craniosynostosis

Question 1

describe the anatomy of the skull i.e the 2 main parts of the skull

Answer 1

the skull consists of 2 parts

neurocranium
- forms the protective case around the brain

the membranous part, which consists of flat bones that surround the brain
the cartilaginous part which forms bones of the base of the skull.
2. Viscerocranium – forms the skeleton of the face

Question 2

how does the skull develop

Answer 2

At birth the flat bones of the neurocranium are separated by narrow connective tissue layers known as sutures.
Where two or more bones meet, the sutures are wide and are termed fontanelles.
During the birth process, the sutures and fontanelles permit the bones of the skull to overlap and soon after birth the bones return to their original positions

Question 3

when do the fontanelles close

Answer 3

A large number of the sutures and fontanelles continue to stay membranous for different periods of time after birth, enabling the skull to continue growing.
The posterior (occipital) fontanelle usually closes around 3 months after birth,
the anterior (frontal) fontanelle closes around 1 ½ years of age
The postero-lateral (mastoid) fontanelle closes around 2 years of age.

Question 4

what are fontanelles

Answer 4

fontanelles = where flat bones meet

Question 5

what is cranysynostosis

Answer 5

Craniosynostosis is a term given to a range of cranial abnormalities which are caused by premature closure of one or more sutures. Premature fusion of cranial sutures will inhibit growth in that area and consequently force growth in areas of non-fusion to accommodate the growing brain, resulting in the development of an abnormally shaped skull and possibly raised intracranial pressure (ICP) with impairment of vision and cerebral functions

Question 6

cranisostosis is the ……

Answer 6

premature fusion of one or more sutures

inhibits growth of skull in that area

force growth in non fused area - abnormally shaped skull

associated features
raised iop
impairment of cerebral function
Impairment of vision

Question 7

what is the prevalence of cranysinostosis

Answer 7

Approximately 1 in 2000 to 3000 infants is affected by a form of craniosynostosis. It may be congenital (sporadic or genetically inherited) or acquired due to metabolic disorders such as hypercalcaemia (is a high calcium (Ca2+) level in the blood serum. It is a recognised feature in over 100 genetic syndromes. Many of these are autosomal dominantly inherited, but may also be of autosomal recessive inheritance.
Primary: the premature fusion is due to developmental error during embryogenesis

Acquired (secondary)
metabolic disorders e.g hypercalcaemia
Mechanical cause e.g Intrauterine compression of skull against maternal pelvis

Question 8

what is the prevalence of cranysinostosis

Answer 8

Approximately 1 in 2000 to 3000 infants is affected by a form of craniosynostosis. It may be congenital (sporadic or genetically inherited) or acquired due to metabolic disorders such as hypercalcaemia (is a high calcium (Ca2+) level in the blood serum. It is a recognised feature in over 100 genetic syndromes. Many of these are autosomal dominantly inherited, but may also be of autosomal recessive inheritance.
Primary: the premature fusion is due to developmental error during embryogenesis

Acquired (secondary)
metabolic disorders e.g hypercalcaemia
Mechanical cause e.g Intrauterine compression of skull against maternal pelvis

Question 9

what are the types of craniosynostosis

Answer 9

sagital
metric
unicronal
bicronal

Question 10

what is unicornonal synostosis

Answer 10

premature fusion of one of the coronal sutures

greater development of the non fused side and thus asymmetrical growth of the skull

Question 11

unicornonal synostosis

Answer 11

on the affected side the forehead is relatively flat and the orbit is elevated

on the non affected side thee forehead tends to be excessively prominent

Question 12

what is unilateral coronal synostosis

Answer 12

On the affected side the forehead is relatively flat and the orbit elevated.
On the non-affected side the forehead tends to be excessively prominent.

