DANDY-WALKER MALFORMATION
DEFINITION:
A congenital anomaly of the cerebellum and 4th ventricle
characterized by hydrocephalus due to a cystic expansion of the 4th
ventricle in the posterior fossa.
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- risk factors:
- familial - autosomal recessive
- exposure to isotretinoin in 1st trimester
- chromosomal malformations
- 3q+, 5p+, 6p+, 8p+, 8q+, 9p+, 17q+, triploidy
- associated anomalies:
- agenesis of the posterior cerebellar vermis & corpus callo-sum,
aqueductal stenosis, infundibular harmartomas, posterior fossa
lymphomas, syringomyelia
- agyria, microgyria, grey matter heterotopias
2. Non-Neural
- abnormal lumbar vertebrae, polydactyly, syndactyly
- cleft palate, polycystic kidneys
- cataracts, retinal dysgenesis, choroid coloboma
PATHOGENESIS:
- a developmental cerebellar defect occurring before the
embryo-logic differentiation of the 4th ventricle foramina
results in the blockage or atresia of these foramina plus the
foramen of Magendie and foramen of Luschka. This, in turn,
results in the cystic transformation of the roof of the 4th
ventricle and in an obstructive (noncommunicating)
hydrocephalus, the cyst arising from the compromised absorption
of CSF
CLINICAL FEATURES:
- rapid increase in head size
- prominent occiput
- positive transillumination of the skull
2. Others
- long-tract signs - spasticity
- cerebellar signs - ataxia, nystagmus
- apnea, infantile hypotonia, seizures, titubation,
developmental delay, mental retardation
INVESTIGATIONS:
- enlargened posterior fossa with superior displacement of
torcular herophil and lateral sinus grooves
2. CT/MRI
- the 4th ventricle is grossly misshapen and is a large,
ependymal-lined cyst that may extend into the spinal canal -
cerebellar hemispheres are hypoplastic and displaced
superiorly
- hypoplastic or absent posterior vermis
- ventriculomegaly with enlarged aqueduct of Sylvius, 3rd
and lateral ventricles
MANAGEMENT:
2. Supportive
- treat complications i.e., anticonvulsants, physiotherapy
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