Cranial sutures are synarthrosis,
a type of fibrous joints that exist between the seven cranial bones – paired frontal,
parietal and temporal bones and one occipital bone – and allow the deformation of the skull during birth,
its growth and brain development.[1,2,3]
Craniosynostosis is the premature fusion of one or more cranial sutures.
According to Virchow’s law,
the skull cannot grow perpendicularly to the prematurely fused suture,
so there is a compensatory parallel expansion and growth along patent sutures,
resulting in calvarium deformities.[1,3,4,5,6] Its incidence is 1 per 2000-2500 live births worldwide.[6,7,8]
Craniosynostosis can be primary,
when related to intrinsic sutural defects,
or secondary to metabolic or systemic entities or iatrogenic causes.[4,9] Most of the primary craniosynostosis are non-syndromic (80-90% of the cases),
but can be syndromic.
More than 60 genes and 150 syndromes,
such as Apert,
Crouzon,
Pfeiffer,
Saethre-Chotzen,
Muenke or Carpenter syndromes,
are related to the premature fusion of cranial sutures.[1,2,3,10] Craniosynostosis can also be classified as simple,
if only one suture is affected (monosutural),
or complex (multisutural),
which is more frequently associated with genetic syndromes.[9] Depending on its severity,
it can lead to intracranial complications and neurocognitive impairment,
cosmetic disfigurement and socially stigmatizing issues.
A careful medical history and a detailed physical examination are the first step in the diagnosis.
Imaging techniques allow for an accurate diagnosis,
pre and post-treatment evaluation,
as well as complications assessment.[4,8,10] The best diagnostic method is the three-dimensional rendered bone CT (CT-3D),
although plain head radiograph,
ultrasonography and MRI may play a valuable role.[8,10]
CT-3D allows for complete assessment of the cranial vault,
skull-base,
orbits and facial bones and is the most sensitive and specific technique,
so it is the modality of choice to confirm the diagnosis,
especially in children with intermediate to high suspicion of craniosynostosis.
It is also useful for the evaluation of the condition’s extent and associated anomalies,
as for the management planning.
It is possible to reduce the radiation exposure on the CT-3D.[4,9,11] Plain skull radiograph uses less radiation,
is very specific but has a low sensitivity,
so it may be performed in children with light head dysmorphia and low probability of a syndromic craniosynostosis to avoid further study.[4,11] In those cases,
some authors suggest that ultrasound should be the first imaging examination to be performed,
since it is radiation-free and may be enough to diagnose a fused suture.[7] The prenatal ultrasound is also useful.
Head MRI is better for brain and soft-tissue evaluation,
so it is important in combination with other techniques in syndromic craniosynostosis.[4,8]