Brain stem nuclei in sudden infant death syndrome (SIDS): volumes, neuronal numbers and positions.

It has been suggested that the defect underlying the sudden infant death syndrome (SIDS) lies in brain stem nuclei involved in cardiac and respiratory function. However, most studies have not used rigorous quantitative techniques to assess brain stem nuclear volumes and neuronal numbers. We have measured the volume, neuronal numbers and position of brain stem nuclei in 11 SIDS and 11 aged-matched control infants. Using serial sagittal sections, nuclei involved in maintaining airway patency (hypoglossal, ambiguus and retroambiguus), heart rate (dorsal vagal) and generation of respiratory rhythm (ambiguus and dorsal vagal) were studied. No significant differences were found in nuclear volume increase with age, total neuronal number or nuclear position between SIDS and control cases. These findings support the hypothesis that the nervous system in SIDS may be normal until the final event that kills these infants.