title: Developmental Coordination Disorder, An Umbrella Term for Motor Impairments in Children: Nature and Co-Morbid Disorders.
abstract: BACKGROUND
  Developmental Coordination Disorder (DCD) defines a heterogeneous class of children exhibiting marked impairment in motor coordination as a general group of deficits in fine and gross motricity (subtype mixed group) common to all research studies, and with a variety of other motor disorders that have been little investigated. No consensus about symptoms and etiology has been established.
  
  
  METHODS
  Data from 58 children aged 6 to 13 years with DCD were collected on DSM-IV criteria, similar to DSM-5 criteria. They had no other medical condition and inclusion criteria were strict (born full-term, no medication, no occupational/physical therapy). Multivariate statistical methods were used to evidence relevant interactions between discriminant features in a general DCD subtype group and to highlight specific co-morbidities. The study examined age-calibrated standardized scores from completed assessments of psychological, neuropsychological, and neuropsychomotor functions, and more specifically the presence of minor neurological dysfunctions (MND) including neurological soft signs (NSS), without evidence of focal neurological brain involvement. These were not considered in most previous studies.
  
  
  RESULTS
  Findings show the salient DCD markers for the mixed subtype (imitation of gestures, digital perception, digital praxia, manual dexterity, upper, and lower limb coordination), vs. surprising co-morbidities, with 33% of MND with mild spasticity from phasic stretch reflex (PSR), not associated with the above impairments but rather with sitting tone (p = 0.004) and dysdiadochokinesia (p = 0.011). PSR was not specific to a DCD subtype but was related to increased impairment of coordination between upper and lower limbs and manual dexterity. Our results highlight the major contribution of an extensive neuro-developmental assessment (mental and physical).
  
  
  CONCLUSIONS
  The present study provides important new evidence in favor of a complete physical neuropsychomotor assessment, including neuromuscular tone examination, using appropriate standardized neurodevelopmental tools (common tasks across ages with age-related normative data) in order to distinguish motor impairments gathered under the umbrella term of developmental coordination disorders (subcortical vs. cortical). Mild spasticity in the gastrocnemius muscles, such as phasic stretch reflex (PSR), suggests disturbances of the motor pathway, increasing impairment of gross and fine motricity. These findings contribute to understanding the nature of motor disorders in DCD by taking account of possible co-morbidities (corticospinal tract disturbances) to improve diagnosis and adapt treatment programmes in clinical practice.
authors.affiliation: Faculty of Medicine, University of Paris Descartes, Sorbonne Paris CitéParis, France; Institut National de la Santé Et de la Recherche Médicale UMR 1018 and CESP, University of Paris Sud-Paris Saclay, UVSQ and Paris Descartes, Sorbonne Paris CitéParis, France; Department of Child Psychiatry, AP-HP Necker-Enfants Malades University HospitalParis, France; Department of Pediatrics, Child Development, Cochin-Port Royal University Hospitals of Paris Center, Assistance Publique-Hôpitaux de ParisParis, France; Necker-Enfants Malades Hospital, University Hospitalo-Institut ImagineParis, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Vaivre-Douret
authors.affiliation: Patient-Centered Outcomes Research, EA 7334 (REMES), University of Paris Diderot, Sorbonne Paris Cité Paris, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Lalanne
authors.affiliation: Faculty of Medicine, University of Paris Descartes, Sorbonne Paris CitéParis, France; Institut National de la Santé Et de la Recherche Médicale UMR 1018 and CESP, University of Paris Sud-Paris Saclay, UVSQ and Paris Descartes, Sorbonne Paris CitéParis, France; Department of Child Psychiatry, AP-HP Necker-Enfants Malades University HospitalParis, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Golse
keywords: brain MRI; co-morbidity; developmental coordination disorder; minor neurological dysfunctions; motor impairment; neuro-developmental assessment; neurological soft signs; neuropsychological assessment