title: Prenatal diagnosis of herniated Dandy-Walker cysts.
abstract: OBJECTIVE
  The purpose of this series is to describe the prenatal diagnosis and pregnancy outcome of fetuses affected with Dandy-Walker malformation in which a posterior cyst herniated through a bony defect of the occipital skull, foramen magnum, or both.
  
  
  METHODS
  Two- and 3-dimensional sonography were used to examine 2 fetuses with poorly delineated cerebellar structures and a large posterior cystic neck mass. Fetal magnetic resonance imaging (MRI) was added to this evaluation as a complementary diagnostic modality.
  
  
  RESULTS
  Three-dimensional sonography helped characterize the precise site of cyst herniation through the occipital skull or foramen magnum. Fetal MRI confirmed the sonographic findings. Neonatal MRI studies identified heterotopic gray matter as evidence of a neuronal migration disorder in both fetuses. The second fetus also had agenesis of the corpus callosum. Retrospective review of the fetal MRI (25.9 weeks' menstrual age) and 3-dimensional sonographic (18.7 weeks' menstrual age) studies confirmed ventricular wall nodularity involving the occipital horns of the second fetus.
  
  
  CONCLUSIONS
  The antenatal detection of a large posterior cystic neck mass and a poorly defined or nonvisualized cerebellar vermis suggest Dandy-Walker malformation with a herniated cyst. Three-dimensional sonography and fetal MRI are important adjunctive methods that can be used to evaluate the herniation site and a possible neuronal migrational disorder.
authors.affiliation: Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, Royal Oak, MI 48073-6769, USA. wlee@beaumont.edu
authors.forename: Wesley
authors.initials: W
authors.lastname: Lee
authors.forename: Ivana M
authors.initials: IM
authors.lastname: Vettraino
authors.forename: Christine H
authors.initials: CH
authors.lastname: Comstock
authors.forename: Nirish
authors.initials: N
authors.lastname: Lal
authors.forename: Chris
authors.initials: C
authors.lastname: Kazmierczak
authors.forename: Anil
authors.initials: A
authors.lastname: Shetty
authors.forename: Gil
authors.initials: G
authors.lastname: Raff
authors.forename: Karol
authors.initials: K
authors.lastname: Zakalik
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
mesh_terms: D000328:Adult; D003616:Dandy-Walker Syndrome / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D006257:Head / Q000000981:diagnostic imaging / Q000196:embryology; D006547:Hernia / Q000000981:diagnostic imaging* / Q000209:etiology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D016216:Ultrasonography, Prenatal