NEONATAL CONDITIONS
Craniosynostosis
A practical guide for SCN clinical staff · Premature fusion of a cranial suture - and telling it apart from benign positional moulding
DO NOT MISS
THE FEW THAT AREN'T
Normal suture biology
Cranial bones are joined by fibrous sutures that act as osteogenic growth centres, letting the skull expand to keep pace with rapid brain growth (the brain nearly trebles in volume in the first year).
Bone grows at the suture
New bone is laid down at the suture edges, perpendicular to the suture, so a patent suture allows growth across it. The fontanelles are the junctions where several sutures meet.
Balanced signalling
An open suture is held open by balanced signalling between bone formation and suture patency - FGFR, TGF-β/BMP and the transcription factor TWIST1.
Premature fusion
Gain-of-function in FGFR (or loss of TWIST1) tips the balance toward premature osteoblast differentiation and ossification, fusing the suture early.
Virchow's law
Growth is then restricted perpendicular to the fused suture, with compensatory growth parallel to it - which is why each suture gives a predictable head shape.
Compensatory deformity
The remaining open sutures over-grow to accommodate the brain, producing the characteristic vault shapes (scaphocephaly, trigonocephaly, brachycephaly, plagiocephaly).
Raised ICP risk
When several sutures fuse, or in syndromic disease, the vault cannot expand enough for the growing brain - reducing intracranial compliance and risking intracranial hypertension.
CLINICAL FINDINGS
- Abnormal head shape: long/narrow (sagittal), triangular forehead (metopic), wide/tall forehead (bicoronal), flattened forehead and orbit (unicoronal)
- A palpable bony ridge over the fused suture
- A small or absent anterior fontanelle
- Top-down look: skull symmetry, forehead contour, occipital flattening, ear position
- Syndromic face: midface hypoplasia, proptosis, hypertelorism, orbital asymmetry
- Limb clues in syndromes: syndactyly (Apert), broad thumbs and great toes (Pfeiffer)
INVESTIGATIONS
- Diagnosis is often clinical - careful examination and serial head circumference
- Low-dose CT skull with 3D reconstruction (bone-only) confirms the suture(s) involved
- Imaging is not routinely needed for simple positional plagiocephaly
- Genetic testing if syndromic features (FGFR1/2/3, TWIST1)
- Screen for associated complications in syndromic disease; assess for raised ICP if multi-suture
COMPLICATIONS & RED FLAGS
- Progressive or worsening deformity
- A palpable suture ridge
- A small or absent fontanelle
- Developmental delay or dysmorphic features
- Multiple sutures involved
- Signs of raised intracranial pressure, especially in multi-suture or syndromic disease
CT 3D reconstruction
Low-dose, bone-only CT with 3D reconstruction confirms which suture(s) have fused and maps the cranial vault deformity for surgical planning. It is not routinely required for simple positional plagiocephaly, where the diagnosis is clinical.
MANAGEMENT
Tell positional moulding from true synostosis, refer suspected synostosis to the craniofacial MDT, and reserve imaging and surgery for those who need them.
Recognise & refer
- Distinguish positional moulding from true synostosis: history, exam, fontanelle and suture ridge
- Track head circumference and shape over time
- Refer suspected synostosis to the craniofacial multidisciplinary team
- Confirm with low-dose CT and 3D reconstruction
Surgical correction
- Endoscopic strip craniectomy in young infants (<4-6 months) for single-suture disease
- Open cranial vault remodelling / fronto-orbital advancement, usually within the first year
- Aims: restore cranial shape, prevent raised ICP, and allow normal brain growth
- Timing and approach are decided by the craniofacial team
Positional & syndromic
- Positional plagiocephaly: repositioning, tummy time and alternating head position; physiotherapy if torticollis
- Helmet therapy for severe or persistent positional cases; most improve with growth and mobility
- Syndromic: genetic testing and screening for associated complications
- MDT follow-up - neurosurgery, craniofacial surgery, genetics and paediatrics
- Measure and plot head circumference accurately and serially, and note the head shape and any change over time.
- Practise and teach repositioning and tummy time - most positional moulding improves with growth.
- Feel for a suture ridge, check the fontanelle, and flag progressive deformity or dysmorphic features for review.
- Support families through referral, imaging and the craniofacial MDT, and reassure that most head-shape concerns are benign.
How do you tell positional plagiocephaly from true craniosynostosis at the cot side?
Which suture produces which head shape, and why (Virchow's law)?
When is CT imaging warranted, and how do you keep the radiation dose low?
Which features point to a syndromic cause (Apert, Crouzon, Pfeiffer, Muenke), and what does that change?
Take-home message: Most neonatal head-shape abnormalities are benign positional moulding, but craniosynostosis - premature fusion of a cranial suture - must not be missed. A palpable ridge, progressive deformity, a small or absent fontanelle, or dysmorphic features point to true synostosis, and the suture involved predicts the head shape (Virchow's law). Diagnosis is largely clinical, confirmed with low-dose 3D CT, and managed by the craniofacial MDT, with surgery in the first year for true synostosis.
For educational purposes only. Always align management to current ANZCOR/NRP guidelines and your local SCN/NICU or NETS protocols.