2. Dandy-Walker Syndrome
Dr Saeed Mokhtary
Resident of Neurosurgery

3. HISTORY

4. The first autopsy description of such a clinical picture was offered in 1887 by Sutton.
It was not until 1914 that Dandy and Blackfan realized an association between hydrocephalus and cystic fourth ventricular dilation in a 13-month old girl.
The malformation was further characterized by Dandy in 1921 and by Taggart and Walker in 1942 as being related to congenital atresia of the fourth ventricular exit foramina.
However, it was Benda in an autopsy series in 1954 who first used Dandy-Walker syndrome to describe this condition and offered a new theory on its etiology.

7. EMBRYOLOGY

8. Cerebellar development begins in the ninth week, when the cerebellar hemispheres develop and subsequently fusing to form the vermis.
The choroid plexus of the fourth ventricle and the foramina of luschka and magendie form around the tenth week of gestation.
Cerebrospinal fluid (csf) then accumulates within the fourth ventricle, forming this space.
The cerebellar lobules develop in an anterior-to-posterior direction and are completely formed by week 18.

9. Persistence of the posterior medullary velum, which remains as a thick arachnoid and ectodermal membrane
Dysgenetic development of the anterior membranous area of the rhombencephalon
Developmental failure of the foramen of magendie is not necessary for the development of DWS

10. TERMINOLOGY AND DIFFERENTIAL DIAGNOSIS

11. Dandy Walker malformation (DWM)
A large posterior fossa cyst communicating with the fourth ventricle
Absence of a portion of the inferior vermis
Hypoplasia, anterior rotation, and upward displacement of the remaining vermis
Absence or flattening of the angle of the fastigium
A large posterior fossa with torcular elevation
Anterolateral displacement of the cerebellar hemispheres

12. Turcula
vermis
4th ventricule

13. Primary
Fissure F
Pre-Pyramidal
Fissure

15. Dandy-Walker variant (DWV)
A milder spectrum of DWS-like signs that were not congruent with the classic definition, but a clear clinical separation has not been defined.
An inferior cerebellar vermian defect and communication between a normal-sized cisterna magna and fourth ventricle.

17. Dandy-Walker complex (DWC)
Continuum of posterior fossa anomalies
Mild (mega–cisterna magna only)
Moderate (mild hypoplasia of vermis, enlarged fourth ventricle)
Severe (agenesis of vermis, dilation of posterior fossa cyst and fourth ventricle)

18. Mega–cisterna Magna

19. Agenesis Of Vermis
Jubert Syndrome

20. CLINICAL FEATURES

21. Occur in 1 of 25,000 to 30,000 newborns
The majority of patients presenting in the first YEAR(3 months)
Hydrocephalus may not be present on prenatal imaging or at birth but has been reported to occur in roughly 80% of all patients with DWS

22. The most common postnatal presentation is macrocrania.
Other signs and symptoms
The sunset sign
A large posterior fossa
Seizures
Spasticity
Lethargy
Delayed milestones
Respiratory failure
Apnea
Deafness,
Visual problems
Increased intracranial pressure
Older children and adults
Headache
Vomiting
Cranial nerve palsies
Nystagmus
Ataxia

23. Numerous malformations are described in the literature in association with DWS and its variants.
CNS anomalies (68%)
Dysgenesis/agenesis of corpus callosum
Occipital meningocele
Systemic abnormalities (25%)
Facial capillary hemangiomas
Cardiac defects
Atrial septal defect
Patent ductus arteriosus
Tetralogy of fallot
Ventricular septal defect

24. Diagnostic tools

25. DIAGNOSIS
Diagnosis of DWS is made on the basis of anatomic findings on imaging.
MRI representing the gold standard
CSF dynamics
cine MRI sequences for detecting the etiology of hydrocephalus

26. PRENATAL IMAGING
Ultrasound
May be discordant with postnatal imaging or postmortem pathologic findings
Fetal MRI
Associated congenital abnormalities cognitive and developmental delays
Insufficient for anatomic analysis of the vermis

27. GENETICS
A disorder of genetic heterogeneity
Chromosomal aberrations
Occur in about 50% of cases
Trisomy 13
Trisomy 18
Triploidy
Inheritance patterns may be x-linked or autosomal recessive

28. TREATMENT

29. CYST MEMBRANE EXCISION
To facilitate spinal fluid flow
On the basis of the belief that hydrocephalus in DWS was due to obstruction of the foramina of luschka and magendie
Poor efficacy (75% of patients still requiring a shunt)
High mortality (10%)
May rarely play a role in the treatment of DWS, particularly in older children or after multiple shunt failures.

30. DIVERSION OF CSF THROUGH SHUNTING
The most widely accepted first-line treatment
Controversy exists in terms of which shunting procedure yields the best results
Shunting the supratentorial compartment
Shunting the cerebellar cyst
Shunting both compartments (dual shunt)

31. NEUROENDOSCOPIC INTERVENTION
Endoscopic third ventriculostomy
An aqueductal “stent” with shunting
Endoscope-assisted transtentorial proximal catheter placement with shunting.

32. Assessment of aqueductal flow
MRI and cine MRI
VPS
The primary option
Safest and most effective treatment
Endoscopic treatment
Controversial
Cyst treatment
Reserved for refractory cases
Presence of aqueductal stenosis
ETV and aqueductal stenting or a dual shunt

33. PROGNOSIS

34. MORTALITY
Has significantly decreased
(from 100% in 1942 to 10% or less today)
This improvement is likely due to advances in medical and surgical care and improved management of hydrocephalus.
Death:
Secondary to shunt malfunction or associated systemic anomalies.

35. ASSOCIATED CONDITIONS
Seizures, hearing or visual problems, and other systemic or CNS abnormalities are predictive of worse outcome IQ
80 or more in 50% of long-term survivors, normal IQs in 30%
vermian lobulation may be a useful prognostic factor of functional development