Diagnosis and management of the Dandy-Walker malformation: 30 years of experience.

Thirty-seven patients with Dandy-Walker malformation were treated between 1959 and 1989. Eighty percent of patients became symptomatic by 3 years of age, with 70% presenting within the 1st year of life. Hydrocephalus was present in 91% of patients at the time of diagnosis. Clinical presentation was most often heralded by symptoms and signs of hydrocephalus with focal neurological findings being a less prominent feature. One third of children demonstrated developmental delay. Associated congenital anomalies were present in 48% of children. Contemporary neuroimaging including computed tomography and magnetic resonance imaging facilitated diagnosis obviating the need for invasive studies such as pneumoencephalography and ventriculography. Patients were initially managed by posterior fossa craniectomy with membrane excision (8), lateral ventricle shunt alone (13), shunting of the cyst alone (4), or combined shunting of the cyst and lateral ventricles (12). Combined shunting proved superior to the other methods, being successful in alleviating hydrocephalus and posterior fossa symptoms in 92% cases. The overall mortality was 24%, the majority occurring before 1970. Of the 28 survivors, 27 (96%) are shunt-dependent, with 19 having a combined shunt system in place. Therefore, we currently favor combined shunting of the cyst and lateral ventricles as the initial procedure for patients with Dandy-Walker malformation.