In a study of preterm infants with extremely low birth weight (1,000 grams or less), clinicians observed smaller global and regional brain tissue volume on volumetric magnetic resonance imaging (MRI) in infants treated with commonly prescribed doses of postnatal dexamethasone as compared to matched untreated infants.
"These volume deficits enhance our understanding of the cognitive and motor deficits reported after postnatal dexamethasone therapy," lead author Dr. Nehal A. Parikh of the University of Texas Medical School at Houston told Reuters Health. He and colleagues published their results in the February 2007 issue of Pediatrics.
Among 41 infants with high-quality MRI studies, 11 received postnatal dexamethasone treatment after postnatal age of 28 days, for an average of 6.8 days and a mean cumulative dose of 2.8 mg/kg. The remaining 30 infants did not receive dexamethasone.
After controlling for postmenstrual age at MRI, Dr. Parikh and colleagues observed a 10.2% smaller total cerebral tissue volume in dexamethasone-treated infants relative to untreated infants.
Similarly, cortical tissue volume was 8.7% smaller in treated infants relative to untreated infants and regional volume studies indicated a 20.6% smaller cerebellum and a 19.9% reduction in subcortical gray matter in dexamethasone- treated compared with untreated infants.
In a series of regression analyses, these dexamethasone-associated changes remained significant after controlling not only for postmenopausal age but also for bronchopulmonary dysplasia and birth weight.
"Despite our best efforts to control for group differences in illness, significant findings may have resulted from incomplete control of confounding," Dr. Parikh emphasized. "Such uncertainties can best be addressed with a well-designed randomized trial with assessment of neurosensory outcomes, as we are currently undertaking."
Until such results are available, Dr. Parikh said, "the latest American Academy of Pediatrics recommendations should be followed to guide management decisions in very preterm infants with bronchopulmonary dysplasia".
Pediatrics 2007;119:265-272
