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.
The confluence of sinuses, part of the drainage system located at the far rear of the occipital lobe, is elevated due to the enlarged posterior fossa. (The adjacent cerebellar tentorium is also elevated. )Due to the inconsistency of the presence of hydrocephalus in DWM, Spennato and Klein suggested that it should not be considered a criterion for DWM. Kleins criteria differed from Spennatos mainly in that it required no apparent cerebellar hemisphere hypoplasia, but it may also have required the vermis to touch the tentorium or an absence of brainstem abnormalities. Methods
DWM can be observed prenatally on ultrasound as early as 14 weeks of gestation, though an MRI scan is the most useful method for diagnosis. MRI can delineate the shape and extent of the malformation as well as assessing additional areas for malformations such as the cerebellar hemispheres, cerebral aqueduct or corpus callosum. Cardiac-gated phase-contrast MRI can observe the flow of cerebrospinal fluid (CSF) during systole and diastole of the heart. In true DWM, this will find a flow from the cerebral aqueduct to the posterior fossa and no flow between the cisterna magna and the space behind the cervical spinal cord.CT may also be used if MRI is unavailable, but it provides less detail. Klein et al. (2003) suggested that a suspected diagnosis based on CT or ultrasound should not be confirmed until an MRI is performed, due to the large number of conditions that can present highly similarly and confound diagnosis.