BACKGROUND: Polymicrogyria, a cortical abnormality usually classified among neuron migration disorders, recognizes different etiologies and pathogenetic mechanisms. In this study, a possible association between histologic chorioamnionitis and polymicrogyria was investigated.

SUBJECTS: Thirty fetuses were examined (M 18, F 12; gestational age, median 19 weeks: range 12-26; body weight, median 420 gr, range 50-996), with severe chorioamnionitis as the cause of spontaneous abortion. No congenital defects were present at gross examination.

METHODS: At autopsy, the brain was removed, and fixed in 4% phosphate-buffered formaldehyde. A large number of representative brain samples were paraffin-embebbed, and sections were stained with hematoxylin-eosin.

RESULTS: Morphologic precursors of polymicrogyria were found in 80% of the examined fetuses (n=24/30), whereas 20% showed no pathological findings. Histologic abnormalities of the primitive cortical architecture, either isolated or combined, included: fine undulation of the cortical ribbon (n = 16), untimely cortical folding / molecular layer fusion (n = 7), and laminar neuronal loss (n=5).

CONCLUSION: These findings first indicate that chorioamnionitis may significantly impair brain cortex morphogenesis. The reported brain abnormalities may evolve in polymicrogyria in the surviving fetuses.