Involvement of the Superior Colliculus in SIDS Pathogenesis.

The aim of this study was to investigate the involvement of the mesencephalic superior colliculus (SC) in the pathogenetic mechanism of SIDS, a syndrome frequently ascribed to arousal failure from sleep. We analyzed the brains of 44 infants who died suddenly within the first 7 months of life, among which were 26 infants with SIDS and 18 controls. In-depth neuropathological investigations of serial sections of the midbrain showed the SC layered cytoarchitectural organization already well known in animals, as made up of seven distinct layers, but so far never highlighted in humans, albeit with some differences. In 69% of SIDS cases but never in the controls, we observed alterations of the laminar arrangement of the SC deep layers (precisely, an increased number of polygonal cells invading the superficial layers and an increased presence of intensely stained myelinated fibers). Since it has been demonstrated in experimental studies that the deep layers of the SC exert motor control including that of the head, their developmental disorder could lead to the failure of newborns who are in a prone position to resume regular breathing by moving their heads in the sleep-arousal phase. The SC anomalies highlighted here represent a new step in understanding the pathogenetic process that leads to SIDS.

Environmental Exposure Science and Human Health.

Human health and environmental exposure form an inseparable binomial [...].

Harmful Effect of Intrauterine Smoke Exposure on Neuronal Control of "Fetal Breathing System" in Stillbirths.

This article is aimed to contribute to the current knowledge on the role of toxic substances such as nicotine on sudden intrauterine unexplained deaths' (SIUDS') pathogenetic mechanisms. The in-depth histopathological examination of the autonomic nervous system in wide groups of victims of SIUDS (47 cases) and controls (20 cases), with both smoking and no-smoking mothers, highlighted the frequent presence of the hypodevelopment of brainstem structures checking the vital functions. In particular, the hypoplasia of the pontine parafacial nucleus together with hypoplastic lungs for gestational age were observed in SIUDS cases with mothers who smoked cigarettes, including electronic ones. The results allow us to assume that the products of cigarette smoke during pregnancy can easily cross the placental barrier, thus entering the fetal circulation and damaging the most sensitive organs, such as lungs and brain. In a non-negligible percentage of SIUDS, the mothers did not smoke. Furthermore, based on previous and ongoing studies conducted through analytical procedures and the use of scanning electron microscopy, the authors envisage the involvement of toxic nanoparticles (such as agricultural pesticides and nanomaterials increasingly used in biomedicine, bioscience and biotechnology) in the death pathogenesis, with similar mechanisms to those of nicotine.

Novel chemical-physical autopsy investigation in sudden infant death and sudden intrauterine unexplained death syndromes.

Aim: Verify the presence of inorganic nanoparticle entities in brain tissue samples from sudden infant death syndrome (SIDS)/sudden intrauterine unexplained death syndrome (SIUDS) cases. The presence of inorganic debris could be a cofactor that compromises proper brain tissue functionality. Materials & methods: A novel autopsy approach that consists of neuropathological analysis procedures combined with energy dispersive spectroscopy/field emission gun environmental scanning electron microscopy investigations was implemented on 10 SIDS/SIUDS cases, whereas control samples were obtained from 10 cases of fetal/infant death from known cause. Results: Developmental abnormalities of the brain were associated with the presence of foreign bodies. Although nanoparticles were present as well in control samples, they were not associated with histological brain anomalies, as was the case in SIDS/SIUDS. Conclusion: Inorganic particles present in brain tissues demonstrate their ability to cross the hemato-encephalic barrier and to interact with tissues and cells in an unknown yet pathological fashion. This gives a rationale to consider them as cofactors of lethality.

The Mesencephalic Periaqueductal Gray, a Further Structure Involved in Breathing Failure Underlying Sudden Infant Death Syndrome.

