendations provided in this paper are intended to assist medical examiners, coroners, and death investigators when a sudden, unexpected death in a person with epilepsy is encountered.

National Association of Medical Examiners position paper: Recommendations for the investigation and certification of deaths in people with epilepsy

Sudden unexpected death of an individual with epilepsy can pose a challenge to death investigators, as most deaths are unwitnessed, and the individual is commonly found dead in bed. Anatomic findings (eg, tongue/lip bite) are commonly absent and of varying specificity, thereby limiting the evidence to implicate epilepsy as a cause of or contributor to death. Thus it is likely that death certificates significantly underrepresent the true number of deaths in which epilepsy was a factor. To address this, members of the National Association of Medical Examiners, North American SUDEP Registry, Epilepsy Foundation SUDEP Institute, American Epilepsy Society, and the Centers for Disease Control and Prevention constituted an expert panel to generate evidence-based recommendations for the practice of death investigation and autopsy, toxicological analysis, interpretation of autopsy and toxicology findings, and death certification to improve the precision of death certificate data available for public health surveillance of epilepsy-related deaths. The recommendations provided in this paper are intended to assist medical examiners, coroners, and death investigators when a sudden unexpected death in a person with epilepsy is encountered.

Neurogenic pulmonary oedema secondary to vertebral artery dissection while playing tennis

We present a case of a patient who developed vertebral artery dissection (VAD) while playing tennis and presented with neurogenic pulmonary oedema. The case highlights two important points: acute pulmonary oedema as an unusual presenting feature of VAD and VAD, an important cause of stroke in young people, as being associated with playing low-impact sports such as tennis. These associations, independent of each other, are under-recognised and can lead to a delay in diagnosis.

Pulmonary and cardiac pathology in sudden unexpected death in epilepsy (SUDEP)

OBJECTIVE

To review studies on structural pulmonary and cardiac changes in SUDEP cases as well as studies showing pulmonary or cardiac structural changes in living epilepsy patients.

METHODS

We conducted electronic literature searches using the PubMed database for articles published in English, regardless of publication year, that included data on cardiac and/or pulmonary structural abnormalities in SUDEP cases or in living epilepsy patients during the postictal period.

RESULTS

Fourteen postmortem studies reported pulmonary findings in SUDEP cases. Two focused mainly on assessing lung weights in SUDEP cases versus controls; no group difference was found. The other 12 reported descriptive autopsy findings. Among all SUDEP cases with available descriptive postmortem pulmonary examination, 72% had pulmonary changes, most often pulmonary edema/congestion, and, less frequently, intraalveolar hemorrhage. Eleven studies reported on cardiac pathology in SUDEP. Cardiac abnormalities were found in approximately one-fourth of cases. The most common findings were myocyte hypertrophy and myocardial fibrosis of various degrees. Among living epilepsy patients, postictal pulmonary pathology was the most commonly reported pulmonary abnormality and the most common postictal cardiac abnormality was transient left ventricular dysfunction - Takotsubo or neurogenic stunned myocardium.

SIGNIFICANCE

Cardiac and pulmonary pathological abnormalities are frequent among SUDEP cases, most commonly pulmonary edema/congestion and focal interstitial myocardial fibrosis. Most findings are not quantified, with subjective elements and undefined interobserver reliability, and lack of controls such as matched epilepsy patients who died from other causes. Further, studies have not systematically evaluated potential confounding factors, including postmortem interval to autopsy, paramedic resuscitation and IV fluids administration, underlying heart/lung disease, and risk factors for cardiac or pulmonary disease. Prospective studies with controls are needed to define the heart and lung changes in SUDEP and understand their potential relationship to mechanisms of death in SUDEP.

Neurogenic pulmonary oedema: a rare cause of maternal collapse

Acute pulmonary oedema is a significant cause of morbidity and mortality in pregnant and postpartum women. We present an unusual case of near-fatal acute pulmonary oedema in a pregnant woman, which was attributed to the acute onset of neurogenic pulmonary oedema secondary to epileptic seizure activity. The patient required supportive management in the intensive care setting for a short period and subsequently made complete recovery with regular neurological follow-up arranged for the management of her epilepsy.

Neurocardiology

Neurocardiology refers to the interplay between the nervous system and the cardiovascular system. Stress-related cardiomyopathy exemplifies the brain-heart connection and occurs in several conditions with acute brain injury that share oversympathetic activation. The brain's influences on the heart can include elevated cardiac markers, arrhythmias, repolarization abnormalities on electrocardiogram, myocardial necrosis, and autonomic dysfunction. The neurogenic stunned myocardium in aneurysmal subarachnoid hemorrhage represents one end of the spectrum, and is associated with an explosive rise in intracranial pressure that results in excess catecholamine state and possibly CBN. A brain-heart link is more known to cardiologists than neurologists. This chapter provides some insight into the pathophysiology of these pathologic neurocardiac states and their most appropriate management relevant to neurologists.

Neurogenic pulmonary edema combined with febrile seizures in early childhood-A report of two cases

Neurogenic pulmonary edema (NPE) is a clinical entity that can occur following central nervous system disorders. However, NPE occurs quite rarely in early childhood, and there has only been one report about pediatric NPE associated with febrile seizures. Two cases are reported here. One case involved a 2-year-old girl who presented with febrile seizures, which rapidly progressed to severe NPE. Since the NPE occurred in the emergency department room, the patient was able to be resuscitated via immediate endotracheal intubation. The other case involved an 11-month-old boy who developed respiratory distress following a 50-min episode of febrile status epilepticus. Both patients required respiratory management in the intensive care unit. However their conditions were dramatically improved within several days and fully recovered without any sequelae.

Neurologic Causes of Acute Respiratory Dysfunction

Many neurologic diseases can cause acute respiratory decompensation, therefore a familiarity with these diseases is critical for any clinician managing patients with respiratory dysfunction. In this article, we review the anatomy of the respiratory system, focusing on the neurologic control of respiration. We discuss general mechanisms by which diseases of the peripheral and central nervous systems can cause acute respiratory dysfunction, and review the neurologic diseases which can adversely affect respiration. Lastly, we discuss the diagnosis and general management of acute respiratory impairment due to neurologic disease.

From unwitnessed fatality to witnessed rescue: Nonpharmacologic interventions in sudden unexpected death in epilepsy

Sudden unexpected death in epilepsy (SUDEP) risk reduction remains a critical aim in epilepsy care. To date, only aggressive medical and surgical efforts to control seizures have been demonstrated to be of benefit. Incomplete understanding of SUDEP mechanisms limits the development of more specific interventions. Periictal cardiorespiratory dysfunction is implicated in SUDEP; postictal electroencephalography (EEG) suppression, coma, and immobility may also play a role. Nocturnal supervision is protective against SUDEP, presumably by permitting intervention in the case of a life-threatening event. Resuscitative efforts were implemented promptly in near-SUDEP cases but delayed in SUDEP deaths in the Mortality in Epilepsy Monitoring Unit Study (MORTEMUS) study. Nursing interventions--including repositioning, oral suctioning, and oxygen administration--reduce seizure duration, respiratory dysfunction, and EEG suppression in the epilepsy monitoring unit (EMU), but have not been studied in outpatients. Cardiac pacemakers or cardioverter-defibrillator devices may be of benefit in a few select individuals. A role for implantable neurostimulators has not yet been established. Seizure detection devices, including those that monitor generalized tonic-clonic seizure-associated movements or cardiorespiratory parameters, may provide a means to permit timely periictal intervention. However, these and other devices, such as antisuffocation pillows, have not been adequately investigated with respect to SUDEP prevention.

Sudden unexpected death in epilepsy: basic mechanisms and clinical implications for prevention

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of death in patients with intractable epilepsy. The substantial lifetime risk of SUDEP and the lack of a clear pathophysiological connection between epilepsy itself and sudden death have fuelled increased attention to this phenomenon. Understanding the mechanisms underlying SUDEP is paramount to developing preventative strategies. In this review, we discuss SUDEP population studies, case-control studies, witnessed and monitored cases, as well as human seizure cardiorespiratory findings related to SUDEP, and SUDEP animal models. We integrate these data to suggest the most probable mechanisms underlying SUDEP. Understanding the modifiable risk factors and pathophysiology allows us to discuss potential preventative strategies.

