What is the Dandy-Walker Malformation?
The Dandy-Walker malformation is a congenital (present at birth) defect affecting the cerebellum, the back part of the brain that controls movement, behavior, and cognitive ability.
Dandy-Walker can cause obstruction of the normal drainage of cerebrospinal fluid (CSF), resulting in a build-up of CSF and a condition called hydrocephalus.
The Dandy Walker malformation is part of a spectrum of conditions that include the classic form and other mild variants. It is important to make a correct diagnosis because the different conditions may have very different outcomes. The classic form of Dandy Walker malformation has certain key features:
- Enlarged back compartment (posterior fossa) of the brain
- Malformed or missing cerebellar vermis (part of the cerebellum)
- Large cyst in the fourth ventricle of the brain
In addition, most children will develop hydrocephalus (CSF buildup in the brain) before their first birthday.
What Causes Dandy-Walker Malformation?
Experts still do not fully understand the causes of classic Dandy-Walker malformation and its variants. In many cases, a specific cause cannot be identified. Potential causes include:
- Chromosomal defects that affect fetal brain development
- Certain viral infections in the mother that pass to the developing baby
- Exposure of the unborn baby to certain toxins or medications
- Maternal diabetes
Symptoms of Dandy-Walker Malformation
Symptoms of Dandy-Walker malformation usually appear by age 1. These symptoms may include:
- Developmental delays in motor and language skills such as sitting up, walking, and talking
- Poor muscle tone, balance, and coordination
- Problems with eye movement, mainly jerky eye movement
- Vision and hearing impairment
Hydrocephalus complicates the majority of Dandy-Walker malformations. Symptoms of hydrocephalus include:
- Abnormally rapid head growth
- Excessive sleepiness
How Is Dandy-Walker Malformation Diagnosed?
Your physician may detect Dandy-Walker malformation in your baby with a fetal high-resolution (level II) ultrasound during the second or third trimester. Your doctor may refer you to our Fetal Medicine Institute for further testing to evaluate your baby’s condition. Tests may include:
- Fetal MRI to help confirm the diagnosis and rule out other conditions (e.g., arachnoid cysts, Blake’s pouch cysts, vermian hypoplasia, mega cisterna magna) that look like Dandy-Walker malformation on ultrasound tests.
- MRI after birth to confirm the condition and diagnose any complications affecting your baby
- Ultrasound after birth to confirm the condition and diagnose any complications affecting your baby
Fetal MRI is an advanced, high-resolution imaging test that gives the best information about the underlying cause and the best picture of the rest of the baby’s brain. Obtaining a MRI scan and an expert fetal neurological opinion is important because the long-term outcome for conditions resembling Dandy-Walker malformations may be much better than in cases of Dandy-Walker malformation. The Fetal Brain Program of our Fetal Medicine Institute has a team of experts including a fetal radiologist, fetal neurologist, and fetal neurosurgeon. This multidisciplinary team is most qualified to make this determination.
Read more about the high-risk prenatal care services at the Fetal Medicine Institute of Children’s National.
Treatments for Dandy-Walker Malformation
The main course of treatment for Dandy-Walker malformation is to manage any complications that may arise. Treatment options may include:
- Medications to control seizures
- Speech therapy to help with speech and language development
- Physical therapy to improve muscle strength and coordination
- Surgical insertion of a ventriculoperitoneal shunt in cases of severe or worsening hydrocephalus
- Occupational therapy to help build self-care and mobility skills such as eating, getting dressed, and walking
- Special education as necessary for cognitive and learning problems
The neurologists and neurosurgeons in the Fetal Brain Program at our Fetal Medicine Institute have extensive experience in diagnosing and managing Dandy Walker malformations. We develop plans that ensure continuity of care from the early stages of pregnancy, after birth, and across childhood.
Learn more about our Fetal Medicine Institute.