The aim of this study was to investigate the involvement of the periaqueductal gray (PAG), an area of gray matter surrounding the cerebral aqueduct of Sylvius, in the pathogenetic mechanism of SIDS, a syndrome frequently ascribed to arousal failure from sleep. We reconsidered the same samples of brainstem, more precisely midbrain specimens, taken from a large series of sudden infant deaths, namely 46 cases aged from 1 to about 7 months, among which 26 SIDS and 20 controls, in which we already highlighted significant developmental alterations of the substantia nigra, another mesencephalic structure with a critical role in breath and awakening regulation. Specific histological and immunohistochemical methods were applied to examine the PAG cytoarchitecture and the expression of the tyrosine hydroxylase, a marker of catecholaminergic neurons. Hypoplasia of the PAG subnucleus medialis was observed in 65% of SIDS but never in controls; tyrosine hydroxylase expression was significantly higher in controls than in SIDS. A significant correlation was found between these findings and those related to the substantia nigra, demonstrating a link between these neuronal centers and the brainstem respiratory network and a common involvement in the sleep-arousal phase failure leading to SIDS.

Substantia Nigra Abnormalities Provide New Insight on the Neural Mechanisms Underlying the Sleep-Arousal Phase Dysfunctions in Sudden Infant Death Syndrome.

The purpose of this study was to research possible developmental alterations of the substantia nigra (SN) in sudden infant death syndrome (SIDS), a syndrome frequently attributed to arousal failure from sleep. Brain stems of 46 victims of sudden infant death, aged from 1 to about 7 months (4 to 30 postnatal weeks), were investigated. Twenty-six of these cases were diagnosed as SIDS, due to the lack of any pathological finding, while the remaining 20 cases in which the cause of death was determined at autopsy served as controls. Maternal smoking was reported in 77% of SIDS and 10% of controls. Histopathological examination of the SN was done on 5-µm-thick sections of caudal midbrain stained with both hematoxylin-eosin and Klüver-Barrera. Densitometry, immunohistochemistry and histochemistry were applied to highlight the neuronal concentration, the tyrosine hydroxylase (TH) expression, and the presence of neuromelanin (NM) in this structure. Hypoplasia of the pars compacta portion of the SN was observed in 69% of SIDS but never in controls; TH expression was significantly higher in controls than in SIDS; and NM was observed only in 4 infants of the control group but not in SIDS. A significant correlation was found between SIDS, hypoplasia/low neuronal density, low TH expression in the pars compacta, and maternal smoking. Because the SN pars compacta, being the major dopamine brain center, controls many functions, including the sleep-arousal phase, its alterations, especially concurrently with smoking exposure, may contribute to explain the pathogenesis of SIDS that occur in the great part of cases at awakening from sleep.

Massive Amniotic Fluid Aspiration in a Case of Sudden Neonatal Death With Severe Hypoplasia of the Retrotrapezoid/Parafacial Respiratory Group.

We report a case of a baby, who, after pregnancy complicated by maternal Addison's disease and Hashimoto's thyroiditis and natural delivery, unexpectedly presented a cardiorespiratory collapse and died 1 hour after birth without responding to prolonged neonatal resuscitation maneuvers. The cause of death was reliably established by carrying out a forensic postmortem examination. More specifically, the histological examination of the lungs showed the presence of abundant endoalveolar and endobronchial cornea scales caused by absorption of amniotic fluid. The neuropathological examination of the brainstem highlighted severe hypodevelopment of the retrotrapezoid/parafacial respiratory group, which is a complex of neurons located in the caudal pons that is involved in respiratory rhythm coordination, especially expiration, in conditions of enhanced respiratory drive, as well as in chemoreception. This neuropathological finding shed new light on the mechanisms underlying the massive amniotic fluid aspiration which led to this early death.

Neuropathology of Early Sudden Infant Death Syndrome-Hypoplasia of the Pontine Kolliker-Fuse Nucleus: A Possible Marker of Unexpected Collapse during Skin-to-Skin Care.

OBJECTIVE: To find a possible pathogenetic mechanism of the early sudden infant death occurring in newborns during the skin-to-skin care (SSC), through the examination of neuronal centers regulating the vital activities. STUDY DESIGN: This is an in-depth examination of the brain stem in 22 healthy term newborns, suddenly died in the first hour of life without the identification of a cause at autopsy (early sudden infant death syndrome [eSIDS]), 12 of them concomitantly with SSC, and 10 with age-matched controls died of known pathology. RESULTS: Developmental alterations of neuronal structures of the brain stem were highlighted in 19 of the 22 eSIDS, but not in control. The hypoplasia of the pontine Kölliker-Fuse nucleus (KFN), an important respiratory center, was diagnosed at the histological examination, validated by morphometric quantifications, in 11 of the 12 eSIDS while they were placed on the mother's chest and in 2 of the 10 SSC unrelated neonatal deaths. CONCLUSION: The delayed development of the KFN could represent a specific finding of eSIDS occurring during SSC. Therefore, it is necessary to point out that the SSC represents a further risk factor that must be added to others already known for sudden infant death syndrome. Then this practice needs appropriate monitoring strategies of the infant's conditions.

