Motor impairment in very preterm infants: implications for clinical practice and research JILL G ZWICKER 1,2,3,4,5 1 Department of Occupational Science and Occupational Therapy, University of British Columbia, Vancouver, BC; 2 Department of Pediatrics, University of British Columbia, Vancouver, BC; 3 Child & Family Research Institute, Vancouver, BC; 4 Sunny Hill Health Centre for Children, Vancouver, BC; 5 CanChild Centre for Childhood Disability Research, Hamilton, ON, Canada doi: 10.1111/dmcn.12454 This commentary is on the original article by Van Hus et al. on pages 587–594 of this issue.
Infants born very preterm (≤32wks gestation) are at high risk of motor impairments in childhood. While the incidence of cerebral palsy (CP) is declining,1 other motor impairments, such as developmental coordination disorder (DCD), remain a considerable concern.2 These so-called ‘minor motor difficulties’ are far from minor in the child’s life; they have a significant and persistent impact on the child’s ability to perform daily activities and learn motor skills, such as tying shoelaces, using a knife and fork, riding a bicycle, or participating in sports.3 Often co-occurring with these motor problems are other developmental disorders, such as attention-deficit–hyperactivity disorder, learning disabilities, and specific language impairment, which is suggestive of a shared etiology.3 Van Hus et al.4 report that 32% of their very preterm cohort without CP (n = 81) had poor motor scores at age 5 years, less than the 42% prevalence of DCD reported in other preterm cohorts.5,6 Van Hus et al. examined what other developmental deficits were most associated with motor impairment, finding that four deficits – minor neurological dysfunction, low IQ, slow processing speed, and hyperactivity/inattention – mediated the relationship between preterm birth and motor impairment. While the association of other developmental deficits with motor impairment is not surprising, it is unclear whether these other impairments mediate the relationship, or if the opposite is true. For example, early motor performance has been shown to be predictive of cognitive
function at 1 year;7 however, it is not clear if this relationship persists later in childhood. As Diamond indicates, to be a close relationship between motor and cognitive development exists, likely due to the mutual brain circuitry involved in these functions.8 As Van Hus et al.4 indicate, it is important to recognize that preterm infants with motor impairments are also highly likely to have other deficits, such as lower IQ or attention difficulties. This has implications for intervention, as current best-practice rehabilitation interventions for motor difficulties consistent with DCD rely on cognitive strategies and/or verbal mediation to support motor performance.9 It is largely unknown whether these interventions designed to improve motor function are effective in children with co-occurring developmental deficits, particularly in the preterm population. While white matter injury has been hypothesized to account for motor and cognitive deficits in children born preterm,10 recent research suggests that altered brain maturation is also an important predictor of neurodevelopmental outcomes.11 Recent evidence also suggests that it is not preterm birth per se, but early life experiences (e.g., early illness severity, postnatal infection, pain-related stress) that are associated with altered brain development.12–14 These findings suggest that these risk factors may be modifiable and offer opportunities to improve both motor and cognitive outcomes of preterm infants. As indicated by Van Hus et al.,4 motor difficulties in the absence of CP are highly prevalent in 5-year-old children born preterm and are associated with minor neurological dysfunction, low IQ, slow processing speed, and hyperactivity/inattention. The overlap of motor and cognitive impairment calls for early intervention and a comprehensive approach to address the multiple needs and improve outcomes of this population. Further research should continue to identify and better manage risk factors for altered brain development, which in turn may positively influence neurodevelopmental outcomes of children born preterm.
REFERENCES 1. Van Haastert IC, Groenendaal F, Uiterwaal C, et al.
3. Zwicker JG, Missiuna C, Harris SR, Boyd LA. Develop-
5. Zwicker JG, Yoon SW, Mackay M, Petrie-Thomas J,
Decreasing incidence and severity of cerebral palsy in
mental coordination disorder: a review and update. Eur
Rogers M, Synnes A. Perinatal and neonatal predictors
J Paediatr Neurol 2012; 16: 573–81.
of developmental coordination disorder. Arch Dis Child
prematurely born children. J
Pediatr 2011; 159:
86–91.
