Lactic acid concentrations in vitreous humor: their use in asphyxial deaths in children

Lactic acid concentrations in brain tissue of humans have been shown to increase with an extended agonal period. Infants and children dying from various causes are undergoing different stress conditions terminally and the postulate of this study is that natural death cases and traumatic asphyxia cases are characterized by varying agonal periods, the former being somewhat prolonged with the latter being rather brief. One-hundred-and-two cases of infants and children were examined for vitreous humor lactic acid concentrations. They were divided into two major categories, Sudden Infant Death Syndrome (SIDS) and non-SIDS cases. SIDS was further divided into SIDS without additional findings and SIDS with secondary findings which contributed to death. The non-SIDS category included traumatic asphyxia cases as well as those dying from blunt trauma, known respiratory diseases, and other causes. Categorical mean values and standard deviations were calculated. The vitreous humor lactic acid mean value for traumatic asphyxia was significantly lower than the mean value for SIDS. Also the mean value for known respiratory diseases was statistically lower than the mean value for SIDS with secondary findings. These findings are probably suggestive of agonal time differences and may be a reflection of the various mechanisms of death.     

Melatonin concentrations in the sudden infant death syndrome

To examine a possible relationship between pineal function and the sudden infant death syndrome (SIDS), samples of whole blood, ventricular cerebrospinal fluid (CSF) and/or vitreous humor (VH) were obtained at autopsy from 68 infants (45 male, 23 female) whose deaths were attributed to either SIDS (n = 32, 0.5-5.0 months of age; mean +/- S.E.M., 2.6 +/- 0.2 months) or other causes (non-SIDS, n = 36, 0.3-8.0 months of age 4.3 +/- 0.3 months). The melatonin concentrations were measured by radioimmunoassay. A significant correlation was observed for melatonin levels in different body fluids from the same individual. After adjusting for age differences, CSF melatonin levels were significantly lower among the SIDS infants (91 +/- 29 pmol/l; n = 32) than among those dying of other causes (180 +/- 27; n = 35, P less than 0.05). A similar, but non-significant trend was also noted in blood (97 +/- 23, n = 30 vs. 144 +/- 22 pmol/l, n = 33) and vitreous humor (68 +/- 21, n = 10 vs. 81 +/- 17 pmol/l, n = 15). These differences do not appear to be explainable in terms of the interval between death and autopsy, gender, premortem infection or therapeutic measures instituted prior to death. Diminished melatonin production may be characteristic of SIDS and could represent an impairment in the maturation of physiologic circadian organization.     

The epidemiology of sudden infant death syndrome in Finland in 1969-1980

SIDS cases were defined by examining all death certificates, in which sudden deaths were expected to be found from the years 1969-80 from the Central Statistical Office of Finland. The age limits were 28-364 days. If the death certificate did not give enough information as to whether the cause of death was explained or unexplained, autopsy records and microscopic specimens were examined. If the death was sudden, but no autopsy was done, no microscopic specimens were taken, or there were some slight findings which could have partly explained the death were classified as borderline cases. The mean annual incidence of SIDS in Finland was 0.41/1000 livebirths in 1969-80. In 1969-74 and 1975-80 the incidences were 0.31 and 0.51, respectively. The increasing tendency of SIDS was partly due to more borderline cases in the first period and partly due to more twins, and infants with small birth weight, dying of SIDS in the second period. Deaths at weekends and sleeping with parents in the second period were more common than in the first study period. In the SIDs group the young maternal age, low social class, family type unmarried couple or single mother, maternal anemia during pregnancy were more common than in the control group. Mothers of SIDS infants had more previous children and fewer visits and later first visit to prenatal clinics than control mothers. The duration of gestation was shorter and the mean birth weight and length were smaller in the SIDS case than in the control group. Twins were more common among SIDS infants than in the common population. The most important risk factor of SIDS was maternal smoking during pregnancy. The epidemiological results conform with the hypoxia hypotheses.     

