Craniosynostosis

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Deffinition:
Craniosynostosis is a defect in which one or more of the flexible and fibrous joints (cranial sutures) between the skull bones closes too soon; it occurs before birth or within a few months after birth.  It is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses. This results in restricted skull and brain growth. Because the brain cannot expand in the direction of the fused suture, it is forced to grow in the direction of the open sutures, often resulting in an abnormal head shape and facial features. Some cases of craniosynostosis may result in increased pressure on the brain and developmental delays.  It can be the result of an inherited syndrome or sporadic. In sporadic cases, the cause is unknown.Craniosynostosis can occur alone or as part of a syndrome of craniofacial defects.
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Craniosynostosis is a very rare occurrence. The sagittal form of the disorder, in which the sagittal suture closes prematurely, is the most common form of craniosynostosis, occurring in three to five of every 1,000 babies, typically males. The frequencies of the various types of craniosynostosis are 50–60% sagittal, 20–30% coronal, 4–10% metopic, and 2–4% lambdoid.It is estimated that craniosynostosis affects 1 in 2,000 live births.

Description:
The skull of a newborn is composed of five bones that are held together by the fibrous sutures positioned at the front, top, sides, and back of the skull. By remaining open, the sutures allow the skull to normally expand in all directions as the brain is growing.

The premature closing of one or more of these cranial sutures stops the normal capacity of the skull to expand in early childhood. As not all of the cranial sutures will close, the skull expands in the areas that are still flexible. This results in an abnormally shaped skull or face. The forehead may be very pronounced and inclined forward. Viewed from above, the skull may be more rectangular in shape rather than oval.

Other forms of craniosynostosis include coronal craniosynostosis (affecting the coronal suture that crosses the top of the skull from temple to temple), metopic craniosynostosis (affecting the metopic suture of the forehead), sagittal craniosynostosis (affecting the sagittal suture that unites the two parietal bones), and lambdoidal craniosynostosis (affecting the lambdoid suture between the occipital and parietal bones of the skull).

Causes:
The cause of craniosynostosis is unknown.However, there’s a hereditary component to craniosynostosis when it occurs with certain genetic syndromes such as Apert’s syndrome and Crouzon syndrome.It is usually caused by a genetic mutation. Mutations in several genes (designated TWIST, FGFR-1, FGFR-2, and FGFR-3) have been linked with craniosynostosis. In particular, the protein encoded for by TWIST is critical in the initiation and maintenance of the cranial suture process. As of 2004, the favored hypothesis is that the protein that normally functions to ensure that the formation of the cranial sutures occurs at the right time in development somehow goes awry and causes premature fusion of the bones of the brain.

Symptoms:
Infant’s skull has seven bones. Normally, these bones don’t fuse until around age 2, giving your baby’s brain time to grow. Joints called cranial sutures, made of strong, fibrous tissue, hold these bones together. In the front of your baby’s skull, the sutures intersect in the large soft spot (fontanel) on the top of your baby’s head. Normally, the sutures remain flexible until the bones fuse.
Joints called cranial sutures, made of strong, fibrous tissue, hold the bones of your baby’s skull together until the bones fuse, normally around age 2. Until then, the sutures intersect at the fontanels, the soft spots on your baby’s head. The largest of the four fontanels is at the front of the skull (anterior); the next largest is at the back (posterior). Each side of the skull has a tiny fontanel.
Craniosynostosis signs in general
Signs of craniosynostosis include:

#A misshapen skull, with the shape depending on which of the cranial sutures are affected
#Abnormal feeling “soft spot” (fontanel) on your baby’s skull
#Early disappearance of the fontanel
#Slow or no growth of head as your baby grows
#Development of a raised, hard ridge along affected sutures
#Increased pressure within the skull (intracranial pressure)
The signs of craniosynostosis may not be noticeable at birth, but they will become apparent during the first few months of your baby’s life.

Main categories and characteristics :-
There are two categories of craniosynostosis:

1.Primary craniosynostosis. If your baby has primary craniosynostosis, usually one, but sometimes more, of the cranial sutures become rigid, fusing the connecting bones and inhibiting the brain’s ability to grow normally.
2.Secondary craniosynostosis. With secondary craniosynostosis, which occurs more frequently than the primary type, your infant’s brain stops growing, usually due to an underlying hereditary syndrome, allowing the sutures to fuse prematurely. Secondary craniosynostosis is often associated with facial deformities and developmental delays.

Common types and characteristics :-
The most common types of craniosynostosis are:

#Sagittal synostosis (scaphocephaly). Premature fusion of the suture at the top of the head (sagittal suture) forces the head to grow long and narrow, rather than wide. Scaphocephaly is the most common type of craniosynostosis, and it is more common in boys.
#Coronal synostosis (anterior plagiocephaly). Premature fusion of one of the sutures that run from each ear to the sagittal suture on top of the head may force your baby’s forehead to flatten on the affected side. It also may raise the eye socket and cause a deviated nose and slanted skull. This second most common type of craniosynostosis is more common in girls. Untreated, it may lead to vision loss on the affected side (amblyopia).
#Bicoronal synostosis (brachycephaly).
When both of the coronal sutures fuse prematurely, your baby may have a flat, elevated forehead and brow.


