Sudden unexplained death in childhood (1-4 years) in Ireland: an epidemiological profile and comparison with SIDS

Sudden Unexplained Death in Childhood: Current Understanding

ABSTRACT

Sudden unexplained death in childhood is a term that encompasses apparently natural deaths in children aged older than 1 year with no discernible cause despite a thorough assessment. Definitive underlying causes vary but most cases remain largely unexplained. Research has furthered the view that sudden unexplained death in childhood is not an accident, but rather a sentinel medical event for which a thorough postmortem investigation is indicated. Emerging evidence in genetics, neurology, and neuropathology point to heterogeneous causes that in some cases share features of recognized diseases.

Unexplained and Unexpected Pediatric Deaths: Forensic Review and New Perspectives

Unexplained and unexpected pediatric deaths are a major challenge in global healthcare. The role of the forensic pathologist is crucial in determining the cause and manner of death in these cases, although to date, there are many limitations in post-mortem diagnosis. The role of the autopsy and related forensic investigations become a fundamental tool to investigate and give an explanation for an unacceptable event, considering the young age of the victims. From this point of view, even today, it is necessary that this phenomenon is correctly recorded through standardized systems and universally accepted methods. Furthermore, it is essential that scientific research on this topic is increased through the implementation of universally accepted operating protocols recognizing real risk factors in order to prevent such events. The purpose of the study is to offer a review of the state of the art about unexplained pediatric death and, above all, to propose an international reporting platform, extending proper investigations not only to judicial cases but also to all the other cases of unexpected pediatric death.

Cardiac Genetic Investigation of Sudden Infant and Early Childhood Death: A Study From Victims to Families

Background Sudden infant death syndrome (SIDS) is the leading cause of death up to age 1. Sudden unexplained death in childhood (SUDC) is similar but affects mostly toddlers aged 1 to 4. SUDC is rarer than SIDS, and although cardiogenetic testing (molecular autopsy) identifies an underlying cause in a fraction of SIDS, less is known about SUDC. Methods and Results Seventy-seven SIDS and 16 SUDC cases underwent molecular autopsy with 25 definitive-evidence arrhythmia-associated genes. In 18 cases, another 76 genes with varying degrees of evidence were analyzed. Parents were offered cascade screening. Double-blind review of clinical-genetic data established genotype-phenotype correlations. The yield of likely pathogenic variants in the 25 genes was higher in SUDC than in SIDS (18.8% [3/16] versus 2.6% [2/77], respectively; P=0.03), whereas novel/ultra-rare variants of uncertain significance were comparably represented. Rare variants of uncertain significance and likely benign variants were found only in SIDS. In cases with expanded analyses, likely pathogenic/likely benign variants stemmed only from definitive-evidence genes, whereas all other genes contributed only variants of uncertain significance. Among 24 parents screened, variant status and phenotype largely agreed, and 3 cases positively correlated for cardiac channelopathies. Genotype-phenotype correlations significantly aided variant adjudication. Conclusions Genetic yield is higher in SUDC than in SIDS although, in both, it is contributed only by definitive-evidence genes. SIDS/SUDC cascade family screening facilitates establishment or dismissal of a diagnosis through definitive variant adjudication indicating that anonymity is no longer justifiable. Channelopathies may underlie a relevant fraction of SUDC. Binary classifications of genetic causality (pathogenic versus benign) could not always be adequate.

A ten-year retrospective case review of risk factors associated with sleep-related infant deaths

AIM

The study aimed to identify risk factors associated with sleep-related deaths of infants (0-24 months) in the province of Manitoba, Canada, between January 2009 and December 2018.

METHODS

A systematic retrospective case review of autopsies and administrative records in Manitoba between 2009 and 2018.

RESULTS

A total of 145 infants died in cases where unsafe sleep environments were known to have contributed to or resulted in their death and where no explained medical causes were identified. Where data complete, all infants had at least one known risk factor for sleep-related deaths, and 96% had multiple. The most common risk factors increased over time and included objects in the sleeping environment (90% of cases), not approved sleep surfaces (77%) and bedsharing (50%). Indigenous infants, infants of young mothers and infants in low-income neighbourhoods are overrepresented. Risk factors for Indigenous infants differed from cases involving non-Indigenous infants.

