Neurobehavioral assessment as a predictor of neurodevelopmental outcome in preterm infants

Preterm infants are at risk for neurodevelopmental impairment. The Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS) is a standardized assessment for the neurobehavioral integrity of the newborn. The use of NNNS as a prognostic tool is still emerging. We hypothesized that the NNNS examination performed at term equivalent can detect neurobehavioral alterations in very low birth weight infants and can help in predicting their neurodevelopmental outcome at 18 months corrected age (CA).

This is a prospective study that included preterm infants with birth weight <1500  g and gestational age ≤ 34 weeks. They were evaluated with NNNS at term-equivalent and 12 summary scores were assigned. Infants who had 2 or more NNNS summary scores that were 2 s.d. beyond the mean of the study group were categorized as having abnormal NNNS. Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) of Bayley Scales of Infant Development (BSID-II) were determined at 18 months CA. Multiple linear regression models were used to examine the predictivity of the NNNS summary scores for both MDI and PDI.

A total of 41 infants were evaluated at term and at 18 months CA. The average MDI was 78±15 and the average PDI was 80 ± 14. Significant neurodevelopmental delay was observed in 50% and 31% of infants with abnormal and normal NNNS, respectively. Using multiple linear regression, NNNS was predictive for both MDI (P=0.011, adjusted R (2)=0.295) and PDI (P=0.002, adjusted R (2)=0.441). Lower MDI was associated with less regulation and more nonoptimal reflexes, whereas lower PDI was associated with less regulation, more nonoptimal reflexes, hypertonicity and handling.

NNNS at term-equivalent age can detect neurobehavioral alterations in very low birth weight infants. Individual summary scores showed significant correlation with both the MDI and PDI at 18 months CA.