Dandy-Walker Syndrome Treatment 

Treatment of the  Dandy-Walker syndrome has undergone evolutionary change since the entity was originally recognized, and even today there is no universal agreement regarding its management. Dandy and Blackfan were the first to describe posterior fossa exploration and excision  of the cyst membrane. This was the only treatment available for several decades until the advent of ventricular shunting devices. Initially, shunting was performed only  if membrane excision did not successfully control the hydrocephalus. Subsequent reviews of several clinical series led  to the recognition that the incidence of success from membrane excision was sufficiently small that the primary mode of therapy should be shunting. This has been universally accepted during the past decades, but disagreement still exists as to the optimum position of the proximal end of the shunt. Many authors have advocated using a standard shunt system originating in the lateral ventricle. Raimondi and co-workers have advocated simultaneous Y shunting of the lateral ventricles and the posterior fossa cyst because there is a significant incidence of aqueduct occlusion and because shunting of only the lateral ventricles leads to upward transtentorial herniation from lack of decompression of the cyst. Other observers believe that aqueductal stenosis is rare and can be easily detected by injecting a contrast substance into a lateral ventricle at the time of computed tomography (CT) scanning. On the assumption that communication between the lat¬eral ventricles and the cyst does exist, it is recommended that the proximal end of the shunt  be placed within the cyst. This reservoir of CSF, unlike the lateral ventricles, does not collapse on decompression, partially because of the large posterior fossa  and the associated cerebellar dysgenesis. Therefore, shunt malfunction due to proximal catheter occlusion is less likely to occur. If communication between the lateral ventricles and the cyst does not exist, an endoscope may be inserted via a lateral ventricle and the membrane responsible for the noncommunication fenestrated to facilitate creation  of one compartment. A catheter is directed through the ventricle into the posterior fossa cyst to avoid a complex shunt system. 

One can measure the results of treatment of the Dandy-Walker syndrome in terms of mortality, morbidity, or a long-term developmental and functional competence. Mortality ranged between 41-26 percent by several authors. The principal causes of death were shunt infection and cardiorespiratory arrest. The latter complication is a recognized risk in the Dandy-Walker syndrome and has been attributed to the precarious function of a maldeveloped brain stem. 

Morbidity associated  with ventricular shunting primarily relates to mechanical shunt malfunction and infection. The incidence of each of these entities has decreased in recent years. It is believed that malfunction of the shunt will be reduced further by using the cyst, rather than the ventricles, for shunting. 

Several authors reporting, that among the survivors 40-71 percent had subnormal intelligence (IQ <83). The potential inclusion of Dandy-Walker variants into the clinical series  may favorably skew the developmental outcome of these individuals. The presence of associated anomalies does not correlate well with lower IQ scores except for the consistently low scores of those patients with agenesis of the corpus callosum. From these observations, one can conclude that the Dandy-Walker syndrome is not limited  to a mechanical disturbance of CSF circulation but rather represents a  more generalized disorder of neural development.