Dandy-Walker variant (DWv) is a less severe posterior fossa anomaly than the classic Dandy-Walker malformation (DWM) and is considered being on the lesser end of the disease spectrum in the Dandy-Walker continuum.
This term was created to include those malformations that do not meet the criteria for Dandy-Walker malformation, however, some authors recommend to avoid it as there is a lack of specificity that may create some confusion. Instead, a more detailed anatomic description is recommended 4.
Please refer on isolated inferior vermian hypoplasia for a broad discussion in this defined entity.
- the diagnosis of a Dandy-Walker variant can not be made definitely until the 18th week of gestation as the inferior vermis does not form till then
- may show a connection between the cisterna magna and fourth ventricle
- the fourth ventricle is large but less dilated and better formed than the classic Dandy-Walker malformation 1
- the cerebellar hemispheres are hypoplastic but there is less severe hypoplasia of the inferior vermis
On antenatal ultrasound, consider:
- communication between the fourth ventricle and the cisterna magna can be a normal finding up to ~18 weeks of gestation
- incorrect angulation of the scan may make the posterior fossa larger than usual