title: Botulinum toxin injection for restrictive myopathy of thyroid-associated orbitopathy: success rate and predictive factors.
abstract: OBJECTIVE
  To evaluate the rate of and predictive factors for successful treatment of restrictive myopathy in thyroid-associated orbitopathy (TAO) using botulinum toxin injection.
  
  
  METHODS
  Twenty patients with restrictive myopathy of TAO were enrolled in the study. Abnormal thyroid function test results were not a prerequisite for inclusion. In each extraocular muscle 25 units of botulinum toxinA were injected. The success rate, calculated at 2 years or last follow-up before surgery, was defined as proportion of the cases with esotropia of <10(Δ), vertical deviation of <5(Δ), and no diplopia in primary position and downgaze for at least 1 year. Both univariate analysis and multivariate logistic regressions were performed to identify the factors associated with success.
  
  
  RESULTS
  The procedure was successful in 11 cases (55%): in 8 patients with predominantly esotropia, 1 patient with predominantly hypotropia, and 2 patients of mixed type. Four factors were significantly associated with the success: type of deviation (P = 0.007), lower amounts of hypotropia (P = 0.001) and esotropia (P = 0.05), and lower degree of extorsion (P = 0.01). In the multivariate logistic regression, only lower amount of hypotropia was significantly associated with the success (P = 0.09, OR = 1.36).
  
  
  CONCLUSIONS
  Botulinum toxin injection can be an effective alternative for the treatment of the restrictive myopathy in TAO. The best candidates for injection of the toxin are patients with esotropia, smaller angle of horizontal and vertical deviations, and lower degree of extorsion.
authors.affiliation: Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Akbari
authors.affiliation: Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Ameri
authors.affiliation: Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Keshtkar Jaafari
authors.affiliation: Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: a1sadeghi@yahoo.com.
authors.forename: Arash
authors.initials: A
authors.lastname: Mirmohammadsadeghi
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D004172:Diplopia / Q000503:physiopathology; D005260:Female; D049970:Graves Ophthalmopathy / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D009801:Oculomotor Muscles / Q000187:drug effects*; D011446:Prospective Studies; D013285:Strabismus / Q000188:drug therapy* / Q000503:physiopathology; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A