Dandy Walker Malformation

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Dandy Walker Malformation is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Dandy-Walker Cyst
  • Dandy-Walker Deformity
  • Dandy-Walker Syndrome
  • DWM
  • Hydrocephalus, Internal, Dandy-Walker Type
  • Hydrocephalus, Noncommunicating, Dandy-Walker Type
  • Luschka-Magendie Foramina Atresia

Disorder Subdivisions

  • None

General Discussion

Dandy-Walker malformation (DWM) is a brain malformation that occurs during embryonic development of the cerebellum and 4th ventricle. The cerebellum is the area of the brain that helps coordinate movement, and is also involved with cognition and behavior. The 4th ventricle is a space around the cerebellum that channels fluid from inside to around the outside of the brain. DWM is characterized by underdevelopment (small size and abnormal position) of the middle part of the cerebellum known as the cerebellar vermis, cystic enlargement of the 4th ventricle and enlargement of the base of the skull (posterior fossa). DWM is sometimes (20-80%) associated with hydrocephalus, in which blockage of the normal flow of spinal fluid leads to excessive amounts of fluid accumulating in and around the brain. This leads to abnormally high pressure within the skull and swelling of the head, and can lead to neurological impairment.


The symptoms of Dandy Walker syndrome typically include developmental delay, low tone (hypotonia) or later high tone (spasticity), poor coordination and balance (ataxia), and sometimes enlarged head circumference and increased pressure within the skull due to hydrocephalus. Mental retardation occurs in fewer than half, most often in those with severe hydrocephalus, chromosome abnormalities or other birth defects. Seizures occur in 15-30% of those affected. Respiratory control centers in the brainstem are sometimes affected and can lead to respiratory failure, again most likely with severe hydrocephalus. The age at diagnosis varies depending on the onset and severity of hydrocephalus, and presence of other birth defects or medical problems.

The clinical presentation and imaging features of DWM overlap with isolated cerebellar vermis hypoplasia (CVH) and mega-cisterna magna (MCM), and these have been classified together as a spectrum of anomalies known as the Dandy-Walker complex. But emerging experience suggests that this is an oversimplification that may contribute to inaccurate information about both outcome and genetic risks. CVH consists of a small vermis without the striking upward rotation of the vermis, cystic enlargement of the 4th ventricle or enlarged posterior fossa that characterize typical DWM. This malformation has also been called the "Dandy-Walker variant", a potentially confusing term. The available data regarding outcome is limited, but this is often more severe than in typical DWM. MCM is characterized by an enlarged posterior fossa despite normal or very nearly normal size of the cerebellum. The increased size is associated with an enlarged fluid collection beneath and often behind the cerebellum. This has been reported as a normal variant, but emerging experience suggests that it may be associated with developmental disabilities although these are usually less severe than seen in DWM or CVH. The uncertainty in prognosis for these three overlapping conditions is accounted for by both natural variability and difficulty in distinguishing them.


DWM results from defects in early embryonic development of the cerebellum and surrounding structures. A few patients have chromosome abnormalities including deletion of chromosome 3q24.3 (the location of the first DWM genes, known as ZIC1 and ZIC4), 6p25 or 13q32.2-q33.2, or duplication of 9p. In the remainder, it is probably due to other more complex genetic and perhaps environmental factors (teratogens) as the recurrence risk in siblings less than 5%. A few examples of affected siblings with isolated Dandy-Walker malformation have been reported, suggesting autosomal recessive or X-linked inheritance, but most of these are probably CVH and not typical DWM. In these families, the recurrence risk is higher, up to 25%. DWM may also occur as part of a genetic syndrome that includes multiple birth defects, such as the PHACES syndrome of facial hemangioma, heart and sternal defects and DWM. Many other syndromes and chromosome abnormalities have been reported with DWM, but most of these appear to have CVH rather than typical DWM.

Affected Populations

The frequency of Dandy Walker malformation in the US is approximately 1 per 25,000 -35,000 live births and affects more females than males.

Standard Therapies


Dandy Walker malformation is diagnosed with the use of ultrasound, CT and MRI. Prenatal diagnosis of Dandy-Walker malformation is sometimes made by ultrasound or fetal MRI.


Hydrocephalus associated with Dandy Walker syndrome is treated with surgery to insert a tube to redirect the fluid that surrounds the brain and to assist fluid drainage into other parts of the body that can absorb the fluid.

A supportive team approach for children with Dandy-Waller malformation is often warranted and may include special education, physical therapy and other medical, social or vocational services.

Genetic counseling is recommended for families that have a child with Dandy Walker malformation.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:




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Ecker J Shipp T, Bromley B, et al. The sonographic diagnosis of Dandy-Walker and Dandy-Walker variant: associated findings and outcomes. Prenat Diagn 2000;20(4):328-32.

Grinberg I, Northrup H, Ardinger H, et al. Heterozygous deletion of the linked genes ZIC1 and ZIC4 is involved in Dandy-Walker malformation. Nature Genetics 2004;36:1053-1055.

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Incesu L and Khosia A. Dandy-Walker Malformation. eMedicine; last updated 10/31/03.

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Lighthouse International

111 E 59th St

New York, NY 10022-1202

Tel: (800)829-0500

Email: info@lighthouse.org

Internet: http://www.lighthouse.org

National Hydrocephalus Foundation

12413 Centralia Rd.

Lakewood, CA 90715-1653


Tel: (562)924-6666

Fax: (562)924-6666

Tel: (888)857-3434

Email: nhf@earthlink.net

Internet: http://www.nhfonline.org

Hydrocephalus Association

4340 East West Highway Ste 950

Bethesda, MD 20814


Tel: (301)202-3811

Fax: (301)202-3813

Tel: (888)598-3789

Email: info@hydroassoc.org

Internet: http://www.hydroassoc.org

NIH/National Institute of Neurological Disorders and Stroke

P.O. Box 5801

Bethesda, MD 20824

Tel: (301)496-5751

Fax: (301)402-2186

Tel: (800)352-9424

TDD: (301)468-5981

Internet: http://www.ninds.nih.gov/

Dandy-Walker Syndrome Network

5030 142nd Path West

Apple Valley, MN 55124


Tel: (612)423-4008

Hydrocephalus Support Group, Inc.

1933 Mistflower Glen Ct.

Chesterfield, MO 63005-4236


Tel: (636)532-8228

Fax: (314)251-5871

Email: hydrob@earthlink.net

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/

Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766

Email: getinfo@madisonsfoundation.org

Internet: http://www.madisonsfoundation.org

Dandy-Walker Alliance, Inc.

10325 Kensington Pkwy

Suite 384

Kensington, MD 20895

Tel: (877)326-3992

Email: comments@dandy-walker.org

Internet: http://www.dandy-walker.org

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html.