CONCLUSION

A high proportion of sleep-related infant deaths were associated with not approved sleep surfaces and bedsharing, especially for infants under one year. Families in low-income neighbourhoods, Indigenous families and families with young mothers were disproportionately affected by sleep-related infant deaths. There is a need to enhance messaging and smoking cessation messaging in Indigenous communities to prevent sleep-related deaths.

Proteomic differences in hippocampus and cortex of sudden unexplained death in childhood

Sudden unexplained death in childhood (SUDC) is death of a child over 1 year of age that is unexplained after review of clinical history, circumstances of death, and complete autopsy with ancillary testing. Multiple etiologies may cause SUDC. SUDC and sudden unexpected death in epilepsy (SUDEP) share clinical and pathological features, suggesting some similarities in mechanism of death and possible abnormalities in hippocampus and cortex. To identify molecular signaling pathways, we performed label-free quantitative mass spectrometry on microdissected frontal cortex, hippocampal dentate gyrus (DG), and cornu ammonis (CA1-3) in SUDC (n = 19) and pediatric control cases (n = 19) with an explained cause of death. At a 5% false discovery rate (FDR), we found differential expression of 660 proteins in frontal cortex, 170 in DG, and 57 in CA1-3. Pathway analysis of altered proteins identified top signaling pathways associated with activated oxidative phosphorylation (p = 6.3 × 10^-15, z = 4.08) and inhibited EIF2 signaling (p = 2.0 × 10^-21, z = - 2.56) in frontal cortex, and activated acute phase response in DG (p = 8.5 × 10^-6, z = 2.65) and CA1-3 (p = 4.7 × 10^-6, z = 2.00). Weighted gene correlation network analysis (WGCNA) of clinical history indicated that SUDC-positive post-mortem virology (n = 4/17) had the most significant module in each brain region, with the top most significant associated with decreased mRNA metabolic processes (p = 2.8 × 10^-5) in frontal cortex. Additional modules were associated with clinical history, including fever within 24 h of death (top: increased mitochondrial fission in DG, p = 1.8 × 10^-3) and febrile seizure history (top: decreased small molecule metabolic processes in frontal cortex, p = 8.8 × 10^-5) in all brain regions, neuropathological hippocampal findings in the DG (top: decreased focal adhesion, p = 1.9 × 10^-3). Overall, cortical and hippocampal protein changes were present in SUDC cases and some correlated with clinical features. Our studies support that proteomic studies of SUDC cohorts can advance our understanding of the pathogenesis of these tragedies and may inform the development of preventive strategies.

Blinded review of hippocampal neuropathology in sudden unexplained death in childhood reveals inconsistent observations and similarities to explained paediatric deaths

AIMS

Hippocampal findings are implicated in the pathogenesis of sudden unexplained death in childhood (SUDC), although some studies have identified similar findings in sudden explained death in childhood (SEDC) cases. We blindly reviewed hippocampal histology in SUDC and SEDC controls.

METHODS

Hippocampal haematoxylin and eosin (H&E) slides (n = 67; 36 SUDC, 31 controls) from clinical and forensic collaborators were evaluated by nine blinded reviewers: three board-certified forensic pathologists, three neuropathologists and three dual-certified neuropathologists/forensic pathologists.

RESULTS

Among nine reviewers, about 50% of hippocampal sections were rated as abnormal (52.5% SUDC, 53.0% controls), with no difference by cause of death (COD) (p = 0.16) or febrile seizure history (p = 0.90). There was little agreement among nine reviewers on whether a slide was within normal range (Fleiss' κ = 0.014, p = 0.47). Within reviewer groups, there were no findings more frequent in SUDC compared with controls, with variability in pyramidal neuron and dentate gyrus findings. Across reviewer groups, there was concordance for bilamination and granule cell loss. Neither SUDC (51.2%) nor control (55.9%) slides were considered contributory to determining COD (p = 0.41).

CONCLUSIONS

The lack of an association of hippocampal findings in SUDC and controls, as well as inconsistency of observations by multiple blinded reviewers, indicates discrepancy with previous studies and an inability to reliably identify hippocampal maldevelopment associated with sudden death (HMASD). These findings underscore a need for larger studies to standardise evaluation of hippocampal findings, identifying the range of normal variation and changes unrelated to SUDC or febrile seizures. Molecular studies may help identify novel immunohistological markers that inform on COD.

