Vitreous humour and cerebrospinal fluid hypoxanthine concentration as a marker of pre-mortem hypoxia in SIDS

The fundamental need for unifying phenotypes in sudden unexpected pediatric deaths

A definitive, authoritative approach to evaluate the causes of unexpected, and ultimately unexplained, pediatric deaths remains elusive, relegating final conclusions to diagnoses of exclusion in the vast majority of cases. Research into unexplained pediatric deaths has focused primarily on sudden infant deaths (under 1 year of age) and led to the identification of several potential, albeit incompletely understood, contributory factors: nonspecific pathology findings, associations with sleep position and environment that may not be uniformly relevant, and the elucidation of a role for serotonin that is practically difficult to estimate in any individual case. Any assessment of progress in this field must also acknowledge the failure of current approaches to substantially decrease mortality rates in decades. Furthermore, potential commonalities with pediatric deaths across a broader age spectrum have not been widely considered. Recent epilepsy-related observations and genetic findings, identified post-mortem in both infants and children who died suddenly and unexpectedly, suggest a role for more intense and specific phenotyping efforts as well as an expanded role for genetic and genomic evaluation. We therefore present a new approach to reframe the phenotype in sudden unexplained deaths in the pediatric age range, collapsing many distinctions based on arbitrary factors (such as age) that have previously guided research in this area, and discuss its implications for the future of postmortem investigation.

Biochemical markers of time since death in cerebrospinal fluid: A first step towards "Forensomics"

The accurate estimation of the time of death is a challenge in forensic medicine, as the methods routinely used to assess the postmortem interval (PMI) are far from being precise. Over the past decades, biochemical methods have been implemented on postmortem samples to improve the precision of PMI estimation. Studies have focussed on the biochemical profiles of closed compartment body fluids, as they are preserved longer than blood after death and are thus subject to confined postmortem chemical changes. Cerebrospinal fluid (CSF) has been considered a suitable fluid to investigate these changes, as it is found in large amounts and is easy to sample. Moreover, the main molecules found in CSF have known reference values in living subjects, unlike most other body fluids. In this literature review, we focus on the panel of biomarkers that have been studied in CSF based on their potential of offering information on the time of death. The interest in these biomarkers for casework and the research perspectives in this field are discussed. Integrating data from different methods, including biochemistry, for better estimation of the time of death would represent a step forward in the forensic field, paving the way for an innovative approach that we suggest to call "Forensomics."

Pulmonary arterial medial smooth muscle thickness in sudden infant death syndrome: an analysis of subsets of 73 cases

Previous studies addressing pulmonary artery morphology have compared cases of sudden infant death syndrome (SIDS) to controls but none have compared demographic profiles, exposure to potentially hypoxic risk factors and other pathologic variables in SIDS cases grouped according to pulmonary artery medial smooth muscle thickness. Aims: To compare the relative medial thickness (RMT) in alveolar wall arteries (AW) in SIDS cases with that in age-matched controls and 2. Compare demographic, clinical, and pathologic characteristics among three subsets of SIDS cases based upon alveolar wall (AW) RMT. Retrospective morphometric planimetry of all muscularized arteries in standardized right apical lung sections in 73 SIDS cases divided into three groups based on increasing AW RMT as well as 19 controls age-matched to 19 of the SIDS cases. SIDS and age-matched control cases did not differ with respect to AW RMT or other demographic variables. The SIDS group with the thickest AW RMT had significantly more males and premature birth than the other groups, but the groups did not differ for known clinical risk factors that would potentially expose them to hypoxia. Pathologic variables, including pulmonary inflammation, gastric aspiration, intra-alveolar siderophages, cardiac valve circumferences, and heart and liver weights, were not different between groups. Age was not significantly correlated with RMT of alveolar wall and pre-acinar arteries but was significant at p = .018 for small intra-acinar arteries. The groups were different for RMT of small pre-acinar and intra-acinar arteries, which increased with increasing AW RMT. Statistical differences should not necessarily be equated with clinical importance, however future research incorporating more quantified historical data is recommended.

Sudden infant death—focus subject of medico-legal research

The compilation of research activities concerning SID in the field of legal medicine could only choose those out of a great abundance of high-quality examinations which represent applied research. By this they have contributed either to the clarifying of the aetiology which has not been cleared up or to the prophylaxis. For this looking through in a widest sense the basic approach was to consider SID being the result of an intrinsic and/or extrinsic disturbance of the modulation of respiratory regulation of the infant. This namely means a metabolic disturbance of respiratory neurons. One must not share this opinion even if it is given a certain plausibility by newer physiological examinations. But this also means that some examinations did not receive the acknowledgement which they would have received if there had been an immunological approach. The compilation was completely done without a presentation of the primary crisis intervention and the long-term care as being a fundamental medico-legal approach. Altogether may be summarized that legal medicine has completely fulfilled its duty to take care of the problem SID and that the examinations did not remain without success.

Hypoxanthine levels in vitreous humor: a study of influencing factors in sudden infant death syndrome

Elevated hypoxanthine (Hx) levels in the vitreous humor of victims of the sudden infant death syndrome (SIDS) have been been claimed to indicate hypoxia before death. An important methodologic problem is the temperature-dependent Hx increase after death. Although most previous studies have corrected for expected postmortem Hx increase, the aim of the present study was to omit this problem by matching the subjects of the different groups studied for similar postmortem time. Thirteen cases of violent death, 11 cases of borderline SIDS, 22 cases of death from infectious disease, and 17 cases of death from heart/lung disease were compared with a 3-fold number of SIDS cases. To investigate the impact of environmental factors on the Hx levels of the SIDS cases, the following possible confounding factors were investigated: attempt to resuscitate, slight infections before death, sleeping position, and time of the day when found dead. To investigate whether the size of the eyeball would influence the Hx level, five cases of violent death in children were compared with 15 adults who died suddenly. The vitreous humor Hx level was significantly higher in SIDS victims than in cases of violent death (p < 0.01) and deaths due to heart/lung disease (p < 0.01), whereas no such difference was found either between SIDS and borderline SIDS or SIDS and infectious death. There were no differences between any of the subgroups of SIDS victims. The vitreous humor Hx level in small children and adults did not differ. The findings raise the question of possible similarities in death mechanism in SIDS and infectious death.

Vitreous humor hypoxanthine levels in SIDS and infectious death

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-performance 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.