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