Seizure-related deaths in children: The expanding spectrum

Although seizures are common in children, they are often overlooked as a potential cause of death. Febrile and nonfebrile seizures can be fatal in children with or without an epilepsy diagnosis and may go unrecognized by parents or physicians. Sudden unexpected infant deaths, sudden unexplained death in childhood, and sudden unexpected death in epilepsy share clinical, neuropathological, and genetic features, including male predominance, unwitnessed deaths, death during sleep, discovery in the prone position, hippocampal abnormalities, and variants in genes regulating cardiac and neuronal excitability. Additionally, epidemiological studies reveal that miscarriages are more common among individuals with a personal or family history of epilepsy, suggesting that some fetal losses may result from epileptic factors. The spectrum of seizure-related deaths in pediatrics is wide and underappreciated; accurately estimating this mortality and understanding its mechanism in children is critical to developing effective education and interventions to prevent these tragedies.

Determining the prevalence of sudden and unexplained death in childhood (SUDC): a national Australian perspective

Sudden unexplained death in childhood (SUDC) is defined as the unexplained death of a child over the age of 12 months. The National Coronial Information System (NCIS) Australia was used to access data for deaths of children aged 1 to 4 years over the period 2010 to 2014. Cases were classified as those in which the cause of death was determined and those in which the child died suddenly and unexpectedly, and the cause of death remained undetermined. Categorical information was extracted for each case to determine risk factors associated with the cause of death. The overall rate of death in Australian children aged 1 to 4 years and for whom coronial data was available from 2010 to 2014 was 9.69/100,000 children. A cause of death was determined in 87% of cases with the average rate of death in this group being 8.49/100,000. Death remained undetermined in 13% of cases. The study determined that the SUDC rate in Australian children aged 1 to 4 years was 0.02/100,000. However, this rate may be as high as 0.40/100,000 children should further investigation be undertaken. These children tended to be 18-20 months of age and male, with death occurring primarily while prone during a sleep period in cooler months, thus having similar characteristics to sudden infant death syndrome.

Sudden Unexplained Death in Childhood: A Neuropathology Review

Sudden Unexplained Death in Childhood (SUDC) is the unexpected death of a child over age 12 months that remains unexplained after a thorough case investigation, including review of the child's medical history, circumstances of death, a complete autopsy and ancillary testing (1). First defined in 2005, SUDC cases are more often male, with death occurring during a sleep period, being found prone, peak winter incidence, associated with febrile seizure history in ~28% of cases and mild pathologic changes insufficient to explain the death (1, 2). There has been little progress in understanding the causes of SUDC and no progress in prevention. Despite reductions in sudden unexpected infant death (SUID) and other causes of mortality in childhood, the rate of SUDC has increased during the past two decades (3-5). In Ireland, SUID deaths were cut in half from 1994 to 2008 while SUDC deaths more than doubled (4). Surveillance issues, including lack of standardized certification practices, affect our understanding of the true magnitude of unexplained child deaths. Mechanisms underlying SUDC, like SUID, remain largely speculative. Limited and inconsistent evidence implicates abnormalities in brainstem autonomic and serotonergic nuclei, critical for arousal, cardiorespiratory control, and reflex responses to life-threatening hypoxia or hypercarbia in sleep (6). Abnormalities in medullary serotonergic neurons and receptors, as well as cardiorespiratory brainstem nuclei occur in some SUID cases, but have never been studied in SUDC. Retrospective, small SUDC studies with non-standardized methodologies most often demonstrate minor hippocampal abnormalities, as well as focal cortical dysplasia and dysgenesis of the brainstem and cerebellum. The significance of these findings to SUDC pathogenesis remains unclear with some investigators and forensic pathologists labeling these findings as normal variants, or potential causes of SUDC. The development of preventive strategies will require a greater understanding of underlying mechanisms.

Evaluation of Concordance Between Original Death Certifications and an Expert Panel Process in the Determination of Sudden Unexplained Death in Childhood

IMPORTANCE

The true incidence of sudden unexplained death in childhood (SUDC), already the fifth leading category of death among toddlers by current US Centers for Disease Control and Prevention estimates, is potentially veiled by the varied certification processes by medicolegal investigative offices across the United States.

OBJECTIVE

To evaluate the frequency of SUDC incidence, understand its epidemiology, and assess the consistency of death certification among medical examiner and coroner offices in the US death investigation system.

