This is an MRI of a child with absent corpus callosum
The parts of a normal corpus callosum are the rostrum ( beak), genu ( bend), body, isthmus, splenium (padding/bandage)
In partial agenesis of the corpus callosum the posterior portion including splenium may be missing. In holoprosencephaly the agenesis may be atypical with rostrum and splenium missing.
In 75% no etiology is traceable.
Antenatal diagnosis by USG is possible by 20 weeks.
MRi saggital view is most useful.
CT head may show parallel ventricles, colpocephaly, a high up third ventricle between the lateral ventricles.
Clinical spectrum includes
1. Severe neuro deficits especially when other brain malformations associated
2. Neurodevelopmental defects such as autism
3. Near normal IQ with some subtle defects of higher order cognition and social skills
