The pathological approach to sudden infant death--consensus or confusion? Recommendations from the Second SIDS Global Strategy Meeting, Stavangar, Norway, August 1994, and the Third Australasian SIDS Global Strategy Meeting, Gold Coast, Australia, May 1995

Butyrylcholinesterase is a potential biomarker for Sudden Infant Death Syndrome

Background

Autonomic dysfunction has been implicated in the pathophysiology of the Sudden Infant Death Syndrome (SIDS). Butyrylcholinesterase (BChE) is an enzyme of the cholinergic system, a major branch of the autonomic system, and may provide a measure of autonomic (dys)function. This study was undertaken to evaluate BChE activity in infants and young children who had died from Sudden Infant Death or Sudden Unexpected Death.

Methods

In this case-control study we measured BChE activity and total protein in the eluate of 5μL spots punched from the dried blood spots taken at birth as part of the newborn screening program. Results for each of 67 sudden unexpected deaths classified by the coroner (aged 1 week-104 weeks) = Cases, were compared to 10 date of birth - and gender-matched surviving controls (Controls), with five cases reclassified to meet criteria for SIDS, including the criterion of age 3 weeks to 1 year.

Findings

Conditional logistic regression showed that in groups where cases were reported as “SIDS death” there was strong evidence that lower BChE specific activity (BChEsa) was associated with death (OR=0·73 per U/mg, 95% CI 0·60-0·89, P=0·0014), whereas in groups with a “Non-SIDS death” as the case there was no evidence of a linear association between BChEsa and death (OR=1·001 per U/mg, 95% CI 0·89-1·13, P=0·99).

Interpretation

BChEsa, measured in dried blood spots taken 2-3 days after birth, was lower in babies who subsequently died of SIDS compared to surviving controls and other Non-SIDS deaths. We conclude that a previously unidentified cholinergic deficit, identifiable by abnormal -BChEsa, is present at birth in SIDS babies and represents a measurable, specific vulnerability prior to their death.

Funding

All funding provided by a crowd funding campaign https://www.mycause.com.au/p/184401/damiens-legacy

Review of risk factors for sudden infant death syndrome

Sudden infant death syndrome (SIDS) accounts for the largest number of deaths during the first year of life in developed countries. The possible causes of SIDS are numerous and, to date, there is no adequate unifying pathological explanation for SIDS. Epidemiological studies have played a key role in identifying risk factors, knowledge of which has underpinned successful preventive programmes. This review critically assesses information on the main risk factors and causal hypotheses put forward for SIDS, focusing on research published since 1994. The overall picture that emerges from this review is that affected infants are not completely normal in development, but possess some inherent weakness, which may only become obvious when the infant is subjected to stress. Initially there may be some minor impairment or delay in development of respiratory, cardiovascular or neuromuscular function. None of these is likely to be sufficient, in isolation, to cause death and, provided the infant survives the first year of life, may no longer be of any significance. However, when a compromised infant is confronted with one or more stressful situations, several of which are now clearly identified as risk factors, and from which the majority of infants would normally escape, the combination may prove fatal.

Sudden unexpected non-violent death between 1 and 19 years in north Spain

AIMS

To study the epidemiological, clinical, and pathological characteristics of sudden unexpected non-violent deaths between 1 and 19 years.

METHODS

Population based observational study of all sudden unexpected non-violent deaths between 1 and 19 years, from 1990 to 1997, in a north Spain county (Bizkaia). In each case, clinical information and circumstances of death were obtained and a complete forensic autopsy was performed.

RESULTS

There were 34 sudden unexpected non-violent deaths. The mortality rate was 1.7 per 100 000 persons per year (representing 9% of the mortality rate of all non-violent deaths). In 10 cases the cause of death was cardiac, in 13 cases extracardiac, and 11 cases were unexplained. In 17 cases there were no pathological antecedents and in nine cases death occurred in patients with known disorders. Syncopes prior to death were present in five cases. Exercise related deaths occurred in seven cases (mainly associated with cardiac causes). Eight cases were "death in bed".

Laryngeal basement membrane thickening is not a reliable postmortem marker for SIDS: results from the Chicago Infant Mortality Study

It has been suggested that laryngeal basement membrane (LBM) thickening is a pathognomonic postmortem marker for sudden infant death syndrome (SIDS) and is not seen in other causes of explained sudden infant death. To test this hypothesis, we evaluated longitudinal sections of the right hemilarynx taken through the midpoint of the true vocal cord from 129 SIDS cases and 77 postneonatal sudden infant death controls. Using a five-point semi-quantitative scale, maximum LBM thickness (LBMT) for SIDS cases and controls was not statistically different (mean, 2.39 + 0.69 and 2.40 + 0.77, respectively). Likewise, scores based on the average thickness along the entire basement membrane (i.e., "average" score), were not found to be different between SIDS cases and controls. Average and maximum LBMT increased with age in both SIDS cases and controls and were not different between SIDS cases and controls within each age interval. Similar trends in the distribution of maximum and average LBMTs were found between black and Hispanic SIDS and controls; the number of white/non-Hispanic infants was too low for meaningful comparisons. Maximum and average LBMTs were not different in SIDS cases and controls exposed to environmental tobacco compared with unexposed infants. The LBMTs also increased significantly with body weight and length in both SIDS cases and controls. Finally, there were no differences in LBMT in infants intubated prior to death compared with those who were not intubated. From these data, we conclude that LBMT is not pathognomonic of SIDS, is present or absent with equal frequency in SIDS and controls, increases with postnatal age, and does not correlate with passive smoke exposure. Therefore, LBMT should not be used to diagnose SIDS.

The value of a thorough protocol in the investigation of sudden infant deaths

AIMS

To review the diagnostic value of using a thorough necropsy protocol for the investigation of sudden infant deaths, with particular emphasis on the value of routine ancillary laboratory investigations.

METHODS

The necropsy and related records of all neonatal, infant, and young childhood deaths (under three years) referred for medicolegal investigation at Dundee from 1990 to early 1998 were reviewed retrospectively. Relevant positive and negative findings were abstracted from the police reports, hospital medical records, necropsy reports, and the results of routine bacteriological, virological, toxicological, and biochemical laboratory investigations.

RESULTS

Within the study period, 63 deaths presented as apparent "cot deaths," nine as suspected homicides, nine as neonatal deaths, and 14 in some other manner. An adequate cause of death was identified on the basis of necropsy and laboratory investigations in 35% of the 63 apparent cot deaths, leaving 63% to be finally categorised as sudden infant death syndrome (SIDS). Ten (16%) of the apparent cot deaths were explained on the sole basis of unexpected positive microbiological findings, mostly pneumococcal or meningococcal meningitis and/or septicaemia. Petechial haemorrhages were identified at one or more intrathoracic site in 90% of SIDS and in 55% of explained cot deaths.

CONCLUSIONS

Early and extensive laboratory investigations performed routinely in apparent cot deaths provide an unexpectedly high positive diagnostic yield. Routine early bacteriological culture of the CSF (by cisternal puncture) and blood before necropsy should be mandatory in the investigation of all sudden infant deaths.

Issues in diagnosis following the sudden infant death syndrome intervention campaigns

The fall in numbers of sudden infant death syndrome (SIDS) deaths in recent years has resulted in questions being asked as to whether changes in the pathological assessment and diagnosis of such cases have influenced reported death rates. Specific concerns have been raised about possible changes in diagnostic criteria, differences in the evaluation of these infants and the possibility of changes in the pathological findings at autopsy. However, no major changes in either diagnostic criteria or in pathological features appear to have occurred, despite some changes in the epidemiological characteristics of cases.