DESIGN, SETTING, AND PARTICIPANTS

In this case series, 2 of 13 forensic pathologists (FPs) conducted masked reviews of 100 cases enrolled in the SUDC Registry and Research Collaborative (SUDCRRC). Children who died aged 11 months to 18 years from 36 US states, Canada, and the United Kingdom had been posthumously enrolled in the SUDCRRC by family members from 2014 to 2017. Comprehensive data from medicolegal investigative offices, clinical offices, and family members were reviewed. Data analysis was conducted from December 2014 to June 2020.

MAIN OUTCOMES AND MEASURES

Certified cause of death (COD) characterized as explained (accidental or natural) or unexplained, as determined by SUDCRRC masked review process.

RESULTS

In this study of 100 cases of SUDC (mean [SD] age, 32.1 [31.8] months; 58 [58.0%] boys; 82 [82.0%] White children; 92 [92.0%] from the United States), the original pathologist certified 43 cases (43.0%) as explained COD and 57 (57.0%) as unexplained COD. The SUDCRRC review process led to the following certifications: 16 (16.0%) were explained, 7 (7.0%) were undetermined because of insufficient data, and 77 (77.0%) were unexplained. Experts disagreed with the original COD in 40 cases (40.0%). These data suggest that SUDC incidence is higher than the current Centers for Disease Control and Prevention estimate (ie, 392 deaths in 2018).

CONCLUSIONS AND RELEVANCE

To our knowledge, this is the first comprehensive masked forensic pathology review process of sudden unexpected pediatric deaths, and it suggests that SUDC may often go unrecognized in US death investigations. Some unexpected pediatric deaths may be erroneously attributed to a natural or accidental COD, negatively affecting surveillance, research, public health funding, and medical care of surviving family members. To further address the challenges of accurate and consistent death certification in SUDC, future studies are warranted.

Postural change for supine position does not disturb toddlers' nap

This study examined whether forced postural change from prone to supine during toddlers’ nap, a preventative measure taken in Japan for sudden unexplained death in childhood (SUDC), disturbs toddlers’ sleep. When the "Back to Sleep" campaign (BSC) was introduced to Japan in 1996, its recommendations were also applied to infants aged 1 year old and over with the expectation that the BSC recommendations may also contribute to a decrease in the occurrence rate of SUDC. Since then, Japanese nurseries have routinely conducted sleeping position checks and positional adjustments of toddlers every 5–10 min during naps. A total of 52 toddlers (age 18.4 ± 3.3 months, means ± SD) were continuously monitored for 8 h during daytime at nursery schools for wake-sleep status and body position (prone, supine and lateral) with actigraphs and 3-orthogonal-axis accelerometers. Out of the 52 toddlers, 24 toddlers adopted prone positions during naps, which were adjusted by nursery staff back to supine. When nursery staff manually changed the toddlers position from prone to supine, the toddlers either did not wake or woke only briefly (3.1 ± 4.9 min) and returned to sleep soon after the positional change. Our study indicates that manual change of toddlers’ sleeping position from prone to supine, a potential SUDC prevention method, does not disturb toddlers’ sleep during their naps.

Neuropathologic Changes in Sudden Unexplained Death in Childhood

Sudden unexplained death in childhood (SUDC) affects children >1-year-old whose cause of death remains unexplained following comprehensive case investigation and is often associated with hippocampal abnormalities. We prospectively performed systematic neuropathologic investigation in 20 SUDC cases, including (i) autopsy data and comprehensive ancillary testing, including molecular studies, (ii) ex vivo 3T MRI and extensive histologic brain samples, and (iii) blinded neuropathology review by 2 board-certified neuropathologists. There were 12 girls and 8 boys; median age at death was 33.3 months. Twelve had a history of febrile seizures, 85% died during apparent sleep and 80% in prone position. Molecular testing possibly explained 3 deaths and identified genetic mutations in TNNI3, RYR2, and multiple chromosomal aberrations. Hippocampal abnormalities most often affected the dentate gyrus (altered thickness, irregular configuration, and focal lack of granule cells), and had highest concordance between reviewers. Findings were identified with similar frequencies in cases with and without molecular findings. Number of seizures did not correlate with hippocampal findings. Hippocampal alterations were the most common finding on histological review but were also found in possibly explained deaths. The significance and specificity of hippocampal findings is unclear as they may result from seizures, contribute to seizure pathogenesis, or be an unrelated phenomenon.

