title: The increased range of cervical flexed motion detected by radiographs in Hirayama disease.
abstract: OBJECTIVE
  Cervical flexion movement is supposed to play an important role in the pathogenesis of Hirayama disease. But there is no report on the range of cervical flexed motion in this disease. The purpose of current study was to compare the range of cervical flexed motion in patients with Hirayama disease with the one in healthy controls using conventional lateral flexion radiographs of the cervical spine, and to investigate the diagnostic value of radiographs for Hirayama disease.
  
  
  METHODS
  This prospective study was approved by a local institutional review board and written informed consent was obtained. From August 2007 to March 2009, conventional flexion cervical radiographs and flexion cervical MRI were performed on 31 Hirayama disease patients (all men, age range, 16-24 years, mean age, 19.52±2.29 years) and 40 control subjects (all men, age range, 16-25 years, mean age, 23.10±2.20 years). The segmental and overall range of cervical flexed motion was quantitatively measured. Receiver operating characteristic curve was calculated and the diagnostic accuracy was qualified by using the area under the curve Az.
  
  
  RESULTS
  Both the segmental and overall range of cervical flexed motion of patients determined by flexion cervical radiographs was greater than that of controls. The Az value was 0.90, indicating a moderate to good ability of conventional flexion radiographs in the diagnosis of Hirayama disease.
  
  
  CONCLUSIONS
  Hirayama disease patients have an increased flexed motion range of cervical spine which would contribute to the pathophysiological change and determine its treatment. Conventional flexion radiographs might be suitable to be used as first line radiographic examination, followed by MRI in cases of suspected Hirayama disease.
authors.affiliation: Department of Radiology, Peking University Third Hospital, North Huayuan Road No.49, Haidian District, Beijing 100191, China. xu_xiaojuan@126.com
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Xu
authors.forename: Hongbin
authors.initials: H
authors.lastname: Han
authors.forename: Hui
authors.initials: H
authors.lastname: Gao
authors.forename: Chao
authors.initials: C
authors.lastname: Hou
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Fan
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D016059:Range of Motion, Articular / Q000502:physiology*; D014897:Spinal Muscular Atrophies of Childhood / Q000175:diagnosis* / Q000503:physiopathology*