Experimentally induced laminar necrosis, status verrucosus, focal cortical dysplasia reminiscent of microgyria, and porencephaly in the rat.

Different types of cortical malformation were produced, following focal cortical freezing, electrocoagulation, focal cortical aspiration or gentle brushing of uncovered meninges, in newborn or 1- to 3-day-old rats. Malformations included laminar necrosis of the cerebral cortex, status verrucosus, focal cortical dysplasia reminiscent of microgyria, and porencephaly. Similar procedures from postnatal day 4 onwards, at a time when a reactive astrogliosis is possible, produced cavitating infarcts and tissue scars. Cytoarchitectonic studies revealed an abnormal distribution of different types of pyramidal and non-pyramidal neurons in these malformations. These indicated three subtypes of focal cortical dysplasia, which probably depend on different pathogenic mechanisms. Autoradiographic studies with [3H] methylthymidine showed normal positioning of late-generated neuroblasts in the cerebral cortex, thus suggesting preserved migration. The present experimentally induced cortical malformations are useful models of similar cortical abnormalities in humans.