What is a characteristic ultrasound finding of Agenesis of the Corpus Callosum?

Agenesis of the corpus callosum is a condition characterized by the partial or complete absence of the corpus callosum, the structure that connects the two cerebral hemispheres. One of the notable ultrasound findings associated with this condition is the presence of colpocephaly. Colpocephaly refers to the enlargement of the posterior horns of the lateral ventricles, which occurs because the corpus callosum, which normally helps to regulate ventricular size and shape, is absent. This abnormality leads to an atypical shape of the ventricles where the posterior portions are more significantly enlarged compared to the anterior portions, giving rise to the term "colpocephaly."

The other options, while they may present in different neurological conditions, are not characteristic findings of agenesis of the corpus callosum. In particular, the absence of the cerebellar vermis is more closely associated with conditions like Dandy-Walker malformation. Enlargement of lateral ventricles can occur in various types of congenital malformations and is not specific to corpus callosum agenesis. The missing fourth ventricle would not be consistent with corpus callosum agenesis as it typically retains its normal position and appearance.

Thus, the presence of colpo