OC6.02: Growth rate of corpus callosum in very premature infants

Abstract

Objective: A bedside method for assessing the effectiveness of strategies to improve cerebral development in very premature infants is desirable. The aim of this study was to compare the growth trajectory of the corpus callosum on cranial ultrasound in very premature infants and compare it with the growth rate seen antenatally. Methods: We recruited 100 very low birth weight infants admitted to a single regional Level III neonatal intensive care unit from November 1998 to November 2000. Sixty-four (32 boys) infants, mean gestational age 28 weeks (range 23–33 weeks), had cranial ultrasound images of the corpus callosum adequate for measurement obtained in the first week of life and at term equivalent. The length of corpus callosum was identified as the most reproducible measurement in a sub-group of 16 infants. The growth rate of the corpus callosum was compared in the 64 study infants to the expected growth rate of 0.20–0.27 mm/day from antenatal data; and correlated with clinical outcome at two years of age in 55 infants using Mental Development Index and Psychomotor Development Index. Results: The average growth rate of the corpus callosum was half the rate expected from antenatal data. Mean growth rates were similar for all age ranges (p = 0.4); 0.12 mm/day (0.07–0.17) for the 9 infants born at 23–25 weeks’ gestation; 0.11 mm/day (0.06–0.18) for the 35 infants born at 26–29 weeks; 0.11 mm/day (0.05–0.29) for the 20 born at 30–33 weeks. Growth rate of the corpus callosum was greater in infants who had antenatal steroids (p = 0.02) or who were born IUGR (p = 0.04). There was no correlation with gender, PROM, multiple birth; or BPD or indomethicin postnatally. There was poor correlation with mental and psychomotor outcome. Conclusion: Measurement of the length of the corpus callosum at cranial ultrasound is reproducible. The length of corpus callosum grows at a much lower rate postnatally than in utero among very premature infants.