Investigating sudden unexpected death in infancy and early childhood

Sudden Unexpected Death in Infancy [SUDI]: What the clinician, pathologist, coroner and researchers want to know

The loss of an apparently healthy infant is confronting for any family, puzzling for a clinician and challenging for the pathologist charged with the task of demonstrating a cause for death. The term "cot death" evolved to "sudden infant death syndrome" [SIDS] and now "sudden unexpected death in infancy [SUDI]" as the epidemiology and pathology of infant death changed. Community interventions were successful in changing sleep practices for young babies. The current research focus is on understanding genetic predispositions to unexpected death in early childhood. Whilst much has been achieved in reducing the infant mortality rate from SUDI by between 50%, and 80% in some countries, over the last 30 years, there remain challenges for improving rates of accurate diagnosis and reaching out to more vulnerable families with clearly modifiable risk factors for SUDI. These challenges directly involve the clinician through taking a systematic and detailed history and better standardised death scene evaluations with specifically accredited assessors. Better knowledge regarding circumstances of SUDI cases will help Coroners and researchers provide answers for grieving families now, and in the future contribute to further reductions in the rate of SUDI in communities across the world.

Respiratory syncytial virus-associated mortality in a healthy 3-year-old child: a case report

Background

Respiratory syncytial virus (RSV) is the most frequently identified pathogen in children with acute lower respiratory tract infection. Fatal cases have mainly been reported during the first 6 months of life or in the presence of comorbidity.

Case presentation

A 47-month-old girl was admitted to the pediatric intensive care unit following sudden cardiopulmonary arrest occurring at home. The electrocardiogram showed cardiac asystole, which was refractory to prolonged resuscitation efforts. Postmortem analyses detected RSV by polymerase chain reaction in an abundant, exudative pericardial effusion. Histopathological examination was consistent with viral myoepicarditis, including an inflammatory process affecting cardiac nerves and ganglia. Molecular analysis of sudden unexplained death genes identified a heterozygous mutation in myosin light chain 2, which was also found in two other healthy members of the family. Additional expert interpretation of the cardiac histology confirmed the absence of arrhythmogenic right ventricular dysplasia or hypertrophic cardiomyopathy.

Conclusions

RSV-related sudden death in a normally developing child of this age is exceptional. This case highlights the risk of extrapulmonary manifestations associated with this infection, particularly arrhythmia induced by inflammatory phenomena affecting the cardiac autonomic nervous system. The role of the mutation in this context is uncertain, and it is therefore necessary to continue to assess how this pathogenic variant contributes to unexpected sudden death in childhood.

Infant mortality in Brazil attributable to inborn errors of metabolism associated with sudden death: a time-series study (2002-2014)

Background

The literature suggests that 0.9 to 6% of infants who die unexpectedly may have had a metabolic disorder. At least 43 different inborn errors of metabolism (IEMs) have been associated with sudden death (SUDI). To date, the frequency of IEM-associated SUDI has not been studied in Brazil. The present study sought to characterize infant mortality related to IEMs known to cause SUDI disaggregated by each of the regions of Brazil.

Methods

This was a descriptive, cross-sectional, population-based study of data obtained from the Brazilian Ministry of Health Mortality Information System (SIM). Death records were obtained for all infants (age < 1 year) who died in Brazil in 2002–2014 in whom the underlying cause of death was listed as ICD-10 codes E70 (Disorders of aromatic amino-acid metabolism), E71 (Disorders of branched-chain amino-acid metabolism and fatty-acid metabolism), E72 (Other disorders of amino-acid metabolism), or E74 (Other disorders of carbohydrate metabolism), which are known to be associated with SUDI.

Results

From 2002 to 2014, 199 deaths of infants aged < 1 year were recorded in the SIM with an underlying cause corresponding to one of the IEMs of interest. The prevalence of IEM-related deaths was 0.67 per 10,000 live births (0.58–0.77). Of these 199 deaths, 18 (9.0%) occurred in the North of Brazil, 43 (21.6%) in the Northeast, 80 (40.2%) in the Southeast, 46 (23.1%) in the South, and 12 (6.0%) in the Center-West region. Across all regions of the country, ICD10-E74 was predominant.

Conclusions

This 13-year time-series study provides the first analysis of the number of infant deaths in Brazil attributable to IEMs known to be associated with sudden death.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1421-y) contains supplementary material, which is available to authorized users.