Question 13

what can unicoronal synosysois cause optically

Answer 13

Due to the asymmetrical position of the two orbits and the trochleas, it can produce a mechanical weakness of the superior oblique muscles resulting in vertical strabismus, which is frequently associated with inferior oblique over-actions and V-pattern. Other common ocular features include amblyopia and astigmatism.

affected side - forehead flat orbit and superior orbital rim elevated

unaffected side - prominent forehead

Question 14

what are the positions of the orbits and trochlea like in unicoronal synostosis

Answer 14

Orbits and trochlears are asymmetrical
can produce a mechanical weakness of the superior oblique muscles
vertical strabismus
inferior oblique over-actions
V-pattern
AHP common
amblyopia
astigmatism

Question 15

what is the treatment for unicoronla synostosis

Answer 15

Fronto-orbital advancement surgery (FOA)
performed at 4-12 months of age.
Aims to correct the existing deformity and minimise the developing facial asymmetry.
May need further surgery in teenage years
Long term follow up till skeletal maturity to monitor forehead and facial form.

Question 16

what surgery is done for uni coronal synostosis

Answer 16

Fronto-orbital advancement surgery

make an incision over the top of child’s head from ear to ear.
cut through the coronal sutures to remove the front portion of the upper skull and re-shape it by cutting and trimming the bone to form a more normal shape.
the bone will be fixed in place using strong stitches that dissolve very gradually over the next few months while the bone heals.

Question 17

what is bicornonal synostosis

Answer 17

Premature fusion of both coronal sutures

Short anterior-posterior length

Increased lateral & vertical growth

Question 18

what does bicornonal synostosis result in

Answer 18

This condition results from premature fusion of both the coronal sutures, resulting in a short anteroposterior skull length with increased lateral and vertical growth. The face appears flat and broad with very prominent and wide set eyes (hypertelorism). Brachycephaly is associated with mental retardation in approximately 50%, together with cleft palate, syndactyly and polydactyly. It may also be seen in association with Down’s syndrome.

Question 19

what surgery is done for bicornonal synostosis

Answer 19

Fronto-orbital advancement surgery (FOA)

performed at 4-12 months of age.

Question 20

saggital synostosis meaning

Answer 20

Premature closure of the sagittal suture

Prevents lateral expansion of the skull

Elongation along the anteroposterior axis

Question 21

what does sagittal synostosis

Answer 21

characteristic ,long and narrow skull

Scaphocephaly (sagittal synostosis)
This condition results from premature closure of the sagittal suture, preventing lateral expansion of the skull. Elongation along the anteroposterior axis thus occurs resulting in the skull becomes long and narrow.

Question 22

what is saggital synostosis associated with

Answer 22

Strong, prominent forehead
Prominent occipital area
Associated with
Speech & language delay
Raised intracranial pressure

Question 23

what surgical intervention is needed for saggitla synostosis

Answer 23

Vault expansion surgery:
Indication: raised ICP and improve appearance (most commonly before 10)
Aim: enlarge space within the skull to allow the growing brain develop and reduce ICP
Procedure: insert metal springs thatgradually widen a gap made between the skullbones, which encourage new bone to grow inbetween the two cut surfaces.

Aim Reduce ICP and its associated complications
Sagittal synostosis

Question 24

what is oxycephaly

Answer 24

Premature fusion of coronal, sagittal & lambdoidal sutures
This condition occurs due to premature fusion of the coronal, sagittal and lambdoidal sutures. As growth is restricted both anteroposterior and lateral, the skull has to grow vertically, developing as a tall and narrow pointed or dome-shaped skull. These patients typically have a high forehead, poorly developed supercilliary ridges, superior prognathism, a high, narrow palatal arch and hypertelorism. Raised intracranial pressure (ICP) is a common finding causing an increased risk of seizures and brain damage.
Ocular findings include optic atrophy, proptosis (due to shallow orbits), amblyopia, strabismus and nystagmus.

Question 25

what are the characteristics of oxycephaly

Answer 25

Most severe form
premature closure of the coronal, saggital and lamboidal sutures
top of the skull is pointed or conical
Tall, narrow skull
High forehead

Question 26

what is trigonocephaly

Answer 26

This condition occurs as a result of premature closure of the metopic suture causing a prominent central ridge down the forehead and a triangular-shaped skull. The orbits are ovoid in shape and slope downwards and outwards. The eyes may be closely placed (hypotelorism). Microcephaly and hypoplasia of the forebrain are frequently observed, and some may also have increased ICP. Some have associated developmental delay and mental retardation. Astigmatism (usually bilateral) is a common ocular finding, strabismus with associated alphabet-pattern may also be observed.

