Agenesis of the corpus callosum

Case contributed by Antonio Rodrigues de Aguiar Neto
Diagnosis certain


Brought to the emergency department after fall from standing height and sudden bilateral convergent strabismus.

Patient Data

Age: 6 years
Gender: Female

The anterior horns of lateral ventricles are small, with parallel widely separated bodies - the “racing car” sign, with the third ventricle sited highly. There is dilation of the occipital horns of the lateral ventricles, corresponding to colpocephaly. The corpus callosum and septum pellucidum are absent.

Impression: Dysgenesis of the corpus callosum. 

Agenesis of the corpus callosum with absent septum pellucidum and hemispheric sulci reaching the high-riding third ventricle roof, giving a “sunray” appearance in the midsagittal plane. The bodies of lateral ventricles have a parallel orientation and are widely separated, with narrow frontal horns - the “racing car” sign. There is dilation of the occipital horns and prominent trigones, known as colpocephaly. Narrowed frontal horns give “Viking helmet” or “Moose head” signs on coronal images. Mild focal parenchymal signal intensity abnormality in the left superior frontal gyrus may represent cortical dysplasia.

Impression: Agenesis of the corpus callosum.

Case Discussion

Dysgenesis of the corpus callosum is a cerebral malformation that can present as an isolated condition or associated with other anomalies and classified as complete agenesis or partial agenesis (dysgenesis)1-7. This case demonstrates the typical imaging features of callosal agenesis.

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