INFLAMMATORY PATHOGENESIS OF CORTICAL POLYMICROGYRIA - AN AUTOPSY STUDY

Polymicrogyria, a cortical abnormality usually classified among neuron migration disorders, is characterized by different etiologies and pat hogeneses. Recently, it has been proposed that polymicrogyria could be acquired as a consequence of a lasting damage to the developing brain . In this study, we test the hypothesis that an infection in the fetal adnexa may give rise to distant brain defects and eventually polymicr ogyria. Thirty-two fetuses spontaneously aborted for extensive ascendi ng chorioamnionitis at 15-26 wk of gestation were evaluated. Control s ubjects were represented by 8 fetuses aborted at 15-24 wk of gestation . A complete autopsy was carried out between 4 and 12 h after fetal ex pulsion. We found different histologic alterations in the primitive co rtical architecture, both isolated and combined (undulation of the cor tical ribbon, untimely cortical folding/molecular layer fusion, and ne uronal loss). A total of 25 cases presented one or more of the above-d escribed morphologic alterations in the brain (78%). On the contrary, similar alterations were never observed in any of the control brains ( p = 0.019). Our findings indicate that chorioamnionitis significantly impairs brain cortex morphogenesis. Such neuron damage may be caused b y an unspecific, indirect mechanism of injury to the developing cortex involving hypoxia and free radical generation. The reported brain abn ormalities may even evolve into polymicrogyria in surviving fetuses.