Question 27

metric synostosis is premature fusion of

Answer 27

premature fusion of metric sutures

triangular shaped skull

Prominent central ridge down forehead
Orbits slope down & outwards
Mental retardation and developmental delay

Question 28

what ocular features associated with trignocephaly

Answer 28

Trigonocephaly
This condition occurs as a result of premature closure of the metopic suture causing a prominent central ridge down the forehead and a triangular-shaped skull. The orbits are ovoid in shape and slope downwards and outwards. The eyes may be closely placed (hypotelorism). Microcephaly and hypoplasia of the forebrain are frequently observed, and some may also have increased ICP. Some have associated developmental delay and mental retardation. Astigmatism (usually bilateral) is a common ocular finding, strabismus with associated alphabet-pattern may also be observed.

Question 29

what syndrome is associated with craniosynostosis

Answer 29

This syndrome was originally described by Crouzon in 1912. The inheritance pattern is autosomal dominant with variable expression but may also develop as a sporadic occurrence. Genetic studies suggest it may be caused by a defect on chromosome 10.
Brachycephaly is most frequently observed, but scaphocephaly and trigonocephaly may also be evidenced. The malformation seen is dependant upon the order and progression of sutural synostosis. The synostosis develops during the first year of life and is completed by 2-3 years and thus Crouzon’s syndrome is rarely identified at birth but generally within the first 2 years of age.
Most common type of craniosynostosis syndromes
Linked to markers on chromosome

Question 30

what are the clinical characteristics of crouton syndrome

Answer 30

inical Characteristics
Midfacial hypoplasia (flattened appearance of midface )
Orbital shallowing
Hypertelorism
Antimogoloid palpebral fissures (downward slanting)
Prominent lower jaw
Hooked nose
Increased ICP
High palatal arch – mouth is often half open
Respiratory difficulties caused by airway obstruction
These patients may have associated deafness, suffer from epilepsy and/or mental retardation.

Question 31

what ocular features are associated with crouton syndrome

Answer 31

The orbital shallowing causes proptosis and spontaneous subluxation of the globe may occur. The propotosis can also lead to corneal exposure problems such as conjunctivitis and keratitis. V-pattern exotropia and optic atrophy are commonly observed. Other ocular features include:
Nystagmus
Iris coloboma
Blue sclera
Aniridia (absence of iris)
Micro/ megalocornea
Keratoconus (bilateral)
Cataract
Ectopia lentis
Glaucoma

Question 32

what globe defects are associated with crouton syndrome

Answer 32

Spontaneous sub-luxation of globe
Associated with coughing
Globe needs to be positioned
Lateral tarsorrhaphy
Craniosynostois sx

Question 33

what is alert syndrome

Answer 33

both coronal sutures fuse before birth
skull is short from front to back but wide from side to side
Other sutures may also be affected either from birth or later
The facial bones are also affected
cheekbones and upper jaw do not grow in proportion to the rest of the skull.
The bones around the eyes (orbits) are wider spaced and shallower than usual, causing the eyes to bulge outwards

Question 34

what Is apert syndrome

Answer 34

As well as the skull and face, the hands and feet are also affected in Apert syndrome with the fingers and toes joined or webbed

Question 35

what is alert syndrome characterised by

Answer 35

This condition is characterised by premature fusion of the bones of the skull associated with fusion of the fingers and toes. During infancy a gaping midline defect is evident that extends from the foot of the nose to the posterior fontanelle via the metopic and sagittal sutures. This gaping defect gradually fills during the third year of life starting as islands of bone that grow and gradually coalesce to fill the gap. Premature fusion of the coronal suture may also be seen.
Apert’s syndrome is inherited as an autosomal dominant trait, however sporadic cases exist.

