Craniosynostosis

(medicine) The union of separate cranial bones into a single bone structure.

For more information on craniosynostosis, visit Britannica.com.

Definition

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. The skull cannot expand normally with growth of the brain, and so assumes an abnormal shape. Craniosynostosis can occur alone or as part of a syndrome of craniofacial defects.

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).

Demographics

Craniosynostosis is a 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.

Causes and symptoms

Craniosynostosis 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.

Research published in 2003 in the Annals of the Royal College of Surgeons of England identified Saethre-Chotzen syndrome (a rare disorder characterized by an exaggerated forehead and drooping eyelids) as a genetic disorder that produces craniosynostosis.

Craniosynostosis can also be caused by maladies that affect the metabolism (rickets, vitamin D deficiency, overactive thyroid) and by bone marrow disorders. Furthermore, some cases have been associated with an abnormally small head (microcephaly) and the accumulation of cerebrospinal fluid in the brain (hydrocephalus).

Involvement of the different sutures produces different effects. Closure of the sagittal suture (located at the top of the skull and to the rear) produces an elongated head, prominent and protruding forehead, and narrow temples. Closure of the coronal suture (located on the side of the skull) produces a flattened forehead, higher-than-normal eye socket, abnormal nose, and a skull that slants from side to side. Closure of the metopic suture (which runs down the front-middle portion of the skull) results in a pointed-shaped forehead, triangular-shaped skull, closer-than-normal eyes, and a protruding rear portion of the skull. Finally, closure of the lambdoidal suture (located at the back of the skull) produces a mild flattening of the back of the head, forward-shifted ears, and the coronal symptoms.

Diagnosis

Diagnosis is made on the basis of a physical examination.

Treatment team

Treatment involves medical specialists (pediatric neurosurgeons, pediatric plastic surgeons, craniofacial surgeons) and specialized nurses.

Treatment

Surgery is the common treatment for craniosynostosis. The traditional surgeries involve the exposure of the skull, physical breakage of the fused suture region, and the restoration of the scalp. These surgeries all carry the risks associated with surgery in the brain region. Also, the surgeries produce much bleeding (sometimes a blood transfusion is necessary) and leave a large scar, and transient swelling and bruising can occur.

A new surgical technique called endoscopic strip craniectomy has been pioneered by two pediatric surgeons from the University of Missouri Health Care Center. This surgery is much less invasive, produces only a relatively small scar, and leaves little physical after effects such as swelling and bruising. In the procedure, an endo-scope is used to remove the closed suture through incisions that are only several inches in length. In the more than 100 surgeries performed as of January 2001, most of the infants were in a condition satisfactory enough to leave the hospital the following day. Endoscopic strip craniectomy can only be done on infants under six months of age. After the surgery, the baby wears a protective helmet for several months, which molds the growing head into the correct shape.

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.

Clinical trials

The National Institute for Neurological Diseases and Stroke directly undertakes and funds a range of studies examining the mechanisms of early neurological development. However, there are no clinical trials scheduled to study craniosynostosis as of January 2004.

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.

Resources

PERIODICALS

Johnson, D. "A Comprehensive Screen of Genes Implicated in Craniosynostosis." Annals of the Royal College of Surgeons of England (November 2003): 371–377.

OTHER

Sheth, R.D. "Craniosynostosis." eMedicine. January 22, 2004 (March 30, 2004). http://www.emedicine.com/neuro/topic80.htm.

National Institute of Neurological Disorders and Stroke. Craniosynostosis Information Page. January 22, 2004 (March 30, 2004). http://www.ninds.nih.gov/health_and_medical/disorders/craniosytosis_doc.htm.

University of Missouri Health Care. "Craniosynostosis: A New and Better Treatment." MU Health. January 19, 2004 (March 30, 2004). http://www.muhealth.org/~neuromedicine/craniosynostosis.shtml.

ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) 663-4637; Fax: (914) 428-8203. askus@ marchofdimes.com. http://www.marchofdimes.com.

National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-6673; Fax: (203) 798-2291. orphan@rarediseases.org. http://www.rarediseases.org.

World Craniofacial Foundation. 7777 Forest Lane, Suite C-621, Dallas, TX 75251-5838. (972) 566-6669 or (800) 533-3315; Fax: (972) 566-3850. worldcf@worldnet.att.net. http://www.worldcf.org/cran_3c5.html.

Brian Douglas Hoyle, PhD

Definition

Craniosynostosis is a birth defect of the brain in which the cranial sutures (the fibrous joints between the bones of the skull) in the skull of an infant close too early, causing problems with normal brain and skull growth. Premature closure of the sutures may cause the skull or facial bones to change from a normal, symmetrical appearance to an abnormal, asymmetrical appearance and may also cause the pressure inside of the head to increase.