Potential Role of Febrile Seizures and Other Risk Factors Associated With Sudden Deaths in Children

IMPORTANCE

Sudden unexplained death in childhood (SUDC) is the fifth leading category of death among toddlers but remains underrecognized and inadequately studied.

OBJECTIVE

To assess the potential role of febrile seizures (FS) and other risk factors associated with SUDC and describe the epidemiology, mechanisms, and prevention of SUDC.

DESIGN, SETTING, AND PARTICIPANTS

This case series study reviewed 622 consecutive sudden child death cases aged 1 to 17 years from 2001 to 2017 from 18 countries. Data were collected from family members of children who died suddenly; these families voluntarily registered with the SUDC Foundation. Data analysis was conducted from November 2017 to February 2019.

MAIN OUTCOME MEASURES

Certified manner of death characterized as accident, natural, or undetermined.

RESULTS

A total of 391 families with decedents aged 1 to 6 years completed a comprehensive interview on medical and social histories, and circumstances of death with forensic evaluations revealing a cause of death (sudden explained death in childhood [SEDC]) or no cause of death (SUDC). Of these children, 231 (59.1%) were male, the mean (SD) age at death was 24.9 (12.8) months, and 104 (26.6%) had a history of FS. Compared with the general population FS prevalence (2%-5%), FS prevalence among SUDC (28.8%; 95% CI, 23.3%-34.2%) and SEDC (22.1%; 95% CI, 14.8%-29.3%) were elevated. The odds of death during sleep was 4.6-fold higher in SUDC than in SEDC cases (odds ratio, 4.61; 95% CI, 1.92-11.09; adjusted P = .008). The siblings of SUDC cases were followed up for 3144 life-years, and none died prematurely from SUDC.

CONCLUSIONS AND RELEVANCE

This analysis of the largest SUDC cohort confirmed an increased FS rate and found significantly increased rates of FS among SEDC. This study suggests that seizures may contribute to some SUDC and SEDC deaths. The risk of sudden death in a sibling was low. To develop and assess preventive strategies, population-based studies are needed to define the epidemiology and spectrum of risk factors and identify biomarkers of patients with FS at high risk of sudden death.

Sleep-disordered breathing, neuroendocrine function, and clinical SUDEP risk in patients with epilepsy

INTRODUCTION

Sudden unexpected death in epilepsy (SUDEP) is a major contributor to epilepsy-related mortality. It is associated with nocturnal seizures and centrally mediated postictal cardiorespiratory dysfunction (CRD), but mechanisms and contributors remain poorly understood.

METHODS

We performed a prospective, cross-sectional, observational pilot study in the Columbia University Medical Center (CUMC) adult epilepsy monitoring unit (EMU) to explore relationships between periictal CRD, sleep-disordered breathing (SDB), neuroendocrine function, and clinical SUDEP risk. Thirty patients (twenty women, ten men) underwent video-electroencephalogram (EEG) with electrocardiogram (EKG) and digital pulse oximetry, inpatient or outpatient polysomnography (PSG), and comprehensive laboratory evaluation of sex steroid hormones. Sudden unexpected death in epilepsy risk was defined as Low (0-2) or High (≥3) using the revised SUDEP-7 Inventory. Sleep-disordered breathing was defined using standard criteria. Neuroendocrine dysfunction was defined as ≥1 laboratory abnormality.

RESULTS

Cardiorespiratory dysfunction occurred more frequently in high-risk patients (60% vs. 27%, p = 0.018). Endocrine dysfunction was seen in 35% of patients, more in men (p = 0.018). Sleep-disordered breathing was found in 88% of fully scoreable PSGs.

CONCLUSIONS

There was no significant relationship between CRD, SDB, and neuroendocrine status, though all PSGs in those with high SUDEP risk or neuroendocrine dysfunction revealed SDB. Larger studies are needed to further elucidate relationships between CRD, SDB, neuroendocrine factors, and SUDEP.

The French prospective multisite registry on sudden unexpected infant death (OMIN): rationale and study protocol

INTRODUCTION

Even after 'back-to-sleep' campaigns, sudden unexpected infant death (SUID) continues to be the leading cause of death for infants 1 month to 1 year old in developed countries, with devastating social, psychological and legal implications for families. To sustainably tackle this problem and decrease the number of SUIDs, a French SUID registry was initiated in 2015 to (1) inform prevention with standardised data, (2) understand the mechanisms leading to SUID and the contribution of the already known or newly suggested risk factors and (3) gather a multidisciplinary group of experts to coordinate and develop innovative and urgent research in the SUID area.

