title: Prevalence and characteristics of abnormal head posture in children with Down syndrome: a 20-year retrospective, descriptive review.
abstract: OBJECTIVE
  To characterize the abnormal head posture (AHP) in children with Down syndrome (DS). The study had 3 aims: to estimate the prevalence of AHP, to describe the distribution of different causes for AHP, and to evaluate the long-term outcomes of AHP in children with DS evaluated at the University of Iowa Hospitals and Clinics between 1989 and 2009.
  
  
  METHODS
  Retrospective chart review.
  
  
  METHODS
  Two hundred fifty-nine patient records.
  
  
  METHODS
  The study data were analyzed using chi-square tests (the Fisher exact test when appropriate) to describe the relationship between the outcome of interest and each study covariate. A predictive logistic regression model for AHP was constructed including all the significant covariates.
  
  
  METHODS
  Abnormal head posture.
  
  
  RESULTS
  Over the study period, 259 records of patients with DS were identified. Of these, 64 (24.7%) patients had AHP. The most frequent cause of AHP was incomitant strabismus in 17 (26.6%) of 64 patients. The second most frequent cause of AHP was nystagmus, in 14 (21.8%) of 64 patients. For a substantial number of patients with AHP, the cause could not be determined. They represented 12 (18.8%) of all the patients with AHP in this study and 12 (4.6%) of all patients with DS examined. When compared with patients with AHP from a determined cause, this subgroup has a statistically significantly (P = 0.027, Fisher exact test) higher percentage of atlantoaxial instability. In the study population, 9 (14.1%) of 64 patients with AHP had more than 1 cause for AHP. Refractive errors, ptosis, unilateral hearing loss, and neck and spine musculoskeletal abnormalities were responsible for AHP in a small percentage of patients. Of all the patients with AHP, 23 (35.9%) improved their head posture with treatment (glasses or surgery). An additional 6 (9.4%) patients improved their posture spontaneously, over time and without treatment.
  
  
  CONCLUSIONS
  The prevalence of AHP in the children with DS evaluated was 24.7%. From this analysis, having strabismus of any kind and particularly incomitant strabismus, nystagmus, or both is highly correlated with the development of an AHP. Almost 19% of DS patients with AHP had no definitive cause that could be determined.
authors.affiliation: Pediatric Ophthalmology, Department of Ophthalmology and Visual Science, University of Iowa Hospital and Clinics, Iowa City, Iowa 52246, USA.
authors.forename: Alina V
authors.initials: AV
authors.lastname: Dumitrescu
authors.forename: Daniela C
authors.initials: DC
authors.lastname: Moga
authors.forename: Susannah Q
authors.initials: SQ
authors.lastname: Longmuir
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Olson
authors.forename: Arlene V
authors.initials: AV
authors.lastname: Drack
mesh_terms: D002675:Child, Preschool; D004314:Down Syndrome / Q000150:complications*; D005139:Eyeglasses; D005260:Female; D005500:Follow-Up Studies; D006257:Head; D006801:Humans; D008297:Male; D009139:Musculoskeletal Abnormalities / Q000209:etiology* / Q000628:therapy; D009759:Nystagmus, Pathologic / Q000150:complications; D013508:Ophthalmologic Surgical Procedures; D011187:Posture; D015995:Prevalence; D012030:Refractive Errors / Q000150:complications; D012189:Retrospective Studies; D013285:Strabismus / Q000150:complications