Craniosynostosis is the
premature partial or complete ossification of one or more of the sutures
separating the membranous bones of the skull.
The incidence of craniosynostosis has been estimated to be 1 in 2,500 live
Primary, or simple,
craniosynostosis is ‘single- or multiple/compound’ suture synostosis in
children who are otherwise neurologically normal, and
almost always present
prenatally except in some with cranio facial syndromes of Crouzan's,
Apert's and Carpenter's type in whom progressive postnatal closure may
Synostosis that occurs as part of a syndrome of complex congenital
malformations is frequently called complex, or syndromic, craniosynostosis.
Secondary stenosis may occur
in children with
metabolic disorders, and hematological disorders.
Rickets, Hyperthyroidism, Thalassaemia, or Mucopolysaccharidosis may be
associated. It can also
occur as the consequence of lack of growth at the suture lines because of
microcephaly, encephalocele, or shunted hydrocephalus.
The cranial vault develops
intramembranous bone formation between the periosteum and the dura. This
process begins during the 6th week of embryonic development. The posterior
fontanel closes at 3 mths of age and the anterior one, at 8mths of age.
The bones ossify by the end of first year. The skull growth ceases by
10-12 yrs of age. The ossification of the cranial sutures occurs by the
4th-5th decade. The base develops from a series of primordial cartilages
that undergo ossification. The growth of the base proceeds at a slower
The skull contains two types
of sutures- syndesmoses and synchondroses.
Syndesmoses occur in the
vault and consist of fibrous tissue interposed between bone surfaces.
Synchondroses occur in the skull base from a bar of cartilage. The role of
sutures is unclear.
The normal infant's skull is
oval shaped and widest posteriorly. The growth occurs in the direction
perpendicular to the suture lines, the direction of least resistance.
In craniosynostosis the
deformity is related to the suture involved and the effects of increasing
growth of the brain upon the unfused skull plates.
comprise a heterogeneous group of disorders of multifactorial origin.
Most cases of simple
craniosynostosis, are sporadic.
The cause is unknown. Many
Genetic determinants play a
part in some coronal and pansynostosis, particularly where there is an
associated craniofacial abnormality.
Some cases are inherited. Affected families may have members with
involvement of different sutures, and, in the case of familial coronal
synostosis, family members may have unilateral or bilateral involvement.
Mendelian disorders may cause simple or complex craniosynostosis, but
craniosynostosis associated with chromosomal aberrations is usually part
of a syndrome.2 Approximately 27 different chromosomal
aberrations have been reported for craniosynostosis, and more continue to
be described each year. Dominant inheritance is more common than recessive
inheritance. Most cases of simple craniosynostosis, however, are sporadic.
Abnormal tensile forces along
the dural tracts running from the cranial base to the vault induce
premature suture fusion. These dural tracts consist of tentorium cerebelli,
the falx and dural bands from the lesser wing to the vault.
Some blame the fetal head
constraint in utero. The periosteum overlying the suture may be involved.
Premature fusion of
the sagittal suture results in boat skull.
The skull grows parallel
to the fused sagittal suture, the skull becomes elongated as the
frontal and occipital bones compensate for the restricted lateral
growth of the parietal bones resulting in frontal bossing. The
sagittal suture may become prominent as a ridge. 2% of the cases are
familial, and about 80% are males.73
to 80 per cent of scaphocephaly patients are males.
There is premature
closure of one coronal suture resulting in under development of the
forehead, supraorbital ridge and anterior fossa on the ipsilateral
side. Radiologicaly, in addition to the obliteration of the coronal
suture, there is a deformity of the orbit resulting from elevation of
the ipsilateral sphenoid ridge, commonly described ‘harlequin orbit'.
This type of synostosis is more commonly associated with a clinical
syndrome than is scaphocephaly, but the majority of cases remain
sporadic. Males are affected twice as often as females.
If it is inherited
in families, other family members tend to have bilateral coronal
synostosis, suggesting that the two conditions may have a similar
lambdoid synostosis produces a posterior plagicephalic skull as a
result of the flattening of the parietooccipital region ipsilateral to
the fused suture,
and may be seen as
a part of a complex craniofacial syndrome.
It is a broad short skull
due to bicoronal synostosis and brain growth ipsilateral to the
coronal sutures. Radiologicaly, there is bilateral harlequin’ orbits.
It is the commonest.
There is premature fusion
of the metopic suture. The transverse growth of the forehead is
compromised. It is associated with orbital hypotelorism. The resultant
shape gives rise to triangular shaped skull.
It may be associated with Christian syndrome II, an X-linked,
semidominant syndrome consisting of hypertelorism, clinodactyly,
vertebral anomalies, and imperforate anus. Metopic synostosis is one
of many different suture synostoses seen in Carpenter's syndrome.
of multiple sutures may produce a conical-shaped head and is seen in 5
to 10 per cent of primary craniosynostoses.
It is the result of
pansynostosis where all the sutures are prematurely fused and the
skull assumes a towering shape-towering skull. Increased ICT is more
The deformity is
progressive over the period of maximal brain growth, during the first
12mths,less progressive during the 2nd year and reaches its maximum at
the age of 2yrs and unchanged after that time.
This condition is heterogeneous in origin and may be seen in Crouzon's
sagittal synostosis is rarely associated with other abnormalities.
