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Terms in this set (27)
What are the three theories of suture closure?
-result from abnormal tension, through the dura, leading to premature suture fusion
Theory does not account for isolated synostoses
Intrinsic suture biology
-result from the osteoinductive properties of dura mater, which contains osteoblast-like cells
-Synostoses result from extrinsic forces or systemic disease
-In utero compression or ischemic event
-Multiple gestation, large infant head size, abnormal intrauterine lie, uterine abnormalities
-Abnormal brain growth (microcephaly)
-Systemic pathology (ex. hypthyroidism, rickets)
What is Virchow's law?
-Premature synostosis of cranial sutures inhibits normal skull growth perpendicular to the fused suture
-Compensatory growth along a plane parallel to the fused suture
What percentage of syndromic and isolated craniosynostoses are hereditary?
-50% of syndromic
- 2% of isolated
-More than 130 syndromes involve craniosynostosis
-Etiology syndromic: mutation in fibroblast growth factor receptor (FGFR) most common
What are the 5 most common syndromic craniosynostosis conditions and their inheritance patterns?
Crouzon syndrome: AD
Apert's syndrome: AD
Pfeiffer syndrome: AD
Saethre-Chotzen syndrome: AD
Carpenter syndrome: AR
Features of Crouzon syndrome
-Most common form of syndromic craniosynostosis (1 in 25,000)
-Multiple mutations in FGFR2 & 3, Twist
-Most commonly bilateral coronal synostosis, but sagittal and metopic common
-Higher risk for increased ICP thoughout childhood
-Progessive hydrocephalus, cerebellar herniation, and jugular foramen stenosis
-Otherwise few functional concerns
* NO LIMB ABNORMALITIES
Features of Apert's syndrome
1 in 100,000
Usually sporadic but can be AD
Mutations of FGFR2
ICP elevation in up to 83%
Intelligence: normal to MR
-Short nose with depressed bridge
-Hypertelorism, shallow orbits, downslanting palpebral fissures
-Developmental delay and low IQ
-Craniosynostosis: bicoronal synostosis + significant turribrachycephaly, enlarged anterior fontanel, bitemporal widening, occipital flattening
Features of Pfeiffer syndrome
1 in 100,000
Mutations FGFR1 - 3
-BROAD thumbs or great toes
-Midface hypoplasia - BEAK nose
-Mild cutaneous syndactyly
-Class III malocclusion
-Shallow orbits / exorbitism
-High risk for Chiari malformation
-Usually normal mental status
Features of Saethre-Chotzen syndrome
1 / 50,000
TWIST gene mutation
Characteristics: (Many - variable)
-Craniosynostosis (brachycephaly common)
-Facial asymmetry with ptosis of the eyelids
-Intelligence usually normal
Features of Carpenter syndrome
Rare - 1 / 1,000,000
-Craniosynostosis (various sutures)
-Preaxial polysyndactyly of the feet
-May have mental deficiencies
-Congential heart defects (up to 30%)
What is the incidence of craniosynostosis?
1:1000-2000 in the general population
When do the sutures normally fuse?
Metopic: 2 years
Sagital: 22 years
Coronal: 24 years
Lambdoid: 26 years
When do the anterior and posterior fontanelles usually close?
anterior: 9-12 months
posterior: 3-6 months
What are some possible sequelae of early suture closure?
Early suture closure results in decreased intracranial volume, restricted brain growth, and may lead to increased ICP, mental impairment, growth impairment, neuropsychiatric disorders, and optic atrophy and vision loss
What is the incidence of elevated ICP in isolated synostosis vs multiple?
Multiple: 42% (increases as number of sutures involved increases)
How fast does the brain grow?
Triples by 1 year of age, quadruples by 2 years, and reaches 85% of adult size by 3 years
Normal growth occurs both parallel and perpendicular to sutures
What are some findings on history of elevated ICP?
What investigations should be done for a child with isolated synostosis and a child with multiple synostoses?
- Xray PA, lateral, Townes (angulated PA - see image) view head
- No CT or MR indicated
- Xray as above
- CT to look for hydrocephalus, signs of elevated ICP, and other bone/brain abnormalities, better define suture fusion
- MR usually unnecessary
What are signs of elevated ICP on Xray?
All late findings:
- Cortical thickening
- loss of cisternae
- Beaten copper sign (Luckenschadel) - see image
What are the terms to describe the skull shape in coronal (bilateral and unilateral), metopic, sagittal, and lambdoidal synostoses?
Coronal bilateral: brachycephaly
Coronal unilateral: anterior plagiocephaly
Lambdoid unilateral: posterior plagiocephaly
What are the most to least common synostoses?
Sagittal (50%) > Unilateral Coronal (20%) = Bilateral Coronal (20%) = Metopic (10%) > Lambdoidal (3%)
What is the incidence and morphology of sagittal synostosis?
50% of craniosynostosis
Increase AP length, decreased biparietal width
Frontal bossing and occipital bulge
What is the morphology of unilateral coronal synostosis?
- Anterior plagiocephaly
- Ipsilateral frontal flattening, parietal flattening, occipitomastoid bossing, recessed supraorbital, infraorbital rim, exorbitism/proptosis, midface hypoplasia, constricted nasal base deviated towards affected side, ear posteriorly displaced
- Cranial base short in AP direction
- Contralateral frontal and occipito parietal bossing, and
- Harlequin deformity: failure of descent of greater wing of sphenoid
What is the Kleeblattschädel deformity?
'Cloverleaf' deformity: Partial fusion of the sagittal, coronal, and lambdoid sutures
What is the morphology of bilateral coronal synostosis?
Brachycephaly (most common deformity seen in Crouzon and Apert's syndromes)
midface hypoplasia, shallow orbits with exorbitism/proptosis leading to conjunctivitis/keratitis, hypertelorism, width of cranial base increased (decreased AP), recession of supraorbital ridges with bulging forehead
What is the morphology of metopic synostosis?
midline ridge on forehead, hypotelorism, upper slant of bilateral canthi, anterior cranial based increased in AP dimension
What is the incidence of increased ICP in trigonocephaly?
What is deformational plagiocephaly and its incidence?
1:300 general population
Not a craniosynostosis
Presents with ipsilateral occipital flattening and frontal bossing
Results from supine positioning or rotational forces (torticollis, vertebral abnormalities, and visual field deficits may all cause preferential rotation and unequal pressure on the occiput)
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