craniosynostosis Flashcards
describe the anatomy of the skull i.e the 2 main parts of the skull
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
how does the skull develop
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
when do the fontanelles close
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.
what are fontanelles
fontanelles = where flat bones meet
what is cranysynostosis
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
cranisostosis is the ……
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
what is the prevalence of cranysinostosis
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
what is the prevalence of cranysinostosis
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
what are the types of craniosynostosis
sagital
metric
unicronal
bicronal
what is unicornonal synostosis
premature fusion of one of the coronal sutures
greater development of the non fused side and thus asymmetrical growth of the skull
unicornonal synostosis
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
what is unilateral coronal synostosis
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.
what can unicoronal synosysois cause optically
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
what are the positions of the orbits and trochlea like in unicoronal synostosis
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
what is the treatment for unicoronla synostosis
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.
what surgery is done for uni coronal synostosis
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.
what is bicornonal synostosis
Premature fusion of both coronal sutures
Short anterior-posterior length
Increased lateral & vertical growth
what does bicornonal synostosis result in
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.
what surgery is done for bicornonal synostosis
Fronto-orbital advancement surgery (FOA)
performed at 4-12 months of age.
saggital synostosis meaning
Premature closure of the sagittal suture
Prevents lateral expansion of the skull
Elongation along the anteroposterior axis
what does sagittal synostosis
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.
what is saggital synostosis associated with
Strong, prominent forehead
Prominent occipital area
Associated with
Speech & language delay
Raised intracranial pressure
what surgical intervention is needed for saggitla synostosis
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
what is oxycephaly
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.
what are the characteristics of oxycephaly
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
what is 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.
metric synostosis is premature fusion of
premature fusion of metric sutures
triangular shaped skull
Prominent central ridge down forehead
Orbits slope down & outwards
Mental retardation and developmental delay
what ocular features associated with trignocephaly
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.
what syndrome is associated with craniosynostosis
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
what are the clinical characteristics of crouton syndrome
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.
what ocular features are associated with crouton syndrome
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
what globe defects are associated with crouton syndrome
Spontaneous sub-luxation of globe
Associated with coughing
Globe needs to be positioned
Lateral tarsorrhaphy
Craniosynostois sx
what is alert syndrome
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
what Is apert syndrome
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
what is alert syndrome characterised by
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.
what are the features of apert syndrome
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
how is alert syndrome inherited
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
what are the ocular features of apert syndrome
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
what is pfeffier syndrome
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.
what are the additional ocular features of pfieffer syndrome
OM disorder present in 70-75%
Severe proptosis
Exotropia more common
A or V-pattern
what is saethre chozen syndrome
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
what are the ocular features of seethe chosen syndrome
Ocular features
Ptosis
Strabismus 50%
Nasolacrimal drainage abnormalities with epiphoria 50%
Less common (25%)
Optic atrophy
Proptosis
what is cleating syndrome
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
what is treacher collins syndrome
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
what are the characteristics of teacher collins syndrome
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
what is goldenhars syndrome
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
what are the ocular features of goldenhars syndrome
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
what ocular findings do these syndromes commonly present with
ocular anomalies
visual loss, amblyopia, refractive error, exposure keratopathy
optic neuropathy
strabismus eom defect esotropia, esotropia , vertical deviation , abormal om
what ophthalmic investigation is needed
VA
Orthoptic assess
Baseline refraction and fundoscopy
Visual fields if able
OPTOS fundus photography
OCT scans
EDT / VEP
what are the associations between refractive error and amblyopia In craniosynostosis
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.
how is strabismus associated with the previously mentioned syndromes
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.
what type of ocular motility defects are most commonly associated with craniosynostosis
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
what is the most common cause of visual loss in these patients
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
what additional tests may be ordered if abnormal intracranial pressure
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)
what does the approach to the management of craniosynsostis need to be
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.
what is an orthoptist role
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
what is the aim of ophthalmological management
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).