30% of the unilateral coronal synostosis and 60% of those with bicoronal
synostosis have other congenital abnormalities, such as syndactyly and
patients with craniofacial syndromes of the Crouzon’s, Apert’s or
Carpenter’s variety almost invariably have associated craniosynostosis.
Apert's syndrome: There is brachycephaly with midface hypoplasia.
There is a unique hand malformation. Both hands are
affected equally, as are the feet. This unusual variation of
syndactyly can be used to identify Apert's from other similar
Usually, cases are sporadic, but the syndrome may be inherited in an
autosomal dominant fashion.
|| Apert's feet
|| Apert's hands
Crouzon’s syndrome: It
is commoner. There is brachycephaly with midface hypoplasia and shallow
orbits with proptosis.
The skull base is
implicated, and sphenofrontal synostosis is a factor involved in producing
exophthalmos. Maxillary hypoplasia, the characteristic facial deformity,
is a more important cause of exophthalmos. In 5 per cent of cases, the
calvaria is normal. Hydrocephalus is more common in Crouzon's syndrome
than in simple craniosynostoses.
Unlike in Apert’s there is no
This condition is
inherited in an autosomal dominant fashion, but there is an equal
incidence of sporadic cases, which probably represent new mutations.
Penetrance is high, although severity is variable. Within the same family,
members tend to have similar facial deformities but variable calvarial
deformities. This phenotypic heterogeneity makes genetic counseling
Variations of this type of
craniofacial dysostosis are seen.
syndrome, the calvarial deformity is variable and is less striking than
the facial and digital anomalies. Mental retardation, cardiac anomalies,
and hypogonadism are also common.
syndrome is a relatively benign condition. The features of this condition
include brachycephaly or plagiocephaly, facial asymmetry with
hypertelorism and orbital dystopia, low frontal hairline, ptosis, and mild
maxillary hypoplasia. Syndactyly is usually mild, and mental retardation
is much less common.
Pfeiffer's syndrome is
characterized by tall, broad skull, hypertelorism, slanted palpebral
fissures, and broad thumbs and toes; mentation is usually normal.
skull deformity is obvious, so also are the associated facial deformities.
Mental retardation can occur due to associated brain malformations,
or increased ICT. It is unknown in single suture synostosis.
Hydrocephalus is infrequent. The mechanism is not known.
Increased ICT is rare in single synostosis. It is more frequent in the
first 2 yrs.The pressure tends to normalize at six years of age. The
pressure may take months to come down after decompressive surgery.
plain x-rays and CT scan in axial and coronal planes, with bone
windows, will give adequate information and also reveal brain
malformations and the presence of increased ICT, if any.
adds to the clarity.
MRI shows any associated cerebral malformations better.
Positional deformity, due to birth molding, may be diagnosed by the
presence of patent sutures and absence of any orbital deformity.
the brain fails to grow and the head remains small. The fontanels
close early. The x-rays reveal a thick vault, and the frontal vault is
disproportionally small. X-rays do not show any silver beaten
appearance or sellar changes.
Apert's -3D CT
3D CT- craniolacunae
management is by a multidisciplinary team comprising of the neurosurgeon,
the plastic surgeon, the pediatrician, the ophthalmologist, dental
surgeon, anesthetist and the social worker.
of surgery is
1) to allow normal brain growth.
2) to correct increased ICT.
3) to achieve cosmetically acceptable head.
4) to protect the eyes.
ideal time for surgery in the absence of increased ICT, is 3 - 6mths of
age to give the growing brain the ideal surroundings and also to
facilitate normal shape to the skull. Surgery for cosmetic reasons,
especially in coronal synostosis, can be performed at a later age.
generous craniectomy with extension to adjacent sutures is the basic
procedure. Frontal and orbital advancement techniques are needed in
coronal synostosis. Dural-pericranial stitches or use of tantalium foils
at the site of craniectomy is advised to prevent reossification.
associated facial deformities can wait until about 5 yrs of age to allow
the roots of the teeth to descend and permit safe correction of the
Frontal bones exposed
supra orbital ridge
Scapocephaly-3D-CT-post- op ( lat)
metopic synostosis, the surgery is for cosmetic reasons and involves
remodeling of the frontal bone and supralateral orbital advancement. The
triangular forehead is removed and recontoured to the appropriate shape or
bone may be taken from another area of the skull to replace this bone. The
entire bony supraorbital bar is removed and reshaped with supralateral
orbital advancement to restore the normal brow contour. Wires or
micro-plates are used to secure the frontal bar to the facial bones and
maintain the normal contour.
In bicoronal synostosis, both
frontal bones are reconstructed. The supraorbital bar is completely
removed, reshaped, and straightened. The supraorbital bar is advanced and
lowered as necessary on the affected side and rigidly fixed in position to
the face. The reconstructed forehead is then secured to the supraorbital
unicoronal synostosis, the surgery is for cosmetic reasons and restricted
to the involved side.
lambdoid synostosis, the surgery is purely for cosmetic reasons and
consists of extensive posterior skull craniectomies with remodeling of
both sides of the occiput and posterior advancement of the affected
oxycephaly, the aim is to relieve the increased ICT and the surgery
involves multiple craniectomies of the fused sutures.
Restenosis is well known
and may require resurgery.