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Rectus muscle excyclorotation and V-pattern strabismus: a quantitative appraisal of clinical relevance in syndromic craniosynostosis
  1. Linda R Dagi1,
  2. Sarah MacKinnon1,
  3. David Zurakowski2,
  4. Sanjay P Prabhu3
  1. 1Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
  2. 2Department of Anesthesia, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
  3. 3Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
  1. Correspondence to Dr Linda R Dagi, Department of Ophthalmology, Boston Children's Hospital, 300 Longwood Avenue, Fegan 4, Boston, MA 02115, USA; linda.dagi{at}


Purpose V-pattern strabismus observed with syndromic craniosynostosis has been attributed to disparate causes. We compared severity of V pattern with degree of excyclorotation of rectus muscles to appraise significance of this proposed aetiology.

Methods 43 patients with Apert, Crouzon or Pfeiffer syndrome referred to Boston Children's Hospital Department of Ophthalmology were identified. 28 met inclusion criteria for retrospective cohort study, specifically: (1) sensorimotor measurements in minimum of seven cardinal gazes, (2) quantified fundus torsion and (3) orbital CT imaging sufficient to measure rectus muscle cyclorotation in coronal and quasicoronal planes, posteriorly (near orbital apex) and anteriorly (near pulleys). Patients were placed in one of four V-pattern severity groups. The most severe group demonstrated inability to elevate abducted eye above midline with characteristic ‘seesaw’ misalignment during horizontal saccades. Rectus muscle cyclorotation was measured by paediatric neuroradiologist blinded to group placement. Primary outcome was correlation of severity of V pattern with degree of excyclorotation. Secondary outcome was correlation of severity with craniosynostosis syndrome.

Results Increasing severity of V pattern correlated with greater excyclorotation in anterior coronal (p=0.009), anterior quasicoronal (p=0.021), posterior coronal (p=0.014) and posterior quasicoronal (p=0.040) planes for moderate-to-severe V pattern. Even greater excyclorotation was associated with seesaw V pattern in anterior quasicoronal (p=0.004) and posterior quasicoronal (p=0.001) views. Highly significant association was found between Apert syndrome and severity of V pattern (p=0.004).

Conclusions Severity of V pattern is associated with magnitude of excyclorotation. More severe V pattern and seesaw strabismus noted with Apert syndrome may relate to distinctive orbital morphology.

  • Anatomy
  • Muscles
  • Orbit
  • Genetics

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  • Twitter Follow Sanjay Prabhu @sanjayprabhu

  • Contributors All authors have given final approval of this version to be published. Design of the study: LRD, SMaK and SPP. Conduct of the study: LRD, SMaK and SPP. Management of the data: LRD, SMaK and DZ. Analysis of the data: LRD and DZ. Interpretation of the data: LRD and SPP. Preparation of the manuscript: LRD and SMaK. Overall coordination: LRD.

  • Funding This work was supported by the Boston Children's Hospital Ophthalmology Foundation Chair fund, held by LRD.

  • Competing interests LRD: Honoraria from lectures and via expert testimony. SPP: Expert testimony for medico-legal cases. Boston Children's Hospital project with General Electric (Boston Children's Hospital receives compensation, but SPP does not) grants from the Cooper Trewin Foundation, the U.S. Department of Defense and the Boston Investment Consortium.

  • Patient consent Obtained.

  • Ethics approval The Institutional Review Board of Boston Children's Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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