SPR Unknown # 100 -- FINAL

Chetan C. Shah, MD, MBA

Charles M. Glasier, MD


Publication Date: 2013-11-06

History

22 year old female with abnormal routine prenatal ultrasound.

Findings

Fetal MRI shows agenesis of corpus callosum with parallel lateral ventricles and central extension of the interhemispheric fissure. Additional findings include subependymal heterotopias, cyst at left foramen of Luschka, and a coloboma of the right eye. Post-natal MRI of the infant confirmed these findings.

Diagnosis

Agenesis of corpus callosum, subependymal gray matter heterotopias, cyst at foramen of Luschka, and coloboma.

Discussion

The corpus callosum is made up of commissural fibers that connect the cerebral hemispheres. The callosum consists of rostrum, genu, body and splenium from anterior to posterior. Partial agenesis/dysgenesis of the corpus callosum is typified by presence of genu and anterior body with absence of the posterior body. This pattern of posterior body absence is often found in patients with myelomeningocele/Chiari 2 malformation. Localized absence of the anterior or central corpus callosum is often associated with lobar forms of holoprosencephaly

Imaging features of agenesis of corpus callosum includes:

Isolated absence of corpus callosum has better outcome than when it is associated with other anomalies. Less than 20% of patients with agenesis of corpus callosum have chromosomal anomalies.

Agenesis or dysgenesis of corpus callosum may be associated with migration anomalies, interhemispheric cyst or pericallosal lipoma.

Heterotopias are a form of migration anomaly with ectopic gray matter abnormally located within the white matter due to failure of migration of fetal neurons to the cerebral cortex. Subependymal heterotopias are usually nodular collections of gray matter located along the lining of the lateral ventricles. Subcortical heterotopias are located in the cerebral white matter either as islands of gray matter or as extensions of the cortex. Band heterotopias form two layers of cortex separated by white matter.

Coloboma of the eye is deficiency of ocular tissue. Optic disc coloboma has defect at the site of insertion of optic nerve. Choroidoretinal coloboma has a defect in the choroid, retina or both which can be partial or complete. Abnormal shape of the globe is seen in coloboma and there may be an associated cyst behind the globe.

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