Pontoneocerebellar hypoplasia: report of a case in a newborn and review of the literature.

A case of pontoneocerebellar hypoplasia (PNCH) in a 9-day-old child--the youngest in the literature--is described. Right after birth the child showed serious respiratory insufficiency and developed frequent episodes of apnea and cardiorespiratory arrests, dying on the 9th day. Postmortem examination showed significant alterations only in the brain. There was intense neuron reduction in the pontine, arcuate, inferior olivary and dentate nuclei, reduction of Purkinje cells and of the granular layer of the cerebellum and the disappearance of the pontocerebellar fibers, together with dense fibrillary astrocytosis, which seems to have first appeared in the pontine nuclei. This case is compared with others in the literature and attention is drawn to the more intense, and probably initial, involvement of the pontine nuclei. The time of appearance of pontoneocerebellar hypoplasia is commented upon, based on data concerning the ontogenesis of the structure and on the presence or absence of gliosis in the pontine nuclei and persistence of the fetal pattern in the inferior olivary and dentate nuclei. It is suggested that the process may start in the 2nd or 3rd month of fetal life, or even later, as probably occurred in the present case, during the second or third trimester of intrauterine life.