Craniosynostosis is a birth defect of the Skull (which may
affect the Brain) that is characterized by the premature
closure of one or more of the fibrous joints between the bones of the
Skull (called the cranial sutures) before
Brain growth is complete. While the premature fusion of the
cranial sutures results in disproportionate growth of the cranial
bones, it may also affect the growth of the facial bones. When a
suture is fused there is no growth in a plain perpendicular to the
line of the suture. The abnormally shaped Skull that
results is due to the Brain not being able to grow in its
natural shape because of the closure. Instead it compensates
with growth in areas of the Skull where the cranial sutures
have not yet closed.
The Skull has two different components, the first of
which forms the "vault" of the Cranium and is called
the "membranous" part. The other portion, the
"chondrocranium" forms the Base of the Skull. After a
certain age there is little likelihood of further growth in defects
of the Skull vault whereas there may be subsequent growth of defects
in the Skull Base (chondrocranium.)
Brain growth stimulates the progressive formation the bone of
the Skull which normally occurs in a homogeneous and
symmetrical manner. There is rapid Skull grows from birth to the 7th
year with the greatest part of the increase of its cranial vault
occurring in during the first year of life. This is due to the rapid
growth of the Brain during this time period. The Brain is expected to
reach its maximum growth at about the age of two years.
The Fontanelles are the "soft spots" in a baby's
Skull. They are the locations where several of the
various Skull bones have yet to grow together. There are
six (6) Fontanelles at the edges of the Parietal bones
(2 anterolateral and posterolateral as well as the Anterior and
Posterior Fontanelle.) Due to the normally expected rapid bone growth,
the Posterior and Anterolateral Fontanelles are usually closed
within three months after birth. The Posterolateral Fontanelle is
usually closed about the end of the first year of
life and the Anterior Fontanelle about the middle of
the second year.
- The "Metopic" (or Frontal) suture separates
the Frontal bone into two halves. Union starts in the
first year and is completed by the 8th year.
- The "Sagittal" suture separates the two
Parietal bones and extends from the Anterior
Fontanelle to the Posterior Fontanelle.
- The "Coronal" suture separates the Frontal
bones from the Parietal bones.
- The "Lambdoid" suture separates the
posterior edge of the Parietal bone from the Occipital
bone.
- The "Squamosal" suture is quite complex and
is the superior border of the Squamous part of the Temporal
bone while anteriorly it articulates with the
Greater Wing of Sphenoid, superiorly it articulates with the
Parietal bone and posteriorly and inferiorly it articulates
with the Occipital bone.
Craniosynostosis can be gene-linked, or caused by
metabolic diseases, such as rickets (Vitamin D
deficiency) or an overactive thyroid. Some cases are associated
with other disorders such as Microcephaly (abnormally
small head) and
Hydrocephalus
(excessive accumulation of Cerebrospinal Fluid in the Brain).
Closure of a single suture is most common. Depending on
the severity of the Craniosynostosis, the child may have some or all
of these problems:
- abnormal Skull shape
- abnormal forehead
- asymmetry of the eyes and/or ears
- increases intracranial pressure which can possibly cause delays in development
The issue of a risk to permanent Brain damage if the
Craniosynostosis is not corrected is controversial. In our opinion,
there is no good scientific data to support this claim. However,
in view of the fact that there is a risk to some "developmental
delays", one should be aware of this potential.
