Central nervous system malformations in a perinatal/neonatal autopsy series.

Congenital malformations of the central nervous system (CNS) are among the most common anomalies, but data on the incidence of CNS malformations in autopsy populations are scant. We examined 4122 autopsies between the years 1958 and 1995. There were 363 cases (8.8%) with CNS malformations; 235 were neonates and 128 stillborns. The overall gender ratio was 1:1, although more male neonates and more female stillborns had malformations. The body weights ranged from 24 to 6440 g. Neural tube defects were the most common types of malformations (45.5%) and included anencephaly, meningoencephalocele, meningocele/meningomyelocele, craniospinal rachischisis, and spina bifida occulta. The incidences of other malformations were: congenital hydrocephalus (12.4%), neuronal/glial proliferation disorders such as micro- and macrocephaly (8.8%), neuronal migration disorders (8.8%), prosencephalon growth disorders such as holoprosencephaly and arhinencephaly (8.5%), abnormalities of the midline structures such as agenesis of corpus callosum (4.1%), developmental cysts (3.3%), cerebellar malformations (3%), and vascular malformations (2%). Miscellaneous malformations (3%) consisted of acephalia in four cases with twin reversed arterial perfusion (TRAP), two cases of hydranencephaly, and four cases of rare degenerative and metabolic encephalopathies.