title: Comparison of orbital magnetic resonance imaging in duane syndrome and abducens palsy.
abstract: OBJECTIVE
  To help resolve the clinical ambiguity between Duane syndrome with severe abduction deficit and abducens palsy, we performed orbital magnetic resonance imaging (MRI) to qualify abnormalities of the lateral rectus (LR) muscle in these entities.
  
  
  METHODS
  Prospective observational case series.
  
  
  METHODS
  Orbital MRI was performed in 13 subjects with Duane syndrome (19 eyes), 10 subjects with chronic abducens palsy (10 eyes), and 10 orthotropic control subjects (18 eyes). High-resolution, surface coil, T(1)-weighted MRI was used to obtain contiguous, 2-mm thick quasi-coronal images of the orbits in central gaze. Digital image analysis was used to quantify cross-sectional area of the ipsilesional and contralesional LR to provide comparison with control measurements.
  
  
  RESULTS
  Mean maximum LR cross-sectional area in Duane syndrome was statistically similar to control (P = .454) and contralesional LR cross-sectional area (P = .227). However, in chronic abducens palsy, mean maximum ipsilesional LR cross-sectional area was markedly smaller than contralesional (P = .003) and control cross-sectional areas (P < .0001), as well as smaller than the LR in Duane syndrome (P= .0017).
  
  
  CONCLUSIONS
  The LR muscle in abducens palsy exhibits profound atrophy. The sparing of the LR in Duane syndrome from denervation atrophy despite absence of normal abducens innervation suggests existence of alternative LR innervation. High-resolution MRI can noninvasively demonstrate LR muscle size and distinguish Duane syndrome from chronic abducens palsy in uncertain cases.
authors.affiliation: Department of Ophthalmology, Holy Family Hospital, College of Medicine, Catholic University of Korea, Seoul, Korea.
authors.forename: Nam-Yeo
authors.initials: NY
authors.lastname: Kang
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Demer
mesh_terms: D020434:Abducens Nerve Diseases / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001284:Atrophy; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D004370:Duane Retraction Syndrome / Q000175:diagnosis*; D004948:Esotropia / Q000175:diagnosis; D005133:Eye Movements; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000294:innervation / Q000473:pathology*; D009915:Orbit / Q000473:pathology*; D011446:Prospective Studies