Study of the human hypoglossal nucleus: normal development and morpho-functional alterations in sudden unexplained late fetal and infant death.

This study evaluated the development and the involvement in sudden perinatal and infant death of the medullary hypoglossal nucleus, a nucleus that, besides to coordinate swallowing, chewing and vocalization, takes part in inspiration. Through histological, morphometrical and immunohistochemical methods in 65 cases of perinatal and infant victims (29 stillbirths, 7 newborns and 29 infants), who died of both unknown and known cause, the authors observed developmental anomalies of the hypoglossal nucleus (HGN) in high percentage of sudden unexplained fetal and infant deaths. In particular, HGN hypoplasia, hyperplasia, positive expression of somatostatin and absence of interneurons were frequently found particularly in infant deaths, with a significant correlation with maternal smoking.

Infant and perinatal pulmonary hypoplasia frequently associated with brainstem hypodevelopment.

Recent anatomo-pathological studies have revealed a frequent associated hypoplasia of both arcuate nucleus and lungs in stillbirths. The purpose of this study is to analyze the lung and brainstem development in sudden unexplained perinatal death and sudden infant death syndrome (SIDS). A total of 51 cases were investigated. A complete autopsy was performed in each case. Anatomo-pathologic examination of the central autonomic nervous system included an in-depth study on histological serial sections of the brains where the main structures participating in control of the vital functions are located. The stage of lung development was evaluated by macroscopic and microscopic criteria. In 52.9% of cases, a pulmonary hypoplasia was detected. The pulmonary hypoplasia was significantly more frequent in the SIDS group compared to the sudden perinatal unexplained death groups (p < 0.05). In 72.5% of cases, histological examination of the brainstem on serial sections showed hypodevelopment of the brainstem nuclei, particularly hypoplasia, of the arcuate nucleus (60.8%). In 47.1% of cases, pulmonary hypoplasia was associated with brainstem hypodevelopment.

Analysis of the human locus coeruleus in perinatal and infant sudden unexplained deaths. Possible role of the cigarette smoking in the development of this nucleus.

We investigated the immunohistochemical expression of the tyrosine hydroxylase (TH) enzyme and the morphometric parameters of the human locus coeruleus (LC) in the brainstems of 32 subjects aged from 17 gestational weeks to 12 postnatal month, died of unknown (sudden unexplained perinatal and infant deaths) and known causes. The goals of this study were: (1) to obtain basic information about the structure and physiology of the LC during the first phases of human nervous system development; (2) to evaluate whether there is altered expression of TH and/or structural alterations of the LC in cases of sudden perinatal and infant death; and (3) to verify if morphological and/or physiological abnormalities of the LC could be related to maternal cigarette smoking. Morphometric analysis showed homogeneous data in cases of sudden perinatal and infant death and in age-matched controls who had died of known aetiology. However, immunohistochemistry demonstrated in a wide subset of sudden and unexplained deaths a negativity or low positivity of TH. High distribution of TH protein were instead detectable in the LC neurons of foetuses aged 17-18 gestational weeks who had died of known causes. Therefore, we postulate the functional importance of the LC in the early phases of central nervous system development. Besides, the observation of a significant correlation between sudden unexplained death, negativity of TH staining and maternal smoking, prompted us to suppose a close relation between smoking in utero and a decrease of the noradrenergic activity of the LC, leading to sudden death in the last part of pregnancy and in the first year of life.