Presentation Summary: Normal Cranial Development (Anatomy and Genetic), Imaging Technique (how to do 3D CT, when to do MRI, why to do not do Plain Film), Imaging Patterns of Craniosynostosis, Associated Complications, Pitfalls.

1. A Radiological Approach to
Craniosynostosis
felice.d’arco@gosh.nhs.uk

2. Summary
 Normal Cranial Development: Anatomy &
Genetic
 Imaging Technique: How to do 3D CT, when
to do MRI, why do NOT do Plain Film
 Imaging Patterns of Craniosynosinostosis:
Pre- and Post-surgical
 Associated Complications
 Pitfalls

3. Normal Cranial
Development
Anatomy & Genetic

4. Single-Suture Synostosis
- Defective dural-mesenchymal signaling issues
- Thought to Be Idiopathic  BUT genetic causes are increasingly being
identified
- Minimal Complications/Associated Brain Abnormalities
Multi-Suture Synostosis
- Genetic Factors  Single Gene or Chromosomal Abnormalities
- Iatrogenic Factors  teratogens, early post-natal shunting of hydrocephalus,
early craniofacial irradiation for tumor control
- Metabolic Diseases  Mucopolysaccharidoses, I-Cell disease (extremely
rare!!)
Delay in sutural fusion
- Hypothyrodism
- Cleido-cranial dysostosis (RUNX2 mutation)
- Zelweger Syndrome (peroxisomal disorder )
Blaser et al. Pediatr Radiol 2015

5. f: Anterior
Fontanel
g: Posterior
Fontanel
b : Coronal Suture
c : Sagittal Suture
d : Lambdoid Suture
sphenoid
al fontanel
Mastoid
fontanel
Spheno-Squamosal
Suture
a : Metopic suture

6. Basioccipital bone
Exoccipitals bones
Supraoccipital bone (derived
from cartilage)
Interparietal bone (derived from
membrane)
Mendosal Suture

7. Shapiro and Robinson, Embryogenesis
of The Human Occipital Bone Am J
Roentgenol 1976
1) Basioccipital Bone
2) / 3) Exoccipital Bones
4) Supraoccipital
5) Interparietal
Mendosal Suture (arrows)
OPISTHION
BASION

8. Genetic of Craniosynostosis
 Suture form at the site of meeting bone fronts
 Interdigitating fingers of bone project into the suture
 Multiple genes govern this process through
osteoblast differentiation, apoptosis, osteogenesis
etc…
 Some genes are suture specific (e.g. TWIST1 along
the frontal and parietal edge) some are not.
 Genes Involved in Syndromic Craniosynostosis :
FGFR1-3, TWIST1, MSX2, RAB23
 Some single-suture non-syndromic synostoses have
been found to have genetic causes (Sagittal:
WDR35, BBS9, BMP2; FREM1, Cr9p del: Metopic)

9. Phenotypic and Genetic Veriability
FGFR1-3
Pfeifer S.
Crouzon
S.
Apert S.
from internet

10. Phenotypic and Genetic Veriability
MSX2
Saethre-
Chotzen S.
One coronal +
sagittal
Two coronal +
sagittal
All the syndromic craniosynostosis
may progress to cloverleaf skull
deformity

11. Imaging technique
 Clinical Observation: 93% concordance with
3D CT
 Radiography: Not Longer Indicated
 CT  low dose with 3D reformats
 MRI  Brain Abnormalities (in complex
syndromic craniosynostoses)
 CTV and MRV  sinovenous thrombosis (in
complex syndromic craniosynostoses)

12. 3D CT
 Dx with mimics: Positional Plagiocephaly, Fractures
 Unsuspected additional sutural stenosis
 Pre-operative planning
 Very Low Dose
 3D CT dose : 40.00 DLP mGy-cm
 Unenhanced head CT: 285.00 DLP
 Average dose reduction: 85%

13. How to Scan a 3D Head CT
Branson HM 2011
 True Axial Plane (parallel to the hard palate)
 From the bottom of the chin to the top of the head
 Helical scan: kV 80, mA 60, rotation 0.5 sec (MAS
of 30). Slice thickness: 0.625 mm, pitch 0.969:1,
table speed: 19.37 mm/rotation
 Scan on Bone Window (this is not a scan for the
brain parenchyma)
 3D reconstruction: different projections

14. Branson HM 2011

15. How to Report a 3D Head CT
 Look at the axial images for gross
ventriculomegaly, hemorrhages, calcifications,
copper beaten skull (raised intracranial
pressure?)