METHODS AND ANALYSIS

This observational multisite prospective observatory includes all cases of sudden unexpected deaths in children younger than 2 years occurring in the French territory covered by the 35 participating French referral centres. From these cases, various data concerning sociodemographic conditions, death scene, personal and family medical history, parental behaviours, sleep environment, clinical examinations, biological and imagery investigations and autopsy are systematically collected. These data will be complemented as of 2018 with a biobank of diverse biological samples (blood, hair, urine, faeces and cerebrospinal fluid), with other administrative health-related data (health claim reimbursements and hospital admissions) and socioenvironmental data. Insights from exploratory descriptive statistics and thematic analysis will be combined for the design of targeted strategies to effectively reduce preventable infant deaths.

ETHICS AND DISSEMINATION

The French sudden unexpected infant death registry (Observatoire National des Morts Inattendues du Nourrisson registry;OMIN) was approved in 2015 by the French Data Protection Authority in clinical research (Commission Nationale de l'Informatique et des Libertés: number 915273) and by an independent ethics committee (Groupe Nantais d'Ethique dans le Domaine de la Santé: number 2015-01-27). Results will be discussed with associations of families affected by SUID, caregivers, funders of the registry, medical societies and researchers and will be submitted to international peer-reviewed journals and presented at international conferences.

The Cerebellum and SIDS: Disordered Breathing in a Mouse Model of Developmental Cerebellar Purkinje Cell Loss during Recovery from Hypercarbia

The cerebellum assists coordination of somatomotor, respiratory, and autonomic actions. Purkinje cell alterations or loss appear in sudden infant death and sudden death in epilepsy victims, possibly contributing to the fatal event. We evaluated breathing patterns in 12 wild-type (WT) and Lurcher mutant mice with 100% developmental cerebellar Purkinje cell loss under baseline (room air), and recovery from hypercapnia, a concern in sudden death events. Six mutant and six WT mice were exposed to 4-min blocks of increasing CO₂ (2, 4, 6, and 8%), separated by 4-min recovery intervals in room air. Breath-by-breath patterns, including depth of breathing and end-expiratory pause (EEP) durations during recovery, were recorded. No baseline genotypic differences emerged. However, during recovery, EEP durations significantly lengthened in mutants, compared to WT mice, following the relatively low levels of CO₂ exposure. Additionally, mutant mice exhibited signs of post-sigh disordered breathing during recovery following each exposure. Developmental cerebellar Purkinje cell loss significantly affects compensatory breathing patterns following mild CO₂ exposure, possibly by inhibiting recovery from elevated CO₂. These data implicate cerebellar Purkinje cells in the ability to recover from hypercarbia, suggesting that neuropathologic changes or loss of these cells contribute to inadequate ventilatory recovery to increased environmental CO₂. Multiple disorders, including sudden infant death syndrome (SIDS) and sudden unexpected death in epilepsy (SUDEP), appear to involve both cardiorespiratory failure and loss or injury to cerebellar Purkinje cells; the findings support the concept that such neuropathology may precede and exert a prominent role in these fatal events.

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.

Sudden unexpected death in early childhood: general observations in a series of 151 cases: Part 1 of the investigations of the San Diego SUDC Research Project

PURPOSE

The purpose of this study was to determine the major subcategories and clinicopathologic features of sudden unexpected death in young children in a large retrospective cohort, and to confirm the association of sudden unexplained death in children (abbreviated by us for unexplained deaths as SUDC) with hippocampal pathology and/or febrile seizures.

METHODS

We undertook analysis of a retrospective cohort of 151 cases, of which 80% (121/151) were subclassified as SUDC, 11% (16/151) as explained, 7% (10/151) as undetermined, and 3% (4/151) as seizure-related.

