Cry features in siblings of SIDS

AIM: To examine the acoustic features of crying demonstrated by infants whose older sibling died of sudden infant death syndrome (SIDS) and compare these features to a nonrisk group of infants. METHODS: Pain-induced crying episodes were collected from a group of healthy term (HT) infants and siblings of SIDS infants. One complete crying episode was obtained from each infant and analyzed acoustically with regard to durational and spectral features. RESULTS: The cries of SIDS siblings were found to be significantly higher in pitch and reflected hyperadductory vocal fold vibratory behaviour compared to the HT group. There were no group differences with regard to durational features of crying. CONCLUSIONS: The laryngeal behaviour of infant crying, as inferred via acoustic analyses, differs between HT infants and siblings of SIDS infants. Accordingly, acoustic features of infant crying may serve as an additional diagnostic marker in the identification of children who may be at risk for SIDS.     

Mitochondrial tRNA genes and flanking regions in sudden infant death syndrome

AIM: Mitochondrial DNA (mtDNA) mutations have been proposed as a genetic risk factor for sudden infant death syndrome (SIDS). The aim of this study was to further investigate this issue, by sequencing the mitochondrial tRNA genes with flanking regions in SIDS cases and controls. METHOD: The selected genes were investigated in 24 cases of SIDS and 10 controls, the method used were direct sequencing. In addition, the A10398G mutation in the ND3 gene was investigated in 220 SIDS cases, 26 cases of infectious death and 93 controls, using allele-specific PCR. RESULTS: Mutations, recorded as differences from the revised Cambridge sequence, were found in 32 different sites in the coding regions investigated. There was no difference in mutation frequency between SIDS cases and controls, and no single mutation was found associated with SIDS. CONCLUSION: The present study does not indicate an association between a specific mitochondrial tRNA gene mutation and SIDS, nor a higher mtDNA tRNA mutation frequency in SIDS cases than in controls.     

Child care practice in the United Arab Emirates: the ESACCIPS study

AIMS: This study was undertaken to monitor infant care practice associated with SIDS and establish the incidence of SIDS in the UAE. METHODS: A total of 996 families were recruited for the study. One questionnaire was completed during the first 7 days after delivery, and was used to collect information about the socio-demographic features, mother's medical history, delivery status and infant's medical history, and another questionnaire was completed after 12 weeks through telephone interviews of the mothers. 716 completed both questionnaires. Registers at the two hospitals, and at the Preventive Medicine Department were studied and all infant deaths in a 5-year period were recorded. RESULTS: In all 18.9% of infants were placed in the prone position. Mothers preferred supine position (49.3%) to other positions when putting their babies to bed. Ninety eight percent preferred that their infant slept in the same room as the parents. On the whole, 40% occasionally shared their beds with their infants. Swaddling the babies was quite common (83.2%) and 91.9% of their mothers were also swaddled when they were babies. More than 80% of all infants used bedding duvets for their infants both in the summer and in the winter. SIDS mortality rate was 0.66 per thousand live births and contributed 7.25% to the infant mortality rate. CONCLUSION: These data provide useful baseline information on child care practice and should be of immense benefit to the understanding of the risks and causal mechanisms of SIDS and to the UAE health authorities should they wish to develop strategies to reduce the risk of SIDS.     

Analysis of the mitochondrial genome in sudden infant death syndrome

AIM: To investigate the mitochondrial genome and its association with sudden infant death syndrome (SIDS). METHODS: Twenty SIDS infants were screened for previously reported mitochondrial DNA mutations using direct sequencing. The whole mitochondrial genome was also sequenced for six of the infants. RESULTS: Three substitutions, A11467G, A12308G and G12372A, comprising a haplogroup were present in four infants diagnosed as pure SIDS. This haplogroup was also common in a control group. CONCLUSIONS: No specific mutation or polymorphism was found in association with SIDS.     

Overview of sudden infant death syndrome in Japan

In spite of rapid medical advancement in the care of infants and children, not only the general public but also many medical personnel have remained unaware of sudden infant death syndrome (SIDS) until very recently in Japan. In 1981, a research project team on SIDS financed by the Ministry of Health and Welfare was founded. Current incidence of SIDS is estimated to be about 0.5 per 1000 live births. The SIDS Family Association was organized in 1993 in Japan and began to publicize the social importance of SIDS and to support SIDS families by training befrienders. A series of articles on current achievements from SIDS research projects and from the SIDS Family Association are submitted to this issue. The present paper summarizes the status of SIDS in Japan by overviewing the activities of the research team and the SIDS Family Association.     

