TY - CHAP M1 - Book, Section TI - Dandy–Walker Malformation and Variants A1 - Bianchi, Diana W. A1 - Crombleholme, Timothy M. A1 - D'Alton, Mary E. A1 - Malone, Fergal D. Y1 - 2015 N1 - T2 - Fetology: Diagnosis and Management of the Fetal Patient, 2e AB - Key PointsDandy–Walker malformation refers to the combination of hypoplasia of the cerebellar vermis, cystic dilation of the fourth ventricle communicating with the cisterna magna, and increase in size of the posterior fossa.Related conditions include Dandy–Walker variant (varying hypoplasia of the inferior vermis without enlargement of fourth ventricle or cisterna magna), mega cisterna magna (enlarged cisterna magna in the setting of normal vermis), and Blake’s pouch cyst (extension of the fourth ventricle into the cisterna magna, represented by septae within the cisterna magna).Some authors feel that there is no role in differentiating Dandy–Walker malformation and variant, as both can be associated with CNS and non-CNS malformations, aneuploidy, and adverse neurological outcome.False-positive diagnoses of Dandy–Walker malformation are possible, especially if noted before 18 weeks, or if the abnormality is confined to the cerebellar vermis alone.Following diagnosis, a detailed search for other CNS and non-CNS malformations is required, including prenatal MRI, and karyotype analysis.Other than multidisciplinary counseling, no other alterations to standard obstetric care are indicated. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/19 UR - obgyn.mhmedical.com/content.aspx?aid=1106396308 ER -