title: Type 4 Duane syndrome.
abstract: To identify cases of synergistic divergence whose characteristics suggest that this entity is a form of Duane syndrome.
  
  
  
  The records of all patients with a Duane syndrome diagnosis, including standardized eye position photographs, from the E-Consultation program of Cybersight, Orbis International were analyzed.
  
  
  
  A total of 350 Duane syndrome cases were identified. Of these, 19 (5%) had features consistent with synergistic divergence, or type 4 Duane syndrome. Of the 19, 16 (84%) were male, 15 (79%) had palpebral fissure narrowing, all had anomalous head posture, and 18 (95%) were exotropic. Only 9 (47%) patients were reported to have undergone surgery.
  
  
  
  Synergistic divergence is a rare entity with features similar to those of Duane syndrome. We suggest that this entity be classified as type 4 Duane syndrome, because it has unique findings and an innervation pattern that differs from the other 3 recognized types.
authors.affiliation: Dixie Ophthalmic Specialists at the Zion Eye Institute, St. George, Utah. Electronic address: josh.schliesser@gmail.com.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Schliesser
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: Derek T
authors.initials: DT
authors.lastname: Sprunger
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: Eugene M
authors.initials: EM
authors.lastname: Helveston
mesh_terms: D004370:Duane Retraction Syndrome; D005099:Exotropia; D005143:Eyelids; D005260:Female; D006257:Head; D006801:Humans; D008297:Male; D011187:Posture