Abnormal shoulder girdle muscle tone in premature infants during their first 18 months of life

To document the incidence of and neonatal factors associated with abnormal shoulder girdle muscle tone in premature infants at follow-up, we studied 125 consecutively admitted infants weighing < 1,750 g treated in The Children's Hospital of Philadelphia intensive care nursery and subsequently seen in the Neonatal Follow-up Program up to 18 months of age. Fifty-seven infants (46%) displayed abnormal shoulder girdle muscle tone which presented clinically as scapular retractions. These infants had significantly lower birth weights (P < .001) and gestational age (P < .001) as well as a higher incidence of acute and chronic pulmonary disease (P < 0.01) and CNS insults (P < .05) when compared with infants without scapular retractions. The 57 infants with scapular retractions were further divided into two groups: 42 infants (74%) in whom scapular retractions were associated with generalized mild hypertonicity and 15 infants (26%) in whom scapular retractions compensated for trunk and neck hypotonicity. The infants with scapular retractions and hypotonicity had a significantly higher incidence of neonatal neurologic morbidity including seizures, major resuscitations, and birth asphyxia (P < .01) when compared with the infants with scapular retractions and hypertonicity. Shoulder girdle tone abnormalities in the first year of life inhibit crawling, sitting, and object manipulation and, therefore, may manifest as delays in motor development. Identification of infants with significant neonatal risk factors for tone abnormalities is important to allow for earlier therapeutic intervention.