title: Presence of the abducens nerve according to the type of Duane's retraction syndrome.
abstract: OBJECTIVE
  To analyze whether the presence of the abducens nerve might depend upon the type of Duane's retraction syndrome (DRS).
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  Sixteen patients with type 1 DRS, 2 patients with type 2 DRS, and 5 patients with type 3 DRS.
  
  
  METHODS
  Ophthalmologic examination and thin-sectioned magnetic resonance imaging (MRI) at the brain stem level were performed in 23 DRS patients. To confirm the accuracy of the procedure, we compared the results obtained with those of a control group of 30 individuals using the same technique.
  
  
  METHODS
  Examination of ductions and versions and the presence of the abducens nerve on MRI.
  
  
  RESULTS
  The abducens nerve on the affected side could not be observed using MRI in 18 (100%) of 18 eyes (16 patients) with type 1 DRS and in 3 of 5 eyes with type 3 DRS. Conversely, the abducens nerve was observed in 2 of 2 eyes with type 2 DRS and 2 of 5 eyes with type 3 DRS. The abducens nerve was observed in 60 (100%) of 60 eyes screened as controls.
  
  
  CONCLUSIONS
  The abducens nerve on the affected side was absent in type 1 DRS patients and some type 3 DRS patients, but present in type 2 DRS patients as well as in some type 3 DRS patients. In terms of the presence or absence of the abducens nerve, type 1 and type 2 DRS were homogenous, and type 3 DRS was heterogenous.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Sungnam, Korea.
authors.forename: Jae Hyoung
authors.initials: JH
authors.lastname: Kim
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Hwang
mesh_terms: D000010:Abducens Nerve / Q000473:pathology*; D020434:Abducens Nerve Diseases / Q000175:diagnosis*; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004370:Duane Retraction Syndrome / Q000145:classification* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging