title: MRI findings in Duane's ocular retraction syndrome.
abstract: OBJECTIVE
  To investigate the innervation pattern of extra-ocular muscles in patients with clinically diagnosed Duane's ocular retraction syndrome (DRS) using magnetic resonance imaging (MRI).
  
  
  METHODS
  The study population consisted of 11 patients. Six patients had type I DRS (eight eyes), four patients had type II DRS (five eyes) and one patient had inverse DRS. Images were acquired using a Siemens 3 T MRI system. The type of DRS, corresponding innervation findings, and condition of the affected muscles were evaluated by two experienced neuroradiologists in consensus.
  
  
  RESULTS
  All patients with clinically diagnosed DRS type I showed absence of the abducens nerve (CN6), hypoplasia of the superior oblique muscle (SOM), and aberrant innervation of lateral rectus muscle (LRM) by an extra branch of oculomotor nerve (CN3). All patients with type II DRS show dual-innervation of the LRM (by CN6 and an aberrant CN3 branch) and hypoplasia of SOM. The single patient with inverse DRS showed hypoplasia of CN3, the medial rectus muscle (MRM), the inferior rectus muscle (IRM), and the inferior oblique muscle (IOM).
  
  
  CONCLUSIONS
  Each type of DRS has characteristic MRI appearances. Therefore, MRI is a useful diagnostic tool for the confirmation and classification of suspected cases of DRS.
authors.affiliation: Department of Radiology, Tianjin First Central Hospital, Tianjin, China. Electronic address: xiashuang77@163.com.
authors.forename: S
authors.initials: S
authors.lastname: Xia
authors.affiliation: Department of Radiology, Tianjin First Central Hospital, Tianjin, China.
authors.forename: R L
authors.initials: RL
authors.lastname: Li
authors.affiliation: Tianjin Eye Hospital, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.
authors.forename: Y P
authors.initials: YP
authors.lastname: Li
authors.affiliation: Tianjin Medical University, Eye Hospital, Tianjin, China.
authors.forename: X H
authors.initials: XH
authors.lastname: Qian
authors.affiliation: Department of Diagnostic Radiology, National University Hospital, National University of Singapore, Singapore.
authors.forename: V
authors.initials: V
authors.lastname: Chong
authors.affiliation: Department of Radiology, Tianjin First Central Hospital, Tianjin, China.
authors.forename: J
authors.initials: J
authors.lastname: Qi
mesh_terms: D000010:Abducens Nerve / Q000002:abnormalities / Q000473:pathology*; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003937:Diagnosis, Differential; D004370:Duane Retraction Syndrome / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009801:Oculomotor Muscles / Q000294:innervation / Q000473:pathology*; D009802:Oculomotor Nerve / Q000473:pathology* / Q000503:physiopathology