Genetics of inherited arrhythmias in pediatrics

PURPOSE OF REVIEW

Recent international expert consensus statements have updated the clinical and genetic diagnoses of patients suffering from arrhythmogenic diseases. However, a lack of genotype-phenotype correlations has hampered the development of a risk stratification scale for sudden cardiac death.

RECENT FINDINGS

The improvement in the field of genetics has prompted the discovery of new genes associated with sudden cardiac death. Sudden cardiac death is a socially devastating event, especially when it occurs in the pediatric population. Physical activity can often trigger the arrhythmia and sudden death may be the first symptom. These inherited cardiac diseases may be difficult to diagnose, leaving family members also at risk. Thanks to the development of new high-throughput technologies, genetics may be used in the diagnosis of these diseases and even cases that remain unexplained after a comprehensive autopsy. Genetic testing cannot only identify the causative genetic variant in the index case, but it enables the detection of relatives at risk of sudden death, despite remaining clinically asymptomatic.

SUMMARY

We review the recent advances in the genetics of inherited arrhythmias associated with sudden cardiac death. We focus on the pediatric population, the main group of people suffering from lethal inherited arrhythmias.

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.

Infant deaths in slings

Although the incidence of sudden unexpected death in infancy (SUDI) decreased markedly after campaigns to promote supine positioning during sleeping, it has remained unchanged over the last decade. Epidemiological data suggest a role for new causes such as suffocation, asphyxia, and entrapment. Health authorities in several countries have issued warnings about slings used to carry infants. However, few reports of infant deaths in slings have been published in medical journals. Our paediatric intensive care unit has admitted two infants who experienced cardiorespiratory arrest while carried in a sling. Diagnostic investigations including a post-mortem examination established asphyxia as the mechanism of death. In conclusion, baby slings may carry a risk of SUDI, either by compression of the baby into a forward-flexed position or by direct suffocation. European recommendations for the cautious use of baby slings should be disseminated to families and professionals involved in caring for infants, as done recently in Australia, Canada, and the USA.

Learning from child death review in the USA, England, Australia, and New Zealand

Despite pronounced reductions in child mortality in industrialised countries, variations exist within and between countries. Many child deaths are preventable, and much could be done to further reduce mortality. For the family, their community, and professionals caring for them, every child's death is a tragedy. Systematic review of all child deaths is grounded in respect for the rights of children and their families, and aimed towards the prevention of future child deaths. In a Series of three papers, we discuss child death in high-income countries in the context of evolving child death review processes. This paper outlines the background to and development of child death review in the USA, England, Australia, and New Zealand. We consider the purpose, process, and outputs of child death review, and discuss how these factors can contribute to a greater understanding of children's deaths and to knowledge for the prevention of future child deaths.

Patterns of child death in England and Wales

In the past century, child mortality has fallen to very low rates in all developed countries. However, rates between and within countries vary widely, and factors can be identified that could be modified to reduce the risk of future deaths. An understanding of the nature and patterns of child death and of the factors contributing to child deaths is essential to drive preventive initiatives. We discuss the epidemiology of child deaths in England and Wales. We use available data, particularly that of death registration and other available datasets, and published literature to emphasise issues relevant to reduction of child deaths in developed countries. We examine the different patterns of mortality at different ages in five broad categories of death: perinatal causes, congenital abnormalities, acquired natural causes, external causes, and unexplained deaths. For each category, we explore what is known about the main causes of death and some of the contributory factors. We then explain how this knowledge might be used to help to drive prevention initiatives.

Apparent life-threatening events: assessment, risks, reality

Apparent life-threatening events (ALTEs), because of their prevalence as well as their potential to hide serious diseases and consume significant medical resources, remain a challenge for physicians caring for infants. In this review, we focused on the assessment of the well-appearing infant for the most serious diagnoses, namely serious bacterial infections, seizure disorders, child abuse, metabolic disorders and severe apnoea with hypoxemia. Our extensive review of the literature has highlighted the difficulties physicians are facing in this evaluation, especially for the youngest infants (aged less than 2 months). Large-scale prospective studies are needed to identify risk factors and to guide physicians as to who should be investigated and the minimal investigation needed to avoid missing such conditions as serious bacterial infection, abusive head injury or repeated severe cardiorespiratory events. While infants with severe forms of metabolic disorders typically present with evident signs and symptoms, less severe forms of metabolic disorders, seizure disorders, and some forms of child abuse will often be diagnosed only when recurrent events are investigated.