Sudden infant death due to neurofibromatosis type I

Sudden infant death syndrome (SIDS) is the unexpected death of an infant under the age of 1 year, where a complete autopsy, including scene investigation, fails to reveal a cause of death. Although the frequency of SIDS has decreased almost 50% over the past 10 years, it remains the leading cause of death in infants aged 1 to 6 months. SIDS is a diagnosis of exclusion and requires the elimination of a wide range of possible causes, including asphyxia, poisoning, abuse, occult heart disease, and other natural disease processes. In this report, we describe the case of an infant death initially suspected to be a SIDS death in which autopsy revealed an optic pathway glioma (optic glioma or hypothalamic glioma) and other stigmata of neurofibromatosis type I.     

Beta-endorphin in the brainstem, pituitary, and spinal fluid of infants at autopsy: relation to sudden infant death syndrome

Immunohistochemical localization of beta-endorphin was studied in the pituitaries and medullas of forty human infants at autopsy. beta-Endorphin immunoreactivity was found in anterior pituitary cells in all cases. In the medulla, beta-endorphin immunoreactivity was found in the neurons of the medial and lateral cuneate nuclei in ten out of the forty cases. In eight of these ten cases, the infants died of causes other than sudden infant death syndrome (SIDS). Only two of 25 SIDS cases had demonstrable beta-endorphin in the brainstem nuclei. Beta-endorphin levels in the spinal fluids of all the cases showed no correlation to cause of death, age or gender.     

An hepatic metabolic profile in sudden infant death (SIDS)

Levels of 18 enzymes and metabolites were measured in liver obtained at autopsy from 41 infants, 28 of whom were found unexpectedly dead at home. Four infants had meningitis, 11 had pathologic findings not clearly sufficient to explain death (SUD), and 13 were considered totally unexplained pathologically (SIDS). The possible contributions of postmortem interval, age and diet to the results are reviewed. No characteristic metabolic profile was recognized amongst SUD and SIDS groups. It is speculated that the amount of glycogen found in liver may provide insight into premortal events and reflect the rapidity of the death mechanism. Five individuals (20%) were suspected of having major metabolic abnormality including glycogenosis (1), urea cycle defect (1), and possibly abnormal levels of carnitine palmityl transferase (3).     

An analysis of the usefulness of specific stages in the pathologic investigation of sudden infant death

Retrospective analysis of autopsy findings in 60 infants who had been found unexpectedly dead in their cribs or beds in South Australia from 1994 to 1998 was undertaken to determine the diagnostic usefulness of individual stages in the postmortem investigation. Positive findings occurred in 2 of 43 scene examinations (3%), 2 of 60 external examinations (3%), 2 of 11 radiologic examinations (18%), 8 of 60 internal examinations (13%), 7 of 60 histologic examinations (12%), and 3 of 58 microbiologic examinations (5%). No positive findings were detected on toxicologic screening. Not every case underwent each diagnostic step. This gave alternative diagnoses to sudden infant death syndrome (SIDS) in 15 cases (25%). This study demonstrates an increase in the percentage of cases of unexpected infant death due to causes other than SIDS; it also shows the diagnostic yield of individual stages in the postmortem evaluation of such cases. Negative findings were important in giving validity to the diagnosis in the 45 cases that were ultimately designated as SIDS.     

The Institution of a Standardized Investigation Protocol for Sudden Infant Death in the Eastern Metropole,Cape Town,South Africa,,

The rate for the sudden infant death syndrome (SIDS) in Cape Town, South Africa, is estimated to be among the highest in the world (3.41/1000 live births). In several of these areas, including those of extreme poverty, only sporadic, nonstandardized infant autopsy, and death scene investigation (DSI) occurred. In this report, we detail a feasibility project comprising 18 autopsied infants with sudden and unexpected death whose causes of death were adjudicated according to the 1991 NICHD definitions (SIDS, n = 7; known cause of death, n = 7; and unclassified, n = 4). We instituted a standardized autopsy and infant DSI through a collaborative effort of local forensic pathology officers and clinical providers. The high standard of forensic investigation met international standards, identified preventable disease, and allowed for incorporation of research. We conclude that an effective infant autopsy and DSI protocol can be established in areas with both high sudden unexpected infant death, and elsewhere. (SUID)/SIDS risk and infrastructure challenges.     

