Abnormal truncal muscle tone as a useful early marker for developmental delay in low birth weight infants.

Thirty-four outborn premature infants of appropriate gestational ages with birth weights less than 1,750 g were seen in follow-up at 3, 6, 12, and 18 months, corrected age to assess the incidence of abnormalities of muscle tone and the relationship of the site of early abnormalities to 18-month developmental status. The incidence of abnormal tone was most common at 3 months and declined with increasing age. The percentages of infants with abnormal tone at 3, 6, 12, and 18 months, respectively, were: increased lower extremity tone--62%, 71%, 38%, 9%; decreased lower extremity tone--3%, 3%, 6%, 9%; increased truncal tone--41%, 15%, 6%, 0%; decreased truncal tone--21%, 18%, 15%, 6%. Infants with truncal hypertonicity at 3 months had significantly lower Bayley motor and mental scores at 18 months when compared with infants with normal truncal tone (P less than .05). However, infants with lower extremity hypertonicity at 3 months were no different developmentally at 18 months from infants with normal tone. Infants with truncal or lower extremity hypotonicity fared the worst developmentally (P less than .05). We conclude that there is a high incidence of abnormal muscle tone in premature infants up to 18 months of age and that early truncal tone abnormalities are associated with a worse developmental outcome.

Effect of neonatal caloric deprivation on head growth and 1-year developmental status in preterm infants.

The effects of neonatal illness and caloric intake on head growth velocity and on 1-year developmental outcome were studied in 73 appropriate (AGA) and small for gestational age (SGA) premature infants of (mean +/- SD) 30 +/- 2 weeks gestation who received intensive care during the neonatal period. Head growth from birth to 1 year of corrected age was characterized by a triphasic curve initiated by a period of growth arrest or suboptimal growth followed by a period of catch-up growth and terminated by a period of growth along standard curves. Head growth arrest or suboptimal head growth were directly related to the duration of the initial period of caloric deprivation (less than 85 kcal/kg/day) and to the duration of mechanical ventilation. Catch-up head growth was influenced by the duration of the preceding period of caloric deprivation in all infants and by the caloric intake during that phase only in SGA infants; catch-up growth was unrelated to the duration of mechanical ventilation. Head growth along standard curves occurred in all infants by 3 months of corrected age and persisted up to 1 year of corrected age. Infants calorically deprived the longest (AGA 4 to 6 weeks, SGA 2 to 3 weeks) had head growth along standards at curves below -1 SD on the growth chart; all other groups had this phase of head growth at curves between the mean and -1 SD. Infants calorically deprived for more than 4 weeks had developmental scores below normal ranges by 1 year of corrected age.