title: Morphometry of the trochlear nerve and superior oblique muscle volume in congenital superior oblique palsy.
abstract: OBJECTIVE
  To infer the pathogenic mechanism of congenital superior oblique palsy (SOP) by evaluating trochlear nerve diameter (CN4D) and superior oblique muscle (SO) volume in patients with congenital SOP.
  
  
  METHODS
  The medical records of 125 patients diagnosed with unilateral congenital SOP and 34 age-matched healthy controls were reviewed retrospectively. Using thin-section high-resolution magnetic resonance imaging, we evaluated the presence of the trochlear nerve, CN4D, SO volume, and their relationship.
  
  
  RESULTS
  Of the 125 patients with congenital SOP, 87 showed absence of the trochlear nerve (n = 87, 70%, absent group) and 38 showed bilateral presence of the trochlear nerve (n = 38, 30%, present group). The nonparetic side CN4D was smaller than controls in the absent group (P = 0.001), and larger than controls in the present group (P = 0.001). Trochlear nerve diameter positively correlated with SO volume in controls (P = 0.014, R(2) = 0.174) and in the nonparetic sides of congenital SOP (present group P = 0.023, R(2) = 0.135; absent group, P = 0.008, R(2) = 0.079). The paretic side SO volume did not show a linear correlation between CN4D and SO volume in the present group (P = 0.243).
  
  
  CONCLUSIONS
  In congenital SOP patients without a trochlear nerve, the nonparetic side CN4D was also reduced in contrast to those with a trochlear nerve. The relatively weaker relationship of CN4D and nonparetic side SO volume in the absent group than that of the present group suggests different pathogenic mechanisms underlying these two entities of congenital SOP.
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Dae Seung
authors.initials: DS
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Yang
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jae Hyoung
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Hwang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005124:Eye Abnormalities / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000002:abnormalities* / Q000473:pathology; D012189:Retrospective Studies; D014321:Trochlear Nerve / Q000002:abnormalities* / Q000473:pathology; D020432:Trochlear Nerve Diseases / Q000151:congenital* / Q000175:diagnosis; D055815:Young Adult
keywords: congenital superior oblique palsy; superior oblique muscle; trochlear nerve