Brain water content in sudden unexpected infant death

The extensive and rapid development of the human brain during the first years of life complicates the postmortem diagnosis of brain edema in infancy. The aim of this study was to describe brain water content, the brain weight/body weight ratio, and the brain weight/head circumference ratio throughout the first years of life. Furthermore, we examined the relationship between these parameters and rs2075575 in the AQP4 gene. Our hypothesis was that dysregulated water homeostasis might be a risk factor for sudden infant death syndrome (SIDS), which may be reflected by increased water content in the brain. The study included 90 subjects with sudden unexpected death < 4 years of age: 22 cases of sudden infant death syndrome, 11 cases of sudden unexplained death in childhood, 47 cases of death due to disease, and 10 cases of accident/violent death. Brain water content, brain weight/body weight ratio, and brain weight/head circumference ratio were investigated according to corrected age, diagnosis group, attempt to resuscitate, and presence of brain edema. We found that brain water content and brain weight/body weight ratio were significantly reduced with increasing age, while brain weight/head circumference were increased. Brain weight/head circumference was correlated with brain water content. Cases with brain edema had a significantly higher brain weight/head circumference than the non-edematous cases. No differences were found between the diagnosis groups for any of the investigated parameters. In summary, the findings contribute to the current body of knowledge regarding brain growth during the first months of life.