4. Van Hus JW, Potharst ES, Jeukens-Visser M, Kok
2013; 98: 118–22. 6. Goyen
2. Edwards J, Berube M, Erlandson K, et al. Developmen-
JH, Van Wassenaer-Leemhuis AG. Motor impair-
tal coordination disorder in school-aged children born
ment in very preterm-born children: links with
preterm and/or at very low birth weight: a systematic
developmental deficits at 5 years of age. Dev Med
born extremely preterm. Arch Dis Child 2009; 94:
review. J Dev Behav Pediatr 2011; 32: 678–87.
Child Neurol 2014; 56: 587–94.
298–302.
514 Developmental Medicine & Child Neurology 2014, 56: 509–514
disorder
TA, in
Lui
K.
Developmental
“apparently
normal”
coordination schoolchildren
7. Metgud DC, Patil VD, Dhaded SM. Predictive validity of the Movement Assessment of Infants (MAI) for sixmonth-old very low birth weight infants. J Phys Ther 2011; 3: 19–23. 8. Diamond A. Close interrelation of motor development and cognitive development and of the cerebellum and prefrontal cortex. Child Dev 2000; 71: 44–56. 9. Smits-Engelsman BC, Blank R, van der Kaay AC, et al.
combined systematic review and meta-analysis. Dev Med Child Neurol 2013; 55: 229–37.
12. Bonifacio SL, Glass HC, Chau V, et al. Extreme premature birth is not associated with impaired development
10. Spittle AJ, Cheong J, Doyle LW, et al. Neonatal white
of brain microstructure. J Pediatr 2010; 157: 726–32.
matter abnormality predicts childhood motor impair-
13. Brummelte S, Grunau RE, Chau V, et al. Procedural
ment in very preterm children. Dev Med Child Neurol
pain and brain development in premature newborns. Ann Neurol 2012; 71: 385–96.
2011; 53: 1000–6. 11. Chau V, Synnes A, Grunau RE, et al. Abnormal brain
14. Zwicker JG, Grunau RE, Adams E, et al. Score for
with
Neonatal Acute Physiology-II and neonatal pain predict
Efficacy of interventions to improve motor performance
adverse developmental outcomes. Neurology 2013; 81:
corticospinal tract development in premature newborns.
in children with developmental coordination disorder: a
2082–9.
Pediatr Neurol 2013; 48: 123–9.
maturation
in
preterm
neonates
associated
Commentaries
515
Infants born very preterm (≤32wks gestation) are at high risk of motor impairments in childhood. While the incidence of cerebral palsy (CP) is declining,1 other motor impairments, such as developmental coordination disorder (DCD), remain a considerable concern.2 These so-called ‘minor motor difficulties’ are far from minor in the child’s life; they have a significant and persistent impact on the child’s ability to perform daily activities and learn motor skills, such as tying shoelaces, using a knife and fork, riding a bicycle, or participating in sports.3 Often co-occurring with these motor problems are other developmental disorders, such as attention-deficit–hyperactivity disorder, learning disabilities, and specific language impairment, which is suggestive of a shared etiology.3 Van Hus et al.4 report that 32% of their very preterm cohort without CP (n = 81) had poor motor scores at age 5 years, less than the 42% prevalence of DCD reported in other preterm cohorts.5,6 Van Hus et al. examined what other developmental deficits were most associated with motor impairment, finding that four deficits – minor neurological dysfunction, low IQ, slow processing speed, and hyperactivity/inattention – mediated the relationship between preterm birth and motor impairment. While the association of other developmental deficits with motor impairment is not surprising, it is unclear whether these other impairments mediate the relationship, or if the opposite is true. For example, early motor performance has been shown to be predictive of cognitive
function at 1 year;7 however, it is not clear if this relationship persists later in childhood. As Diamond indicates, to be a close relationship between motor and cognitive development exists, likely due to the mutual brain circuitry involved in these functions.8 As Van Hus et al.4 indicate, it is important to recognize that preterm infants with motor impairments are also highly likely to have other deficits, such as lower IQ or attention difficulties. This has implications for intervention, as current best-practice rehabilitation interventions for motor difficulties consistent with DCD rely on cognitive strategies and/or verbal mediation to support motor performance.9 It is largely unknown whether these interventions designed to improve motor function are effective in children with co-occurring developmental deficits, particularly in the preterm population. While white matter injury has been hypothesized to account for motor and cognitive deficits in children born preterm,10 recent research suggests that altered brain maturation is also an important predictor of neurodevelopmental outcomes.11 Recent evidence also suggests that it is not preterm birth per se, but early life experiences (e.g., early illness severity, postnatal infection, pain-related stress) that are associated with altered brain development.12–14 These findings suggest that these risk factors may be modifiable and offer opportunities to improve both motor and cognitive outcomes of preterm infants. As indicated by Van Hus et al.,4 motor difficulties in the absence of CP are highly prevalent in 5-year-old children born preterm and are associated with minor neurological dysfunction, low IQ, slow processing speed, and hyperactivity/inattention. The overlap of motor and cognitive impairment calls for early intervention and a comprehensive approach to address the multiple needs and improve outcomes of this population. Further research should continue to identify and better manage risk factors for altered brain development, which in turn may positively influence neurodevelopmental outcomes of children born preterm.
