title: Progression to musculoskeletal deformity in childhood dystonia.
abstract: OBJECTIVE
  Dystonia is a movement disorder characterized by involuntary muscle contractions, resulting in abnormalities of posture and movement. Children with dystonia are at risk of developing fixed musculoskeletal deformities (FMDs). FMDs cause pain, limit function and participation and interfere with care. We aimed to explore factors relating to the development of FMD in a large cohort of children with dystonia.
  
  
  METHODS
  The case notes of all children referred to our Complex Motor Disorder service between July 2005 and December 2011 were reviewed. Data from 279 children (median age 9 years 10 months, Standard Deviation 4 years 2 months) with motor disorders including a prominent dystonic element were analyzed. Parametric accelerated failure time regression was used to identify the factors related to development of contractures.
  
  
  RESULTS
  FMDs were present at referral in more than half (n = 163, 58%) of cases. Three quarters (n = 120, 74%) of children with FMD had deformities around the hip, and 42% had spinal deformity (n = 68). Compared to pure primary dystonia, FMD onset was earlier with a diagnosis of secondary or heredodegenerative dystonia, and a mixed spastic-dystonic phenotype (all p < 0.001). FMD onset was also earlier with increasing Gross Motor Function Classification System (GMFCS) level (p < 0.001). The effect of aetiological classification was lost when controlling for GMFCS level and motor phenotype.
  
  
  CONCLUSIONS
  Children with secondary or heredodegenerative dystonia are at greater risk of progression to FMD compared to primary dystonia, likely due to more severe dystonia within these groups. Children with additional spasticity are at particular risk, requiring close monitoring.
authors.affiliation: Complex Motor Disorder Service, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK; Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK. Electronic address: Daniel.lumsden@nhs.net.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Lumsden
authors.affiliation: Complex Motor Disorder Service, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Hortensia
authors.initials: H
authors.lastname: Gimeno
authors.affiliation: Department of Statistics, University of Warwick, Coventry, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Elze
authors.affiliation: Complex Motor Disorder Service, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Kylee
authors.initials: K
authors.lastname: Tustin
authors.affiliation: Complex Motor Disorder Service, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Kaminska
authors.affiliation: Complex Motor Disorder Service, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lin
mesh_terms: D001847:Bone Diseases / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018450:Disease Progression; D020821:Dystonic Disorders / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D009128:Muscle Spasticity / Q000150:complications*; D009135:Muscular Diseases / Q000209:etiology*; D012720:Severity of Illness Index
keywords: Childhood; Contracture; Deformity; Dystonia; Spasticity