What are the other Names for this Condition? (Also known as/Synonyms)

• DW Complex

What is Dandy-Walker Complex? (Definition/Background Information)

• Dandy-Walker Complex is a group of disorders that affect the development of the brain. The changes in brain development are present from birth (congenital)
• Dandy-Walker Complex affects the formation of the area of the brain known as the cerebellum, which is responsible for coordinating movement, and the fluid-filled spaces around it
• People with Dandy-Walker Complex may have a portion of the brain called the cerebellar vermis that is smaller than expected (hypoplastic) or completely absent (aplastic). The cerebellar vermis is the area of the brain between the two halves of the cerebellum
• People with Dandy-Walker Complex have a larger than expected fourth ventricle of the brain. This ventricle allows fluid to flow between the upper and lower areas of the brain and spinal cord
• People with Dandy-Walker Complex may have an enlarged portion of the base of the skull (posterior fossa)
• Dandy-Walker complex is a group of disorders that have overlapping symptoms. These disorders include:
  • Dandy-Walker malformation (also known as Dandy-Walker syndrome): having a small cerebellar vermis, large fourth ventricle, and enlarged posterior fossa
  • Isolated cerebellar vermis hypoplasia (sometimes known as Dandy-Walker variant): having a small cerebellar vermis without other features of Dandy-Walker complex
  • Mega-cisterna magna: having an enlarged posterior fossa with a typically developed cerebellum. This may be a normal variant and may not cause any health problems
  • Posterior fossa arachnoid cyst: the development of a cyst on the posterior fossa without any other features of Dandy-Walker complex
• Each of these disorders can have separate causes and different long-term outlooks
• In some cases, Dandy-Walker complex is caused by an underlying genetic change. These genetic changes may cause Dandy-Walker complex alone, or they may cause Dandy-Walker complex as well as other health problems. In these situations, the complex can run in families. However, in most situations, Dandy-Walker complex is caused by a combination of genetic and environmental factors
• Treatment options may include a surgery to place a ventriculoperitoneal shunt that relieves excess fluid from the brain, as well as physical and occupational therapies

(Source: Dandy-Walker Complex; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Dandy-Walker Complex? (Age and Sex Distribution)

• Dandy-Walker Complex is a rare congenital disorder. The presentation of symptoms may occur at birth or in infancy. In most cases, affected individuals develop symptoms within the first year of life
• Both males and females may be affected. However, the condition may be more prevalent in females
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Dandy-Walker Complex? (Predisposing Factors)

• A positive family history may be an important risk factor, since Dandy-Walker Complex can be inherited
• Other risk factors may include:
  • Diabetes during pregnancy
  • Exposure to viruses such as Rubella during pregnancy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Dandy-Walker Complex? (Etiology)

In majority of cases, the exact cause of Dandy-Walker Complex is not known.

• Scientists believe that both genetic and environmental factors may play a role in the development of this disorder in the embryonic stages
• In some cases, the condition may be caused by chromosomal abnormalities, such as trisomy, mosaicism or monosomy of chromosomes
• In most cases, the condition occurs sporadically, with no family history. Rarely, the condition can be inherited. However, the pattern of inheritance is not known in such cases
• Additionally, Dandy-Walker Complex may co-occur with other genetic syndromes, and the pattern of inheritance is determined by the gene mutation involved in the development of that condition

What are the Signs and Symptoms of Dandy-Walker Complex?

The signs and symptoms of Dandy-Walker Complex may vary in type and severity among affected individuals. They may also be determined by the age of an affected individual.

Signs and symptoms of Dandy-Walker Complex in infancy:

• A head circumference that is becoming larger faster than expected 
• Low muscle tone (hypotonia) 
• Stiff muscles (spasticity) 
• Developmental delay

Signs and symptoms of Dandy-Walker Complex in older children:

• Irritability
• Vomiting
• Jerky movements of the eyes (nystagmus) 
• Trouble coordinating movements (ataxia)

The general signs and symptoms of Dandy-Walker Complex may include:

• Agenesis of cerebellar vermis
• Cranial nerve paralysis
• Dilated fourth ventricle
• Elevated imprint of the transverse sinuses
• Heterogeneous
• Hydrocephalus, causing
  • Breathing problems
  • Seizures
  • Difficulty controlling movements of eyes, face and neck
• Intellectual disability
• Nystagmus
• Partial absence of cerebellar vermis
• Posterior fossa cyst at the fourth ventricle
• Sporadic
• Thinning and bulging of the posterior fossa bones
• Truncal ataxia

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

• Dandy-Walker malformation
• Platybasia
• Prominent occiput

Frequently present symptoms in 30-79% of the cases may include frontal bossing.

Occasionally present symptoms in 5-29% of the cases:

• Aplasia/hypoplasia of the corpus callosum
• Cleft palate
• Encephalocele 
• Tetralogy of Fallot

In addition, if Dandy-Walker Complex co-exists with other conditions, the signs and symptoms pertaining to that condition may be present, including health problems or differences from birth that can affect other parts of the brain as well as the heart, face, limbs, fingers, and toes.

(Source: Dandy-Walker Complex; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Dandy-Walker Complex Diagnosed?

Dandy-Walker Complex is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies, such as computed tomography, magnetic resonance imaging and ultrasound imaging of the brain
• Biopsy studies, if necessary
• Explorative molecular genetic testing to check for gene mutation(s) in affected individuals

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Dandy-Walker Complex?

The complications of Dandy-Walker Complex may include:

• Problems with movement
• Respiratory distress
• Risk of falls and injury due to seizures
• Severe intellectual difficulty
• Negative impact on quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Dandy-Walker Complex Treated?

The treatment for Dandy-Walker Complex may include the following:

• Medication to control seizures
• Ventriculoperitoneal shunt in the brain to allow draining of excess fluid from the brain
• Special education for affected children, if necessary
• Physical therapy to improve muscle tone and movement
• Occupational therapy

How can Dandy-Walker Complex be Prevented?

Currently, Dandy-Walker Complex may not be preventable, since the exact cause is not known in most cases.

• Maintaining good glycemic index during pregnancy may aid in reducing the risks of giving birth to a child with the disorder
• Getting vaccinated against preventable viral infections may also help reduce the risk of having a child with Dandy-Walker Complex, in some cases
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Dandy-Walker Complex? (Outcomes/Resolutions)

• The prognosis of Dandy-Walker Complex is dependent upon the extent of structural changes in the brain, severity of the signs and symptoms, associated complications, as well as co-existing genetic conditions 
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• The prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Dandy-Walker Complex:

The types of DW Complex may include:

• Dandy-Walker syndrome or malformation
• Dandy-Walker variant
• Mega cisterna magna

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/