Vagal nerve complex in normal development and sudden infant death syndrome

Abstract

Background: Although the pathogenesis :of sudden infant death syndrome (SIDS) is not understood, one of the major hypotheses is that a subtle defect in respiratory circuitry is an important underlying factor. The vagus nerve is a critical component of respiratory control, but its neuroanatomic complexity has limited its investigation in human disease. Methods: Correlating developmental studies on different parts of the vagus nerve allows a more comprehensive assessment of its maturation process. Comparison of the normal developing vagus nerve with nerves examined in SIDS patients suggests alterations in the nucleus tractus solitarius and dorsal vagal nucleus as well as in the peripheral vagus nerve. Results and conclusions: The persistence of dendritic spines and lack of appropriate axonal growth implies delays in vagal maturation. Since nodose ganglia can be examined in vitro from autopsy material, perturbation to this system can be explored to evaluate further the mechanism involved in terminal vagal maturation. Although the reason for the delayed vagal maturation in SIDS is not apparent, the presence of astrogliosis in the region of the vagal nuclei is consistent with an exposure to hypoxic-ischemic events some time before death.