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Assessment and Evaluation of the High Risk Neonate: The NICU Network Neurobehavioral Scale
Published on: August 25, 2014
SNAP-II and SNAPPE-II and the risk of structural and functional brain disorders in extremely low gestational age
Olaf Dammann1, Mary Naples, Francis Bednarek
1Division of Newborn Medicine, Floating Hospital for Children at Tufts Medical Center, Boston, Mass. 02111, USA. odammann@tufts-nemc.org
Insights
Illness severity scores in newborns can predict brain damage and neurodevelopmental issues in preterm infants. High scores indicate increased risk, reflecting instability and vulnerability in the early postnatal period.
Area of Science:
- Neonatalogy
- Pediatric Neurology
- Developmental Pediatrics
Background:
- Illness severity measures are established predictors of mortality and morbidity in newborns.
- Their ability to predict specific brain lesions and neurodevelopmental outcomes in preterm infants remains largely uncharacterized.
Purpose of the Study:
- To evaluate the predictive value of Scores for Neonatal Acute Physiology (SNAP-II and SNAPPE-II) for brain lesions and neurodevelopmental dysfunction in preterm infants.
Main Methods:
- 1,399 infants born before 28 weeks gestation were assessed using SNAP-II and SNAPPE-II within 12 hours of ICU admission.
- Brain ultrasound scans were performed, and neurodevelopmental assessments (neurologic examination, Bayley Scales) were conducted at ~24 months post-term for survivors.
- SNAP scores were analyzed using various dichotomized cut-offs, including gestational age quartiles, deciles, and Z-scores.
Main Results:
- High SNAP-II and SNAPPE-II scores predicted intraventricular hemorrhage, moderate/severe ventriculomegaly, and echodense white matter lesions.
- Specific SNAP-II extremes predicted echolucent white matter lesions, but neither score predicted cerebral palsy.
- Both scores consistently predicted severe neurodevelopmental impairment (MDI/PDI <55) and inconsistently predicted milder impairment, autism spectrum disorder, and small head circumference.
Conclusions:
- Physiologic instability in early postnatal hours, as measured by illness severity scores, provides valuable information on the risk of brain damage and neurodevelopmental issues.
- These findings suggest that early instability may reflect postnatal factors contributing to adverse outcomes.
- Elevated SNAP scores may also serve as indicators of prematurity and inherent vulnerability in preterm infants.
Background:
Illness severity measures predict death and illnesses in the newborn. It is unknown how well they predict brain lesions evident on ultrasound scans or neurodevelopmental dysfunctions in preterm infants.
Methods:
A total of 1,399 inborn infants born before the 28th week of gestation were given Scores for Neonatal Acute Physiology (SNAP-II and SNAPPE-II) based on data collected within the first 12 h of admission to the intensive care unit and had a protocol brain ultrasound scan read independently by 2 sonologists. Of the surviving 1,149 infants, 1,014 (88%) had a neurologic examination at approximately 24 months post-term equivalent, and 975 (85%) had a Bayley Scales of Infant Development assessment. SNAP-II and SNAPPE-II were dichotomized at arbitrary cut-offs (30 for SNAP-II and 45 for SNAPPE-II), using the highest quartile and decile of the week of gestation as a cut-off, and at a Z score of >1 standard deviation from an external mean.
Results:
After adjustment for gestational age, high SNAP-II and SNAPPE-II scores predicted intraventricular hemorrhage, moderate/severe ventriculomegaly and echodense lesions in cerebral white matter. Only 2 SNAP-II extremes, the highest decile for gestational age and a Z score >1, also predicted echolucent lesions in the white matter. Neither SNAP-II nor SNAPPE-II predicted any statistically significant diagnosis of cerebral palsy. MDI and PDI scores <55 were consistently predicted by both high SNAP-II and SNAPPE-II, whereas scores in the 55-69 range were inconsistently predicted. High SNAP-II and SNAPPE-II inconsistently predicted a positive screen for autism spectrum disorder and small head circumference at 24 months.
Conclusion:
The physiologic instability in the first 12 post-natal hours identified by illness severity scores conveys information about the risks of brain damage and neurodevelopmental dysfunctions. This risk information might reflect postnatal characteristics in the causal chain. On the other hand, high SNAP scores might be indicators of immaturity and vulnerability.
