Neonatal MRI as Predictor of Neurodevelopmental Outcome in Preterm Infants
Neonatal MRI as Predictor of Neurodevelopmental Outcome in Preterm Infants
Abstract & Commentary
By Barry Kosofsky, MD, PhD, Professor of Pediatrics and Neurology, and Chief of Pediatric Neurology at Weill Cornell Medical Center. Dr. Kosofsky reports no financial relationships relevant to this field of study.
Synopsis: This article reports a strong correlation between abnormal MRI at term equivalent in preterm infants with adverse neurodevelopmental outcomes at 2 years of age, suggesting its utility for risk stratification.
Source: Woodward LJ, et al. Neonatal MRI to Predict Neurodevelopmental Outcomes in Preterm Infants. N Engl J Med. 2006; 355:685-694.
Very preterm infants born before 32 weeks have significant rates of neurodevelopmental disabilities ranging from neurosensory impairments and learning disabilities to cerebral palsy (CP). Known risk factors for neurodevelopmental adverse outcomes include sepsis, surgery, postnatal use of steroids, bronchopulmonary dysplasia, intraventricular hemorrhage, and periventricular leukomalacia. MRIs on these newborns show a variety of white matter and some gray matter abnormalities.
This prospective longitudinal study reports an association between gray and white matter abnormalities on MRI at term equivalent and neurodevelopmental outcomes defined by a battery of standardized tests at age 2. It also compares MRI to existing prognostic indicators. The subjects included 167 very preterm infants enrolled at 2 different institutions, all born at 30 weeks of gestation or less. MRIs were performed at term equivalent using 1.5 Tesla magnets. Scans were categorized using a standardized scoring system developed during this study, consisting of five 3-point scales for white matter abnormalities (signal abnormalities, volume loss in periventricular area, cystic abnormalities, ventricular dilatation, callosal thinning) and three 3-point scales for gray matter abnormalities (signal abnormalities, quality of gyral maturation, size of subarachnoid space). Cranial ultrasounds were performed during the first 2 days and at 4-6 weeks of life. At 2 years of age, these children were assessed clinically, and identified as having severe cognitive delay, severe motor delay, CP, or neurosensory impairment based on scoring on standardized tests like the Bayley scale and the Mental Development Index, as well as examination by a pediatric neurologist.
This study found poorer performance on the cognitive and psychomotor scales and increased risk of severe cognitive delay, severe motor delay, CP and severe neurosensory impairment with increasing severity of white matter abnormalities. Children with gray matter abnormalities also fared similarly except there was no significant association with neurosensory impairment. The study found the presence of moderate-to-severe white matter abnormalities to independently correlate with adverse neurodevelopmental outcome more strongly than known predictors. In particular, MRI identified patterns of brain injury were demonstrated to be more sensitive and specific than cranial ultrasonography. Postnatal use of corticosteroids remained a significant predictor of adverse outcomes after adjusting for MRI abnormalities and other known risk factors.
Of note, a substantial proportion of infants with moderate-to-severe white matter abnormalities were free of severe impairment at 2 years of age thus indicating the potential protective role of other genetic and environmental factors.
Commentary
This study demonstrates the superiority of MRI over cranial ultrasound to predict neurodevelopmental outcome of very low-birth-weight preterm infants, which is probably a result of both the superior spatial resolution as well as the increased sensitivity of MR to detect neuronal and axonal damage. The additional cost and reduced access to MRI may make it a less attractive option for routine screenings, particularly for serial assessments during the early postnatal period when cranial ultrasonography can assess 4 out of 5 parameters for white matter abnormalities that authors measured on MRI. However, the added sensitivity and specificity of MRI warrants its use, particularly when performed at 40 weeks post-conception, to utilize the positive and negative predictive value demonstrated in this report, which will be of tremendous help for practicing neonatologists and child neurologists to assist with the prognosis and care of this population of infants at significant risk for developmental disabilities.
This article reports a strong correlation between abnormal MRI at term equivalent in preterm infants with adverse neurodevelopmental outcomes at 2 years of age, suggesting its utility for risk stratification.Subscribe Now for Access
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