Redefinition of the Sudden Infant Death Syndrome: the Disadvantages

For many years the definition of SIDS has been the sudden death of an infant that was unexpected by history and in which a thorough postmortem examination failed to demonstrate an adequate cause of death. In 1991 a report was published in this journal from a panel convened by the NICHD which recommended that the diagnosis of SIDS not be made unless a death scene investigation has been conducted. The panel recommended further exclusions from the diagnosis of SIDS of certain “unresolved” cases. We believe the changes recommended by the NICHD panel are impractical and may have a serious negative impact on SIDS research and on the surviving family members of the SIDS victims.     

The continuing decline in SIDS mortality

The "Back to Sleep" campaign resulted in a dramatic decrease in sudden infant death syndrome (SIDS) worldwide. SIDS mortality has continued to decline (in New Zealand by 63% from 1993 to 2004), but the reason for this has not been explained. A postal survey found that the proportion of infants sleeping on their back has increased substantially (from 24.4% in 1992 to 72.3% in 2005), and this could account for the 39%-48% decrease in SIDS mortality.     

Bedsharing, roomsharing, and sudden infant death syndrome in Scotland: a case-control study

OBJECTIVE: To examine the hypothesis that bedsharing with an infant is associated with an increased risk of sudden infant death syndrome (SIDS). STUDY DESIGN: A 1:2, case:control study in Scotland UK, population 5.1 million, including 123 infants who died of SIDS between January 1, 1996 and May 31, 2000, and 263 controls. The main outcome measure was sharing a sleep surface during last sleep. RESULTS: Sharing a sleep surface was associated with SIDS (multivariate OR 2.89, 95% CI 1.40, 5.97). The largest risk was associated with couch sharing (OR 66.9, 95% CI 2.8, 1597). Of 46 SIDS infants who bedshared during their last sleep, 40 (87%) were found in the parents' bed. Sharing a bed when <11 weeks (OR 10.20, 95% CI 2.99, 34.8) was associated with a greater risk, P = .010, compared with sharing when older (OR 1.07, 95% CI 0.32, 3.56). The association remained if mother did not smoke (OR 8.01, 95% CI 1.20, 53.3) or the infant was breastfed (OR 13.10, 95% CI 1.29, 133). CONCLUSIONS: Bedsharing is associated with an increased risk of SIDS for infants <11 weeks of age. Sharing a couch for sleep should be strongly discouraged at any age.     

Sudden infant death syndrome: risk factors for infants found face down differ from other SIDS cases

OBJECTIVE: To test the hypothesis that infants with sudden infant death syndrome (SIDS) found face down (FD) would have SIDS risk factors different from those found in other positions (non-face-down position, NFD). STUDY DESIGN: We used the New Zealand Cot Death Study data, a 3-year, nationwide (1987 to 1990), case-control study. Odds ratios (univariate and multivariate) for FD (n = 154) and NFD SIDS (n = 239) were estimated separately, and statistical differences between the two groups were assessed. RESULTS: Of 12 risk factors for SIDS, there were 8 with a statistically significant difference between FD and NFD infants. After adjustment for the potential confounders, younger infant age, Maori ethnicity, low birth weight, prone sleep position, use of a sheepskin, and pillow use were all associated with a greater risk of SIDS in the FD than the NFD group. Sleeping during the nighttime, maternal smoking, and bed-sharing were associated with a risk of SIDS only in the NFD group. Pacifier use was associated with a decreased risk for SIDS only in the NFD group, whereas being found with the head covered was associated with a decreased risk for SIDS for the FD group. CONCLUSIONS: Infants with SIDS in the FD position appear to be a distinct subgroup of SIDS. These differences in risk factors provide clues to mechanisms of death in both SIDS subtypes.     

A mitochondrial DNA polymorphism associated with cardiac arrhythmia investigated in sudden infant death syndrome

AIM: Long QT syndrome (LQTS) has been shown to be the cause of death in some cases originally diagnosed as sudden infant death syndrome (SIDS). Such cardiac arrhythmias have also been noted in families with mitochondrial disease, and studies indicate that mitochondrial disease could be involved in SIDS. This makes the mtDNA polymorphism T3394C interesting, as a previous study has shown it to be associated with electrocardiographic (ECG) changes after exercise in a family with LQTS, where some members harboured a KCNH2 mutation. SUBJECTS: A total of 245 SIDS cases and 176 control cases. METHODS: DNA was prepared from blood/tissue samples. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were performed to search for the mtDNA polymorphism and KCNH2 mutation. Differences were confirmed by sequencing. RESULTS: The T3394C polymorphism was found in 3 pure SIDS cases (1.5%), 2 borderline SIDS cases (4.4%), 1 case of explained death (1.6%) and 2 living control cases (1.8%) (p = 0.62). The KCNH2 mutation was not found in cases or controls. CONCLUSION: The mtDNA polymorphism studied was found in a small number of SIDS cases and the frequency did not differ statistically from control subjects, making an association with increased SIDS risk unlikely.     

