A compressed brainstem is not a contraindication, however. ETV has a more modest success rate than shunts, as the hole often closes over. It is more likely to fail in younger patients (below 1 year), and its effects on the developing brain are not yet known. Cysts posterior to the cerebellum, presenting in children younger than 5 years, have been labeled developmental retrocerebellar cysts under a new classification in relation to the proposed neuroendoscopic management.Previously, craniotomy of the posterior fossa and excision of the cystic membrane was used, which was often unsuccessful in preventing cyst reformation and carried a degree of mortality. This may still be reserved for patients with repeated shunt failures/infections. Other
Treatments for any other symptoms are generally focussed on the specific condition involved and may include supported education, physical therapy or other services. Genetic counselling may be offered to parents for future conceptions. Prognosis
The prognosis is first and foremost dependent on the early and successful treatment of hydrocephalus, if present. The other significant factor affecting prognosis is the presence of a comorbid genetic condition or brain anomaly.Mortality rates from DWM are roughly 15%. In a study of Dandy–Walker variant (DWV), a mortality rate of 12.5% was observed. The most common cause of death is complications from hydrocephalus or its treatment. Untreated hydrocephalus can lead to increased intracranial pressure and brain damage. Shunts used to treat DWM have a moderate-to-good success rate, but they have a higher-than-average failure rate, which can result in failure to reduce the intracranial pressure or infection, such as meningitis.
This usually presents within the first year of life (85% of the time), most often within the first 3 months. Signs of hydrocephalus in infants include increasing head size, vomiting, excessive sleepiness, irritability, downward deviation of the eyes (known as "sunsetting eyes") and seizures. In contrast to classic DWM, only around 30% of those with Dandy–Walker variant (DWV), in which the posterior fossa is not enlarged, have hydrocephalus. Neurological
Despite the hypoplastic cerebellar vermis, just over half of individuals with DWM (between 27% and 84%) do not appear to have significant intellectual disability or developmental delay. However, many of the genetic conditions associated with DWM can present with developmental delay and other brain anomalies. Agenesis of the corpus callosum has been found in between 5% and 17% of those with DWM. This does not seem to result in intellectual disability on its own, however. Other brain abnormalities known to be sometimes associated with DWM include grey matter heterotopia, pachygyria (fewer ridges in the brain), lissencephaly (shallower ridges), polymicrogyria, holoprosencephaly and schizencephaly. Individuals with these features tend to have developmental delay or seizures. Those without any other central nervous system abnormalities tend to have normal or close-to-normal intellectual development. A 2003 review found that moderate-to-severe intellectual disability and non-DWM brain abnormalities were only present in those with the most severe cerebellar vermis malformations (less than two fissures/three lobules in the vermis), and these comprised 16% of their sample.