Disorder of cerebellar foliation in walker’s lissencephaly and neu-laxova syndrome

A diffuse disorder of cerebellar foliation was found in eight infants and one fetus with Walker’s lissencephaly. Th cerebellar cortex consisted of fused and irregularly distorted folia. In the white matter, trilaminated rings of cortex wei concentrically arranged around blood vessels and mesenchymal tissue. The normal relative position of the different classc of cortical nerve cells was preserved. Cells of the external granular layer invaded the meninges and migrated along penetratin blood vessels. We believe that this foliation disorder is caused by a defect in the external basal lamina that allows adjacer folia to be fused and sulci obliterated by intrameningeal ectopias of external granule layer cells. Physical forces applied durir development probably contribute to the distortion of the gyral pattern. There was a volumetric reduction of the neocerebellun which might also be a consequence of the basal lamina defect. The cerebellum of a fetus with the Neu-Laxova syndrom showed the same abnormalities as in Walker’s lissencephaly. It is postulated that these two conditions belong to a class c prenatal developmental disorders that involves a defect of the extracellular matrix.