REFERENCES 1. Van Haastert IC, Groenendaal F, Uiterwaal C, et al.
3. Zwicker JG, Missiuna C, Harris SR, Boyd LA. Develop-
5. Zwicker JG, Yoon SW, Mackay M, Petrie-Thomas J,
Decreasing incidence and severity of cerebral palsy in
mental coordination disorder: a review and update. Eur
Rogers M, Synnes A. Perinatal and neonatal predictors
J Paediatr Neurol 2012; 16: 573–81.
of developmental coordination disorder. Arch Dis Child
prematurely born children. J
Pediatr 2011; 159:
86–91.
4. Van Hus JW, Potharst ES, Jeukens-Visser M, Kok
2013; 98: 118–22. 6. Goyen
2. Edwards J, Berube M, Erlandson K, et al. Developmen-
JH, Van Wassenaer-Leemhuis AG. Motor impair-
tal coordination disorder in school-aged children born
ment in very preterm-born children: links with
preterm and/or at very low birth weight: a systematic
developmental deficits at 5 years of age. Dev Med
born extremely preterm. Arch Dis Child 2009; 94:
review. J Dev Behav Pediatr 2011; 32: 678–87.
Child Neurol 2014; 56: 587–94.
298–302.
514 Developmental Medicine & Child Neurology 2014, 56: 509–514
disorder
TA, in
Lui
K.
Developmental
“apparently
normal”
coordination schoolchildren
7. Metgud DC, Patil VD, Dhaded SM. Predictive validity of the Movement Assessment of Infants (MAI) for sixmonth-old very low birth weight infants. J Phys Ther 2011; 3: 19–23. 8. Diamond A. Close interrelation of motor development and cognitive development and of the cerebellum and prefrontal cortex. Child Dev 2000; 71: 44–56. 9. Smits-Engelsman BC, Blank R, van der Kaay AC, et al.
combined systematic review and meta-analysis. Dev Med Child Neurol 2013; 55: 229–37.
12. Bonifacio SL, Glass HC, Chau V, et al. Extreme premature birth is not associated with impaired development
10. Spittle AJ, Cheong J, Doyle LW, et al. Neonatal white
of brain microstructure. J Pediatr 2010; 157: 726–32.
matter abnormality predicts childhood motor impair-
13. Brummelte S, Grunau RE, Chau V, et al. Procedural
ment in very preterm children. Dev Med Child Neurol
pain and brain development in premature newborns. Ann Neurol 2012; 71: 385–96.
2011; 53: 1000–6. 11. Chau V, Synnes A, Grunau RE, et al. Abnormal brain
14. Zwicker JG, Grunau RE, Adams E, et al. Score for
with
Neonatal Acute Physiology-II and neonatal pain predict
Efficacy of interventions to improve motor performance
adverse developmental outcomes. Neurology 2013; 81:
corticospinal tract development in premature newborns.
in children with developmental coordination disorder: a
2082–9.
Pediatr Neurol 2013; 48: 123–9.
maturation
in
preterm
neonates
associated
Commentaries
515
