Correlation of prenatal events with the development of polymicrogyria.

We report two cases of polymicrogyria in which maternal insults were well documented during the first half of the second trimester of pregnancy. The clinical histories, MR studies, and, in one patient, autopsy results were carefully reviewed, and the timing and nature of the injuries correlated with known developmental events at the time of the injury. Our results support the theory that polymicrogyria results from injury to, or disruption of normal cellular interactions at, the external limiting membrane (the "glial-pial barrier").