Hypoplasia of the cerebellar vermis with communication of the fourth ventricle with the magna cistern. The fourth ventricle is dilated.
Ascent of the third ventricle with dilation and parallelization of the lateral ventricles. Note communication between the third ventricle and the interhemispheric fissure.
Dilation of the occipital horns of the lateral ventricles (colpocephaly) is also visualized.
This is a case of agenesis of the corpus callosum.