Question 36

what are the features of apert syndrome

Answer 36

Features
Symmetrical syndactyly of fingers and toes
Second up to fourth or fifth digit
Steep forehead
Midfacial hypoplasia
Orbital shallowing
Sloping palpebral fissures
Ear anomalies – ears tend to be low set
Small beaked, humped nose
High palatal arch – mouth is often half open
Cleft palate
Dental anomalies
Prominent lower jaw

Question 37

how is alert syndrome inherited

Answer 37

Features
↑ ICP - hydrocephalus
Respiratory difficulties
shortening of the nasopharyngeal space
Congenital heart disease
Learning disability / developmental delay

Inheritance
Autosomal dominant
Sporadic
Mutation in the FGFR2 gene
Prevalence
1 per 160000 livebirth
4.5% of all cases of craniosynostosis

Question 38

what are the ocular features of apert syndrome

Answer 38

Esotropia or exotropia with V-pattern
Alterations/absence of EOM
Amblyopia
Anisometropia/ astigmatism
Ptosis
Hypertelorism
Mild to moderate proptosis
Corneal abnormalities
Keratoconus
Corneal scars / ulcers
Optic atrophy
Ectopia lentis
Congenital glaucoma

Question 39

what is pfeffier syndrome

Answer 39

This syndrome was first described by Pfeiffer in 1964. Inheritance is autosomal dominant with variable expressivity, although sporadic cases have been reported. The facial and ophthalmic features are similar to those seen in Apert’s syndrome, but learning disability is less common and intelligence may in fact be normal. Additional clinical features include acrocephaly, broad thumbs and great toes, and mild syndactyly of the hands. Proptosis is often severe and the majority require medial and lateral tarsorrhaphies.
Ocular motility disorders present in approximately 70-75%. Exotropia is slightly more common than esotropia. A- or V-patterns may also be noted.

Question 40

what are the additional ocular features of pfieffer syndrome

Answer 40

OM disorder present in 70-75%
Severe proptosis
Exotropia more common
A or V-pattern

Question 41

what is saethre chozen syndrome

Answer 41

Features
Facial asymmetry
Low set frontal hairline
Flat forehead
Ears often small, low set
Dental abnormalities 50%
Short fingers with mild syndactyly
Usually normal intelligence
Inheritance
Autosomal dominant
Chromosome 7 p21-22
Mutation in TWIST1 gene

Question 42

what are the ocular features of seethe chosen syndrome

Answer 42

Ocular features
Ptosis
Strabismus 50%
Nasolacrimal drainage abnormalities with epiphoria 50%

Less common (25%)
Optic atrophy
Proptosis

Question 43

what is cleating syndrome

Answer 43

Disorders of the face
Abnormal development of first and second branchial arch mesoderm in early pregnancy
Treacher Collins
Goldenhar’s syndrome
Features
Cleft lip
Cleft palate

Question 44

what is treacher collins syndrome

Answer 44

Incidence: approx. 1:50,000
Inheritance
Autosomal dominant
Chromosome 5 q32-33.1
Mutation in TCOF1 gene

Bones of the cheek
Bilateral, symmetrical hypoplasia of the zygomatic bone
Lower jaw
Hypoplasia of lower jaw → breathing and feeding problems
Receding chin
Abnormal dentition
Ears
Small & malformed ears
Middle and inner ear abnormalities - deafness
Eyes
Downward slanting palpebral fissures
Colobomas of outer 3rd of lower eyelid
Limbal/orbital dermoids
Nasolacrimal duct obstruction
Astigmatism

Question 45

what are the characteristics of teacher collins syndrome

Answer 45

The abnormalities observed in this condition solely affect the face and associated anatomical structures.
Bones of the cheek
Bilateral, symmetrical hypoplasia of the malar bones
Hypoplasia of zygoma
Lower jaw
Hypoplasia of lower jaw – often causing breathing and feeding problems
Receding chin
Ears
Small and malformed ears
Middle and inner ear abnormalities – frequently leading to deafness, thus early audiological examination is essential
Eyes
Antimongoloid palpebral fissures
Colobomas of the outer third of the lower eyelid
Limbal / orbital dermoids
Nasolacrimal duct obstruction

Question 46

what is goldenhars syndrome

Answer 46

Inheritance
Sporadic
Often unilateral
Can be bilateral & asymmetrical

Features
Malformations of external & middle ear, maxilla & muscle of mastication
Facial asymmetry
Cleft palate
Deafness
Dental defects
Vertebral fusion
Cardiac abnormalities
Renal abnormalities
Pulmonary abnormalities

Question 47

what are the ocular features of goldenhars syndrome

Answer 47

Orbit on affected side lower & smaller in size
Colobomas of upper eyelid
Dermoid cysts on globe or within orbit
Nasolacrimal duct obstruction
Micropthalmos

