Microanatomy of vagal body paraganglia in infancy including victims of sudden infant death syndrome.

The microanatomy of vagal body paraganglia (VBP) in the cephalic segment of both vagus nerves was evaluated in an autopsy study of 32 infants one year of age or younger. The study group included 14 victims of sudden infant death syndrome (SIDS) and 18 non-SIDS cases. VBP in both groups were located at or below the lower border of the ganglion nodosum, and were histologically identical to carotid body chemoreceptors, although spatially dispersed and much smaller in size. Using a combined step and serial sectioning technique, there were no significant differences between the two groups (i.e. SIDS vs. non-SIDS) with regard to microanatomy, number, distribution and size of VBP. The proportion of chief and sustentacular cells was similar to carotid body paraganglia. For the study group as a whole, VBP were present in 89% of vagus nerves, and were typically multiple with good correlation between the number of separate paraganglia on the two sides. Small collections of ectopic parathyroid chief cells were identified in 6% of nerve segments, and histologically should be distinguished from VBP. Although the microanatomy of VBP in the SIDS group was identical to that of non-SIDS, one cannot exclude an underlying functional abnormality with autonomic malregulation.