Dandy Walker Malformation is a rare congenital condition involving severe abnormalities in the cerebellum area of the brain and the fluid-filled spaces around it. The abnormalities are caused due to areas of the brain developing incorrectly. It affects around one in 25-35,000 births, and seems to affect both sexes equally.
The key features of the condition include cystic dilation (enlargement) of the fourth ventricle (an inner cavity for carrying cerebrospinal fluid - CSF - in the brain), the underdevelopment or the non development of the cerebellar vermis (the middle portion of the cerebellum) and cysts containing CSF which form at the base of the skull. In Dandy-Walker Malformation (DWM) the CSF produced by the brain cannot travel through the brain as it needs to due to a developmental defect, causing it to build up within the fourth ventricle and the posterior fossa (the area containing the brain stem and the cerebellum).
It is frequently associated with other disorders of the central nervous system and is often present with other birth defects such as malformations of the face and heart, cleft palate, and extra fingers.
The genetics involved in the condition are not yet fully understood, but in some cases having a parent with DWM may increase the risk of occurrence in a child. Apart from this there are no known risk factors.
Symptoms such as hydrocephalus (the collection of cerebrospinal fluid on the brain causing it to swell) can be detected before birth by ultrasound. Once born a child may have difficulties developing their motor skills and may have an enlarged skull (due to build up of fluid). In older children the build up of pressure inside the brain can lead to symptoms including convulsions, irritability and vomiting. Damage to the cerebellum can also lead to lack of co-ordination, jerky movements of the eyes and unsteadiness. Bulging at the back of the skull, an increased head circumference and abnormal breathing patterns may also be present.
The condition is usually diagnosed within the first year with a key consideration being an enlargement of the head due to cysts forming in the brain. X-rays, CT scans and MRI tests are carried out to evaluate the development of cerebellar vermis, and check the forth ventricle and posterior fossa for areas of swelling.
There is currently no known cure for the condition, with attention instead placed on managing and treating the symptoms. Hydrocephalus (excess fluid on the brain) is usually treated by using a shunt to drain off the excess fluid which helps relieve swelling and associated symptoms. Ventriculostomy is a procedure involving a tube connecting one ventricle to another allowing the affected ventricle to be drained. In cases of delayed puberty hormones may be given and anti-convulsant medication may be prescribed. Doctors will generally construct a treatment plan based on the symptoms present, and sometimes other therapies such as vision therapy, speech therapy and physiotherapy may be required.
The prognosis for children with Dandy-Walker malfunction varies depending on the severity of the malformation and the amount of associated conditions that may be present. Children with severe cases may not survive infancy. The chances of normal intellectual development vary depending on the individual case, with some proven instances of children reaching adulthood with a reasonable degree of happiness and quality of life.