Dandy Walker Syndrome
Dandy Walker syndrome is a rare type of abnormality in
the brain that is present from birth. There are two main
abnormalities that characterize Dandy Walker
Syndrome, which are described below. The first main
abnormality found in Dandy Walker Syndrome is the
presence of a large cyst on the fourth ventricle which
causes it to be grossly misshapen (see picture to the
right). A cyst is an abnormal lump, swelling, or sac that
contains fluid, a part solid material, or a gas, and is
covered with a membrane. A membrane is a thin layer
of flexible tissue that covers something. Ventricles are
openings in the brain that produce cerebrospinal fluid,
which is the cushiony fluid that protects the brain and
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The fourth ventricle is located in the back, bottom part of the brain. It connects the
ventricles in the cerebrum (the upper part of the brain) through a narrow canal called the
cerebral aqueduct. The cerebrospinal fluid comes through the fourth ventricle to bathe
and cushion the outside of brain and spinal cord.

In Dandy-Walker syndrome, the fourth ventricle (and other ventricles in the brain)
becomes abnormally wide, which leads to an abnormal buildup of cerebrospinal fluid in the
head known as hydrocephalus.
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The second main abnormality found in Dandy Walker syndrome is
an underdeveloped cerebellum. The cerebellum is an area in the
back, bottom part of the brain that plays an important role in
movement and coordination.The cyst that is present in Dandy
Walker syndrome begins to form long before the baby is born, when
it is inside of the mother. The cyst can eventually grow to such a
size that it lifts up and distorts the cerebellum. An area in the
cerebellum known as the vermis is either partially incomplete or
totally missing in Dandy Walker syndrome. The vermis of the
cerebellum is a wormlike appearing structure in the middle of the
cerebellum. The vermis plays an important role in controlling the
posture and tension of muscles.

The cerebellum and other some other important lower brain structures rest in an indented area of bone in
the lower, back part of the skull known as the posterior cranial fossa. The posterior cranial fossa becomes
larger in patients with Dandy Walker syndrome. In addition, people with Dandy Walker syndrome can
develop cysts can in the posterior cranial fossa.


In addition to the abnormalities mentioned in the previous section, there are other brain abnormalities that
are sometimes present in Dandy Walker syndrome. In some individuals, the cyst that forms in the fourth
ventricle (see above) closes two normal openings in that ventricle. These two openings are known as the
foramen of Luschka and the foramen of Magendie. As a result, the cerebrospinal fluid that is in the fourth
ventricle cannot escape out of those openings and the fluid builds up, causing hydrocephalus.
Hydrocephalus is a condition in which there is an abnormal increase in cerebrospinal fluid inside the head.

Another characteristic is the partial or total absence of the corpus callosum, which is a large band of
nerve fibers in the brain that help the two sides of the brain communicate with each other. A partial
absence of the corpus callosum is common in Dandy Walker Syndrome. Heterotopia can be present as
well. Heterotopia refers to when gray matter (a gray appearing substance) in the brain is out of its normal
place and has typically made its way into the white matter (a white appearing substance) of the cerebrum,
where it should not be. The cerebrum is the top section of the brain.

Other brain abnormalities include an absence of gyri (rounded elevations) or abnormally small gyri. Gyri
are normally present on the brain and help increase its surface area (the total area exposed on the


It is important to note that the signs and symptoms of Dandy Walker Syndrome can occur suddenly or
never occur at all. In fact, sometimes Dandy Walker syndrome is not diagnosed until the person reaches
adulthood, although most people are diagnosed by age one. The following is a list of some signs and
symptoms that can occur in Dandy Walker syndrome. The list is variable and does not occur in all people
affected with this condition.

Most of the signs and symptoms of Dandy Walker syndrome are due to a buildup of cerebrospinal fluid in
the head, a condition known as hydrocephalus. Hydrocephalus is usually accompanied by increased
pressure within the bones that surround the brain. This pressure can also cause the sutures (places
where two bones join together) of the skull to separate, resulting in an abnormally large skull. Sometimes
this is the only sign of Dandy Walker syndrome, and it can happen rapidly. The "soft spot" in infants, which
is the area where the skull bones have not yet closed together, can bulge outwards.

