[A case of brain malformation without a change in skull configuration]

The brain of a 5-months old female baby was investigated. The baby died following operation for myelomeningocystocoele of the lumbosacral region. The post mortem finding showed that there were no other malformations present besides the changes at the level of the central nervous system. Lack of the falx was observed on the dura mater, while the tentorium cerebelli was well developed. The cerebrum was on the whole of a bulbular form with a larger transversal diameter and was not divided into 2 hemispheres. A complete lack of the rhinencephalon was observed on the basal aspect of the brain. Between the dorsal surface of the cerebral trunk and the cerebrum there was a specious transversal fissure through which a considerable part of the choroidal plexus emerged from the ventricle and was positioned extraventricularly. The posterior edge of this fissure is formed by the commissura hippocampi behind which there are well developed gyri dentati which are interconnected in the medial line. The cerebellum is normally developed but antepositioned, with a considerably pronounced vermis cerebelli. Frontal sections of the brain showed an emphasised contrast between the gray and the white brain substance which is indicative of a higher level of brain maturity. The third brain ventricle, as well as the frontal horns of the lateral ventricle were missing, and there was a developed central common cavity and the temporal horns. The basal ganglia were merged with the central gray matter spread in a transversal direction which was separated from the cortex by an arc-formed white brain substance.