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Abnormal truncal muscle tone as a useful early marker for developmental delay in low birth weight infants
Insights
Abnormal muscle tone is common in premature infants up to 18 months. Early truncal tone issues in premature infants are linked to poorer developmental outcomes by 18 months.
Area of Science:
- Neonatal Neurology
- Developmental Pediatrics
- Perinatal Medicine
Background:
- Premature infants often exhibit muscle tone abnormalities.
- Understanding the trajectory and impact of these tone issues is crucial for early intervention.
Purpose of the Study:
- To determine the incidence of muscle tone abnormalities in premature infants up to 18 months corrected age.
- To investigate the relationship between early muscle tone abnormalities and 18-month developmental status.
Main Methods:
- Follow-up study of 34 outborn premature infants (<1750g birth weight).
- Muscle tone assessed at 3, 6, 12, and 18 months corrected age.
- Bayley Scales of Infant Development used for 18-month developmental assessment.
Main Results:
- Abnormal muscle tone was most frequent at 3 months, decreasing with age.
- Truncal hypertonicity at 3 months correlated with lower 18-month Bayley motor and mental scores (P<.05).
- Hypotonicity (truncal or lower extremity) at 3 months was associated with the worst developmental outcomes (P<.05).
Conclusions:
- Premature infants show a high incidence of abnormal muscle tone persisting up to 18 months.
- Early detection of truncal tone abnormalities in premature infants may predict poorer neurodevelopmental outcomes.
Abstract:
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.