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| Dandy-Walker Malformation |
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Dandy-Walker malformation. Angled coronal view through the head demonstrates a keyhole-shaped defect (arrow) between the cerebellar hemispheres (arrowheads) due to absence of the cerebellar vermis, permitting communication between the fourth ventricle and the cisterna magna.
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B 
Dandy-Walker malformation with large posterior fossa cyst and hydrocephalus. A: Axial image of the posterior fossa demonstrates absence of the cerebellar vermis as well as splaying and flattening of the cerebellar hemispheres (arrowheads) by a large fluid-filled space (*) connecting the fourth ventricle to the cisterna magna. B: Axial image superior to (A) demonstrates a dilated lateral ventricle (calipers), representing hydrocephalus, and the large posterior fossa cyst (*).
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The Dandy-Walker malformation is characterized by a posterior fossa cyst that communicates with the fourth ventricle, agenesis or hypoplasia of the cerebellar vermis, and hydrocephalus. The posterior fossa cyst, or Dandy-Walker cyst, is a fluid collection that extends from the fourth ventricle between the cerebellar hemispheres to the cisterna magna. The cerebellar hemispheres are separated by the fluid of the Dandy-Walker cyst, and they often are abnormally formed. The degree of hydrocephalus is variable.
Dandy-Walker malformations are associated with a variety of genetic syndromes and chromosomal abnormalities. They can also result from in utero infection. |
10-21 |
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