Pediatric Sudden Unexpected Death in Epilepsy

BACKGROUND

Epilepsy is a common neurological disorder among children and adolescents that is associated with increased mortality for numerous reasons. Sudden unexpected death in epilepsy is a critically important entity for physicians who treat patients with epilepsy. Many pediatric neurologists are hesitant to discuss this condition with patients and families because of the lower risk in the pediatric age group.

METHODS

We searched for studies published between January 2000 and June 2015 by means of a PubMed search and a cumulative review of reference lists of all relevant publications, using the keywords "sudden unexpected death in epilepsy patients," "pediatric SUDEP," "sudden unexpected death in epilepsy patients and children," "sudden unexpected death in children" and "sudden infant death syndrome."

RESULTS

SUDEP is a rare condition in children. Its mechanism is poorly understood and may have a distinct pathogenesis from adult sudden unexpected death in epilepsy. Limited comfort, experience, and knowledge to provide appropriate education about sudden unexpected death in epilepsy leads to fewer physicians discussing this subject leading to less informed and less prepared patients and families.

CONCLUSION

We provide a detailed review of the literature on pediatric SUDEP, including the definition, classification, and proposed mechanisms of sudden unexpected death in epilepsy in children, as well as discuss the incidence in the pediatric population and risk factors in children, concluding with possible prevention strategies.

[Current possibilities of treatment of generalized convulsive seizures]

Current possibilities of treatment of generalized convulsive seizures are presented. Progress in the field of pharmacotherapy of epilepsy allowed to introduce new antiepileptic drugs (AED). Some of them are modified AED with higher efficacy or better tolerability and others represent a generation of new drugs with different mechanisms of action. Perampanel, an agonist of AMPA-receptors, is a new drug approved in more than 40 countries, including Russia. At present, the use of some AED is limited by the high risk of sudden death (sudden unexpected death in epilepsy (SUDEP)). SUDEP is a common cause of death directly associated with epilepsy, with the highest frequency in patients with active epilepsy. Subtherapeutic concentrations of SED in the serum of SUDEP patients may be the consequence of inadequate treatment and low compliance to treatment that causes the development of pseudoresistant seizures and, hence, the higher risk of SUDEP. At the same time, AED per se play an important role in the modification of functions of the autonomic nervous system and may induce disturbances of heart rate and conductivity.

Postictal generalized EEG suppression and SUDEP: a review

SUMMARY

Sudden unexpected death in epilepsy (SUDEP) remains a leading cause of epilepsy-related death, and yet, its pathogenic mechanisms remain ill-defined. Although epidemiological studies of SUDEP in heterogenous populations have established a number of clinical associations, evaluation and stratification of individual risk remains difficult. Thus, potential markers as predictors of risk of SUDEP are important not only clinically but also for research on SUDEP prevention. Recordings from rare monitored cases of SUDEP demonstrate postictal generalized EEG suppression after terminal seizures, raising expectations that postictal generalized EEG suppression may identify individuals at higher risk. In this review, we consider the literature on postictal generalized EEG suppression and evaluate its relevance and utility as a possible marker of SUDEP.

Mechanisms of sudden unexpected death in epilepsy: the pathway to prevention

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy, with an estimated 35% lifetime risk in this patient population. There is a surprising lack of awareness among patients and physicians of this increased risk of sudden death: in a recent survey, only 33% of Canadian paediatricians who treated patients with epilepsy knew the term SUDEP. Controversy prevails over whether cardiac arrhythmia or respiratory arrest is more important as the primary cause of death. Effective preventive strategies in high-risk patients will rely on definition of the mechanisms that lead from seizures to death. Here, we summarize evidence for the mechanisms that cause cardiac, respiratory and arousal abnormalities during the ictal and postictal period. We highlight potential cellular mechanisms underlying these abnormalities, such as a defect in the serotonergic system, ictal adenosine release, and changes in autonomic output. We discuss genetic mutations that cause Dravet and long QT syndromes, both of which are linked with increased risk of sudden death. We then highlight possible preventive interventions that are likely to decrease SUDEP incidence, including respiratory monitoring in epilepsy monitoring units and overnight supervision. Finally, we discuss treatments, such as selective serotonin reuptake inhibitors, that might be personalized to a specific genetic or pathological defect.

