Interhemispheral neuroepithelial (glio-ependymal) cysts, associated with agenesis of the corpus callosum and neocortical maldevelopment. A case study.

Callosal agenesis and interhemispheral cysts containing ependyma, choroid plexus and glial cells are reported in a male infant. To the authors' knowledge this represents the 4th recorded case. Other findings were: nodular neuronal heterotopias with fully differentiated spiny neocortical neurons, widespread neocortical microgyria, cerebellar hypoplasia and bony abnormalities of the foramen magnum and atlas. This study confirms that glio-ependymal cysts are heterotopias of embryonic ventricular epithelium. The existence of more than one type of heterotopia (i.e. neuronal and ependymal) in 1 individual is significant. This indicates an error of cell generation and cell migration affecting the original structure from which both cell types are derived: the embryonic (sub)ventricular zone.