Use of new Nordic criteria for classification of SIDS to re-evaluate diagnoses of sudden unexpected infant death in the Nordic countries

To investigate whether changes in diagnostic practice might be the cause of the SIDS epidemic in the Nordic countries in the 1970s and 1980s a cooperative study was initiated in 1990. Common morphologic diagnostic criteria for SIDS were established in 1992 and 127 randomly selected sudden unexpected infant deaths from all Nordic countries from 1970 to 1995 and 205 cases from the Institute of Forensic Medicine, Oslo, Norway (RMI) from 1984 to 1995 were re-evaluated blindly using the new criteria. Neither the increase nor the decline in the SIDS rate since 1989 seemed to be due to changed diagnostic practices. SIDS seemed to have been under-diagnosed before the new criteria came into operation in 1992. There were fewer discrepancies between the original and revised diagnoses in the RMI cases than in the rest of the Norwegian cases, both before and after 1992.     

Diagnostic categories in infants referred for an acute event suggesting near-miss SIDS

Among 857 infants admitted between 1977 and 1984 for a life-threatening apnoeic event a definite pathologic condition was found in 576 (66%). In 32 (6.5%) of the latter the polysomnogram was abnormal. The major clinical diagnostic categorics were, with decreasing frequency: digestive (n=263), vasovagal (n=95), neurological (n=78), respiratory obstructions (n=33), and respiratory infections (n=27); miscellaneous causes were found in 80 infants. No obvious cause could be traced in the remaining 281 infants. According to those caring for them the episode was severe in 77 (27%) of these infants, 57 (74%) of which had an abnormal polysomnogram, and minor in 204 (73%), 36 (18%) of which had an abnormal sleep study. Home monitoring was performed for 145 patients: all those with an abnormal polysomnogram and the 20 infants with an unexplained severe episode associated with a normal sleep study. We conclude from our experience that when an infant is referred for an acute event suggesting nearmiss sudden infant death syndrome (SIDS), a large array of diagnoses can be found and that an electric monitoring device will ultimately be advocated for only 17% of all infants presented, but for all those with an unexplained severe episode, irrespective of the results of the sleep study.Abbreviation SIDS sudden infant death syndrome     

Why do ALTE infants not die in SIDS?

Aim: To compare known risk factors for sudden infant death syndrome (SIDS) amongst infants with apparent life threatening events (ALTE) with their matched controls, and ALTE infants who subsequently died of SIDS with infants surviving an ALTE.
Methods: Questionnaires with replies were obtained from 58 ALTE infants and 56 sex and age matched ALTE control infants. 244 SIDS cases and 868 SIDS controls were used as comparison.
Results: The incidence of ALTE was found to be 1.9% among SIDS controls, but 7.4% among infants who later on died of SIDS. The parents sought medical advice in 0.9% vs 3.7%. ALTE infants did not differ from their matched controls. In the ALTE group 13.3% of the survivors had the combination of prone sleeping and maternal smoking compared with 33.3% of those who became SIDS victims.
Conclusions: Our results show some major differences between the ALTE infants and SIDS victims not supporting that these conditions belong to the same entity. However, we cannot exclude the possibility that there is a subpopulation of ALTE infants who did not die in SIDS due to that they were sleeping on the back and not exposed to nicotine.     

Risk factors for SIDS in Japan: A record-linkage study based on vital statistics

This study examines the effect of items as reported on birth certificates on sudden infant death. We linked infant death certificates with birth certificates for the infants born in 1989 to residents of the Tohoku, Tokai and Kyushu regions in Japan (n = 409 679), that is, about one-third of the infants born in Japan that year. The mortality rate from sudden infant death, including 88 deaths from sudden infant death syndrome (SIDS) and 17 deaths from instantaneous death, was 25.6 per 100 000 live births. Elevated risk of sudden infant death was associated with low birthweight, late birth order, illegitimacy, male gender and young maternal age. These results correspond to previous studies from Western countries, suggesting a similar pattern for SIDS in Japan.     

C-Reactive Protein and Prealbumin in Suspected Sudden Infant Death Syndrome

This study investigated the levels of C-reactive protein (CRP) and prealbumin in 87 infants suspected of dying from sudden infant death syndrome (SIDS). These proteins change rapidly, within 24 hr, in patients who have an acute phase response, especially a response resulting from bacterial infection. In addition, prealbumin is sensitive to a recent reduction of protein or calorie intake. Eighty patients were determined to have typical SIDS. Only four of these had a minimal increase in CRP (0.8-2 mg/dl), and in none could an explanation be found. Seven patients were uncovered who had a significant infection, four of whom had prominent CRP elevations. Prealbumin was not decreased in the SIDS population. We conclude that there is no evidence that the acute inflammatory response is activated in infants dying of SIDS. An elevation of CRP above 2 mg/dl should prompt additional studies to find the cause. There is also no evidence of a recent, significant decrease in nutrition in these patients.     