Sudden intrauterine unexplained death: time to adopt uniform postmortem investigative guidelines?

BACKGROUND: Worldwide approximately 2.6 million are stillborn, mostly occurring in developing countries. In the great part these deaths are inexplicable. The evenness and standardisation of the diagnostic criteria are prerequisites to understand their pathogenesis. The core goal of this article is to propose new evidence based investigative post-mortem guidelines that should be adopted in all the Institutions especially when a fetal death, after a routine autopsy procedure, is diagnosed as "unexplained". The proposed protocol is mainly focused on the anatomopathological examination of the autonomic nervous system and in particular of the brainstem where the main centers that control vital functions are located. METHODS: Updated investigative guidelines for the examination of unexplained stillbirths, prevalently focused on the histological examination of the brainstem, where the main centers that are involved in monitoring the vital functions are located, are here presented. A section of this protocol concerns the Immunohistochemical evaluation of specific functional markers such as the neuronal nuclear antigen, nicotinic acetylcholine receptors, serotonin, orexin, apoptosis and gliosis. The important role of risk factors, having regard in particular to maternal smoking and air pollution is also contemplated in these guidelines. RESULTS: Specific morphological and/or functional alterations of vital brainstem structures have been found with high incidence in over 100 cases of unexplained fetal death sent to the "Lino Rossi Research Center" of the Milan University according to the Italian law. These alterations were rarely detected in a group of control cases. CONCLUSIONS: We hope this protocol can be adopted in all the Institutions notably for the examination of unexplained fetal deaths, in order to make uniform investigations. This will lead to identify a plausible explanation of the pathogenetic mechanism behind the unexplained fetal deaths and to design preventive strategies to decrease the incidence of these very distressing events for both parents and clinicians. TRIAL REGISTRATION: not applicable for this study.

Pathobiological expression of the brain-derived neurotrophic factor (BDNF) in cerebellar cortex of sudden fetal and infant death victims.

Brain-derived neurotrophic factor (BDNF), a neurotrophin of the central nervous system, is able to regulate neuronal differentiation and modulate synaptic plasticity, being particularly involved in the development of the cerebellar cortical structure. The main aim of this study was to delineate, by immunohistochemistry, the BDNF expression in human cerebellar cortex of victims of fetal and infant death. The study was performed on a total of 45 cases, aged between 25 gestational weeks and 6 postnatal months, including 29 victims of sudden fetal and infant death and 16 age-matched subjects who died of known causes (Controls). We observed, in sudden death groups compared with Controls, a significantly higher incidence of defective BDNF expression in granule layers of the cerebellar cortex, which was particularly evident in the posterior lobule, a region that participates in respiratory control. These results were related to maternal smoking, allowing to speculate that nicotine, in addition to the well-known damages, can exert adverse effects during cerebellar cortex development, in particular in hindering the BDNF expression in the posterior lobule. This implies modifications of synaptic transmission in the respiratory circuits, with obvious deleterious consequences on survival.

Sudden unexpected postnatal collapse at 20 hours from birth during skin-to-skin care related to brainstem developmental alterations - a case report.

This report describes a case of sudden collapse of a 20-hour-old newborn, while he was placed close to their mother according to skin-to-skin care, attributed to developmental alterations of brainstem nuclei involved in regulation of the vital functions. The infant, after a normal pregnancy, appeared well developed at birth, with no evidence of malformations or trauma, but showing severe asphyxia. The routine autopsy did not reveal a possible cause of death. Only the in-depth anatomopathological examination of the autonomic nervous system, according to the protocol developed by the "Lino Rossi" Research Center of Milan University, provided an explanation of the pathogenetic mechanism of this early death. The sudden death, a few hours after birth, was the unavoidable outcome of a complex of abnormalities of brainstem nuclei, particularly of the Kölliker-Fuse nucleus, an essential structure for eupneic breathing at birth, exacerbated by the prone position implied by the skin-to-skin contact.

