Infants born preterm have delayed development of adaptive postural control in the first 5 months of life.

Research Report
Population: Pediatric

Stacey C Dusing, PhD, PT, PCS, Associate Professor, Virginia Commonwealth University and Children’s Hospital of Richmond scdusing@vcu.edu

Leroy Thacker, PhD, Assistant Professor, Virginia Commonwealth University s2lrthac@vcu.edu

James Galloway, PT, PhD, Professor, University of Delaware jacgallo@udel.edu

Keywords: Prediction, Preterm, Adaptation, Infancy

Infants born prematurely are at-risk for learning difficulties, lower quality of life, and disability. Early experiences with repetitive practice of atypical movement in the first months of life, when the brain is most plasticity, may contribute to motor and learning disabilities.  Infants born preterm have demonstrated reduced ability to learn motor skills yet federally mandated Early Intervention provides low intensity intervention to eligible infants. Identifying infants at the highest risk of disabilities remains difficult, limiting our ability to provide intense early intervention.  The purpose of this paper was to evaluate the ability of infants born preterm to adapt their postural control to changing task demands.  This work may help identify atypical postural control strategies leading to early detection methods and preventative interventions.    Methods: This study included 18 infants born at 32 weeks of gestation or less (gestational age 28.3 ± 3.1 weeks).  Posture was measured in supine during 2 conditions, without a visual stimulus and with a visual stimulus to encourage reaching.  Postural variability, measured with the root mean squared displacement of the center of pressure, and postural complexity, measured with the approximate entropy of the center of pressure displacement time series were measured longitudinally from 2.5 to 5 months of age during the development of midline head control and reaching. A mixed linear model was used to quantify the impact of Condition over time (Age) on the postural variability and postural complexity.  Results:  The infants in this study looked at the toy in midline 64.7% of the time and kept their head in midline (78.0%) more with a visual stimulus than without (55.0%) by 3 months of age.  There was a significant interaction between Condition and Age on the postural variability in the caudal cephalic direction (F1,72 = 5.05, p=0.03). Post-hoc analysis revealed that postural variability in the caudal cephalic direction was significantly lower at 4.0 and 5 months of age in the Toy Condition than in the No Toy Condition, p = 0.01 and p < 0.01, respectively.  There was a condition effect (F 1,11 = 7.09, p = 0.02) but no age effect (F 1,73 = 0.82, p = 0.37, Figure 1b) on postural variability in the medial lateral direction. There was no significant interaction, condition, or age effect on postural complexity in either direction.

 

Discussion: Typically developing infants adapt their postural variability to reduce the displacement of their center of pressure when a toy is presented by 1 months of age.   While reducing postural variability they are able to maintain optimal postural complexity.  In contrast, the infants in this study who were born preterm did not reduce their postural variability until several months after they began looking at and attempting to reach for the toy.  While the infants learned to adapt their postural variability, this study demonstrates reduced adaptability of the postural control system and a need for additional practice to learn postural control skills which is likely to impact learning.

Citation:
Dusing, Stacey C, PhD, PT, PCS; Thacker, Leroy R, PhD; Galloway, James Cole, PT, PhD. Infants born preterm have delayed development of adaptive postural control in the first 5 months of life.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online. https://u.osu.edu/ivstep/poster/abstracts/092_dusing-et-al/

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