Craniosynostosis Flashcards
How many parts are there to the skull and what are they called?
1) Neurocranium
2) Viscerocranium
What is the Neurocranium?
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.
What is the 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
- 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.
When does the posterior (occipital) fontanelle close?
Usually 3 months after birth
When does the anterior (frontal) fontanelle close?
Around 1.5 years old
When does the postero-lateral (mastoid) fontanelle close?
Around 2 years of age
What is Craniosynostosis?
Premature fusion of 1 or more sutures
- Inhibit growth of skull in that area
- Force growth in other non-fused areas –> abnormally shaped skull
What are associated features of Craniosynostosis?
Associated features
- Raised intracranial pressure (ICP)
- Impairment of cerebral function
- Impairment of vision
What is the prevalence of craniosynostosis?
1:2000-3000 infants are affected
What are the features of Primary Craniosynostosis?
- Sporadic
- Genetically inherited – most commonly autosomal dominant
(recognised feature in over 100 genetic syndromes)
What is Secondary Craniosynostosis?
Acquired Craniosynostosis
- Metabolic disorders e.g hypercalcaemia
- Mechanical cause e.g Intrauterine compression of skull against maternal pelvis
What are some types of craniosynostosis?
- Sagittal (Scaphocephaly)
- Metopic (Trignocephaly)
- Unicoronal (Plagiocephaly)
- Bicoronal (Brachycephaly)
- Oxycephaly
What is Unicoronal Synostosis?
Plagiocephaly
- Premature fusion of one of the coronal sutures.
- Greater development on the non-fused side and thus asymmetrical growth of the skull.
How does the skull look in Unicoronal Synostosis/Plagiophaly?
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 are some signs/symptoms of unilateral coronal synostosis/plagiocephaly?
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. This can lead to an AHP (chin depression). Other common ocular features include amblyopia (usually strabismic) and astigmatism.
What is the treatment in unicoronal synostosis/plagiocephaly?
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.
How is Fronto-Orbital Advancement surgery performed?
- 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 Bicoronal synostosis also known as?
Brachycephaly
What is Bicoronal Synostosis (Brachycephaly)?
- Premature fusion of both coronal sutures
- Short anterior-posterior length
- Increased lateral & vertical growth
What does Bicoronal Synostosis/Brachycephaly look like in the skull?
- Short antero-posterior skull
- Wide & tall skull
- The face appears flat and broad with very prominent and wide set eyes (hypertelorism).
What are some features of Bicoronal Synostosis/Brachycepahly (including ocular features)?
- Brachycephaly is associated with learning disabilities in approximately 50%, together with cleft palate, syndactyly and polydactyly (increased number of fingers & toes). It may also be seen in association with Down’s syndrome.
Ocular Features:
- Proptosis
- Hypertelorism - wide set eyes
What is the surgery used in Bicoronal Synostosis/Brachycephaly?
- Fronto-orbital advancement surgery (FOA)
- Performed at 4-12 months of age.
What is Saggital Synostosis?
Scaphocephaly
- Premature closure of the sagittal suture
- Prevents lateral expansion of the skull
- Elongation along the anteroposterior axis
What is Scaphocephaly also known as?
Sagittal Synostosis
What features are present in Sagittal Synostosis/ Scaphocephaly?
- Strong, prominent forehead (frontal bossing of forehead)
- Prominent occipital area
Associated with
- Speech & language delay
- Raised intracranial pressure
What surgical intervention is involved in Sagittal Synostosis/ Scaphocephaly?
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
When is vault expansion surgery used?
In Sagittal Synostosis (Scaphocephaly)
What is the procedure of vault expansion surgery?
- Procedure: insert metal springs thatgradually widen a gap made between the skullbones, which encourage new bone to grow inbetween the two cut surfaces
What is Oxycephaly?
Most severe form of craniosynostosis
Premature fusion of coronal, sagittal & 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.
What are some general signs and symptoms of Oxycephaly?
- Tall & narrow (dome-shaped) skull
- High forehead
- High, narrow palatal arch
- ↑ICP common (increased risk of seizures and brain damage)
What are some ocular signs and symptoms of Oxycephaly?
- Optic atrophy
- Proptosis (shallow orbits)
- Strabismus
- Amblyopia
- Nystagmus
- Hypertelorism
What is Metopic Synostosis also known as?
