abnormal skull shape in nonsyndromic craniosynostosis
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Abnormal skull shape in
nonsyndromic
craniosynostosis: “Spectrum of different types and
accuracy of 3D CT”
M. Mearadji
International Foundation for Pediatric Imaging Aid
Introduction
Postnatal growth and shaping of the skull occurs during the first 2 years of life.
A normal skull is eggshaped, being widest in the parietal area.
An abnormal skull shape is relatively common up to 20% in infancy.
Only a few abnormal head shapes are associated with synostosis of individual or multiple sutures.
Usually the fused sutures are present at birth, but infrequently may take place in the first months of life.
Introduction
The most accepted hypothesis to explain craniosynostosis is an abnormal underlying dura sending abnormal signals to the overlying suture resulting in premature fusion.
Craniosynostosis leads to fairly predictable types based on specific sutural involvement.
Growth restriction at a synostotic suture leads to compensatory exaggeration of growth of the unaffected sutures.
Classification of craniosynostosis
Syndromic craniosynostosis is associated with around 100 familial and hereditary diseases.
Non-syndromic craniosynostosis has an incidence of 0,6 per 1000 life birth.
Secondary craniosynostosis is often a result of microcephaly resulting from several brain diseases.
Positional non-synostotic skull deformity is another entity and should be differentiated from craniosynostosis.
Imaging of craniosynostosis I
Imaging is indicated to define the site and extend of craniosynostosis and to evaluate both pre- and postoperative complications as well as reconstruction results.
Radiological techniques and familiarity with the signs of closure of sutures are important.
Misdiagnosis may result in unwarranted calvarial or craniofacial surgery or delay in surgical procedures.
Imaging of craniosynostosis II The initial examination is plain skull series in
anteroposterior and lateral projection, added by Towne or Caldwel projection.
On a plain film serie a craniosynostosis can be suspected depending on the age with skull deformities and synostosis of one or more large sutures.
The direct signs of suture fusion are sclerosis, bony bridging along the sutures, beaking of the suture and narrowing of the affected side.
3D CT as a valuable modality is only indicated preoperatively before reconstruction surgery with low radiation dose.
Reviewed patient material This presentation is based on a retrospective
study of 191 cases with a nonsyndromic craniosynostosis.
The patient material is divided in 4 groups depending on the affected side:
Scaphocephaly 91 = 48%
Trigonocephaly 54 = 28%
Plagiocephaly 41 = 21.5%
Brachycephaly 5 = 2.5%
48 patient with so-called positional nonsynostotic plagiocephaly were reviewed additionally.
Clinical and radiological data of reviewed
scaphocephaly (sagittal synostosis)
Nr. %
Number of cases 91 100%
Age
Average
1-48 months
7,3
Male
Female
73
18
80%
20%
Skull plain film series
3D CT
91
79
100%
86%
Surgical procedures:
Biparietal or frontoparietal remodelling
82
90%
Non-surgical procedures 9 10%
3 months old
boy
Pre-
operative Post-
operative
10 months old
girl
Pre-
operative
Post-
operative
Impressiones digitatae in craniosynostosis
Clinical and radiological data of
reviewed patients with trigonocephaly Nr. %
Number of cases 54 100%
Age range
Average
1-29 months
7,8
Male
Female
43
11
80%
20%
Skull plain film series
3D CT
54
47
100%
87%
Surgical procedures:
Frontosupraorbital
remodelling and advancement
Non-surgical procedures
39
15
72%
28%
2 months old
girl
Pre-
operative
Post-
operative
12 months old
boy
Pre-
operative
Post-
operative
Clinical and radiological data of
reviewed cases with plagiocephaly Nr. %
Number of cases 41 100%
Age range
Average
1-20 months
7,5
Male
Female
15
26
36.5%
63.5%
Skull plain film series
3D CT
41
37
100%
87%
Surgical procedures:
Frontosupraorbital remodelling with or without
advancement or occipital remodelling
39
95%
Non-surgical procedures 2 5%
Clinical and radiological data of
reviewed cases with plagiocephaly
Nr. %
Number of cases 41 100%
Coronal synostosis right-sided
Coronal synostosis left-sided
15
20
36.5%
49%
Lambdoidal synostosis right-sided
Lambdoidal synostosis left-sided
2
3
5%
7%
Mercedes Benz sign 1 2.5%
5 months old
boy
Pre-
operative
Post-
operative
Right sided
plagiocephaly
1 month old
girl
Left sided
plagiocephaly
Pre-
operative Post-
operative
Clinical and radiological data of
reviewed cases with brachycephaly Nr. %
Number of cases 5 100%
Age range
Average
2-8 months
3.6
Male
Female
3
2
60%
40%
Skull plain film series
3D CT
Bilateral coronal synoses
5
5
5
100%
100%
100%
Surgical procedures:
Frontosupraorbital remodelling and advancement
4
80%
Non-surgical procedures 1 20%
2 months old
boy
Pre-
operative Post-
operative
Clinical and radiological data of reviewed
patients with non-synostotic plagiocephaly
Nr. %
Number of cases 48 100
Agerange
Average
3-15 months
Male
Female
37
11
77%
23%
Skull plain film series
3D CT
Helmet therapy
Surgical procedures
48
2
48
0
100%
4%
100%
0%
9 months old girl with positional non-synostotic plagiocephaly
8 months old boy with positional non-synostotic plagiocephaly
Conclusions An abnormal head shape is a frequent finding
in the first months of life and has to be differentiated from craniosynostosis.
Early recognition of craniosynostosis is important in the first 2 years of life, because of growth and development of brain and skull.
Genetic counselling is needed in differentiating syndromic from non-syndromic craniosynostosis.
Plain radiography acts as a screening tool to make the diagnosis of craniosynostosis and to look for postoperative results.
Conclusions Impressiones digitatae are visible on plain film
incidentally after closure of sutures or postoperatively after remodelling craniotomy.
CT assesses all sites of bony bridging, deformation type and extension of synostosis in one or more sutures.
3D CT is the modality of choice in assessing sutural changes and planning surgical procedures.
Because of high radiation dose the 3D CT should be performed only if surgical remodelling is indicated.
Positional plagiocephaly mimicking a craniosynostosis should be differentiated from craniosynostosis by plain film series.
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