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Dandy Walker Syndrome (DWS) is a brain malformation that occurs during fetal development that involves the fourth ventricle and the cerebellum. The cerebellum is a part of the brain that plays a role in movement, balance, and body coordination. The fourth ventricle is one of the cavities within the brain that contains the circulating cerebrospinal fluid (CSF). If these parts of the brain are not properly developed, the CSF may not flow freely between the upper and lower areas of the brain and spinal cord.
The key features of DWS (triad) include: enlargement (cystic dilation) of the fourth ventricle, partial or complete absence of the cerebellar vermis (a part of the cerebellum), and enlarged posterior fossa with upward and lateral displacement of the surrounding structures of the brain. The enlarged fourth ventricle cyst can block CSF flow in the brain resulting in obstructive (noncommunicating) hydrocephalus.
Dandy-Walker Syndrome is a rare congenital syndrome. This condition is a genetically sporadic disorder that occurs approximately one in every 25,000 live births, and is more common in females. DWS represents approximately 1-4% of all hydrocephalus patients. Cases of families with multiple generations of children with Dandy-Walker Syndrome have been reported. This suggests that there is also a familial inherited form of DWS.
Most patients with DWS present in infancy or childhood. Although adult onset is reported, it is unusual. Symptoms may appear suddenly or gradually. The age at presentation depends on the severity of the malformation and the degree of hydrocephalus. Approximately 90% of patients have hydrocephalus at the time of diagnosis. An infant may demonstrate developmental delay, progressive enlargement of his/her head circumference, or signs and symptoms of hydrocephalus. However, typical signs of hydrocephalus may be absent in some infants secondary to the ability of their head to increase in size and accommodate the build up of CSF. Symptoms of hydrocephalus include vomiting, irritability, or seizures. Signs of cerebellar dysfunction include lack of muscle coordination, unsteadiness, spasticity, or jerky eye movements. At any age, other malformations of the brain may cause additional symptoms depending on where they are located.
Dandy-Walker Syndrome is due to a mutation in the genes within the developing infant. Research has shown that some of these genes are located on chromosomes 3, 5, 6, 8, 9 and 17. The exact cause for the mutations is not known. Research suggests that possible causes may include gestational (first trimester) exposure to rubella, cytomegalovirus, toxoplasmosis, warfarin (Coumadin), alcohol, and isotretinoin.
DWS is best diagnosed with the help of imaging of the brain via ultrasound (US) or Magnetic Resonance Imaging (MRI). Another imaging study that may be used is Computed Tomography (CT). All of these studies can be used to take pictures of the brain and they each provide different types of structural information. MRI allows neurosurgeons to view the cerebellum and adjacent structures to accurately determine which form of the malformation is present and to what extent the malformation has progressed. MRI also allows for a detailed visualization of the ventricles of the brain and assesses the level of hydrocephalus. The results of these studies will dictate a child's diagnosis. A complete assessment of the brain anatomy with close follow-up is very important since the level of hydrocephalous may change over time.
Treatment for individuals with DWS generally consists of treating the associated problems, if needed. The primary modality usually consists of a neurosurgeon placing a CSF shunt to treat the hydrocephalus. A shunt is a special tube that will drain off excess CSF from the brain to another part of the body where it is reabsorbed; for example, the abdominal cavity. This decreases the pressure that may have built up inside the skull, which may also alleviate some of the child's symptoms. Shunts may develop infections or blockages. Parents are taught the warning signs for what to look for if the child's shunt should become infected or if a blockage occurs.
Overall the prognosis is only moderately favorable, even when hydrocephalus is treated early. The mortality rate is 12-50% as reported in Pediatric Neurosurgical literature. It is very difficult to predict the prognosis due to the variable presence or absence of other brain malformations. Some of the associated abnormalities may include absence of the corpus callosum, a brain stem anomaly, or migrational anomaly. If any of these are present, a neurologist can explain the extent of these malformations and how they may affect future prognosis. Additionally, the presence of multiple congenital defects may shorten life span.
The effect of DWS on intelligence is variable, some children have normal intelligence and others never achieve normal intellectual development even when the hydrocephalus is treated early.
The Hydrocephalus Association
This is the website for the Hydrocephalus Association. It is easy to navigate and provides general information on hydrocephalous, one of the signs of Dandy- Walker syndrome.
870 Market Street, Suite 705
San Francisco, CA 94102
Tel: 415-732-7040 888-598-3789
A support group for patients and families affected by the syndrome.
National Institute of Neurological Diseases and Stroke
A comprehensive summary of the syndrome.
Guardians of Hydrocephalus Research Foundation
2618 Avenue Z
Brooklyn, NY 11235-2023
Tel: 718-743-GHRF (4473)
March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: 914-428-7100 888-MODIMES (663-4637)
National Hydrocephalus Foundation
12413 Centralia Road
Lakewood, CA 90715-1623
Tel: 562-402-3523 888-857-3434
If you would like to be connected to parents of children with this disease, please visit http://www.madisonsfoundation.org/ and click on Connecting Parents in the Information and Support section.
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