16. How to Report a 3D Head CT
 Document Head Shape (brachycephaly,
scaphocephaly, turricephaly)
 Look for orbit and facial bone symmetry
 Individually look at each suture: ? Absence ?
Ridging ?Sclerosis ? Partial Fusion
 Skull Base and CVJ

17. Head Shape
 General Rule: The head grows where there is
space!
- Metopic Synostosis:
Trigonocephaly
- Sagittal Synostosis:
Scaphocephaly
- Mono-coronal Synostosis: Ant
Plagiogephaly
- Mono-Lambdoid Synostosi: Post
Plagiocephaly
- Bi-coronal Synostosis:
Brachycephaly

18. Specific Imaging Patterns
in Craniosynostoses

19. Lambdoid Synostosis ?
 The left lambdoid suture is patent and anterior to the right
 The long axis of the left IAC is anterior to the right
 Ispilateral frontal bossing
 Absent mastoid “bump”
 Parallelogram configuration of the skull on axial view
Left LeftLeft
POSITIONAL PLAGIOCEPHALY

20. Positional Plagiocephaly
 Most common cause of abnormal skull shape in
infant (recommended protocol of back/side
positioning during sleep to decrease infant cot
death)
Kadom and Sze AJR:194, March
2010
 Ispilateral frontal bossing
 Parallelogram
configuration of the skull
on axial view

21. Lambdoid Synostosis
Controlateral Posterior
Bossing and trapezoid
shape
Absent Suture on the
Right
Mastoid Bump and
absent suture on the
right

22. L
Long axis of the left IAC
Positional
Plagiocephaly
Right Lambdoid
Synostosis

23. Lambdoid Synostosis
 Unilateral Lambdoid Synostosis is rare  5 % of
isolated non-syndromal craniosynostosis
 Bilateral Non-Syndromic is extremely rare 
marker of underlying Rhomboencephalosynapsis
(suggest MRI)
 Bilateral Syndromic  Apert and Pfeiffer
Syndromes
Blaser et al. Pediatr Radiol 2015

24. Sagittal Synostosis
 Most common craniosynostosis (40-60%)
 Scaphocephaly
 Familial cases with AD transmission (6)
 Males ++ (role of androgens in sutural
osteogenesis)
 Multiple Births / Uterine malformations ++
(intrauterine head constraint)
Abnormal Skull Shape Pediatr Radiol 2008 38 (suppl 3):488-496

25. internet

26. 9 y
?

27. Age of Fusion
 Metopic Suture: 3 months – 2 years
 Lambdoid, Sagittal and Coronal : 40 years
 Squamosal: 40 to 70 years
 Fontanelle:
 Posterior: 2-3 months
 Sphenoidal: 6 months
 Mastoid: 6-18 months
 Anterior: 1-3 years

28. Fused vs Narrowed Sutures
Sagittal Coronal Mitchell et al. AJNR 32:1801– 05 2011
• Suture widths sagittal
and coronal sutures at
zero months of age
were 5.0 and 2.5 mm,
respectively
•From zero to 1 month
of age, these sutures
narrowed significantly
to 2.4 and 1.3 mm,
respectively.
•From 1 to 12 months
of age, sutures
narrowed gradually.

29. Metopic Synostosis
 Was thought to be rare (10% of CS), however
recent studies suggest increasing incidence,
making it the second most frequent CS
 Normal closure 3 months – 2 years
 Can be diagnosed in utero (trigonocephaly)
 1/3 syndromomic: Jacobsen/11q23 selection, Cr 9p
deletion
 Brain malformations are common and should be
excluded (microcephaly, holoprosencephaly,
atrophy)
Lee HQ et al. J Craniofac Surg 2012

30. 1) Narrowed anterior cranial fossa width (trigonocephaly)
2) Ethmoidal hypoplasia
3) Hypotelorism
4) Upward deviation of the medial orbit rim (“quizzical” orbit)
5) Bony ridge (can be normal!!!)
8 months
The Fact that the Metopic S is closed at 8 months is not
enough for the diagnosis of Metopic CS

31. 1) The earliest evidence of metopic suture closure was at 3
months, the age at which 33% of patients were closed.
2) At 5 months of age, 59% of sutures were closed.
3) At 7 months of age, 65% were closed.
4) At 9 months of age, 100% were closed.
5) Evidence of metopic suture fusion before 2 years of age
should not be used as criteria for metopic synostosis
surgery (clinical diagnosis).
6) Diagnosis is Clinical

32. Prenatal trigonocephaly due to
metopic synostosis is seen in a
29-week fetus with trisomy 13
(Blaser 2008)
Prenatal trigonocephaly due in a
26-week fetus with valproate
syndrome (Meizner 1993)
Genetic and Toxic causes of Metopic Synostosis

33. Coronal Synostosis
 Female +++
 Brachycephaly + Complicated effect on craniofacial
appearance
 Associated Skull Base involvement and fronto-sphenoidal
synostosis
 Harlequin Deformity (superior elevation of the lesser wing
of the sphenoid)
 Unilateral Synostosis: some genes are implicated (e.g.
FGFR3, TWIST1)
 Bilateral Synostosis:
 Apert, Crouzon, Muenke, Pfeifer etc.
 Multisutural involvement frequent
 Progressive Pansynostosis (cloverleaf deformity)

