Validation of the Specific Test of Early Infant Motor Performance With Neuroimaging

PURPOSE: Preterm birth is a major risk factor for motor development delays, and occupational therapists with specialized training in the neonatal intensive care unit can identify infants most at risk for early therapy services (Case-Smith et al., 2013; Coker-Bolt et al., 2014; Muhlenhaupt et al., 2015). A newly developed, rapid, and easy-to-administer infant assessment, the 10-item Specific Test of Early Infant Motor Performance (STEP), assesses motor behaviors from birth to age 3 mo. The aims of this study were to explore the concurrent and predictive validity of the STEP with gold standard infant motor assessments at term, 12 wk, and 1 yr corrected age (CA) and the STEP cutoff scores for high- and low-risk infants in relationship to early brain neuroimaging using diffusion kurtosis imaging (DKI) and magnetic resonance spectroscopy (MRS) at term CA.

METHOD: This study was a retrospective analysis of 22 preterm infants (26–34 wk gestational age). Outcome measures were the STEP, Test of Infant Motor Performance (TIMP), and Alberta Infant Motor Scales (AIMS) at term and 3 mo CA and neuroimaging (DKI and MRS) at term CA. Pearson correlations were used to determine relationships among STEP, TIMP, and AIMS scores at term and 3 mo and Bayley Scales of Infant and Toddler Development, Third Edition, Gross Motor (Bayley–III GM) scaled scores at 1 yr.

Receiver operating characteristic (ROC) analysis was used to determine STEP cutoff scores. DKI was analyzed for fractional anisotropy (FA) using voxelwise statistical comparisons between high- and low-risk groups in the white matter tracts. MRS metabolites were analyzed in the frontal white matter and basal ganglia, and generalized linear models with gestational age at scan and birth were created to assess relationships.

RESULTS: This cohort of infants included two infants with cystic periventricular leukomalacia (PVL) but none with Grade 3 or 4 intraventricular hemorrhage. Significant correlations were found between STEP and Bayley–III GM scaled scores at 1 yr (n = 19) and STEP scores at term (r ² = .698, p = .001) and 3 mo (r ² = .621, p = .005). No significant correlation was found between TIMP scores at term or 3 mo with Bayley–III GM scaled scores at 1 yr (term, r ² = .125, p = .621; 3 mo, r ² = .418, p = .075, n = 19). A clear cutoff was shown between high-risk and low-risk infant STEP scores.

Neuroimaging FA values were significantly different in the corpus callosum, left internal capsule, and left inferior fronto-occipital fasciculus between high- and low-risk infants. This signifies greater white matter tract integrity in low-risk infants. Additionally, healthy neuronal metabolite N-acetylaspartate (NAA/Cho, NAA/Cr) in the white matter and basal ganglia positively predicted STEP and TIMP scores.

CONCLUSION: The STEP sensitivity and specificity have a stronger predictive correlation with 1-yr Bayley–III GM scaled scores than the TIMP assessment, which involves prolonged handling of infants and poor utility in a clinical setting. STEP risk categorization accounted for differences in DKI FA values in the white matter. Additionally, NAA ratios in the white matter and basal ganglia predicted higher STEP and TIMP scores. Because of the small sample size, analysis of the psychometric properties of the STEP is only preliminary. Validation of term and 3-mo CA cutoff scores should be explored with a larger, more diverse sample of infants.

IMPACT STATEMENT: The STEP has potential to become a predictive developmental screening tool in the neonatal nursery, potentially leading to earlier referral to occupational therapy services for infants at risk for developmental delays.

References

Case-Smith, J., Clark, G., & Schlabach, T. (2013). Systematic review of interventions used in occupational therapy to promote motor performance for children ages birth–5 years. American Journal of Occupational Therapy, 67, 413–424. https://doi.org/10.5014/ajot.2013.005959

Coker-Bolt, P., Woodbury, M. L., Perkel, J., Moreau, N. G., Hope, K., Ramakrishnan, V., . . . Jenkins, D. (2014). Identifying premature infants at high and low risk for motor delays using motor performance testing and MRS. Journal of Pediatric Rehabilitation Medicine, 7, 219–232. https://doi.org/10.3233/PRM-140291

Donohue, P. K., & Graham, E. M. (2015). Earlier markers for cerebral palsy and clinical research in premature infants. Journal of Perinatology, 27, 259–261. https://doi.org/10.1038/sj.jp.7211741

Muhlenhaupt, M., Pizur-Barnekow, K., Schefkind, S., Chandler, B., & Harvison, N. (2015). Occupational therapy contributions in early intervention: Implications for personnel preparation and interprofessional practice. Infants and Young Children, 28, 123–132.