Agenesis of the Corpus Callosum

Findings:
Sagittal, axial, and coronal T1WI show parallel lateral ventricles and absence of the corpus callosum

Discussion:
ACC is an anomaly of ventral induction that occurs at 5-12 weeks gestation. Other anomalies in the same category include holoprosencephaly, septo-optic dysplasia, diencephalic cysts, cerebral hemihypoplasia/aplasia, and lobar hypoplasia. The inciting event in ACC is felt to be a defective lamina terminalis which could result from a number of intrauterine insults or chromosomal anomaly. Common associations include Aicardi syndrome, anterior encephalocele, craniofacial clefts, Dandy Walker malformations, chiari II malformation, and CC lipomas. Associated radiologic findings include no CC or cingulate gyrus, teardrop shaped occipital horns, parallel lateral vents, high riding 3rd vent, central cyst that extends to inner table, azygous/wandering ACA. The superomedial aspects of the lateral ventricles are indented by longitudinal WM tracts called "Probst bundles". Partial ACC is usually posterior and results from intrauterine injury.
 
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