Bilateral encephaloclastic lesions in a 26 week gestation fetus: effect on neuroblast migration.

A 26 week gestation fetus with bilaterally symmetrical encephaloclastic lesions in the cerebral hemispheres is described. Information about gestation allows dating of the cerebral insult to the 3-4th fetal month. The history and morphology in this case suggest that insults occurring at or before the 3-4th fetal month interfere with normal neuroblast migration, producing a cerebral scar containing a band of neuroblasts arranged without order or lamination.