An abnormal head shape: positional plagiocephaly (parallelogram) versus a fused suture — low-dose 3D CT shows which sutures are closed (sagittal, metopic, coronal, lambdoid) and the syndromic pattern.
Orient first
- Sagittal (scaphocephaly) is commonest; metopic gives trigonocephaly; unicoronal gives anterior plagiocephaly with a harlequin orbit.
- Positional plagiocephaly: parallelogram shape with ipsilateral ear and forehead moved forward — sutures open.
- Multiple sutures suggest a syndrome (Crouzon, Apert).
Acquire the study
- Low-dose CT head with 3D surface reconstruction of the skull (ultra-low-dose protocol); skull radiographs are less reliable.
The manoeuvre
- 3D surface rendering: each suture — patent, partially fused, fused (ridging, bridging).
- Axial bone window: suture lucency present along its length?
- Head shape: cephalic index in % on the axial slice.
- Orbits: harlequin (unicoronal), hypotelorism (metopic).
- Brain: hydrocephalus, Chiari (in syndromic cases).
What confirms it
- A fused suture on CT with the matching head shape.
What licenses you to exclude it
- All sutures patent on CT = positional deformity.
The classic misread
- Calling the normal early metopic closure (from ~3–9 months) synostosis without trigonocephaly.