Sudden infant death and liver phosphoenolpyruvate carboxykinase analysis

In an effort to substantiate the impaired gluconeogenesis-terminal hypoglycemia hypothesis of sudden infant death syndrome (SIDS), 52 infants ranging from 3 weeks to 7 months of age which had been brought to autopsy were studied. The stomach contents, vitreous humor glucose concentrations, hepatic glycogen content and hepatic phospho-enolpyruvate carboxykinase (PEPCK) activity were measured as part of the laboratory component of the postmortem investigation. The stomach contents, vitreous humor glucose concentrations and liver glycogen content were similar in SIDS/and non-SIDS victims. PEPCK activity was, however, significantly lower in SIDS (p < 0.001) victims and in SIDS with other findings (p < 0.01) victims when compared to non-SIDS victims. Despite the fact that SIDS victims had lower hepatic PEPCK activity and hence potentially lower gluconeogenic capacity, terminal hypoglycemia could not be demonstrated in this group as compared to the SIDS with other findings and the non-SIDS infants. The impaired gluconeogenesis-terminal hypoglycemia hypothesis thus could not be substantiated.     

Digoxin-like immunoreactive substance in postmortem blood of infants and children

A digoxin-like immunoreactive substance (DLIS) has been reported in the serum of infants not receiving digoxin. This study was undertaken to determine if DLIS is present in the postmortem blood and tissues of infants or children and whether the endogenous substance could interfere with forensic toxicological analysis in suspected overdose. Ninety blood specimens taken from the heart at autopsy of children or infants were screened for DLIS using commercial radioimmunoassay kits. The average age at death in these cases was 8.6 months, the median age was 2 months. DLIS equivalent to 0.25 to 2.0 ng/mL digoxin was found in one third of the cases. The incidence of positive findings was 5/6 stillborns, 10/45 Sudden Infant Death Syndrome (SIDS), 10/15 deaths as a result of infection, 4/7 homicides, 1/8 deaths caused by congenital defects, and 0/9 accidental deaths. The body distribution of DLIS was investigated and highest levels were found in the liver. Findings of DLIS in blood were correlated with renal failure, (elevated vitreous urea nitrogen), electrolyte imbalance, and liver trauma. Apparent concentrations were in the equivalent therapeutic range of digoxin and would not be confused with accidental or intentional overdose with digoxin.     

The fallacy of the simultaneous sudden infant death syndrome in twins

The likelihood of twin infants dying suddenly and simultaneously of SIDS, a natural disorder, defies credibility. However, injuries associated with environmental hazards provide possible mechanisms of sudden death. A search for hazards in the homes of 13 pairs of healthy twins who died together of no apparent cause formed the basis of this study. Ten of the 13 sets were certified by medical examiners as simultaneous twin SIDS. The findings in this study suggest that all 13 sets died from injuries, either unintentional or otherwise, and that these deaths could have been prevented.     

Delayed death in sudden infant death syndrome: a San Diego SIDS/SUDC Research Project 15-year population-based report

A fraction of SIDS cases have death delayed by successful CPR, yet they have not been compared to SIDS cases which were found dead or not successfully resuscitated. Our aims were to: (1) determine the percent of SIDS cases in the San Diego SIDS Research Project database for whom death was delayed by CPR and subsequent life support; (2) compare demographics, circumstances of death and autopsy findings of delayed death SIDS cases (delayed SIDS) with those whose deaths were not delayed (non-delayed SIDS); (3) examine the evolution of pathologic changes in delayed SIDS as a function of survival interval. A retrospective 15-year population-based study of 454 infant deaths attributed to SIDS revealed 29 delayed SIDS cases (Group I) and 425 non-delayed SIDS cases (Group II). Group I cases were significantly older than Group II cases (mean age 132 days vs. 102 days and p<0.0001). Eighty-nine percent of the Group I cases were discovered between 08.00 and 19.59 h; none were found between 00.00 and 07.59 h, compared to 38% of the Group II cases. Group I infants were found significantly more often away from home (at daycare, or at the home of a relative, friend, or baby sitter) than Group II infants (45% vs. 25%, p<0.05). There were no differences between groups with regard to gender, gestational age, type of delivery, bed sharing, URI within 48 h of death, ALTEs, a history of referral to child protective services, body position when placed or found, or face position when found. Pathologic changes were semiquantitatively evaluated; findings were characteristic of anoxic-ischemic injury that generally became more severe with increasing survival intervals. Anoxic-ischemic brain injury was the immediate cause of death in all delayed SIDS cases. Aspiration of gastric contents was identified in Group I cases surviving less than 48 h and was the likely etiology of acute bronchopneumonia occurring in 83% of the Group I cases. We did not identify factors that would reliably predict which SIDS cases might be discovered soon enough to allow earlier and more effective CPR and survival without permanent brain injury.     