Description

The skull of an infant is made up of five free-floating bones separated by cranial sutures, which allows the infant to pass through the birth canal. The five bones are: the occipital bone, in the back portion of the skull, the two parietal bones, on either side of the skull, and two frontal bones, on the front portion of the skull. The bones fit together like a puzzle, and the areas where the bones meet one another are called the sutures, which are the fibrous joints. The bones and the sutures serve as a protective shield for the brain.

As the infant's brain grows rapidly during early infancy, the open sutures allow the skull to expand and to develop into a normal shape. However, if one or more of the sutures closes prematurely, either before birth or during the first few months of life, the skull compensates by expanding in the direction of the remaining open sutures, resulting in an abnormal shape. Children with craniosynostosis may also have increased pressure on the brain, resulting in developmental delays, and vision problems as a result of an imbalance in their ocular muscles. Craniosynostosis occurs in one out of 2,000 live births and affects males twice as often as females.

There are several types of craniosynostosis. The sagittal suture, the most common single suture involved in craniosynostosis, runs from a spot at the front of the head to the back of the skull. In sagittal synostosis, the sagittal suture closes, resulting in the infant's head growing long and narrow, rather than expanding in width, in order to accommodate the growth of brain. There may or may not be bulging of both the front and back of the head.

The metopic suture runs from the nose up to the top of the skull, where it meets the sagittal suture. When the metopic suture closes, in metopic synotosis, the infant has a ridge down the forehead that can be seen or felt, and the forehead is narrow and triangular. The eyebrows may appear pinched on either side, and the eyes often seem to be close together. This head shape is referred to as trigonocephaly.

Early closure of one side of the coronal suture, which goes from ear to ear on the top of the head, is referred to as unilateral coronal synotosis (plagiocephaly). The forehead and orbital rim (eyebrow) have a flattened appearance on the affected side of the skull, resulting in a "winking" effect. In bicoronal synotosis, both sides of the coronal suture are fused, and the child may have a flat, recessed forehead. In addition, the head is short and wide, and there may be bulging of the eyes and bulging of the skull around the ears. This type of synotosis is most often found in children with Crouzon's and Apert's syndromes.

Lambdoid synotosis, the most rare form, resulting in bulging over the suture, and the ear on the affected side is pulled up and backwards over the suture, resulting in a flattening of the backside of the skull.

Multiple suture synotosis involves the fusing of all of the skull sutures. This condition requires emergency intervention.

The psychological effects of a noticeably misshapen forehead and face can be devastating to a child, resulting in low self-esteem and behavioral problems. Therefore it is important to correct cosmetic deformities of the skull and face.

Causes and Symptoms

Most cases of craniosynostosis have no known causes. Some cases may be attributed to intrauterine restraint or early engagement of the head. Craniosynostosis is also associated with some known genetic chromosomal defects, including Apert, Crouzon, Pfieffer, and Saethre-Chotzen Syndromes.

Most children with craniosynostosis do not have any symptoms, except that the head shape is abnormal, and the face may be malformed. Rarely, the affected child may suffer symptoms such as increased pressure in the head, headaches, decreased appetite, vomiting, or even developmental delays or mental retardation.

Diagnosis

An infant with a distorted, misshapen head at birth should be examined by a pediatric neurosurgeon and a craniofacial surgeon to determine if the abnormality is due to abnormal fetal positions and neck tightness or due to craniosynotosis. The physical examination includes feeling the skull for suture ridges, spot spots, and checking the neck position, and taking measurements of the infant's face and head. Computerized tomography, which is a series of photographic images of the brain, is uses to diagnose early suture fusion and to develop surgical correction plans.

Treatment

Treatment of craniosynostosis is used to correct the deformities associated with craniosynotosis and is accomplished by restoring the normal shape and relationship of the forehead and orbital rims through cranio-facial surgery. Surgery is less often needed to reduce intracranial pressure. In some cases helmet or band therapy is used after surgery to encourage further correction of the skull and face.

Ideally surgery to correct craniosynotosis should be carried out in an affected child who is less than three months old, when a less-invasive, microscopic procedure can be used that results in smaller incisions, less blood loss, and a shorter hospital stay than the traditional corrective surgery that is used on older children. Also the skull bones of an infant are easier to work with, and the covering of the brain, referred to as the dura, can make bone on its own. The growing brain continues to reshape the skull and face after surgery. However, surgery to correct craniosyntosis can be done at any age. Usually only one surgery is required to correct simple craniosynotosis, but some children may require minor surgery at 4-5 years of age to correct remaining minor abnormalities. When multiple sutures are involved, usually multiple surgeries are required.

