Radiology Resident Case of the Week

Agenesis of the Corpus Callosum

June 28, 1996

Etiology/Pathophysiology
Unknown (Congenital anomaly. Normal development is between 12-18/20 weeks.)

Incidence: 0.7 - 5.3%

Pathology:
Findings in agenesis of the Corpus Callosum:

• High riding third ventricle
• Colpocephaly
• Cyst or Lipoma
• Medial impingment of Probst bundle on ventricles.
• Probst bundles are longitudinal "masses" formed by all of the axonal fibers that normally would have crossed.
• Widely spaced, parallel, crescent-shaped lateral ventricles
• Pointed and widely spaced frontal horns
• Incomplete hippocampal formation

Miscellaneous
Associated with the following:

• Agyria
• Pachygyria
• Heterotopias
• Dandy-Walker Syndrome
• Holoprosencephaly
• Septooptic dysplasia
• Chiari I/II Malformations
• Trisomies 13, 15, 18
• Aicardi's Syndrome (females with agenesis, epilepsy, and choroidal abnormalities)
• Abnormal migration/myelination
• Microphthalmia/Colobomas

Imaging

DDX
Rarely, a large dural cyst, an intraventricular cyst, or a prominent cavum septi pellucidi et Vergae may mimic agenesis.

Key references
Grossman and Yousem. Neuroradiology The Requisites. 254-255. Mosby 1994.

Lee and Rao. Cranial Computed Tomography. 147 - 152. McGraw-Hill. 1983.

ACR Code

Keywords:

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Last Modified: April 24, 1997