Fact-sheet: Agenesis of corpus callosum
Updated on 09/17/2021 at 12:16 PM
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Definition
Congenital malformation characterized by hypoplasia or agenesis of all or part of the corpus callosum.
Congenital, the most frequent brain malformation: 0.2%.
Total or partial.
Usually isolated or associated with malformations of the posterior fossa, midline (pericallosal lipoma), or cortical malformations
Clinical features
Most often an incidental finding, asymptomatic or associated with psychomotor delay, epilepsy, neurological disorders, hypotonia.
In 75% of cases, IQ is normal or slightly below average. Usually
isolated or associated with malformations of the posterior fossa, midline (pericallosal lipoma), or cortical malformations.
Ultrasound
Often diagnosed on antenatal ultrasound (from 18-20 weeks GA) based on direct and especially indirect signs:
- colpocephaly (dilatation localized to the occipital horns)
- thin, everted frontal horns, giving a "bull horn" appearance on a coronal section
- radial arrangement of the cerebral sulci
- elevation of the third ventricle
- absence of the cavum septi pellucidi
MRI
MRI:
- partial or total agenesis
- dilatation of the frontal and occipital horns of the lateral ventricles with elevation of the third ventricle
- Probst bundles: reorientation and condensation of fibers unable to cross the midline into longitudinal bundles along the medial surface of the lateral ventricles
- parallelism and widening of the lateral ventricles
- absence of the cingulate gyrus
- hypertrophy of the anterior commissure.
Usually isolated or associated with malformations of the posterior fossa, midline (pericallosal lipoma), or cortical malformations.
Management
The prognosis of callosal agenesis is debatable when the malformation appears isolated, but termination of pregnancy is accepted