People with hydrocephalus have a thin scalp (the skin that covers the skull). As a result, the veins in the
scalp are easily seen in people with hydrocephalus. Also, as was mentioned earlier, infants sometimes
have a difficult time moving their head if they have an abnormal buildup of fluid in it. They may also have a
poor control of their neck muscles. Some people with Dandy Walker syndrome experience titubation,
which is an unsteady posture characterized by staggering or stumbling while walking and swaying of the
head and upper part of the body while sitting.

Because of the incomplete development of the cerebellum, which is important for controlling motor
abilities, infants with Dandy Walker syndrome tend to display poor motor development. For example, many
children with Dandy Walker syndrome have a very difficult time walking. Many people with Dandy Walker
syndrome also have spasticity. Spasticity is a condition in which there is increased tension in muscles
that resist the force of gravity (the natural force that pulls objects downwards) and increased resistance to

In older children with Dandy Walker Syndrome, increased pressure in the head can cause irritability,
vomiting, and convulsions (abnormal, severe, involuntary muscle movements). Approximately 20 to 30%
of children with Dandy Walker syndrome experience seizures, which are involuntary muscle movements
and/or decreased awareness of the environment due to overexcitement of nerve cells in the brain.
Incomplete development of the cerebellum in older children with Dandy Walker syndrome can cause
impaired motor coordination, imbalance, dizziness, and uncontrollable jerky eye movements.

Some other problems with the eyes that can occur in people with Dandy Walker syndrome include
catracts, retinal dysgenesis, and choroid coloboma. Cataracts is a darkening of the lens in the eye(s).
The lens is an organ located between the colored part of the eye, that bends light as it enters the eye.
Retinal dysgenesis is an abnormal formation of the retina that occurs when the baby is developing inside
of the mother. The retina is an area at the back of the eye that is sensitive to light. Choroid coloboma is a
birth defect in which the choroid of the eye is not formed properly. Choroid is a layer in the eye between
the sclera (the outer, white part of the eye) and the retina. All of these abnormalities of the eye make it
difficult to see.

Some people with Dandy Walker syndrome have sleep apnea, which is a disorder in which the person
does not breath for periods of time while sleeping. Other signs and symptoms of Dandy Walker syndrome
include increased head size, a bulge in the back of the head, abnormal breathing, and poor functioning of
the cranial nerves. Cranial nerves are nerves that emerge from the brain. Approximately 30% of children
with Dandy Walker syndrome have abnormal formations of the face, heart, fingers, face, arms, and/or
legs. One type of abnormality is the hands and feet is the presence of more than the normal number of
fingers or toes. In some cases, two are more fingers are joined together.

One type of facial abnormality is cleft lip. In cleft lip, the upper lip has not formed properly and there are
one or more openings in it. Cleft palate, which is an incomplete formation of the roof of the mouth, is also
seen in some cases of Dandy walker syndrome. The incomplete formation in cleft palate is characterized
by a groove in the middle of the roof of the mouth.

Some people with Dandy Walker have abnormalities in the structure of the urinary tract. The urinary tract
is the part of the body that deals with the formation and excretion of urine (pee). To excrete means to
release from the body as waste. An example of such an abnormality would be polycystic kidney, a
condition in which the kidneys are too large and contain many cysts on them. The kidneys are two organs
located on each side of the spine, behind the stomach. The kidneys filter (remove) wastes from the blood.


Yes, but not always. Sometimes, the cyst along the fourth ventricle (see previous sections) extends into
the opening where the spinal cord is located. A condition that affects the spinal cord, which is associated
with Dandy Walker syndrome is syringomyelia. Syringomyelia is a condition in which long, fluid filled
spaces are present in the central gray matter (a gray looking substance) of the spinal cord and
surrounded by thick tissues made of glial cells. Glial cells are supportive cells. The long, fluid filled spaces
look like tubes in the spinal cord. It can also look like one big tube in the spinal cord.

The vertebrae in the lower part of the spine can be abnormal in people with Dandy Walker syndrome.
Vertebrae are bones that form an opening in which the spinal cord passes.


Unfortunately, many children with Dandy Walker syndrome suffer from mental retardation. However, 50%
of children with Dandy Walker syndrome have normal cognitive functioning.


In most cases, the cause of Dandy Walker syndrome is unknown. It has been suggested that
abnormalities in chromosomes may cause some cases of Dandy Walker syndrome. Chromosomes are
structures in a person's cells that contain genes. Genes are units of material that contain coded
instructions as for how certain bodily characteristics (such as eye color) will develop. All of a person's
genes come from his/her parents. Some genes are normal whereas others may be abnormal. Abnormal
genes can cause diseases.

