Nutritional state and growth and functional maturation of the brain in extremely low birth weight infants

It is well-known that an undernutritional status influences central nervous system development in the fetal and early neonatal period. On the other hand, the maturational delay of the central nervous system is reflected as dysmature pattern (DMP) in the neonatal background electroencephalograph (EEG). Therefore, we hypothesized that the postnatal nutritional status influenced electrophysiologic maturation in extremely low birth weight infants (ELBWIs).

ELBWIs between 24 and 27 weeks of gestational age who were admitted to Ogaki Municipal Hospital NICU from April 1997 to December 2000 were considered eligible. From the condition of enteral feeding, infants were divided into 2 groups: 1). normal nutritional group (group N), where enteral feeding had been established (100 mL/kg/d) by 3 weeks after birth; 2). undernutritional group (group U), where enteral feeding had not been established by 3 weeks after birth or was discontinued because of clinical problems. Weekly average body weight and head circumference gains were evaluated as nutritional status. EEG records were performed every 2 to 4 weeks until postnatal 15 weeks of age. DMP was defined as the appearance of immature EEG patterns for postconceptional age.

Twenty-one infants had serial EEG recordings; 11 infants belonged to group N and 10 infants to group U. Gestational age, birth weight, and head circumference at birth were not different between the 2 groups. The body weight of group N was significantly heavier than that of group U after 5 postnatal weeks. Similarly, the head circumference of group N was larger than that of group U after 6 weeks of postnatal age. Nine infants demonstrated DMPs. One infant belonged to group N and 8 to group U. DMPs were significantly more frequently found in group U than group N (80% vs 9%). In 6 of the 9 cases, the DMPs lasted until 38 to 40 weeks of postconceptional age. Five of the 6 infants with persistent DMPs suffered from severe undernutritional conditions. The other, who belonged to group N, was treated with corticosteroid for chronic lung disease. In 3 cases, DMPs were observed transiently and their undernutritional status was not so severe.

Our study indicated that a postnatal undernutritional condition was associated with DMPs in ELBWIs. Undernutritional status may affect electrophysiologic maturation.