Trigonocephaly
What causes metopic synostosis/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.
What are the general features of metopic synostosis/Trigonocephaly?
- Triangular shaped skull
- Prominent central ridge down forehead
- Orbits slope down & outwards
- The eyes may be closely placed (hypotelorism).
- Microcephaly and hypoplasia of the forebrain are frequently observed, and some may also have increased ICP
- Learning disability and developmental delay
- Astigmatism (usually bilateral) is a common ocular finding, strabismus with associated alphabet-pattern may also be observed.
What are the ocular features metopic synostosis/Trigonocephaly?
- Bilateral Astigmatism
- Strabismus
- Alphabet Pattern
What is the most common type of craniosynostosis syndrome?
Crouzon Syndrome
What is the most common synostosis in Crouzon Syndrome?
Brachycephaly (bicoronal synostosis) is most frequently observed, but scaphocephaly (sagittal synostosis) and trigonocephaly (metopic synostosis) may also be evidenced.
What is the inheritance of Crouzon Syndrome?
- Autosomal dominant
- Sporadic
- Chromosome 10q25-q26
What is the prevalence of Crouzon Syndrome?
- 16.5 per million live birth
- 4.8% of all cases of craniosynostosis
When does Crouzon Syndrome develop?
During 1st year of life, often first diagnosed 1-2 years of age (as more development = more obvious)
What are some general clinical features of Crouzon Syndrome?
- Midfacial hypoplasia; flattened appearance of midface
- Orbital shallowing
- Hypertelorism (an abnormally increased distance between the bony orbits (eye sockets))
- Downward slanting palpebral fissures
- Prominent lower jaw
- Hooked nose
- Increased ICP
- High palatal arch (mouth often half open)
- Respiratory difficulties
- Deafness
- Epilepsy
- Learning disability
What are some ocular features of Crouzon Syndrome?
- Strabismus (most common feature)
V-pattern exotropia - Proptosis
spontaneous subluxation of the globe (associated with coughing) - Corneal exposure (due to proptosis)
conjunctivitis and keratitis - Amblyopia
- Hypermetropia
- Optic atrophy
- Nystagmus
- Cataract
- Ectopia lentis
- Glaucoma
- Iris coloboma
- Aniridia (absent iris)
- Blue sclera
- Micro/ megalocornea
- Keratoconus (bilateral)
Crouzon Syndrome - If spontaneous subluxation of globe what surgery do we need to do?
- Globe needs to be positioned
- Lateral tarsorrhaphy (stitch part of eyelids together)
- Craniosynostois sx
What causes Apert Syndrome?
Autosomal Dominant but some sporadic cases exist
- Both coronal sutures fuse before birth
Skull is short from front to back but wide from side to side (Brachycephaly - bicoronal synostosis)
Other sutures may also be affected either from birth or later
How is skull/facial bones affected in Apert Syndrome?
- Both coronal sutures fuse before birth
Skull is short from front to back but wide from side to side (Brachycephaly - bicoronal synostosis)
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 are some facial features of 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
- 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
What are some general features of Apert Syndrome?
- ↑ ICP - hydrocephalus
- Respiratory difficulties
shortening of the nasopharyngeal space - Congenital heart disease
- Learning disability / developmental delay
What is the inheritance/prevalence in Apert Syndrome?
Inheritance
- Autosomal dominant
- Sporadic
- Mutation in the FGFR2 gene
Prevalence
- 1 per 160,000 livebirth
- 4.5% of all cases of craniosynostosis
What are some ocular features in 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 are some features of Pfeiffer Syndrome?
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. Severe proptosis.
What is the inheritance of Pfeiffer Syndrome?
- Autosomal dominant
- Mutation in FGFR2 and FGFR1 genes
- Can be sporadic
What causes Saethre-Chotzen Syndrome & how is it inherited?
Closely related to Crouzon syndrome, Saethre-Chotzen syndrome results from an early closing (fusion) of the skull’s side (coronal) sutures OR back (lambdoidal) suture.
This syndrome is inherited as an autosomal dominant trait with variable expressivity. The gene responsible has been mapped to chromosome 7; mutation in TWIST1 gene
What are some features of Saethre-Chotzen Syndrome?
