Definition
Asymmetric flattening of the infant skull from external pressure on the growing head. The cranial sutures stay open, unlike craniosynostosis.
Aetiology
- Supine sleeping with a preferred head position
- Congenital muscular torticollis holds the head turned to one side
- Limited tummy time
- Male sex, first born, prematurity and multiple birth are risk factors
Epidemiology
- Rose after supine sleep advice to prevent sudden infant death
- About 47% of infants aged 7 to 12 weeks in one Canadian cohort
Clinical Features
- Parallelogram head shape viewed from above
- Ipsilateral ear and forehead displaced forward
- Unilateral occipital flattening
- Sternocleidomastoid tightness and limited neck rotation when torticollis coexists
- Ear and forehead shift together on the same side
Investigations
- Clinical diagnosis, with imaging seldom needed
- Ultrasound or CT of the sutures if synostosis is suspected
Differential Diagnosis
- Lambdoid craniosynostosis, with a trapezoid head and the ear displaced backward
- Congenital muscular torticollis
- Benign paroxysmal torticollis of infancy
- Klippel-Feil syndrome
- Secondary torticollis
Management
- Repositioning and tummy time. First line, with most improving
- Physiotherapy. Stretching for associated torticollis
- Helmet therapy. No better than natural course at 24 months in the HEADS randomised trial
- Referral. Suspected synostosis or failure to improve
Prognosis
- Most improve by 2 years
- Mild residual asymmetry in some, often hidden by hair
References
- van Wijk RM, van Vlimmeren LA, Groothuis-Oudshoorn CG, Van der Ploeg CP, Ijzerman MJ, Boere-Boonekamp MM. Helmet therapy in infants with positional skull deformation. Randomised controlled trial. BMJ. 2014, 348, g2741. PubMed
- Mawji A, Vollman AR, Hatfield J, McNeil DA, Sauvé R. The incidence of positional plagiocephaly. A cohort study. Pediatrics. 2013, 132(2), 298-304. PubMed
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.