Investigation of Trunk and Extremity Movement Associated With Passive Head Turning in Newborns

Abstract

Background and Purpose. Physical therapist examination of pediatric clients or clients with neurological conditions often includes the observation of stereotypical movement patterns such as the asymmetrical tonic neck reflex and righting reactions. The purpose of this study was to investigate whether extremity and trunk responses to passive head turning could be documented in newborn infants. Subjects and Methods. Forty-two newborns with no known medical problems were videotaped within 5 days of birth while an investigator turned their heads left and right. Videotapes were stopped at 5-second intervals to record the direction of head turn with the rest of the body obscured. A second investigator recorded trunk and extremity position with the head obscured. Results. The direction of head turning affected upperand lower-extremity position, with extension stronger on the face side. The direction of trunk convexity was also affected by head position, with the trunk convex to the side to which the face was turned. Conclusion and Discussion. Extremity responses and trunk responses to passive head turning can be documented corresponding to patterns reported for the asymmetrical tonic neck reflex and righting reflexes in neonates with no known medical problems more frequently than would occur by chance. In some approaches to physical therapy, the asymmetrical tonic neck reflex (ATNR) is viewed as a reflex response to turning of the head. 1,2 The response consists of extension of the upper and lower extremities on the side to which the face is turned and flexion of upper and lower extremities on the side to which the skull is turned. The ATNR has been theorized to play an important role in normal development of human movement by facilitating early visual inspection of the hand, and thus eye-hand coordination, as well as by modifying newborn symmetry. 1,2 Similarly, the neonatal righting reflex is another reflex in which the stimulus is head turning. The response is believed to be for the trunk to turn as a block in the direction of the head turn. This righting reflex has been viewed as supporting the infant's ability to align body parts for rolling by causing turning of the body in response to a head turn. 1,2 Magnus 3 first reported the ATNR and believed that the phenomenon occurs only in pathological conditions in humans. Gesell 4 was the first author to report that the reflex was a "normal and prominent feature of early infant behavior" and asserted that the reflex was present universally at 4 weeks when the infant was in a supine position. Since Gesell's time, numerous investigators 5-10 have reported evidence of the ATNR in newborn infants with no known medical problems. These investigators reported prevalence rates of the reflex among full-term neonates in the range of 40% to 67.5%. Increased prevalence as high as 91% among infants born prematurely and tested at 40 weeks postconceptual age has been reported, 8,11,12 and the ATNR has been reported to be universally present in premature infants over 33 weeks postcon...