It has also been suggested that Dandy Walker syndrome can be caused by exposure to an anti-acne
(anti-pimple) medication called isotretinoin during the first three months that the baby is developing inside
the mother.


Dandy Walker syndrome is diagnosed with X-rays and a CT (computerized tomography) scan of the brain.
CT scanning is a more advanced imaging technique that uses x-rays and computer technology to
produces more clear and detailed pictures than a traditional x-ray. Magnetic resonance imaging (MRI)
scans of the brain can also be used. MRI scans produce extremely detailed pictures of the inside of the
body by using very powerful magnets and computer technology. MRI scans are more detailed and more
expensive that CT scans. A rarely used technique to diagnose Dandy Walker syndrome is a
ventriculogram. A ventriculogram is a specific x-ray study of the ventricles in the brain. Ventricles are
openings in the brain that produce the cushiony fluid that protects the brain and spine.


Approximately 80% of children that are diagnosed with Dandy Walker syndrome receive this diagnosis by
age 1. The diagnosis is usually made this early because of the enlarged head caused by the buildup of
cerebrospinal fluid. This buildup of fluid often makes it difficult for the infant to control his/her head, which
usually leads parents to bring the child in to the doctor for an evaluation.


Unfortunately, as of yet, there is no way to reverse the main structural abnormalities caused by Dandy
Walker syndrome. However, some of the other abnormalities associated with this condition can be
treated. For example, physical therapy is often used to help patients improve their abnormal motor
functioning. However, many individuals will still continue to have difficulty walking and have poor balance.
Another treatment is to give medication to reduce seizures. Seizures are involuntary muscle movements
and/or decreased awareness of the environment due to overexcitement of nerve cells in the brain.

To treat the buildup of fluid in the head, a flexible tube called a shunt can be placed in the ventricles of the
brain, the inside of the brain, or the posterior fossa (the indented bone in the lower, back part of the skull).
From one of these areas, the tube will drain the extra fluid into the space between layers that line the
belly. The fluid will then be absorbed along the wall of the belly.

The shunting procedure will decrease the pressure in the head and will thus prevent the head from
widening further. Sometimes, more than one tube needs to be placed, such as a tube in a ventricle and a
tube in the posterior fossa. If these two spaces are not connecting, the surgeon will connect the tubes to
a common valve that drains the fluid.

The cyst cannot be removed with surgery because it already has blood vessels that go through it and
connect to the brain. Taking out the cysts would thus cause too much damage to the brain.


Dandy Walker Syndrome is rare, occurring in about 1 out of every 25,000 to 30,000 births.


Although some studies report that approximately equal numbers of males and females are affected with
Dandy Walker Syndrome, others report that more females are affected than males.


The prognosis of people with Dandy Walker syndrome is variable, even when the buildup of fluid in the
head is correctly treated at an early stage. Generally, the more severe the defects, the worse intellectual
abilities and the less likely the chance of survival will be.


Dandy Walker syndrome is also known as Dandy Walker, Dandy Walker cyst, Dandy Walker variant, and
Dandy Walker malformation.


Dandy Walker syndrome was named after two physicians, Walter E. Dandy and Arthur E. Walker. Walker
was an American surgeon who lived from 1907 to 1995. Dandy was an American neurosurgeon who lived
from 1886 to 1946. Neurosurgeons operate on the brain, spine, and/or nerves outside the brain and

It is interesting to note, however, that the condition was fist described by Dandy and a U.S. physician
named Kenneth Blackfan in 1914. Blackfan lived from 1883 to 1941. Dandy and Blackfan described the
case of a 13-year-old child with an abnormally high amount of cerebrospinal fluid in the head, cysts in the
back of the skull, and an incompletely developed vermis of the cerebellum. Please see the beginning of
this entry for a description of these terms.

Many years went by and it 1942, Arthur Walker and his colleague, Johhn Taggart, gave a talk in which
they described nine cases (including the one described by Walker and Blackfan) in which children were
born with the similar signs mentioned above. The term, "Dandy-Walker syndrome" was first used in 1954
by C. E. Benda in a paper he published entitled, "The Dandy-Walker syndrome or the so-called atresia of
the foramen of Magendie." The article was published in the Journal of Neuropathology and Experimental
Neurology, Volume 13, pages 14-39.