Infantile hypoventilation syndrome, neurenteric cyst, and syringobulbia.

Hypoventilation syndrome was observed in an infant with a neurenteric cyst. She died at 9 months of age following episodic bradycardia and the loss of voluntary as well as autonomic respiratory control. There was a mediastinal neurenteric cyst with anterior spina bifida and extension into the upper thoracic spinal cord. Secondary syringomyelobulbia was present at necropsy. The syringobulbia involved the hypoglossal nuclei, the dorsal motor nuclei of the vagus in the lower medulla, the right nucleus ambiguus, the right fasciculus and nucleus solitarius, the right mediolateral reticular formation, and the right dorsal motor nucleus of the vagus at the level of the obex. This morphologic distribution is attributed to the intraspinal rupture and upward extension of the mucinous contents of the cyst, and appears to be responsible for the hypoventilation syndrome.