Duanes syndrome
Esotropia or exotropia
Astigmatism & amblyopia
induced by dermoid cyst
Ptosis

Question 48

what ocular findings do these syndromes commonly present with

Answer 48

ocular anomalies

visual loss, amblyopia, refractive error, exposure keratopathy

optic neuropathy

strabismus eom defect esotropia, esotropia , vertical deviation , abormal om

Question 49

what ophthalmic investigation is needed

Answer 49

VA
Orthoptic assess
Baseline refraction and fundoscopy
Visual fields if able
OPTOS fundus photography
OCT scans
EDT / VEP

Question 50

what are the associations between refractive error and amblyopia In craniosynostosis

Answer 50

Refractive Error
Regular and accurate cycloplegic refractions are essential because refractive error is common and up to 40% may exhibit astigmatism of greater than 1 Dioptre (Khan et al. 2003). Anisometropia may also be identified. However, glasses may need to be custom designed to fit the individual patient with facial anomaly.

Amblyopia
A large number of the craniosynostosis patients have reduced visual acuity in one or both eyes. If amblyopia is present it may be ametropic, anisomteropic, strabismic, meridional or develop from stimulus deprivation. Dermoids on the globe may induce astigmatism, or, if they encroach upon the visual axis, may result in a reduction of VA. It is important to recognise the presence of amblyopia early and initiate a trial of occlusion therapy to allow maximal chances for visual rehabilitation.

Question 51

how is strabismus associated with the previously mentioned syndromes

Answer 51

Strabismus
Strabismus is a common clinical feature of the syndrome. Generally, exotropia is more common than esotropia in cases of hypertelorism. Vertical strabismus may also be found. Strabismus has been reported to develop secondary to craniofacial surgery.

Question 52

what type of ocular motility defects are most commonly associated with craniosynostosis

Answer 52

Strabismus
Exotropia more common than esotropia
Vertical strabismus
OM
Abnormal due to:
Abnormal origin of the muscles
Absence of muscles or tendons
Abnormal muscles
MRI scans shown displacement of rectus muscle pulleys (Weiss et al 2014)
V-exotropia pattern (majority)
Upshoot on ad-duction with downshoot of ab-ducting eye
Occur as a result of excyclorotated EOM and orbits

Question 53

what is the most common cause of visual loss in these patients

Answer 53

Amblyopia
Amblyopia is the most common cause of visual impairment in this group of patients!
All types of amblyopia
May be induced by dermoids or ptosis
Initiate occlusion therapy

Question 54

what additional tests may be ordered if abnormal intracranial pressure

Answer 54

VEPs
↑ICP not always associated with optic neuropathy
VEP’s recommended as abnormal if ↑ICP

OCT scans – feasible and recommended in clinical surveillance (Rufai et al 2021)

Question 55

what does the approach to the management of craniosynsostis need to be

Answer 55

The management of patients with craniosynostosis requires a multidisciplinary team approach. Members in the team include paediatrician, plastic surgeon, neurosurgeon, ear-nose-throat (ENT) specialist, paediatric nurses, orthodontist, audiologist, speech therapist, psychologist, geneticist, and genetic counsellor. The ophthalmic team include ophthalmologists, optometrists, orthoptists and visual electrodiagnostic scientists.

Question 56

what is an orthoptist role

Answer 56

Monitor visual development carefully
Sudden visual loss
Optic neuropathy - ↑ICP
Amblyopia
Occlusion therapy
Good fit of spectacles
Refer for refraction
Assess strabismus
Presence/ absence
Change in angle over time – indication if stable
Assess OM defects
Any change over time
Associated symptoms

Question 57

what is the aim of ophthalmological management

Answer 57

Aim of ophthalmological management

Observe visual development carefully
Delay strabismus surgery until after craniofacial surgery
Prior to strabismus surgery
Orbital imaging recommended to determine any abnormal or absent EOM

Ophthalmic problems experienced postoperatively may result from trauma to the optic nerve/globe due craniofacial surgery, or due to pressure on the optic nerve/globe by a malpositioned bone graft. It is general practice to delay strabismus surgery until after craniofacial surgery. Orbital imaging is recommended as part of the pre-operative assessment to determine any abnormal or absent extraocular muscles (Nischal, 2002).