abnormal skull shape in nonsyndromic craniosynostosis

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. %


Age range

Average

1-29 months

7,8

Male

Female

43

11

80%

20%


3D CT

54

47

100%

87%


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


reviewed cases with plagiocephaly Nr. %


Age range

Average

1-20 months

7,5

Male

Female

15

26

36.5%

63.5%


3D CT

41

37

100%

87%


Frontosupraorbital remodelling with or without

advancement or occipital remodelling

39

95%



reviewed cases with plagiocephaly

Nr. %


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


reviewed cases with brachycephaly Nr. %


Age range

Average

2-8 months

3.6

Male

Female

3

2

60%

40%


3D CT

Bilateral coronal synoses

5

5

5

100%

100%

100%


Frontosupraorbital remodelling and advancement

4

80%


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%


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.

abnormal skull shape in nonsyndromic craniosynostosis

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