Agenesis of the corpus callosum

Agenesis of the corpus callosum is reported to have an incidence of about 1:4000 live births. In 30-45% of cases, genetic etiologies can be identified, e.g., 10% chromosomal anomalies and 20-35% genetic syndromes. Environmental factors like fetal alcohol syndrome are also known to be prone to callosal agenesis. Callosal agenesis can be complete or partial and can be isolated or associated with other central nervous system (CNS) anomalies (e.g., cortical developmental disorders, callosal lipoma, intracranial cysts) or extra-CNS anomalies (e.g., eyes, face, cardiovascular). Diagnosis is made using ultrasound, computed tomography (CT) or best with magnetic resonance imaging (MRI). Typical imaging findings in callosal agenesis are colpocephaly, high riding enlarged third ventricle, Texas Longhorn configuration of frontal horns and so-called Probst bundles parasagittal. Diffusion tensor imaging and fiber-tracking, based on diffusion-weighted techniques, can also visualize fiber/tract anomalies in the patients' brains. Clinical correlations of callosal agenesis is difficult in general because of the common association of other CNS malformations. Differential diagnosis of primary complete or partial callosal agenesis are secondary callosal changes, e.g. vascular, inflammatory or posttreatment in origin.