Rare types and characteristics :-
Two less common types of synostosis are:


#Metopic synostosis (trigonocephaly).
The metopic suture runs from the baby’s nose to the sagittal suture. Premature fusion gives the scalp a triangular appearance.
#Lambdoid synostosis (posterior plagiocephaly)
. This rare form of craniosynostosis involves the lambdoid suture, which runs across the skull near the back of the head. It may cause flattening of the head on the affected side.

Misshapen head may not mean craniosynostosis
:-
A misshapen head doesn’t always indicate craniosynostosis. For example, if the back of your baby’s head appears flattened, it could be the result of your baby’s sleeping on his or her back.

The “Back to Sleep” campaign, co-sponsored by the National Institute of Child Health & Human Development, encourages parents to put healthy babies to sleep on their backs to reduce the risk of sudden infant death syndrome (SIDS). The campaign has resulted in more cases of misshapen heads. In this case, the flattening is a result of positional molding, not craniosynostosis.

Risk Factors:
Babies with craniosynostosis, particularly those with an underlying syndrome, may develop increased intracranial pressure. Their skulls don’t expand enough to make room for their growing brain.

If untreated, increased intracranial pressure can cause these conditions:

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#Blindness
#Seizures
#Brain damage
#Death, in very rare instances
In addition, facial deformities that affect the middle of your child’s face may cause:

#Upper airway obstructions, compromising your baby’s ability to breathe
#Permanent head deformity

Diagnosis:
Your doctor will feel your baby’s head for abnormalities such as suture ridges, perform a physical exam and look for facial deformities. In addition, your doctor may order other tests, including:

#Imaging studies. X-rays or a computerized tomography (CT) scan of your baby’s skull will show whether any sutures have fused. Fused sutures are identifiable by their absence, because they’re invisible once fused, and by the ridging of the suture line.

#Genetic testing. If your doctor suspects your baby’s misshapen skull is caused by an underlying hereditary syndrome, genetic testing may help identify the syndrome. Genetic tests usually require a blood sample.
Depending on what type of abnormality your doctor is looking for, your baby may be required to give a hair, skin or other tissue sample, such as cells from the inside of the cheek. The sample is then sent to a lab for analysis.

Treatments:-

Surgery is the common treatment for craniosynostosis:
But for Mild cases of craniosynostosis — those that involve only one suture and no underlying syndrome — may require no treatment. Skull abnormalities may become less obvious as your infant grows and develops hair.

Surgery
:-
For other infants, surgery, usually during infancy, is the primary treatment for craniosynostosis. However, the type and timing of surgery depend on the type of synostosis and whether there’s an underlying syndrome.

The purpose of surgery is to relieve pressure on the brain, create room for the brain to grow normally and improve your child’s appearance. A team that includes a specialist in surgery of the head and face (craniofacial surgeon) and a specialist in brain surgery (neurosurgeon) often performs the surgery.

#Traditional surgery. The surgeon makes an incision in your infant’s scalp and cranial bones, then reshapes the affected portion of the skull. Sometimes plates and screws, often made of material that is absorbed over time, are used to hold the bones in place. Surgery, which is performed during general anesthesia, may take up to seven hours.

After surgery, your infant remains in the hospital for at least three days. Some temporary facial swelling is common after surgery. Complications are rare. Some children may require a second surgery later because the synostosis recurs. Also, children with facial deformities often require future surgeries to reshape their faces.

#Endoscopic surgery
. This less invasive form of surgery isn’t an option for everyone. But in certain cases, the surgeon may use a lighted tube (endoscope) inserted through one or two small scalp incisions over the affected suture. The surgeon then opens the suture to enable your baby’s brain to grow normally. Endoscopic surgery usually takes about an hour, causes less swelling and blood loss, and shortens the hospital stay, often to one day after surgery.

If your baby has an underlying syndrome, your doctor may recommend regular follow-up visits after surgery to monitor head growth and check for increased intracranial pressure.

Recovery and rehabilitation:-
Regardless of the type of surgery performed to correct the defects associated with craniosynostosis, the child will be restricted from vigorous activity or rough play while healing. The protective helmet is required for children after endoscopic strip craniectomy, while permanent plates inserted during other corrective surgeries eliminate the need for the helmet. Children who have had surgery to repair craniosynostosis will continue to need periodic examination by the surgeon until approximately age 18, when the skull has grown to its adult size and shape.

Prognosis:-
The outlook for a complete recovery for a child with craniosynostosis depends on whether just one suture is involved or whether multiple sutures have closed. Also, the presence of other abnormalities can lessen the confidence of a satisfactory outcome. Without surgical intervention, craniosynostosis can lead to increased brain pressure, delayed mental development, mental retardation, seizures, or blindness. After surgery is accomplished, the prognosis is excellent.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Craniosynostosis
http://www.mayoclinic.com/health/craniosynostosis/
http://www.answers.com/topic/craniosynostosis

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