Dandy-Walker Malformations (or cysts) are developmental
malformations in which the 4th Ventricle appears as a
"Cystic" structure. This is a defect involving the
Cerebellar Vermis, which may be partially or completely absent,
with resulting dilation of the 4th Ventricle which
becomes a "Cyst". It is thought that the defect results from
abnormal embryogenesis of the roof of the 4th Ventricle.
A milder form is termed the "Dandy-Walker Variant". This disorder
may account for approximately 5% to 10% of cases of
Ventriculomegaly (enlarged Ventricles).
In newborns, the diagnosis can be confirmed by CT
Sonographic Characteristics of Dandy-Walker Malformation
The diagnosis can also be made by identifying the superior
displacement of the Lateral Sinus groove on plain x-rays, or
by transillumination of the Posterior Cranial Fossa.
While many of these patients undergo investigation as
newborns, many others develop normally through
childhood and may only develop symptoms later in
adolescence or early adulthood. Some patients are identified
incidentally when undergoing a Brain scan for some other
reason such as head trauma.
- A Cerebellar Vermis defect (complete or partial). The
defect is inferior in partial conditions.
- A posterior fossa cyst representing a dilated fourth
- Enlargement of the Cisterna Magna (representing the
- Splaying of the cerebellar hemispheres
For the majority of those patients who were incidentally
identified and who are asymptomatic, no treatment is
For symptomatic patients, the most effective treatment
incorporates the partial resection of the Arachnoid
membranes that constitute the "lining" of the Cyst accompanied
by the simultaneous insertion of a "shunt" to divert the
CSF to the peritoneal cavity from where the fluid can be harmlessly
reabsorbed. The resection of the membranes and the intracranial
placement of the "shunt" tubing can be accomplished using
Minimally Invasive Microendoscopic techniques.
In the event that Hydrocephalus is present, this usually requires
a "shunt" of the Lateral Ventricles.
Other anomalies associated with Dandy-Walker Malformation
include agenesis of the Corpus Callosum, Aqueduct of Sylvius
stenosis, microcephaly, encephalocele, gyral malformations
and Lipomas, cardiac & urinary tract anomalies, polydactyly
(extra digits); facial malformations and
National Institute of Neurological Diseases & Stroke (NINDS)
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This page last edited on 2/22