Serum testosterone and estradiol in sudden infant death

OBJECTIVE: To test the hypothesis that among infants who die unexpectedly, testosterone and/or estradiol levels are elevated in those diagnosed with SIDS versus those with known causes of death (controls). STUDY DESIGN: Postmortem blood was collected and coded from infant autopsies, and serum was prepared and frozen until assayed for total testosterone and estradiol by fluoroimmunoassay. Subject information was then collected from the medical examiner's report. RESULTS: Testosterone, but not estradiol, was significantly higher in 127 SIDS cases versus 42 controls for both males (4.8 +/- 0.4 vs 2.2 +/- 0.4 nmol, respectively; P < .005) and females (2.4 +/- 0.2 vs 1.6 +/- 0.2 nmol, respectively; P < 0.03). CONCLUSIONS: Higher testosterone levels in infant victims of unexpected, unexplained death may indicate a role for testosterone or related steroids in SIDS. Further research is needed to understand the potential utility of testosterone as an indicator of SIDS risk.     

The Epidemiology of Sudden Infant Death Syndrome and Attacks of Lifelessness in Sweden

ABSTRACT. Infants who died showing the syndrome of sudden infant death (SIDS) and infants who survived attacks of lifelessness (AL) were examined in a prospective epidemiological multicentre study over 24 months covering close to 40% of all births in Sweden. Seventy SIDS cases and 34 cases of AL were observed, giving an incidence for SIDS of 0.94/1000 and for AL of 0.46/1000. This SIDS incidence is higher than that observed during the seventies. The boy/girl ratio was 1.4: 1 for SIDS and 1.6: 1 for AL. The age distribution for AL resembled that for SIDS. Similarities were also seen with regard to place of occurrence. Sixty per cent of the SIDS cases occurred during the daytime/evening. Twenty-nine per cent of the infants with AL had more than one apneic spell during the three-day-period around the attack, indicating a period of respiratory instability, but only 12% had such spells later on. None of the infants who had had AL died from SIDS. The possible relationship between AL and SIDS is discussed.     

Vitreous humor hypoxanthine levels in SIDS and infectious death

Vege Å, Chen Y, Opdal SH, Saugstad OD, Rognum TO. Vitreous humor hypoxanthine levels in SIDS and infectious death. Acta Pæediatr 1994;83:634–9. Stockholm. ISSN 0803–5253
Hypoxanthine concentrations in vitreous humor were determined in 107 cases of sudden infant death syndrome (SIDS) and compared with levels in 4 cases of borderline SIDS, 26 cases of infectious death and 16 cases of sudden violent death. The hypoxanthine measurements were made using a high-pcrformance liquid chromatography method. The hypoxanthine levels were significantly (p<0.01) higher in SIDS than in violent deaths, while no significant difference was found between SIDS and infectious deaths. The present report demonstrates a similar distribution pattern of hypoxanthine levels in vitreous humor in SIDS and infectious death. We have previously described signs of immune stimulation both in peripheral organs and in the central nervous system in these conditions. This indicates that the death mechanism in SIDS has some similarities with infectious death.     

Wrapping a cot mattress in plastic does not explain the continuing fall in SIDS mortality

In 2005 in Auckland, New Zealand, the prevalence of wrapping cot mattresses in polythene, which has been recommended for sudden infant death syndrome (SIDS) prevention by proponents of the toxic gas theory, was 21.7%. This cannot account for the 63% decline in SIDS from 1994 to 2004.     

Research and sudden infant death syndrome: definitions, diagnostic difficulties and discrepancies

The diagnosis of causes of sudden infant death is an often complex and difficult process. Variable standards of autopsy practice and the use of different definitions for entities such as sudden infant death syndrome (SIDS) have also contributed to confusion and discrepancies. For example, the term SIDS has been used when the requirements of standard definitions have not been fulfilled. In an attempt to correct this situation recent initiatives have been undertaken to stratify cases of unexpected infant death and to institute protocols that provide frameworks for investigations. However, if research is to be meaningful, researchers must be scrupulous in assessing how extensively cases have been investigated and how closely cases fit with internationally recognized definitions and standards. Unless this approach is adopted, evaluation of research findings in SIDS will be difficult and the literature will continue to be beset by contradictions and unsubstantiated conclusions.