ARCUATE NUCLEUS HYPOPLASIA IN SUDDEN-INFANT-DEATH-SYNDROME - A REVIEW

Abnormalities in central ventilatory control during sleep and/or impai red arousal have been reported in some infants who subsequently die of SIDS. Hypothetically, these abnormalities may result from dysfunction of the ventral medullary rim, considered to be an integrative site fo r cardioventilatory control on the basis of research in animals. This paper summarizes comparative neuroanatomic evidence from a previously published study showing that the human medullary arcuate nucleus is ho mologous to neurons in the cat which participate in chemosensory/auton omic integrative processes of the ventral medullary rim. Next, it summ arizes a study of serially or extensively sectioned medullae of 41 SID S and 27 controls which identified 2 SIDS victims with isolated hypopl asia of the arcuate nucleus confirmed by three-dimensional reconstruct ions and volume measurements. The volume of the right arcuate nucleus in the SIDS case was 0.7 mm(3), compared to a range of 3.4-26.3 mm(3) (median 5 mm(3)) in 3 infant controls. On the basis of pre-cerebellar and other anatomic connections of the arcuate nucleus and of neurons i n homologous positions in animals, arcuate hypoplasia may lead to deat h by dyssynergy between the cerebellum's influence on cardioventilatio n and the way this influence is integrated with chemosensation and aro usal during sleep and hypercarbia during a critical developmental peri od.