White matter brain injuries in infants may predict altered childhood cognitive function

Giving preterm infants qualitative MRIs when they reach term-equivalent age may help predict cognitive impairments as late as age 9, according to a study published in the journal Pediatrics. The study found that white matter injury found at 38 weeks to 42 weeks was correlated with altered cognitive function at 9 years old.

“MRI scans can reveal whether babies have any brain damage that is likely to cause problems as they grow and develop.”
-Srinivasa Girish, MBBS, MRCPCH, consultant neonatologist and pediatrician for Cloudnine Hospital in Jayangar, Bangalore, India

Identifying these problems early can help physicians formulate better follow-up strategies, said the authors, who recruited subjects from Nagano Children’s Hospital in Japan. While it is known that white matter injury is linked to[s2If !is_user_logged_in()]…

[/s2If][s2If is_user_logged_in()] cognitive impairment in preterm infants, this study is notable in that it found that the problems persisted even until age 9. Gray matter abnormalities, however, were not linked to cognitive problems at this age.

Key Point: Qualitative MRI performed on preterm infants can help predict whether they will have cognitive problems that could be addressed early on, a prospective study has found. White matter injuries in these children predicted cognitive problems; gray matter injuries did not.

The incidence of preterm deliveries has increased in India, putting the babies at risk for death and disability, said Srinivasa Girish, MBBS, MRCPCH, consultant neonatologist and pediatrician for Cloudnine Hospital in Jayangar, Bangalore. “In the West, it has become almost standard practice to perform MRI scans at corrected age of term, especially in babies born at less than 28 weeks gestation,” he told mdCurrent-India. “MRI scans can reveal whether babies have any brain damage that is likely to cause problems as they grow and develop.”

According to currently available evidence, standard sections of magnetic resonance imaging (MRI) scans should be obtained at least in preterm infants born at less than 28 weeks gestation, as well as in infants born between 28 weeks and 32 weeks of gestation if there are significant abnormalities noted on routine cranial ultrasound scans, Girish said. “I am not aware of any centers in South India doing white and gray matter volumes on MRI,” he said. “This would be a useful addition. It is not a complicated process, just additional software to have 3D reconstruction and to calculate volume.”

Low birthweight (under 2,500 grams) is a major public health issue in India, with one of the highest prevalence rates in the world: 30% of all births, as reported by the World Health Organization (http://www.ncbi.nlm.nih.gov/pubmed/3322602?dopt=Abstract).

In a study of full-term children in South India published in the journal Pediatric Research in 2010, S.R. Veena and colleagues found that higher birthweight and larger head circumference at birth are associated with better childhood cognitive ability. For children with very low birthweight, especially those born prematurely, the problems can be even more severe, but questions persist as to how predictable these problems are.

In the study published recently in Pediatrics, the preterm infants had a birthweight of 1,500 grams or lower and a gestational age of 32 weeks or fewer. In this prospective study, neurodevelopmental outcomes were assessed at 18 months and 36 months corrected age and 6 years chronological age; those results have been published. Of the 1,156 newborns in the original study (which began in 2000-2001), 117 children were assessed at 6 years of age; for this study, 76 were recruited. They were given the Wechsler Intelligence Scale for Children, assessed for cerebral palsy, and parents were asked whether the children needed special help at school for social, emotional, or behavioral issues. By age 9, 16 subjects were lost to follow-up.

For the remaining 60, moderately low verbal, performance, and full-scale IQs were recorded in 2, 7, and 7 subjects respectively, and mildly low verbal, performance, and full-scale IQs were recorded in 14, 25, and 18 subjects. Six subjects were diagnosed with cerebral palsy, and parents of 34 said their children needed special assistance at school. They were compared with 25 peers from the original study who did not have white matter injury.

Subjects with abnormal white matter had lower verbal, performance, and full-scale IQs, a higher incidence of cerebral palsy, and were more likely to need special help at school compared with their peers with normal MRI findings.

The study found that abnormal gray matter appearances were associated with white matter injury in the term MRI, but not with any outcome measures at age 9. This finding suggests that gray matter lesions, unlike white matter injury, may be subject to the “repairing process, plasticity, and extrinsic factors such as education and family environment,” the authors concluded.

Source: Iwata S, Nakamura T, Hizume E, et al. Qualitative brain MRI at term and cognitive outcomes at 9 years after very preterm birth. Pediatrics. 2012;129(5):e1138-e1147.

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