The mechanism of neurogenic pulmonary edema in epilepsy

Neurogenic pulmonary edema (NPE) is found in many epilepsy patients at autopsy. It is a life-threatening complication, known for almost 100 years, but its etiopathogenesis is still not completely understood. In this study, we used the tremor rat (TRM: tm/tm) as an animal model of epilepsy to investigate the potential mechanisms of NPE under epileptic conditions. We performed reverse-phase high-pressure liquid chromatography assay, H&E and Masson staining, TUNEL assay, and Western blot experiments to determine the role of seizures in NPE. We found the level of catecholamine was higher in TRM rats. Also the occurrence of alveolar cell apoptosis was increased. Moreover, pulmonary vascular remodeling including the deposition of collagen and medial thickening was also found in TRM rats. Further study showed that cell apoptosis was mediated by increasing Bax, decreasing Bcl-2, and activating caspase-3. In addition, the protein level of phosphorylated ERK (p-ERK) was found to be decreased while phosphorylated JNK and phosphorylated p38 were upregulated in TRM rats. Thus, these findings suggest that pulmonary vascular remodeling and alveolar cell apoptosis might be involved in epilepsy-induced NPE and that the mitogen-activated protein kinase signal pathway was involved.

Neurogenic pulmonary edema and acute respiratory distress syndrome in a healthy child with febrile status epilepticus

Neurogenic pulmonary edema is a clinical syndrome that manifests as an acute onset of pulmonary edema in the setting of a central nervous system injury, without cardiac dysfunction. Neurogenic pulmonary edema is rare in children, and the mechanism is still not completely understood.  The clinical pathology overlaps with acute lung injury and acute respiratory distress syndrome. The authors report a case of a 14-month-old previously healthy child who presented with febrile status epilepticus, fulminant neurogenic pulmonary edema, and acute respiratory distress syndrome.  Neurogenic pulmonary edema should be considered in the differential diagnosis for the rapid progression of respiratory failure following an acute neurological injury such as status epilepticus in a child. Prompt respiratory support and treatment of the acute neurological insult can prevent further cerebral hypoxemic injury.

Incidence and mechanisms of cardiorespiratory arrests in epilepsy monitoring units (MORTEMUS): a retrospective study

BACKGROUND

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in people with chronic refractory epilepsy. Very rarely, SUDEP occurs in epilepsy monitoring units, providing highly informative data for its still elusive pathophysiology. The MORTEMUS study expanded these data through comprehensive evaluation of cardiorespiratory arrests encountered in epilepsy monitoring units worldwide.

METHODS

Between Jan 1, 2008, and Dec 29, 2009, we did a systematic retrospective survey of epilepsy monitoring units located in Europe, Israel, Australia, and New Zealand, to retrieve data for all cardiorespiratory arrests recorded in these units and estimate their incidence. Epilepsy monitoring units from other regions were invited to report similar cases to further explore the mechanisms. An expert panel reviewed data, including video electroencephalogram (VEEG) and electrocardiogram material at the time of cardiorespiratory arrests whenever available.

FINDINGS

147 (92%) of 160 units responded to the survey. 29 cardiorespiratory arrests, including 16 SUDEP (14 at night), nine near SUDEP, and four deaths from other causes, were reported. Cardiorespiratory data, available for ten cases of SUDEP, showed a consistent and previously unrecognised pattern whereby rapid breathing (18-50 breaths per min) developed after secondary generalised tonic-clonic seizure, followed within 3 min by transient or terminal cardiorespiratory dysfunction. Where transient, this dysfunction later recurred with terminal apnoea occurring within 11 min of the end of the seizure, followed by cardiac arrest. SUDEP incidence in adult epilepsy monitoring units was 5·1 (95% CI 2·6-9·2) per 1000 patient-years, with a risk of 1·2 (0·6-2·1) per 10,000 VEEG monitorings, probably aggravated by suboptimum supervision and possibly by antiepileptic drug withdrawal.

