CNS nontumor


Dandy-Walker Malformation

Last author update: 1 May 2016
Last staff update: 11 September 2023

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PubMed Search: dandy-walker malformation pediatric

Erdener Özer, M.D., Ph.D.
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Cite this page: Özer E. Dandy-Walker Malformation. website. Accessed September 22nd, 2023.
Definition / general
  • Dandy-Walker syndrome (DWS) is a congenital brain malformation involving the cerebellum
  • Note: Dandy-Walker does not represent a single entity, as there are three identified types of Dandy-Walker complexes: DWS malformation, DWS mega cisterna magna and DWS variant
Essential features
  • Dandy-Walker malformation (DWM) has six features (Childs Nerv Syst 2011;27:1665)
    1. Large, median posterior fossa cyst communicating to the fourth ventricle
    2. Absence of the lower portion of the vermis at different degrees
    3. Hypoplasia, anterior rotation and upward displacement of the remnant of the vermis
    4. Antero-lateral displacement of normal or hypoplastic cerebellar hemispheres
    5. Large bossing posterior fossa with elevation of the torcular
    6. Absence or flattening of the angle of the fastigium (highest point of fourth ventricle)

  • All six features are not found in each case
  • The essential features are: enlargement of the posterior fossa, cystic dilatation of the fourth ventricle and agenesis of the vermis
  • Hydrocephalus is present in 80% of the cases and should not be considered a specific component of the malformation
  • Other CNS malformations can be observed like occipital encephaloceles, corpus callosum agenesis, schizencephaly and glial heterotopias

  • Dandy–Walker variant (DWV): cystic posterior mass with variable hypoplasia of the cerebella vermis and no enlargement of the posterior fossa (
  • Dandy Walter mega-cisterna magna: enlarged cisterna magna with normal cerebellar vermis and fourth ventricle
  • Dandy-Walker malformation, Dandy-Walker syndrome
  • DWM may be caused by many conditions affecting the brain development in an early stage
  • The type of insult is less important than the timing and duration of exposure to the noxious agent (J Child Neurol 2011;26:1483)
Dandy-Walker malformation can occur due to:
  • Mendelian conditions: Walker-Warburg syndrome, Mohr syndrome, Meckel-Gruber syndrome
  • Chromosomal aberrations: several duplications involving 5p, 8p, 8q; trisomy 9, duplication on 17q, Turner syndrome
  • Environmentally induced malformation syndrome: prenatal exposure to rubella, cytomegalovirus, toxoplasmosis, coumadin, alcohol and maternal diabetes
  • Also multifactorial and sporadic disorders: see Congenit Anom (Kyoto) 2007;47:113, Childs Nerv Syst 2011;27:1665
Clinical features
  • The symptoms are related to hydrocephalus, cerebellar and cranial nerves dysfunction and to the presence of associated anomalies
  • 80 - 90% present in the first year
  • DWM is often associated with other brain or systemic anomalies (Cerebellum Ataxias 2016;3:1)
  • May be diagnosed in utero by using 3D ultrasound as early as 14 weeks of gestation
  • Fetal MRI is indicated in case of posterior fossa malformation suspected by ultrasonography
Radiology description
  • MRI with sagittal views and T2 weighted images are mandatory for studying precisely the content of the posterior fossa
Radiology images

Images hosted on other servers:

Variant DWS
with dysplasia
of pons and

Prognostic factors
  • The clinical course is very variable and depends on the severity of the associated central nervous system malformations, with neurologic development ranging from normal to severely intellectually disabled
  • The goal of treatment is the control of the hydrocephalus and of the posterior fossa cyst
Gross description
  • In classic DWM, a huge csyt occupies almost the entire posterior fossa, displacing the brainstem forward and flattening the pons against the clivus
  • The neuropathological picture is completed by aplasia of the vermis, heterotopia of the cerebellar cortex and enlargement of the posterior fossa, with a high position of the tentorium and transverse sinuses
Gross images

Contributed by Jean-François Hirsch, M.D.

Dandy-Walker malformation

Differential diagnosis
  • Different cystic lesions may originate in the posterior fossa
  • Lesions that do not meet the diagnostic criteria should NOT be considered as DWM, i.e. cysts that do not communicate directly with the fourth ventricle, cystic fourth ventricle associated with a normal posterior fossa and normally inserted tentorium
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