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Positional plagiocephaly is associated with sternocleidomastoid muscle activation in healthy term infants

Amy Leung1, Allison Mandrusiak2, Pauline Watter2

  • 1School of Health & Rehabilitation Sciences, The University of Queensland, St Lucia, Q4072, Australia. yuen.leung@uqconnect.edu.au.

Child'S Nervous System : Chns : Official Journal of the International Society for Pediatric Neurosurgery
|February 26, 2017
PubMed

Insights

Asymmetry in sternocleidomastoid (SCM) muscle activation contributes to positional plagiocephaly in infants. Early assessment of SCM activation using head-righting responses can identify infants at risk for developing plagiocephaly.

Area of Science:

  • Pediatric physical therapy
  • Infant development
  • Craniofacial abnormalities

Background:

  • Positional plagiocephaly is a common condition in infants.
  • Sternocleidomastoid (SCM) muscle asymmetry may play a role in its development.
  • Understanding the relationship between SCM activation and plagiocephaly is crucial for early intervention.

Purpose of the Study:

  • To investigate the association between sternocleidomastoid (SCM) muscle activation patterns and the presence and severity of positional plagiocephaly in healthy, full-term infants.
  • To determine if SCM activation asymmetry predicts plagiocephaly development.
  • To evaluate the utility of active head-righting responses for assessing SCM activation in early infancy.

Main Methods:

  • A longitudinal study involving 82 healthy, full-term infants.
  • Sternocleidomastoid (SCM) activation was measured using active head-righting responses at 3, 6, and 9 weeks of age.
  • Positional plagiocephaly was quantified using the Modified Cranial Vault Asymmetry Index (mCVAI) at 9 weeks of age.

Main Results:

  • More severe plagiocephaly correlated with greater asymmetry in active head-righting responses across all assessed ages (p < 0.001).
  • Specific patterns of occipital flatness were linked to contralateral SCM activation at 3 and 9 weeks (p = 0.008).
  • Infants with asymmetrical gravity-assisted head-righting responses at 3 weeks showed significantly greater plagiocephaly at 9 weeks (p = 0.011).

Conclusions:

  • Asymmetry in sternocleidomastoid (SCM) muscle activation is a significant factor in the development of positional plagiocephaly by 9 weeks of age.
  • Stronger contralateral SCM activation appears to be a key mechanism contributing to plagiocephaly.
  • Active head-righting responses provide a valid method for assessing SCM activation in infants younger than two months.
Abstract

Keywords:
Head-righting responseInfantModified cranial vault asymmetry indexPositional plagiocephalySternocleidomastoid

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