If this occurs, a suboccipital decompression with duraplasty may be attempted.In DWM, it is not agreed whether a shunt should be placed in the fourth ventricle (a cystoperitoneal shunt, or CP shunt), the lateral ventricles (a ventriculoperitoneal shunt, or VP shunt) or both, due to conflicting studies on whether the cerebral aqueduct is affected by the malformation. However, a CP shunt almost always drains both the fourth and lateral ventricles in DWM, and according to strict definitions of the malformation, the aqueduct should be assumed open, though imaging is important to confirm this. Many authors therefore recommend the CP shunt as the logical option. However, it is associated with a high rate of complications, including shifting and overdrainage. Overdrainage can lead to subdural haematomas, a tethered spinal cord, due to scarring, or downward herniation of the cerebral hemispheres. Spennato et al. therefore recommend a flow-regulating or anti-syphon valve. On the other hand, VP shunts have a lower rate of complications than CP shunts and are recommended initially by some. However, they are less effective in DWM, and the elevated position of the tentorium should be considered before installing a VP shunt.In patients older than 1 year, endoscopic third ventriculostomy (ETV) may be considered as the first-line treatment. This less invasive procedure creates an artificial hole in the third ventricle to allow CSF to bypass any obstruction. It cannot be used on those with brain abnormalities such as agenesis of the corpus callosum, due to the risk of CSF escaping to other brain areas.
Hydrocephalus also affected all of these patients.In Dandy–Walker variant (DWV) and mega cisterna magna specifically, which are less severe malformations, there appears to be an increased rate of psychotic spectrum disorders such as schizophrenia, bipolar disorder, mania or catatonia. Associated anomalies
A 2017 review found the following associations in patients with DWS (usually from an associated genetic condition or abnormality):
27% of patients had a congenital heart defect. These included patent ductus arteriosus, coarctation of the aorta, ventricular septal defect and atrial septal defect. In 2.7% of patients, heart failure was reported. 24% of patients had at least one ocular abnormality. These included cataracts, small eyes (microphthalmia), chorioretinal dysplasia/atrophy, optic nerve dysplasia/atrophy, a small cornea (microcornea) or corneal opacity (leukoma), short-sightedness (myopia) and coloboma (a hole in an eye structure). 16% of patients were diagnosed with a mental or behavioural disorder, with 6.4% also having a learning disability. 5.3% had either bipolar disorder or a psychotic spectrum disorder, and 2.1% had ADHD. Slightly more of these were found in Dandy–Walker variant (DWV) than in classic DWM, despite DWV being less common, at only around 20% of DWS diagnoses. Around 12% of patients had cancers or tumours arising from congenital genetic abnormalities. The most common were neurocutaneous melanosis (5.9%), hemangiomas (4.8%, including those with PHACE syndrome) and Wilms tumour (4.4%). 3.2% of patients had congenital melanocytic nevi, and 2.1% had tongue hamartoma.