Possible role of the nucleus ambiguus in Sudden Infant Death Syndrome (SIDS)

The pathogenic mechanisms underlying SIDS seem to involve the autonomous nervous system, despite the nucleus ambiguous has been rarely if at all considered. The study was carried out in 16 SIDS cases (7 males and 9 females; ranging in age from 1 to 21 weeks) and 11 age-matched controls died of known caused. A morphometric analysis was performed with an Image-Pro Plus Image analyzer (Media Cybernetics, Silver Spring, MD), evaluating the surface area of nucleus ambiguus (mm2) and its numerical Density of neurons (number of cell/mm2). Profile of neurons of the nucleus ambiguus (nuclear and cytoplasmic area expressed in mm2 nuclear/cytoplasmic ratio (N/C), diameter mean neuronal and diameter mean nuclear expressed in mm and form factor of the neurons were also evaluated. The statistical significance of comparisons between SIDS and control cases was determined using the analysis of variance The level of significance was set at p <0.05. Examination of the nucleus ambiguus on serial sections revealed no hypoplasia, while the neuronal maturity parameters except the N/C ratio were decreased compared to the age-matched controls, as confirmed by two-dimensional morphometric reconstruction on both sides of the medulla oblongata. In conclusion, much attention should be paid to the possible role that a delayed neuronal maturity of the nucleus ambiguus might play in determining a lethal outcome in SIDS. Further studies are needed to gain a better understanding of the complex interactions involved in the pathophysiology of SIDS and the herein presented findings seem to usefully contribute literature information for the possible role of ambiguus nucleus in SIDS.