RESULTS

There were no significant differences between SUDC and explained cases in postnatal, gestational, or postconceptional age, frequency of preterm birth, gender, race, or organ weights. In contrast, 96.7% (117/121) of the SUDC group were discovered during a sleep period compared to 53.3% (8/15) of the explained group (p < 0.001), and 48.8% (59/121) of the SUDC cases had a personal and/or family history of febrile seizures compared to 6.7% (1/15) of the explained group (p < 0.001). Of the explained deaths, 56% (9/16) were subclassified as infection, 31% (5/16) cardiac, 6% (1/16) accidental, and 6% (1/16) metabolic. Two of the three cases specifically tested for cardiac channelopathies at autopsy based upon clinical indications had genetic variants in cardiac genes, one of uncertain significance. Bacterial cultures at autopsy typically revealed organisms interpreted as contaminants. Two of the four seizure-related deaths were witnessed, with two of the brains from these cases showing generalized malformations. Hippocampal anomalies, including a specific combination we termed hippocampal maldevelopment associated with sudden death, were found in almost 50% (40/83) of the SUDC and undetermined cases in which hippocampal sections were available.

CONCLUSIONS

This study highlights the key role for the hippocampus, febrile seizures, and sleep in SUDC pathophysiology. It also demonstrates the role of known predisposing conditions such as cardiac channelopathies and infections in causing sudden unexpected death in childhood, and the need for improved ancillary testing and protective strategies in these cases, even when the cause of death is established at autopsy.

Metabolic disease in 10 patients with sudden unexpected death in infancy or acute life-threatening events

In order to determine the associations between sudden unexpected death in infancy (SUDI) or acute life-threatening events (ALTE) and inborn errors of metabolism, particularly organic acidemia and fatty acid oxidation disorders, we evaluated clinical features in patients with SUDI or ALTE. The subjects were infants between the ages of 7 days and 3 years who developed SUDI or ALTE between January 2004 and December 2013. They were then diagnosed as having inborn errors of metabolism on gas chromatography-mass spectrometry (GC/MS) and/or tandem mass spectrometry (MS/MS). The age distribution, onset forms, and clinical findings were evaluated during the acute phase. Inborn errors of metabolism were detected in three of 196 patients with SUDI, and in seven of 167 patients with ALTE. Of these 10 patients, nine had a history of poor feeding and somnolence during the neonatal period, and symptoms of infection such as cough, fever or vomiting during infancy. Routine laboratory tests during an acute phase indicated hyperammonemia, liver dysfunction, increased blood creatine kinase, acidosis, positive ketone bodies in urine or blood, or hypoglycemia. When SUDI or ALTE are encountered in the emergency unit, it is essential that a detailed medical history is taken, particularly with regard to the neonatal period, and that specific abnormalities are investigated on routine laboratory tests. Moreover, samples such as urine, serum, and filter paper blood specimens should be collected for GC/MS and/or MS/MS of organic acids and acylcarnitines, to identify inborn metabolic disorders.

Mortality risks in new-onset childhood epilepsy

OBJECTIVES

Estimate the causes and risk of death, specifically seizure related, in children followed from onset of epilepsy and to contrast the risk of seizure-related death with other common causes of death in the population.

METHODS

Mortality experiences from 4 pediatric cohorts of newly diagnosed patients were combined. Causes of death were classified as seizure related (including sudden unexpected death [SUDEP]), natural causes, nonnatural causes, and unknown.

RESULTS

Of 2239 subjects followed up for >30 000 person-years, 79 died. Ten subjects with lethal neurometabolic conditions were ultimately excluded. The overall death rate (per 100 000 person-years) was 228; 743 in complicated epilepsy (with associated neurodisability or underlying brain condition) and 36 in uncomplicated epilepsy. Thirteen deaths were seizure-related (10 SUDEP, 3 other), accounting for 19% of all deaths. Seizure-related death rates were 43 overall, 122 for complicated epilepsy, and 14 for uncomplicated epilepsy. Death rates from other natural causes were 159, 561, and 9, respectively. Of 48 deaths from other natural causes, 37 were due to pneumonia or other respiratory complications.

CONCLUSIONS

Most excess death in young people with epilepsy is not seizure-related. Mortality is significantly higher compared with the general population in children with complicated epilepsy but not uncomplicated epilepsy. The SUDEP rate was similar to or higher than sudden infant death syndrome rates. In uncomplicated epilepsy, sudden and seizure-related death rates were similar to or higher than rates for other common causes of death in young people (eg, accidents, suicides, homicides). Relating the risk of death in epilepsy to familiar risks may facilitate discussions of seizure-related mortality with patients and families.