Discussion of Hydranencephaly
- Hydranencephaly is a rare, isolated abnormality occurring in less than 1 per 10,000 births.
- It is the most severe form of bilateral cerebral cortical destruction.
- The differential diagnosis for hydranencephaly includes:
- Hydranencephaly occurs after the brain and ventricles have fully formed, usually in the second trimester.
- The brain destruction is complete or almost complete in a bilateral internal carotid artery distribution, with the cerebral hemispheres replaced by fluid covered with leptomeninges and dura.
- Because the ventricles have already been formed, the falx cerebri is present.
- The cerebellum, midbrain, thalami, basal ganglia, choroid plexus, and portions of the occipital lobes, all fed by the posterior circulation, are typically preserved.
- Pathogenesis of hydranencephaly is thought to be a vascular accident involving the internal carotid arteries
 Imaging Findings for Hydranencephaly
- US scans demonstrate no identifiable cortical mantel.
- The cerebellum, midbrain, thalami, basal ganglia, choroid plexus, and portions of the occipital lobes are typically present.
- Falx cerebri is present (falx is absent in holoprosencephaly)
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 External Links
 References for Hydranencephaly
- Alfred B. Kurtz, and Pamela T. Johnson. Case 7: Hydranencephaly. Radiology 1999 210: 419-422.