- Scaphocephaly,
the most common type of
Craniosynostosis, is caused by the fusion of
the Sagittal suture which runs from front to back
down the middle of the top of the Skull. Characteristic
appearance:
- a long narrow shaped head from front to back
- narrow from ear to ear
- the head appears boat-shaped
- Trigonocephaly
is the fusion of the Metopic
suture, which runs from the top of the head, down the
middle of the forehead, towards the nose. Characteristic
appearance:
- triangular shaped forehead
- eyes are closer together than usual
- Plagiocephaly
is the premature fusion of one
of the Coronal sutures, which extend from ear to ear
over the top of the head. Characteristic appearance:
- fusion of either the right or left side
- the forehead and brow look like they are pushed backwards
- the eye on the affected side has a different shape than the one on the unaffected side
- Brachycephaly
results from premature closure
of both sides of the Coronal sutures. Characteristic
appearance:
- wide-shaped head, with short Skull
- tall, flattened forehead (the entire forehead is
prevented from growing in a forward direction)
The first sign of Craniosynostosis is an
abnormally shaped Skull. Other features can include
signs of increased intracranial pressure, developmental delays,
or mental retardation, which are caused by constriction of the
growing Brain. Seizures and blindness may also occur.
Neuroimaging usually includes CT Scanning including 3-D
studies.
Treatment for Craniosynostosis generally consists of
surgery to relieve pressure on the Brain and the
Cranial Nerves. For some children with less severe problems,
cranial molds can reshape the Skull to accommodate Brain growth and
improve the appearance of the head.
The prognosis for Craniosynostosis varies depending on whether
single or multiple cranial sutures are involved or other
abnormalities are present. The prognosis is better
for those with single suture involvement and no associated
abnormalities.
"Craniofacial Syndrome" is a category comprising
additional conditions involving the abnormal growth of the
Skull and face. These syndromes are usually
inherited and in many cases the abnormal genes have been
identified. The most common of these syndromes include:
- Crouzon Syndrome
Crouzon is the commonest among the Craniofacial
Syndromes. While sporadic cases of this condition do
occur, the majority are inherited as a "Mendelian
dominant trait of high penetrance".
The typical appearance of the child with this
condition includes a brachycephalic Skull with a
prominent nose, a protruding jaw with malocclusion,
underdeveloped Maxilla and Exophthalmos (which is
often severe and may constitute a serious
risk to vision.)
While the Skull deformities vary greatly from one
patient to another, the Skull is distinctly
brachycephalic in all. There is usually a
diffuse premature fusion of other Skull sutures including the
basal sutures.
In this condition, the exophthalmos is due to small and
shallow orbits which could result in corneal
ulceration and conjunctival infection. In some cases
the exophthalmos is so severe that the eyes are
dislocated outside the orbit resulting in a high risk to loss
of vision. Many of these patients experience
compromise of the nasal airways and respiratory
difficulties as a result of the maxillary hyperplasia. Raised
intracranial pressure is frequently encountered in
association with this syndrome.
Hydrocephalus
is also present in about 20% of cases.
X-ray examinations often show a "copper beaten
appearance" (an indicator of raised intracranial
pressure) of the Skull in addition to the premature closure
of the Skull sutures.
- Apert Syndrome
Apert is the second most common syndrome after
Crouzon and usually presents with a very high
brachycephalic head and severe syndactyl (which
involves bony fusion) affecting all limbs.
There exists considerable amount of information regarding these
conditions. We invite your consideration to begin by visiting the
nationally acclaimed websites involving one of our Craniofacial
Plastic Surgeons,
Dr. Jeffrey A. Fearon
who is also a member of our
Skull Base Tumor Team.
They are accessible at:
The Craniofacial Center
Children's Craniofacial Association
P.O. Box 280297
Dallas, TX 75228
800-535-3643
Email: contactCCA@ccakids.com
Ask for the Guide to Understanding Craniosynostosis written by Dr. Fearon.
The reader may also wish to review the following websites:
http://www.ninds.nih.gov/disorders/craniosynostosis/craniosynostosis.htm
http://cumc.columbia.edu/dept/nsg/PNS/Craniofacial.html
http://www.health.adelaide.edu.au/paed-neuro/craniofacial.html
FACES: The National Craniofacial Association
AboutFace USA
CAPPS (Craniosynostosis and Positional Plagiocephaly Support, Inc.)
MUMS
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This page last edited on 2/22
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