title: Achondroplasia in children: correlation of ventriculomegaly, size of foramen magnum and jugular foramina, and emissary vein enlargement.
abstract: OBJECTIVE
  Achondroplasia is a skeletal dysplasia with diminished growth of the skull base secondary to defective enchondral bone formation. This leads to narrowing of the foramen magnum and jugular foramina, which further leads to ventricular dilatation and prominence of the emissary veins. The primary goal of our study was to determine a correlation between the degree of ventricular dilatation, jugular foramina and foramen magnum narrowing, as well as emissary vein enlargement.
  
  
  METHODS
  Conventional T2-weighted MR images were evaluated for surface area of the foramen magnum and jugular foramina, ventricular dilatation, and emissary veins enlargement in 16 achondroplasia patients and 16 age-matched controls. Ratios were calculated for the individual parameters using median values from age-matched control groups to avoid age as a confounder.
  
  
  RESULTS
  Compared to age-matched controls, in children with achondroplasia, the surface area of the foramen magnum (median 0.50 cm(2), range 0.23-1.37 cm(2) vs. 3.14 cm(2), 1.83-6.68 cm(2), p < 0.001) and jugular foramina (median 0.02 cm(2), range 0-0.10 cm(2) vs. 0.21 cm(2), 0.03-0.61 cm(2), p < 0.001) were smaller, whereas ventricular dilatation (0.28, 0.24-0.4 vs. 0.26, 0.21-0.28, p < 0.001) and enlargement of emissary veins (6, 0-11 vs. 0, p < 0.001) were higher. Amongst the patients, Spearman correlation and multiple regression analysis did not reveal correlation for severity between the individual parameters.
  
  
  CONCLUSIONS
  Our study suggests that in children with achondroplasia, (1) the variation in ventricular dilatation may be related to an unquantifiable interdependent relationship of emissary vein enlargement, venous channel narrowing, and foramen magnum compression and (2) stable ventricular size facilitated by interdependent factors likely obviates the need for ventricular shunt placement.
authors.affiliation: Section of Pediatric Neuroradiology, Division of Pediatric Radiology, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins School of Medicine, Charlotte R. Bloomberg Children's Center, Sheikh Zayed Tower, Room 4174, 1800 Orleans Street, Baltimore, MD, 21287-0842, USA.
authors.forename: Thangamadhan
authors.initials: T
authors.lastname: Bosemani
authors.forename: Gunes
authors.initials: G
authors.lastname: Orman
authors.forename: Benedikt
authors.initials: B
authors.lastname: Hergan
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Carson
authors.forename: Thierry A G M
authors.initials: TA
authors.lastname: Huisman
authors.forename: Andrea
authors.initials: A
authors.lastname: Poretti
mesh_terms: D000130:Achondroplasia / Q000150:complications*; D016022:Case-Control Studies; D002550:Cerebral Veins / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003251:Constriction, Pathologic / Q000209:etiology*; D005260:Female; D005539:Foramen Magnum / Q000473:pathology*; D006801:Humans; D006849:Hydrocephalus / Q000150:complications*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies