a radiological approach to craniosynostosis
TRANSCRIPT
Abnormal Skull Shape
Felice D’ArcoDiagnostic Imaging
Great Ormond Street Hospital For Children
A Radiological Approach to Craniosynostosis
felice.d’[email protected]
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
Normal Cranial Development
Anatomy & Genetic
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
f: Anterior Fontanelg: Posterior Fontanel
b : Coronal Suture c : Sagittal Suture
d : Lambdoid Suture
sphenoidal
fontanelSquamosal Suture
Mastoidfontanel
Spheno-Squamosal Suture
a : Metopic suture
Basioccipital bone
Exoccipitals bones
Supraoccipital bone (derived from cartilage)
Interparietal bone (derived from membrane)
Mendosal Suture
Shapiro and Robinson, Embryogenesis of The Human
Occipital Bone Am J Roentgenol 1976
1) Basioccipital Bone2) / 3) Exoccipital Bones4) Supraoccipital5) Interparietal
Mendosal Suture (arrows)
OPISTHION
BASION
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)
Phenotypic and Genetic Veriability
FGFR1-3
Pfeifer S.
Crouzon S.
Apert S.
from internet
Phenotypic and Genetic Veriability
MSX2Saethre-Chotzen
S.
One coronal + sagittal
Two coronal + sagittal
All the syndromic craniosynostosis may progress
to cloverleaf skull deformity
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)
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%
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
Branson HM 2011
How to Report a 3D Head CT Look at the axial images for gross
ventriculomegaly, hemorrhages, calcifications, copper beaten skull (raised intracranial pressure?)
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
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
Specific Imaging Patterns in
Craniosynostoses
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
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
Lambdoid Synostosis
Controlateral Posterior Bossing and
trapezoid shapeAbsent Suture on the
Right Mastoid Bump and absent suture on the
right
L
Long axis of the left IAC
Positional Plagiocephaly
Right Lambdoid Synostosis
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
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
internet
9 y
?
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
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 suturesnarrowed significantly to 2.4 and 1.3 mm, respectively.
•From 1 to 12 months of age, sutures narrowed gradually.
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
1) Narrowed anterior cranial fossa width (trigonocephaly)2) Ethmoidal hypoplasia3) 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
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
Prenatal trigonocephaly due tometopic 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
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)
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
Combined Unilateral Coronal and Lambdoid
Synostosis
- Harlequin Orbit
- Masotid Bump
- Angled Skull Base
Blaser et al. Pediatr Radiol 2015
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
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!)
4 day-old, Apert Syndrome
7 y, Crouzon Syndrome with pansynostosis
Wikipaedia
Indian J Radiol Imaging. 2011 Jan-Mar; 21(1): 49–56.
Radiol Bras. 2014 May-Jun; 47(3): 189–190.
Cloverleaf deformity (Kleeblattschadel)
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)
Post-operative Imaging of Craniosynostosis
1) Calvarial Vault Remodeling : traditional surgery, old children (> 6 months)
Can be endoscopic in children < 6 months
Post-operative Imaging of Craniosynostosis
2) Spring-mediated cranial reshaping
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
Pediatr Radiol 2008, 38:S488-496
Crouzon syndrome: bilateral jugular vein stenosis andprofuse extracranial venous collaterals
Complications: Post-Operative
Hemorrhage CSF leaks Sinovenous damage Thrombosis Restenosis (15-89% but only few cases
require reoperation for ICP)
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)
Skull fracture vs. accessory sutures: how can we tellthe 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)
Emerg Radiol (2010) 17:413–418
Accessory Intraparietal or Subsagittal Suture
Midline occipital Fissure and Mendosal Sutures
Radiographic differentiation of skull fractureand 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
fracture
suture
Emerg Radiol (2010) 17:413–418
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