INTERPRETATION

SUDEP in epilepsy monitoring units primarily follows an early postictal, centrally mediated, severe alteration of respiratory and cardiac function induced by generalised tonic-clonic seizure, leading to immediate death or a short period of partly restored cardiorespiratory function followed by terminal apnoea then cardiac arrest. Improved supervision is warranted in epilepsy monitoring units, in particular during night time.

FUNDING

Commission of European Affairs of the International League Against Epilepsy.

SUDEP and other causes of mortality in childhood-onset epilepsy

BACKGROUND

There are few prospective studies on the causes of mortality in well-characterized cohorts with epilepsy and even fewer that have autopsy data that allow for reliable determination of SUDEP. We report causes of mortality and mortality rates in the Finnish cohort with childhood-onset epilepsy.

METHODS

A population-based cohort of 245 children with epilepsy in 1964 has been prospectively followed for almost 40 years. Seizure outcomes and mortality were assessed. Autopsy data were available in 70% of the cases. Sudden unexpected death in epilepsy (SUDEP) rates were assessed, and SUDEP was confirmed by autopsy.

RESULTS

During the follow-up, 60 subjects died. The major risk factor for mortality was lack of terminal remission (p < 0.0001). Remote symptomatic etiology also increased the risk for death (p < 0.0001) but did not remain significant on multivariate analysis after adjusting for effect of remission. Of the deaths, 33/60 (55%) were epilepsy-related including SUDEP in 23/60 (38%) using the Nashef criteria, status epilepticus in 4/60 (7%), and accidental drowning in 6/60 (10%). The nonepilepsy-related deaths occurred primarily in the remote symptomatic group and were often related to the underlying disorder or to medical comorbidities that developed after the onset of the epilepsy. Risk factors for SUDEP on multivariable analysis included lack of 5-year terminal remission and not having a localization-related epilepsy. In cryptogenic/idiopathic cases, SUDEP did not occur in childhood but begins only in adolescence.

CONCLUSION

Childhood-onset epilepsy is associated with a substantial risk of epilepsy-related mortality, primarily SUDEP. In otherwise neurologically normal individuals, the increased SUDEP risk begins in adolescence. The higher mortality rates reported in this cohort are related to duration of follow-up as most of the mortality occurs many years after the onset of the epilepsy.

Potential mechanisms of sudden unexpected death in epilepsy

Sudden unexpected death in epilepsy (SUDEP) accounts for 15% of all deaths in people with epilepsy and 50% in refractory epilepsy. The underlying mechanisms are not well understood, but seizure-induced cardiac and respiratory arrests are involved. The cardiovascular and respiratory systems are subject to precise reflex regulation to ensure appropriate oxygen supply under a wide range of circumstances. Barosensory and chemosensory afferents project into the nucleus tractus solitarius (NTS), which relays systemic data to higher brain centers for integration of homeostatic responses in heart rate, peripheral resistance, respiration, and other autonomic reactions. Being the afferent autonomic gatekeeper, NTS plays a critical role in cardiovascular and respiratory regulation. In the course of studying the kainic acid model, we became aware of progressive neuronal loss in the NTS and noted SUDEP-like deaths in rats with frequent convulsions. Increased autonomic susceptibility with inhalation anesthetics was also observed, often seen after impairment of baroreceptor and chemoreceptor reflex loops. Seizure-induced neuron loss in NTS may play a role impairing the integrative functions of NTS resulting in poor homeostatic responses during seizures and leading to SUDEP.

Neurogenic pulmonary edema associated with underlying lung disease after a breakthrough seizure

Neurogenic pulmonary edema (NPE) can result from various central nervous system disorders such as brain malignancies, traumatic brain injuries, infections, and seizures. Although the pathogenesis is not completely understood, NPE creates an increase in pulmonary interstitial and alveolar fluid. It has been reported with prolonged seizure activity. Treatment for NPE is largely supportive. If unrecognized, it can lead to hypoxia and respiratory arrest. We report a case of NPE in a middle-aged female patient following a breakthrough seizure in whom an immunological cause for respiratory findings was high on the differential list, based on her past medical history and chronicity of symptoms. Rapid symptomatic and radiological improvement following hospitalization led to the correct diagnosis.

