BRAIN DEFECTS IN INFANTS WITH POTTER SYNDROME (OLIGOHYDRAMNIOS SEQUENCE)

Defects of neuronal migration were detected in the brains of five unre lated infants with Potter syndrome (oligohydramnios sequence). These c onsisted of abnormal lamination of cerebral cortex, white matter heter otopias, and meningeal and molecular zone neuronal-glial ectopias. Bes ides, various other brain anomalies were sometimes found. They compris ed one or more of the followings: abnormal gyration patterns (gyral fu sion, cerebellar microgyria), cerebellar granule and Purkinje cell het erotopias, brain stem heterotopias, adysplasia of basal ganglia, glios is, mineralization, and hydrocephalus. Detailed investigations, using standard neuropathologic stains, immunohistochemical and Golgi methods , and a new electron microscopic histochemical technique that we appli ed to study the developing human brain, suggest that migration defects of neurons are caused by an abnormality in their glial guides, the ra dial glial fibers, during the period of cortical histogenesis. We hypo thesize that abnormally and precociously induced radial glial transfor mation into astrocytes is the pathogenic mechanism for the defects in neuronal migration. The etiological factor(s) that precipitates such a bnormal glial transformation seems to be heterogeneous. Its relation t o the Potter anomaly is discussed.