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.     

A comparison of pulmonary intra-alveolar hemorrhage in cases of sudden infant death due to SIDS in a safe sleep environment or to suffocation

The differentiation of SIDS from accidental or inflicted suffocation may be impossible without corroborating findings from the death scene or autopsy or in the absence of a confession from a perpetrator. Pulmonary intra-alveolar hemorrhage (PH) has been proposed as a potential clue to suffocation, but none of the previous studies on this topic have limited SIDS cases to those who were in a safe sleep environment, in which all were found supine and alone on a firm surface with their heads uncovered. Our aims are to: (1) compare PH in SIDS cases found in a safe sleep environment to a control group comprised of infants whose deaths were attributed to accidental or inflicted suffocation and (2) assess the effect of age, CPR, and postmortem interval (PMI), with regard to the severity of PH in this subset of safe-sleeping SIDS cases. We conducted a retrospective study of all postneonatal cases accessioned by the Office of the Medical Examiner in San Diego County, California who died of SIDS or suffocation between 1999 and 2004. A total of 74 cases of sudden infant death caused by SIDS (34 cases as defined above, comprising 8% of the total SIDS cases), accidental suffocation (37), and inflicted suffocation (3) from the San Diego SIDS/SUDC Research Project database were compared using a semiquantitative measure of pulmonary intra-alveolar hemorrhage. The most severe (grade 3 or 4) PH occurred in 35% of deaths attributed to suffocation, but in only 9% of the SIDS cases. Age, duration of CPR attempts and PMI had no effect on the severity of PH in SIDS. Our results indicate that the severity of PH cannot be used independently to differentiate SIDS from suffocation deaths. Each case must be evaluated on its own merits after thorough review of the medical history, circumstances of death, and postmortem findings.     

The epidemiological study on registered cases of sudden infant death syndrome (SIDS) in Tokyo: examination of the effect of autopsy on diagnosis of SIDS and the mortality statistics in Japan

In the United States and most of European countries, a diagnosis of sudden infant death syndrome (SIDS) may be given only after an autopsy has been performed. Under the new definition of SIDS in Japan, an autopsy is now mandatory for the diagnosis of SIDS. However, according to the official records on autopsies, the proportion of autopsy for sudden infant death in Japan is still low (less than 30%). If a physician suspects SIDS from a review of the patient's medical history and medical findings, he can write 'suspected SIDS' as the cause of death on the death certificate without performing an autopsy. Such a clinical diagnosis is entered in the Vital Statistics section by the Japanese Ministry of Health and Welfare. In this report, a comparative epidemiological survey of registered cases of SIDS--after autopsy and with no autopsy--was carried out by examining the data from the death certificates registered by the Japanese Ministry of Health and Welfare (vital statistics in Tokyo from January 1979 to December 1996). There were 369 cases of SIDS registered in Tokyo. We found 247 diagnosed after autopsy (66.9%) and 122 with no autopsy (33.1%). The following epidemiological variables were used: address of the deceased (a specific area in Tokyo), sex, year of death, time of death, month of death, age at death, occupation of householders, and place of death. There were epidemiological differences at the 0.05 significance level between registered cases diagnosed after autopsy and those diagnosed without autopsies, as follows: year (P=0.016) and place of death (P=0.037). In addition, there were slight epidemiological differences at the 0.10 significance level between registered cases diagnosed after autopsy and with no autopsy, as follows: month of death (P=0.076) and age at death (P=0.082). This suggests that the quality of diagnosis of SIDS is not completely guaranteed. With respect to the area of residence, the incidence of SIDS is high in those areas where autopsy is performed frequently. In Tokyo, the medical examiner system is enforced only in the urban area and there is a possibility that SIDS is being underdiagnosed in the rural area of the Metropolitan Tokyo. It is likely that the diagnosis of SIDS without autopsy will influence the quality of SIDS diagnoses. The administrative inadequacy in the autopsy system in Japan should be corrected to improve the accuracy of SIDS diagnosis.     

