title: Ocular overelevation in adduction in craniosynostosis: is it the result of excyclorotation of the extraocular muscles?
abstract: OBJECTIVE
  We sought to determine whether radiological evidence supports excyclorotation of the extraocular muscle cone as a cause of overelevation in adduction in children with craniosynostosis.
  
  
  METHODS
  This was a retrospective case series of 40 patients with craniosynostosis. Ophthalmic findings were assessed for incomitant vertical strabismus in particular excessive elevation in adduction. Computed tomography and magnetic resonance imaging scans were reviewed. Those scans with adequate coronal imaging of their orbits to assess the position and angulation of the horizontal extraocular muscles were identified, and the degree of rotation of the muscles formally measured along with aged matched controls. These groups were analyzed for the association between presence of overelevation in adduction and degree of excyclorotation of the extraocular muscle cone.
  
  
  RESULTS
  The identified updrift on adduction that mimics inferior oblique muscle overaction was present in 63% (25/40) of patients. Imaging that permitted accurate measurement of the muscles positions was available in 10 of the 40 patients. Of these 10, 8 had the updrift, and 7 of these 8 (88%) demonstrated more excyclorotation than their aged matched controls. Comparison of scan measurements of patients revealed a significant difference in degree of excyclorotation (mean difference = 16.2, 95% confidence interval 6.2-31.5; P = 0.006) between patients with and without excess elevation in adduction.
  
  
  CONCLUSIONS
  Overelevation in adduction is significantly associated with excyclorotation of the extraocular muscle cone in children with craniosynostosis. We demonstrate a simple method to assess for the excyclorotation. Our findings support the importance of imaging of the orbits in these children before strabismus surgery.
authors.affiliation: Department of Ophthalmology, British Columbia Children's Hospital, Vancouver, British Columbia, Canada. kimberleytan@iprimus.com.au
authors.forename: Kimberley P
authors.initials: KP
authors.lastname: Tan
authors.forename: Michael A
authors.initials: MA
authors.lastname: Sargent
authors.forename: Ken J
authors.initials: KJ
authors.lastname: Poskitt
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lyons
mesh_terms: D003398:Craniosynostoses / Q000150:complications*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009801:Oculomotor Muscles / Q000000981:diagnostic imaging / Q000473:pathology*; D009915:Orbit / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D013285:Strabismus / Q000209:etiology*; D014057:Tomography, X-Ray Computed; D014102:Torsion Abnormality / Q000150:complications / Q000000981:diagnostic imaging