title: Ocular misalignment in Graves disease may mimic that of superior oblique palsy.
abstract: BACKGROUND
  The Parks-Bielschowsky three-step test (TST) can incorrectly indicate that a superior oblique muscle is paretic in patients with restrictive strabismus. Although this pitfall in diagnosis has been widely reported, no large studies have examined the incidence of a positive TST in patients with Graves disease.
  
  
  METHODS
  We performed a retrospective chart review of 31 consecutive patients with Graves orbitopathy examined at Children's Hospital of Boston from 2003 to 2007. We analyzed ocular ductions, misalignment, and torsion, and thyroid function studies.
  
  
  RESULTS
  Six (20%) of the patients had a positive TST, 3 (10%) of which showed excyclotorsion in at least one eye. However, of the 6 patients, 5 had obvious ocular adnexal signs of Graves disease and 2 had obvious supraduction deficits, leaving only 1 (3%) patient in whom the clinician would have mistakenly diagnosed a superior oblique palsy.
  
  
  CONCLUSIONS
  Although a positive TST occurs frequently in Graves disease, other clinical features should allow distinction from superior oblique palsy in most patients.
authors.affiliation: Department of Ophthalmology, Children's Hospital Boston, Boston, Massachusetts, USA. vchen@tuftsmedicalcenter.org
authors.forename: Vicki M
authors.initials: VM
authors.lastname: Chen
authors.forename: Linda R
authors.initials: LR
authors.lastname: Dagi
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control; D005133:Eye Movements; D005143:Eyelids / Q000503:physiopathology; D005260:Female; D006111:Graves Disease / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000503:physiopathology; D012189:Retrospective Studies; D013285:Strabismus / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology*; D020432:Trochlear Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D055815:Young Adult