Neuropathological protocol for the study of unexplained stillbirth.

An updated neuropathological protocol for the examination of the nervous system in case of unexplained stillbirth has been elaborated and presented in this review. It is focused on the examination of the nervous centers located in the brainstem, which are involved in monitoring the vital functions. Only through a deep analysis of the brainstem it is possible to highlight developmental alterations of these essential centers, and then provide a plausible explanation of the pathogenetic mechanism behind the death. The guidelines, drawn up on the basis of numerous researches performed by the authors, include a histopathological protocol, with an indication of standardized samples, and an immunohistochemical protocol for the study of biological markers, frequently involved in these deaths. The main risk factors that can be related to the neuronal alterations are also reported, together with the indications for the toxicological examination, which should be possibly applied. The authors hope that this protocol will be soon adopted in all the institutions where a fetal death, after a routine autopsy procedure, is diagnosed as "unexplained", in order to make standardized investigations on stillbirth. Nowadays, preventive strategies to decrease the incidence of these very distressing events for both parents and clinicians are necessary. .

Nicotinic Receptor Abnormalities in the Cerebellar Cortex of Sudden Unexplained Fetal and Infant Death Victims-Possible Correlation With Maternal Smoking.

Nicotinic acetylcholine receptors (nAChRs) are cationic channels of the neuronal cell membrane, differentially expressed in the central nervous system which, when activated by endogenous acetylcholine or exogenous nicotine, are able to enhance cholinergic transmission. The aim of this study was to investigate in human perinatal age the immunohistochemical expression of the α7-nAChR subtype, given its involvement in neuronal differentiation and its significant vulnerability to the toxic effects of nicotine. Thirty fetuses (with a gestational age between 25 and 40 weeks) and 35 infants (1-6 months old), suddenly died of known (controls) and unknown causes (unexplained deaths), with smoking and nonsmoking mothers, were included in this study. A negative or low immunoexpression of α7-nAChRs, indicative of their inactivation, was observed in the granular layers of the cerebellar cortex in 66% of the sudden unexplained perinatal deaths and 11% of the controls. A high correlation was also observed between these findings and maternal smoking. Apart from the well-known adverse effects of nicotine exposure during pregnancy, it may also cause significant alterations in cerebellar cholinergic transmission in areas of the brain involved in vital functions. These events may give us insights into the pathogenetic mechanisms leading to sudden unexplained fetal and infant death.

Developmental neuropathology of brainstem respiratory centers in unexplained stillbirth: What's the meaning?

Stillbirth is one of the most stressful life events affecting over 3 million pregnancies per year throughout the world. An accurate autopsy of the stillborn fetus, including the placenta and umbilical cord examination, should be performed promptly after delivery. A thorough maternal history also should be taken, including exposures to risk factors. In many cases a death cause, attributable to fetal, maternal, or placental pathology, is clearly identified. However, in 50% or more of cases the cause remains unknown. The purpose of this study is to highlight possible developmental alterations of the autonomic nervous system in unexplained stillbirths to provide an explanation of the pathogenetic mechanism of their death. We conducted a careful neuropathological study of the brainstem, where the main vital centers are located, in 85 unexplained stillbirths and 52 age-matched controls died of known cause. Information on the maternal lifestyle, including the smoking habit, was collected in all cases. Hypodevelopment of neuronal centers involved in breathing control, all connected together in a "respiratory network", precisely hypoplasia of the facial/parafacial complex, Kölliker-Fuse nucleus, pre-Bötzinger nucleus and intermediolateral nucleus, were frequently observed in unexplained deaths, significantly related to maternal cigarette smoking. We support the hypothesis of a strong action of maternal smoking during pregnancy on the development of brainstem respiratory nuclei and suggest an explanation of the high incidence of the respiratory network alterations in unexplained fetal death, when breathing not represents a vital function.

Decreased argyrophilic nucleolar organiser region (AgNOR) expression in Purkinje cells: first signal of neuronal damage in sudden fetal and infant death.

