The term plagiocephaly, a unilateral flattening of the skull, is used without reference to its aetiology.^[1]
There are two types to distinguish:

• Plagiocephaly resulting from fusion (synostosis) of a coronal or lambdoid suture. In these craniosynostoses, the deformity of the cranium is visible from birth.
• Positional or postural plagiocephaly, in which the flattening is secondary to a pre or post-natal  mechanical pressure on the skull. Positional plagiocephaly is most commonly a posterior flattening of the skull and only rarely affects its anterior aspect. It is more common in boys (71% of cases) and in twins. ^[2] It is associated with a congenital torticollis in 37% of cases. ^[3]

•  It is important to enquire as to the position of the child when put to bed and to determine whether there is a congenital torticollis.
•  A congenital torticollis should be treated with physiotherapy
• Instructions on positioning must be provided as soon as the diagnosis is made :^[4]
  • Ensure that the child does not sleep on the flattened side of the skull
  • Encourage prone positioning while the child is awake
  • Reserve the use of hard-backed child seats for carrying or transporting the child
  • Encourage rotation of the child’s head away from the affected side; arrange the bed in such a way that the light approaches it from the unaffected side. Similarly, objects of interest, toys, mobiles, family pictures should be positioned on the unaffected side of the child.^[5]

If the above simple advice is not followed, the deformity will show no improvement. The best opportunity for improvement is within the first six months of life and this then diminishes progressively until 18 months of age. Beyond 18 months, no further improvement can be expected.

In cases of diagnostic uncertainty, AP and lateral skull X rays are required; the absence of a lambdoid suture suggests a synostosis and a non-urgent appointment with a craniofacial surgeon must be arranged. This single posterior suture craniosynostosis does not result in a significant differential growth of brain and skull and its surgical treatment is therefore optional with essentially an aesthetic indication.^[6]

The deformity is usually obvious, with the combination of a unilateral frontal flattening, with a elevated, yet set-back ipsilateral  eyebrow and a deviation of the nose towards the affected side (in the case of an anterior positional plagiocephaly, the forehead is flat, but the ipsilateral eyebrow region is depressed and the nose deviates to the unaffected side).

Antero-posterior and lateral X rays must be acquired to confirm the diagnosis and the child should be referred to a cranio-facial surgeon. There is no chance of spontaneous improvement of the deformity when the cause is premature synostosis. In the case of a positional aetiology improvement is variable. The treatment of the deformity is surgical and involves remodelling of the frontal bone between the ages of 6 and 18 months. The indication is essentially aesthetic as uni-coronal craniosynostosis has only minimal risk of raised intra-cranial pressure resulting from differential growth of the brain and the skull.

Strange as it may seem, posterior postional plagiocephaly, so frequently seen since the 1994 consensus to ensure newborn infants are put on their backs to sleep, is the clinical entity of most concern, as its improvement is directly related to the precocity with which treatment is begun.
Craniosynostoses responsible for plagiocephaly necessitate additional investigations at the discretion of the surgeon (radio-imaging, genetic studies) and classically undergo surgery, after the age of  6 months. Early diagnostic studies (before 3 months of age) are unhelpful and can result in diagnostic errors. They intensify the anxiety of the parents and constitute an unnecessary expense.

1.  Arnaud E, Marchac D, Renier D. [Diagnosis of facial and craniofacial asymmetry]. Ann Chir Plast Esthet 2001;46(5):410-23.
2. Littlefield TR KK, Pomatto JK, Beals SP. Multiple-birth infants at higher risk for development of deformational plagiocephaly: II. is one twin at greater risk? Pediatrics 2002;109(1):19-25.
3. Hollier L, Kim J, Grayson BH, McCarthy JG. Congenital muscular torticollis and the associated craniofacial changes. Plast Reconstr Surg 2000;105(3):827-35.
4. Neufeld S, Birkett S. What to do about flat heads: preventing and treating positional occipital flattening. Axone 2000;22(2):29-31.
5. Cartwright CC. Assessing asymmetrical infant head shapes. Nurse Pract 2002;27(8):33, 35-6, 39.
6. Ellenbogen RG, Gruss JS, Cunningham ML. Update on craniofacial surgery: the differential diagnosis of lambdoid synostosis/posterior plagiocephaly. Clin Neurosurg 2000;47:303-18.