Neuropathology of Seizure Disorders

Epilepsy is a common neurological disorder characterized by an enduring predisposition to generate recurrent seizures. Pathologists may be called upon to evaluate brain tissue from patients with a history of seizures, and it is important to keep in mind the diversity of histopathologic findings associated with this disorder and the limitations imposed by both, limited sampling and neuroanatomy. Review of the literature has shown that the three most common clinicopathological entities in surgically resected medically refractory epilepsy are mesial temporal sclerosis (MTS), long-term epilepsy-associated tumors (LEAT), and malformations of cortical development (MCD) which includes focal cortical dysplasia (FCD). Here, we will review the most common clinicopathological entities seen in surgically resected cases of refractory epilepsy, such as MTS, MCD, LEAT, as well as vascular and encephalitic lesions. We will also touch upon traumatic brain injuries and SUDEP, and the role of the forensic pathologist. A better understanding of the etiopathology, recent classifications, and underlying molecular mechanisms involved in each entity will be helpful in order to identify the cause of death in patients with seizure disorders, candidates who will benefit from tailored surgical resection strategies, as well as to develop new and targeted drug treatment.

Sudden unexpected death in epilepsy

Sudden unexpected death in epilepsy (SUDEP) refers to the sudden death of a seemingly healthy individual with epilepsy, usually occurring during, or immediately after, a tonic-clonic seizure. The frequency of SUDEP varies depending on the severity of the epilepsy, but overall the risk of sudden death is more than 20 times higher than that in the general population. Several different mechanisms probably exist, and most research has focused on seizure-related respiratory depression, cardiac arrhythmia, cerebral depression, and autonomic dysfunction. Data from a pooled analysis of risk factors indicate that the higher the frequency of tonic-clonic seizures, the higher the risk of SUDEP; furthermore, risk of SUDEP is also elevated in male patients, patients with long-duration epilepsy, and those on antiepileptic polytherapy. SUDEP usually occurs when the seizures are not witnessed and often at night. In this Seminar, we provide advice to clinicians on ways to minimise the risk of SUDEP, information to pass on to patients, and medicolegal aspects of these deaths.

Forensic antiepileptic drug levels in autopsy cases of epilepsy

A 1-year retrospective coroner-based forensic examination of causes of death among persons with a history of epilepsy was conducted at the Allegheny County Coroner's Office to evaluate the phenomenon of sudden unexplained/unexpected death in epilepsy (SUDEP), a diagnosis of exclusion. All cases at the Coroner's Office from January 1, 2001 through December 31, 2001, were examined. Review of a total of 1200 autopsied deaths revealed 12 cases with a past medical history of seizure disorder on the death certificate, which listed seizure disorder as the immediate cause of death or contributory cause of the death. Of the 7 men with seizure disorders, 5 were categorized as definite SUDEP and 2 as possible SUDEP. Of the 5 women with seizure disorders, 2 were listed as definite SUDEP, 2 as possible, and 1 as non-SUDEP because the convulsive seizures developed from a grade II glial tumor. Postmortem findings were evaluated for 11 cases; 1 body was decomposed. Toxicological screens were carried out on blood, bile, urine, and eye fluid for all 12. Antiepileptic drug (AED) levels detected in postmortem toxicological analysis were examined. AED levels were determined in 7 cases. Four of 7 had subtherapeutic AED levels, 2 had therapeutic levels, and only 1 victim of SUDEP had levels above the therapeutic range. Five cases had no detectable AED levels. AED levels at autopsy were either absent or subtherapeutic in 9 of 10 SUDEP cases, findings consistent with the likelihood of poor AED compliance. Subtherapeutic levels of AEDs may be a risk factor for SUDEP that could contribute to increased interictal and/or ictal epileptiform activity with associated autonomic dysfunction leading to disturbance of heart rate, heart rhythm, and/or blood pressure.

Heart and lung in the postictal state

Ictal events include those of the autonomic nervous system. This sympathetic stimulation may persist into the postictal period, affecting cardiopulmonary function. Such postictal effects include potentially fatal alterations in cardiac rhythm and ventilatory function, management challenges such as pulmonary edema, and diagnostically confusing laboratory abnormalities such as fever and cerebrospinal fluid pleocytosis. These and other effects on the heart and lung in the postictal period are accordingly reviewed.