AIMS: The nucleolus is an important cellular component involved in the biogenesis of the ribosome. This study was performed in order to validate the introduction of the argyrophilic nucleolar organiser region (AgNOR) stain technique, specific for the nucleoli detection, in neuropathological studies on sudden fetal and infant death. METHODS: In a wide set of fetuses and infants, aged from 27 gestational weeks to eight postnatal months and dead from both known and unknown causes, an in-depth neuropathological study usually applied at the Lino Rossi Research Center of the Milan University was implemented by the AgNOR method. RESULTS: Peculiar abnormalities of the nucleoli, as partial or total disruption above all in Purkinje cells (PCs), were exclusively found in victims of sudden fetal and infant death, and not in controls. The observed nucleolar alterations were frequently related to nicotine absorption in pregnancy. CONCLUSIONS: We conclude that these findings represent early hallmarks of PC degeneration, contributing to the pathophysiology of sudden perinatal death.

Sudden Infant Death With Area Postrema Lesion Likely Due to Wrong Use of Insecticide.

We report a noteworthy case of a 7-month-old infant who suddenly and unexpectedly died during her sleep. After a complete postmortem examination, review of the clinical history, and detailed death scene investigation, the death remained unexplained, leading to a diagnosis of sudden infant death syndrome. However, an extensive review of the brainstem neuropathology revealed a severe alteration in the area postrema (a highly vascular structure lying at the base of the fourth ventricle outside of the blood-brain barrier). The alteration was likely due to massive and repeated to a common household insecticide in the last few weeks of life. These results provide an explanation for this sudden infant death, allowing a differential diagnosis from sudden infant death syndrome.

Developmental alterations of the auditory brainstem centers--pathogenetic implications in Sudden Infant Death Syndrome.

Sudden Infant Death Syndrome (SIDS), despite the success of campaigns to reduce its risks, is the leading cause of infant death in the Western world. Even though the pathogenesis remains unexplained, brainstem abnormalities of the neuronal network that mediates breathing and protective responses to asphyxia, particularly in the arousal phase from sleep, are believed to play a fundamental role. This is the first study to identify, in SIDS, developmental defects of specific brainstem centers involved in hearing pathways, particularly in the cochlear and vestibular nuclei, in the superior olivary complex and in the inferior colliculus, suggesting a possible influence of the acoustic system on respiratory activity. In 49 SIDS cases and 20 controls an in-depth anatomopathological examination of the autonomic nervous system was performed, with the main aim of detecting developmental alterations of brainstem structures controlling both the respiratory and auditory activities. Overall, a significantly higher incidence of cytoarchitectural alterations of both the auditory and respiratory network components were observed in SIDS victims compared with matched controls. Even if there is not sufficient evidence to presume that developmental defects of brainstem auditory structures can affect breathing, our findings, showing that developmental deficit in the control respiratory areas are frequently accompanied by alterations of auditory structures, highlight an additional important element for the understanding the pathogenetic mechanism of SIDS.

Cytoarchitectural and functional abnormalities of the inferior colliculus in sudden unexplained perinatal death.

The inferior colliculus is a mesencephalic structure endowed with serotonergic fibers that plays an important role in the processing of acoustic information. The implication of the neuromodulator serotonin also in the aetiology of sudden unexplained fetal and infant death syndromes and the demonstration in these pathologies of developmental alterations of the superior olivary complex (SOC), a group of pontine nuclei likewise involved in hearing, prompted us to investigate whether the inferior colliculus may somehow contribute to the pathogenetic mechanism of unexplained perinatal death. Therefore, we performed in a wide set of fetuses and infants, aged from 33 gestational weeks to 7 postnatal months and died of both known and unknown cause, an in-depth anatomopathological analysis of the brainstem, particularly of the midbrain. Peculiar neuroanatomical and functional abnormalities of the inferior colliculus, such as hypoplasia/structural disarrangement and immunonegativity or poor positivity of serotonin, were exclusively found in sudden death victims, and not in controls. In addition, these alterations were frequently related to dysgenesis of connected structures, precisely the raphé nuclei and the superior olivary complex, and to nicotine absorption in pregnancy. We propose, on the basis of these results, the involvement of the inferior colliculus in more important functions than those related to hearing, as breathing and, more extensively, all the vital activities, and then in pathological conditions underlying a sudden death in vulnerable periods of the autonomic nervous system development, particularly associated to harmful risk factors as cigarette smoking.