Dandy‑Walker Syndrome

Alternate Names of the Disease

Dandy‑Walker syndrome is known in English as Dandy‑Walker syndrome or Dandy‑Walker malformation.
In a broader concept, the terms Dandy‑Walker complex or Dandy‑Walker continuum are also used to indicate that cerebellar and ventricular developmental abnormalities can exist on a spectrum from mild to severe.
The name of this disorder originates from American neurologist Walter Dandy, who first reported the condition in 1914, and from Arthur Walker, who in 1942 provided a more detailed description.

Overview of the Disorder

Dandy‑Walker Syndrome (DWS) is a congenital brain malformation characterized primarily by abnormal development of the cerebellum and its surrounding structures (the fourth ventricle and the posterior cranial fossa). As reported by Arthur Walker in 1942, this disorder is important in pediatric neurology and neurosurgery because it significantly affects neural development and cerebrospinal fluid circulation.

The hallmarks of DWS are three principal structural abnormalities:

1. Hypoplasia or absence of the cerebellar vermis
   The vermis, the central structure connecting the two hemispheres of the cerebellum, may not form normally, which can impair coordination and balance.
   
2. Cystic enlargement of the fourth ventricle
   The fourth ventricle is abnormally enlarged, forming a cystic structure in the posterior fossa, interfering with normal cerebrospinal fluid circulation.
   
3. Enlargement of the posterior fossa with upward displacement of structures
   The bony space behind the brain is expanded, displacing nearby venous structures or the tentorium of the cerebellum upward.
   

Such anatomical changes often cause cerebrospinal fluid circulation disturbances (hydrocephalus). It is estimated that 70–90% of cases are complicated by hydrocephalus. Early symptoms may include vomiting, headache, and ocular motility abnormalities caused by increased intracranial pressure.
DWS may occur in isolation, but in many cases it is associated with other brain malformations or systemic anomalies and genetic disorders. For example, it may coexist with corpus callosum agenesis, gray matter abnormalities, cardiac defects, or urinary system malformations. These comorbidities strongly influence severity and treatment planning.

Relation to Dandy‑Walker Complex

Rather than being a single entity, DWS is viewed as part of the broader Dandy‑Walker Complex. Within that spectrum are:

• Dandy‑Walker malformation (DWM): The classic, severe form with all three defining features present
  
• Dandy‑Walker variant (DWV): Partial involvement (e.g. vermis hypoplasia or ventricular enlargement) but without clear posterior fossa enlargement — a milder form
  
• Mega cisterna magna: The fourth ventricle is normal, but the cisterna magna (the CSF space beneath the cerebellum) is enlarged
  
• Blake’s pouch cyst: A remnant pouch that failed to regress during fetal development, forming a cyst; sometimes difficult to distinguish from DWS
  

Thus, DWS is part of a spectrum (continuum) of anomalies, and its manifestations range broadly from severe developmental impairment to nearly asymptomatic cases who can study and work.

Etiology and Diagnostic Methods

Etiology

The precise cause of Dandy‑Walker syndrome is not fully understood, but fetal abnormal brain development is thought to play a key role. Main contributing factors may include:

• Abnormal neurogenesis during the cerebellar formation period (early to mid gestation)
  
• Maternal infections (e.g. rubella, cytomegalovirus) or exposure to drugs (e.g. warfarin)
  
• Genetic factors (mutations in genes such as ZIC1, ZIC4, FOXC1)
  
• Coexistence of congenital chromosomal anomalies (e.g. trisomy 18)
  

In many cases, multiple factors act in combination rather than a single cause.

Diagnostic Methods

• Prenatal diagnosis: In the mid‑pregnancy period, fetal ultrasound may reveal posterior fossa enlargement or cerebellar abnormalities; fetal MRI may be used for detailed evaluation.
  
• Postnatal imaging: MRI or CT in the neonatal/infant period can reveal cerebellar hypoplasia, cysts, and ventricular enlargement.
  
• Genetic and chromosomal testing: Because DWS often coexists with chromosomal abnormalities, genetic counseling and chromosomal or gene testing may be indicated.
  
• Clinical observation: Signs such as macrocephaly, developmental delays, nystagmus, seizures, and abnormal muscle tone may help support the diagnosis.
  

Symptoms and Management

Major Symptoms

Symptoms vary depending on severity and comorbid conditions. Representative manifestations include:

• Macrocephaly, headache, vomiting, irritability (due to hydrocephalus)
  
• Developmental delays (motor, language)
  
• Gait instability, impaired coordination (ataxia)
  
• Nystagmus, muscle weakness
  
• Seizures
  
• Associated anomalies: structural defects of heart, urinary tract, limbs, etc.
  

In mild cases symptoms may be subtle and only become evident later in development.

Management / Treatment

Because there is currently no cure for the malformation itself, care focuses on symptomatic and supportive treatment:

• Surgical treatment of hydrocephalus
   Procedures such as ventriculoperitoneal shunting or cyst‑to‑peritoneal shunting are used to restore cerebrospinal fluid flow. Shunt systems require regular maintenance and monitoring for complications.
  
• Rehabilitation and early intervention
   Physical therapy, occupational therapy, and speech therapy are combined to support motor and cognitive development. Early intervention in infancy is crucial.
  
• Seizure control
   Antiepileptic drugs are used to manage seizures, with periodic EEG monitoring and adjustment.
  
• Developmental support and educational assistance
   When intellectual delays are evident, special education support or therapy center services are provided, with emphasis on maximizing the individual’s potential.
  
• Management of associated anomalies
   If cardiac, urogenital, or other organ defects coexist, treatment should be coordinated with the respective specialists.
  

Prognosis and Outlook

The prognosis for Dandy‑Walker syndrome varies greatly by individual. The following factors are particularly influential:

• Whether hydrocephalus is effectively managed
  
• The extent of cerebellar and other brain malformations
  
• The degree of intellectual development and seizure severity
  
• The timeliness and adequacy of rehabilitation and therapeutic interventions
  

Medical outlook
In severe cases, substantial intellectual disability, motor impairment, frequent seizures, and associated anomalies may necessitate extensive lifelong support. Conversely, in mild cases with no hydrocephalus and limited cerebellar involvement, individuals may pursue education and employment. There are many reports of individuals living into adulthood with appropriate medical care and support.

Social life and welfare support

• Based on individual daily living capacities (ADLs), use of day programs or employment support is possible
  
• In school settings, collaboration between special education and mainstream institutions is fundamental
  
• In adulthood, some may live in welfare settings or group homes if needed
  
• Establishment of family support systems from early on, with planning that includes “life after parents are gone,” is vitally important