Evaluation of diagnostic tools applied in the examination of sudden unexpected deaths in infancy and early childhood

During the period between 1984 and 1999, 309 cases of sudden unexpected death in infancy and early childhood (0-3 years) were investigated at the Institute of Forensic Medicine in Oslo. In 73 cases, an explainable cause of death was found. In this non-sudden infant death syndrome (SIDS) group, 42 cases were due to disease, 14 to accidents, 7 to neglect/abuse and 10 cases were due to homicide. In 43 cases, there were pathological findings at the autopsy or suspect features in the history and/or circumstances, which were, however, insufficient to explain death ("borderline" SIDS). In the remaining 193 cases, nothing of significance was detected ("pure" SIDS).The purpose of the present study was to evaluate the importance of the different diagnostic tools used in diagnosing non-SIDS and borderline SIDS cases. The definition of SIDS requires a negative history as well as a negative autopsy result. Thus, the following variables were analysed: circumstances, medical history and autopsy, which included a gross pathological investigation, histology, neuropathology, microbiology, radiology and toxicology. In diagnosing deaths due to disease, histology, neuropathology and microbiology were the most important diagnostic tools. In contrast, information about the circumstances of death and the gross pathological findings at autopsy most often revealed the cause of death in accidents and cases of neglect/abuse and homicide.Following the drop in SIDS rate in Norway after 1989, the share of pure SIDS in proportion to the total population of sudden unexpected deaths in infancy and early childhood has decreased. The increasing proportion of non-SIDS and borderline SIDS cases presents a challenge to improve the quality of the investigation in cases of sudden death in infancy and early childhood.     

Serum tryptase levels in sudden infant death syndrome in forensic autopsy cases

An elevated serum tryptase concentration is considered to be a specific marker for systemic mast-cell activation, a central feature of anaphylaxis, which has been observed in some cases of sudden infant death syndrome (SIDS). However, it is still unclear whether anaphylaxis is involved in the etiology for SIDS. In the present study, we measured serum tryptase levels in 21 infants with SIDS, and 14 control infants from forensic autopsy cases by Uni-CAP TRYPTASE Fluoroenzyme immunoassay system, which detects both alpha- and beta-tryptase. The assay did not show any significant elevation of tryptase levels in the SIDS group compared with controls. Additionally, increased concentrations of tryptase were not observed in any SIDS case. Our results indicated that anaphylaxis does not seem to be involved in the etiology of SIDS.     

Changing trends in the diagnosis of sudden infant death

A study of 114 consecutive cases of unexpected infant death that occurred in South Australia over a 5-year period from January 1994 to December 1998 was undertaken. There were 45 deaths attributed to sudden infant death syndrome (SIDS), 19 to natural causes, 21 to accidents. and 5 to homicides; 24 cases were listed as "undetermined." Although there has been a genuine and continued decline in SIDS numbers in this population, there has also been an increase in the diagnosis of cases of accidental asphyxia due to unsafe sleeping environments and of cases in which the family background and autopsy findings suggested more complex mechanisms. The change in diagnostic profile has followed the introduction of more rigorous clinical history review, death scene examination, and autopsy testing. Thus, although diagnostic outcomes have altered in this population, it is more likely the result of more careful interpretation of the extensive investigations that are now undertaken rather than arbitrary reclassification.     

Comparison between computed tomography (CT) and autopsy findings in cases of abdominal injury and disease

We report 10 autopsy cases involving fatal pathological changes in abdominal organs, for which findings of computed tomography (CT) on admission or after death were compared with autopsy findings. Two of the cases were death due to natural causes and eight were death due to traffic accidents. From the findings at autopsy, the causes of death were considered to be rupture of an aortic aneurysm in one case, gastrointestinal bleeding due to gastric cancer in one case, retroperitoneal bleeding in two cases, laceration of the liver in three cases, and traumatic rupture of the small intestine in three cases. CT findings revealed ascites or retroperitoneal bleeding in eight cases. However, in the cases of small-intestinal rupture, CT findings on admission revealed no free air. Therefore, ascites on CT should be regarded as a useful indicator of blunt abdominal trauma. Hepatic portal venous gas, known to be a post-mortem change, was significantly evident on post-mortem CT in cases of traumatic liver or intestinal injury, and was also seen in cases where the period between the accident and CT examination was long.