Premature newborn female.

Our appreciation is extended to Dr. Lauren Ladd, Indiana University Department of Radiology, for contributing this case.

Premature newborn female.

Premature newborn female.

• Corpus callosum agenesis
• Ventriculomegaly (3rd ventricle)
• Large cyst (interhemispheric, pineal, etc)
• Lobar holoprosencephaly
• Septo-optic dysplasia

Premature newborn female.

Key points: 

• Corpus callosum agenesis is a when the white matter tracts that connect the right and left hemisphere fail to form (partially or completely).
  • Unknown cause, though possible etiologies include: chromosome errors / genetic factors, prenatal insults (infection, toxins, injury), and other brain abnormalities (cysts, migrational disorders).
  • Corpus callosum normally develops between 8th - 16th weeks of gestation.
• Corpus callosum agenesis is often an incidental finding on prenatal ultrasound, prenatal MRI, neonatal head ultrasound, postnatal head MRI, or head CT.
• Imaging findings:
  • Ultrasound:
    • Ventricular shape abnormality: mild ventriculomegaly, "bullhorn" / "Viking helmet" / "moose head" configuration of lateral ventricles (coronal plane), lateral ventricles more widely spaced anteriorly, and/or elevation of the 3rd ventricle.
    • Enlargement of the interhemispheric fissure.
    • Absent cavum septum pellucidum
    • Abnormal gyral pattern: "spoke wheel" continuation of gyri to the edge of the third ventricle (sagittal plane), absent cingulated gyrus.
  • MR:
    • Absent corpus callosum white matter (sagittal and coronal series)
    • Widened interhemispheric fissure (coronal series)
    • Radially oriented gyri (sagittal series)
    • "Trident shaped" ventricles (lateral ventricles pointed superiorly on coronal series)
    • +/- Probst bundles (white matter tracts running anterior-posterior instead of crossing midline to form corpus callosum).
• Clinically, children with isolated corpus callosum agenesis are often near normal by 3 years of age, though may demonstrate some cognitive defects later in development.
  • Additional CNS abnormalities are seen in half of children with ACC, including: argyria, pachygyria, heterotopias, lipomas, interhemispheric cysts, and Dandy-Walker continuum.
  • More severe deficits are seen when associated with additional cerebral anomalies or other syndromes (Apert, Meckel-Gruber, or Walker-Warburg syndromes).

References: 

1. Donnelly LF. Fundamentals of Pediatric Radiology. Philadelphia: WB Saunders Co, 2001.
2. Yousem DM and Grossman RI. The Requisites: Neuroradiology, 3rd Ed. Philadelphia: Mosby Elsevier, 2010.
3. my.statdx.com. Accessed 7/3/2011.

Premature newborn female.