The major part of fetal cerebrum supplied by internal carotis arteries are destroyed. Hemispheres are reduced to a thin membranous sac filled with abundant cerebrospinal fluid (bubble brain). There is variable preservation of inferior frontal, temporal, occipital lobes (depends on the collateral vascular supply) basal ganglia and diencephalon. The brain stem and cerebellum in the posterior fossa are always intact. Falx cerebri is absent or hypoplastic.