34. Blaser et al. Pediatr Radiol 2008
Unilateral Coronal Synostosis
-Harlequin Orbit
-Retrusion of the lateral/upper
margin of the orbit
-Nasal tilting
-Crooked Aspect of the Normal
Coronal Suture
by Khamykc-Blackout

35. Combined Unilateral Coronal
and Lambdoid Synostosis
-Harlequin Orbit
-Masotid Bump
-Angled Skull Base
Blaser et al. Pediatr Radiol 2015

36. Non-syndromic
Bilateral Coronal
Synostosis
-The other sutures are
normal
-Harlequin less
accentuated because
of patent fronto-
sphenoidal
-Brachycephaly
-Normal skull base
-Exorbitism (shallow
orbits)
6 months

37. Syndromic Craniosynostosis
 TRIAD: Bicoronal Synostosis + FGFR mutations +
Associated Extremity Malformations
 Often other synostoses are associated (++ skull base) 
Occasionally progression to pansynostosis and cloverleaf skull
deformity
 APERT: FGFR2 mut + hands/feet syndactyly + bilateral coronal
craniosynostosis + involvement of posterior fossa sutures
 CROUZON: FGFR2/3 mut + ear malformations + short
humerus/femur + hypoplastic maxilla + bilateral coronal
craniosynostosis + involvement of posterior fossa sutures
 PFEIFER: FGFR1/2 mut + broad first digit of hands and feet
+dental problems + hearing loss + bilateral coronal
craniosynostosis + involvement of posterior fossa sutures
 Known association with brain abnormalities (MRI brain!)

38. 4 day-old, Apert Syndrome

39. 7 y, Crouzon Syndrome with pansynostosis
Wikipaedia

40. Indian J Radiol Imaging. 2011 Jan-Mar; 21(1): 49–56.
Radiol Bras. 2014 May-Jun; 47(3): 189–190.
Cloverleaf deformity (Kleeblattschadel)

41. Other Patterns
 Z-Pattern: craniosynostosis involving the left coronal, sagittal, and
right lambdoid sutures . (Schmelzer and Fearon 2007)
 Mercedes-Benz Pattern: Bilateral lambdoid and sagittal sinostosis.
(Rhodes, Kolar and Fearon 2010)

42. Post-operative Imaging of
Craniosynostosis
1) Calvarial Vault Remodeling : traditional surgery, old children (> 6
months)
Can be endoscopic in children <
6 months

43. Post-operative Imaging of
Craniosynostosis
2) Spring-mediated cranial reshaping

44. Complications
 Hydrocephalus: Rare in unilateral synostosis, 40%
in syndromic synostosis*
Pathogenesis: hypoplastic PF and venous outlet
occlusion with consequent ICP (CTV, MRV)
 Chiari I and Syringomyelia
*Childs Nerv Syst (2005) 21: 902–912

45. Pediatr Radiol 2008, 38:S488-
Crouzon syndrome: bilateral jugular vein stenosis andprofuse extracranial venous
collaterals

46. Complications: Post-Operative
 Hemorrhage
 CSF leaks
 Sinovenous damage
 Thrombosis
 Restenosis (15-89% but only few cases require
reoperation for ICP)

47. Associated Brain Abnormalities
 Metopic Synostosis: Microcephaly,
Holoprosencephaly, Atrophy (Faro 2006)
 Bilateral Lambdoid Synostosis:
Rhombencephalosynapsis (de Mattos 2014)
Rhombencephalosynapsis in a child with Gómez-López-Hernández
syndrome and bilateral Lambdoid synostosis (De Mattos Pediatr Neurol
2014)

48. Skull fracture vs. accessory sutures: how can we tell
the difference?
Emerg Radiol (2010) 17:413–418
 Accessory Sutures in Parietal and Occipital Bones
(multiple ossification centers)
 Accessory Suture: incomplete union of two
ossification centers
 Parietal Bone: 2 ossification centers (accessory
intraparietal or subsagittal suture)
 Occipital bone: 6 ossification centers (mendosal
suture, midline occipital fissure)

49. Emerg Radiol (2010) 17:413–418
Accessory Intraparietal or
Subsagittal Suture
Midline occipital Fissure and
Mendosal Sutures

50. Radiographic differentiation of skull fracture
and accessory suture
FRACTURE:
-sharp, non-sclerotic edges
-widening of the fracture as it approaches the suture
-associated sutural diastasis
-high impact fractures can cross the suture
- often unilateral
ACCESSORY SUTURE:
-zigzag pattern, sclerotic borders
-no changes in the adjacent suture
-they join the suture
-often bilateral

51. fracture suture
Emerg Radiol
(2010)
17:413–418

52. Conclusion
 Knowledge of normal anatomy and
embriology is critical in the radiological
evaluation of craniosynostosis and DDX
between accessory sutures and fractures
 Low dose CT with 3D reformats is the Gold
Standard
 In case of multiple craniosynostosis
(bicoronal +++) suggest syndromic condition
and MRI/CTV for associated complications