Children's Hospital Colorado
Colorado Fetal Care Center

Dandy-Walker Malformation

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What is Dandy-Walker malformation?

Dandy-Walker malformation is a condition in which the brain doesn’t develop properly before birth. It mainly affects the cerebellum, the area of the brain that controls movement, behavior and cognitive ability. The cerebellum may be smaller than typical, malformed or missing. The back compartment of the brain (called the posterior fossa) may be larger than typical.

Dandy-Walker malformation also affects the 4th ventricle (the area around the cerebellum that channels fluid out of the brain). Babies born with Dandy-Walker may have an enlarged, cyst-like 4th ventricle and experience a build up of cerebrospinal fluid. This leads to hydrocephalus, an accumulation of fluid around the brain.

Children with a milder Dandy-Walker variant may not have an enlarged 4th ventricle, putting them at lower risk of hydrocephalus.

What causes Dandy-Walker malformation?

Researchers are still learning why some babies develop Dandy-Walker malformation. In many cases, the cause is not known. Based on what we do know, possible causes include:

  • Genetics: Certain genetic syndromes are associated with Dandy-Walker malformation.
  • Infection: A viral infection may pass from the mother to her developing baby and cause the defect.
  • Exposure to toxins: If the fetus is exposed to certain medications or environmental toxins that cause birth defects, they may develop Dandy-Walker.
  • Maternal diabetes: A mother who has diabetes has an increased risk of her baby developing Dandy-Walker malformation.

Who gets Dandy-Walker malformation?

Dandy-Walker malformation occurs in at least 1 in 5,000 live births. Up to 80% of children with Dandy-Walker also develop hydrocephalus by age 1.

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