title: Congenital absence of the inferior rectus muscle--diagnosis and management.
abstract: BACKGROUND
  Congenital absence of the inferior rectus muscle is a rare cause of apparent inferior rectus palsy especially in the absence of associated cranial facial anomalies.
  
  
  METHODS
  We report three cases of isolated congenital absence of the inferior rectus muscle and its successful surgical management.
  
  
  RESULTS
  Failure of the normal embryologic development of the mesodermal complex around the eye can lead to agenesis of the extraocular muscles. In apparent palsies of the inferior rectus muscle and no definite cause, a high index of suspicion and orbital imaging can confirm the diagnosis of congenitally absent inferior rectus preoperatively. Surgical correction may involve inferior transposition of the horizontal rectus muscles.
  
  
  CONCLUSIONS
  Although rare, congenital absence of the inferior rectus muscle is a possible cause of apparent inferior rectus muscle palsy particularly in the absence of another identifiable cause. Strabismus surgery in conjunction with intramuscular botulinum toxin injection can offer significant improvement in function and cosmesis of these patients.
authors.affiliation: Division of Pediatric Ophthalmology and Strabismus, Alberta Children's Hospital, University of Calgary, 1820 Richmond Road SW, Calgary, Alberta, Canada T2T 5C7.
authors.forename: William F
authors.initials: WF
authors.lastname: Astle
authors.forename: Vivian E
authors.initials: VE
authors.lastname: Hill
authors.forename: Anna L
authors.initials: AL
authors.lastname: Ells
authors.forename: Nguyen Thi Thanh
authors.initials: NT
authors.lastname: Chi
authors.forename: Elaine
authors.initials: E
authors.lastname: Martinovic
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage; D000013:Congenital Abnormalities / Q000175:diagnosis / Q000601:surgery; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D009465:Neuromuscular Agents / Q000008:administration & dosage; D009801:Oculomotor Muscles / Q000002:abnormalities* / Q000601:surgery*; D011182:Postoperative Care; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A