It is characterised by variable skull and facial asymmetry, low set frontal hair-line, flat forehead and short fingers with mild cutaneous syndactyly. The abnormal facial features are often subtle and no proptosis is present. Although ptosis and tear duct abnormalities are commonly present. An esotropia or exotropia with associated V-pattern may be noted.
- Facial asymmetry
- Low set frontal hairline
- Flat forehead
- Ears often small, low set
- Dental abnormalities 50%
- Short fingers with mild syndactyly
- Usually normal intelligence
What are some ocular features of Saethre-Chotzen Syndrome?
- Ptosis
- Strabismus 50%
- Nasolacrimal drainage abnormalities with epiphoria 50%
Less common (25%)
- Optic atrophy
- Proptosis
What are Clefting Syndrome & some examples?
Disorders of the face
- Abnormal development of first and second branchial arch mesoderm in early pregnancy
Features of cleft lip and cleft palate
- Treacher Collins
- Goldenhar’s syndrome
What is Treacher Collins Syndrome an example of?
A Clefting Syndrome
What is the incidence and inheritance of Treacher Collins Syndrome?
Incidence: approx. 1:50,000
Inheritance
- Autosomal dominant
- Chromosome 5 q32-33.1
- Mutation in TCOF1 gene
What are the abnormalities observed in Treacher Collins Syndrome?
Solely affect the face and associated anatomical structures
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 is Goldenhar’s Syndrome an example of?
A Cleft Palate Syndrome
What is the inheritance or Goldenhar’s Syndrome?
- Sporadic (inherited sporadic syndrome)
Is Goldenhar’s Syndrome unilateral or bilateral?
Usually unilateral but can be bilateral and asymmetrical
What are some features of Goldenhar’s Syndrome?
- Malformations of external & middle ear, maxilla & muscle of mastication (skin tags can be amblyogenic factors)
- Facial asymmetry
- Cleft palate
- Deafness
- Dental defects
- Vertebral fusion
- Cardiac abnormalities
- Renal abnormalities
- Pulmonary abnormalities
What are some ocular features of Goldenhar’s Syndrome?
- Orbit on affected side lower & smaller in size
- Colobomas of upper eyelid
- Dermoid cysts on globe or within orbit
- Nasolacrimal duct obstruction
- Micropthalmos
- Strong association to Duanes syndrome
- Esotropia or exotropia
- Astigmatism & amblyopia
induced by dermoid cyst (pressing on cornea causing astigmatism) - Ptosis
What does Goldenhar’s Syndrome have a strong association with?
Duane’s Syndrome
Why do we need to detect ocular abnormalities early?
Important that these disorders are detected early in order to initiate effective management.
What must we include in our ophthalmic investigation of craniosynostosis?
- VA
- Orthoptic assess
- Baseline refraction and fundoscopy
- Visual fields if able
- OPTOS fundus photography
- OCT scans
- EDT / VEP
What are the general ocular abnormalities in craniosynostosis (Strabimus & OMs)?
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 are the general ocular abnormalities in craniosynostosis (Refractive Error & Amblyopia)?
Rx:
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:
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 are the general ocular abnormalities in craniosynostosis (Not Strabismus, OMs, Refractive Error & Amblyopia)?
Optic Neuropathy:
with or without papilloedema
→ by chronically raised ICP or hypoxia
→ by narrowing of optic canals or stretching of optic nerves
Proptosis (exophthalmos):
→ by orbital shallowing &/or maxillary hypoplasia
Exposure keratopathy
Photophobia & corneal scarring
Incomplete closure of eye lids when asleep
Topical lubricants
Medial and lateral tarsorrhaphies
Electrodiagnostics (VEP’s):
↑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 teams are needed to manage craniosynostosis?
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 the general management in Craniosynostosis?
Referred to & managed by 4 designated centres in UK
- Alder Hey Children’s Hospital in Liverpool.
- Birmingham Children’s Hospital.
- Great Ormond Street Hospital in London.
- John Radcliffe Hospital in Oxford.
At these centres the craniofacial surgery is carried out
- Fronto-orbital advancement
Aim of surgery
- Recreate the sutures & prevent them from reuniting
- Enlarges space within skull
What is the orthoptists role in craniosynostosis?
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 ophthalmological management in craniosynostosis?
Ophthalmological management is aimed at ensuring visual development proceeds normally, as facial surgery frequently involves elevations of the orbit and mobilization of the orbital walls. 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).
