Electromyographic assessment of neonatal muscle tone.

A new psychiatric research method for measuring infant muscle tone using quantified electromyography is described. Muscle tone was assessed electromyographically from the arms and legs of 44 neonates; 18 offspring of drug abusing women, 26 control infants. Infants from the drug group had higher muscle tone than control infants. There was also a tendency for smaller infants and females to have higher muscle tone. Electromyographic assessments of tone were correlated with examiners' clinical assessments, but tended to be more sensitive to tone in specific muscle groups.