An infant with macrocephaly, abnormal neuronal migration and persistent olfactory ventricles.

An asphyxiated male infant was delivered by cesarean section at 38 weeks gestation. The patient was macrocephalic with clinical evidence of fetal immobility syndrome. He died aged two days. Autopsy revealed excessive brain weight, pachygyria, enlarged olfactory tracts and hypoplastic optic nerves. Microscopy revealed evidence of impaired neuronal migration throughout the cortex. The olfactory bulbs showed persistence of the primitive olfactory ventricles and absence of olfactory glomeruli. There was persistence of the fetal connection between lateral and olfactory ventricles. The lateral geniculate nuclei, inferior olivary nuclei and dentate nuclei of the cerebellum were abnormally formed. Relevant aspects of fetal brain development and clinical neuropathologic syndromes are discussed.