Dandy-Walker syndrome is a congenital malformation affecting the cerebellum, an area in the back of the brain, and the fluid-filled spaces around it. One of the main features of this condition is a large fourth ventricle, where fluid flows between the spinal cord and the upper and lower parts of the brain. Some people also have an increase in pressure in the brain.
Dandy-Walker syndrome includes other less common brain abnormalities as well, including absent or underdeveloped tissue connecting the right and left sides of the brain, a small protrusion of brain tissue through the back of the skull, or a cluster of nerve cells not migrating to their proper location during fetal development.
Dandy-Walker malformation is relatively rare, occurring in only one of 10,000 to 30,000 births and affecting females more than males. In about 10 to 20 percent of cases, signs and symptoms do not develop until later in childhood or adulthood. These individuals present with a different set of symptoms than people affected in infancy.
The cause of Dandy-Walker syndrome is unknown in most cases. In some, it results from a combination of genetic and environmental factors affecting early fetal development. Some problems during pregnancy may also increase the risk of Dandy-Walker syndrome, including the mother having diabetes or an infection.
Although some people with Dandy-Walker syndrome have family members who also have the disease, the connection with inheritance is not clear. Sometimes, the syndrome is caused by another underlying genetic issue, but the inheritance pattern in these cases seems to be connected to the underlying abnormalities. Researchers are currently studying the gene changes that cause Dandy-Walker syndrome.
Most cases of Dandy-Walker syndrome present within the first year of life. The first sign that something is wrong is usually increased pressure in the brain, which may cause the infant's head to measure larger than the averages on infant growth charts. Some forms of Dandy-Walker syndrome also cause heart, limb, and face abnormalities or malformations in the digestive or urinary system that could require medical intervention.
Dandy-Walker syndrome is not always evident. Symptoms can appear quickly and dramatically, while others may develop slowly and go unnoticed for a time. In infants, these symptoms include enlargement of the skull and slow motor development. As the child gets older, symptoms of increased pressure in the brain appear, like vomiting, irritability, lack of muscle coordination, and jerking of the eyes. Abnormal breathing may also occur.
The first diagnostic test that most doctors perform for suspected Dandy-Walker syndrome is a fetal ultrasound to visualize the brain. After the 20th week of gestation, an MRI is more definitive, allowing for imaging of the brain structure not possible with ultrasound. Even so, however, physicians can diagnose prenatal Dandy-Walker syndrome as early as 18 weeks into the pregnancy, when the affected parts of the brain are fully developed.
The main treatment for Dandy-Walker syndrome is relieving pressure on the brain. The most common procedure is a ventriculoperitoneal (VP) shunt — a narrow plastic tube that drains fluid from the ventricles into the abdomen to prevent the fluid from accumulating and causing increased pressure in the brain. Medications can control seizures, and occupational or physical therapy can improve motor skills.
The prognosis for people with Dandy-Walker syndrome depends on the severity of the symptoms and the complexity of the changes in the brain. The presence of other genetic syndromes plays a huge role in the long-term outlook of people with this condition. Some people with Dandy-Walker syndrome face severe intellectual and physical disabilities, but with early treatment, those who have an isolated type of the disease can experience better outcomes.
The biggest complication of Dandy-Walker syndrome is the presence of other genetic abnormalities and the possibility of the involvement of other parts of the body. About sixteen percent of patients with Dandy-Walker syndrome have other chromosomal abnormalities, and this greatly impacts their quality of life. There are some complications of a VP shunt to consider, too, including shunt malfunction and infection.
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