Sudden infant death triggered by dive reflex

Abstract

The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of sudden infant death syndrome (SIDS). This seems to persist in human beings as an inheritance from diver birds and amphibians. It has been reported that washing the face with cold water or plunging into cold water can provoke cardiac deceleration through the intervention of the ambiguus and the vagal dorsal nuclei. This report describes a case of SIDS that offers a unique insight into the role of the dive reflex in determining a lethal outcome. Examination of the brainstem on serial sections revealed severe bilateral hypoplasia of the arcuate nucleus and gliosis of the other cardiorespiratory medullary nuclei. The coronary and cardiac conduction arteries presented early atherosclerotic lesions. The possible role of parental cigarette smoking in the pathogenesis of arcuate nucleus hypoplasia and early coronary atherosclerotic lesions is also discussed.

Figure 1

Bilateral hypoplasia of the arcuate nucleus (ARCn). VMS, ventral medullary surface; PYR, pyramid. Klüver-Barrera stain; original magnification, ×25.

Figure 2

Aspects of gliosis throughout the brainstem. Haematoxylin and eosin stain; original magnification, ×200.

Figure 3

Histological section of the circumflex branch of the left coronary artery showing two opposed early atherosclerotic lesions, consisting of soft thickening with numerous foam cells and narrowing of the coronary lumen. Trichromic Heidenhain (Azan) stain; original magnification, (A) ×25 and (B) ×200.

Figure 4

Narrowing as a result of an early atherosclerotic lesion of the sinoatrial node artery; SAN, sinoatrial node. Azan stain; original magnification, (A) ×25 and (B) ×400.

Figure 5

Narrowing as a result of an early atherosclerotic lesion of the atrioventricular node artery. AVN, atrioventricular node; CF, central fibrous body. Azan stain; original magnification, (A) ×25 and (B) ×400.