The surgeons make an incision in the skull behind the hairline so that the scar will be covered by hair. The bone in the area of the defect is reshaped or replaced with bone from a different area of the skull.

Surgery for sagittal synostosis involves removing the suture and widening the skull by opening up the coronal and lambdoid sutures, which are found on both sides of the head. In some case bone grafts are used to keep the bones apart.

Surgery for unilateral coronal synotosis involves removing the fused suture, reshaping the forehead and brow, and bringing the forehead and brow forward to match the other side. The cheek is also brought forward to reposition the eye socket. For bicoronal synotosis, both sutures are removed, and the skull is narrowed and lengthened. Both cheekbones are brought forward to reposition the eye socket.

Metopic synotosis is corrected by releasing the metopic suture and expanding and rounding out the upper face, forehead, and skull. Surgery for lambdoid synotosis entails reconstruction of the back portions of the skull.

When all of the sutures are fused, the child must be operated on as soon as possible, with all of the sutures released and repositioned to allow for normal brain growth and to relieve the pressure on the eyes and brain.

Alternative Treatment

Conventional surgical treatments should be relied upon for the treatment of craniosynotosis.

Prognosis

The prognosis for craniosynostosis is dependent on whether single or multiple cranial sutures are involved and whether other abnormalities are present. The prognosis is better when there is only single suture involvement and no abnormalities. Surgery is usually successful, and children can lead normal lives with no residual effects from craniosynostosis.

Prevention

Since the causes of craniosynostosis have not been identified, it is unknown as to what measures could be taken that would prevent the condition.

Resources

Books

Parker, James M. and Parker, Philip M., editors. The Official Parent's Sourcebook on Craniosynostosis. San Diego, CA: Icon Health Publications, 2003.

Periodicals

Organizations

Children's Craniofacial Association, 13140 Coit Road, Suite 307, Dallas, TX 75240. Telephone: (800) 535-3643; Fax: (214) 570-3643. Web site: www.ccakids.com

Other

Craniosynostosis And Positional Plagiocephaly Support, Inc.6905 Xandu Court, Fredericksburg, VA 22407. Telephone: Website: http://www.cappskids.org

Premature fusion of the cranial sutures resulting in a malformed head, which may lead to an increase in intracranial pressure and consequential brain damage.

Definition

Craniosynostosis is one of a diverse group of deformities in the head and facial bones called craniofacial anomalies. An infant or child with craniosynostosis has improperly fused or joined bones (sutures) in the skull. ("Cranio" means skull; "synostosis" means fused bones.) When children with craniosynostosis also show other body deformities, their condition is called syndromic craniosynostosis. Primary craniosynostosis occurs when one or more of an infant's sutures (where skull bones meet) fuse prematurely. Secondary craniosynostosis results when one or more of an infant's sutures fuse prematurely as a result of lack of proper brain growth.

Description

A baby's skull is often thought of as a single piece of bone. However, it is actually made up of several bones that fit together like a jigsaw puzzle. These areas meet at what are called sutures. Sutures allow a growing baby's brain to expand. The four sutures come together at the fontanel, or "soft spot" in a baby's head. Eventually the sutures stop growing, and the cranial bones fuse.

Sometimes a suture is fused too early, however, preventing a growing child's brain from expanding. This condition can cause the brain to grow more rapidly in another area of the skull. The result is an abnormally shaped skull. Sometimes this happens before birth (congenital), or sometimes it occurs as the baby develops after birth.

There are four sutures of the skull that may be affected by craniosynostosis:

• Metopic: This suture extends from the top of the head down the middle of the forehead to the nose.
• Coronal: This suture extends from each ear to the fontanelle.
• Sagittal: This suture extends from the front of the head to the back, down the middle of the top to the head.
• Lambdoidal: This suture extends across the back of the head.

Types

The form of craniosynostosis depends on the suture or sutures that are affected.

Plagiocephaly (Unicoronal Synostosis)

Plagiocephaly is the most common form of craniosynostosis. It occurs in approximately one out of every 2,500 births. Plagiocephaly involves early fusion of either the right or left side of the coronal suture, the suture that extends from each ear over the top of the head to the fontanelle. The forehead and brow of a child with plagiocephaly look as if they have been pushed back or flattened because the forehead and brow have stopped their normal growth.

Brachycephaly (Bicoronal Synostosis)

Brachycephaly, which means "short headed," occurs when the right and left coronal sutures close prematurely. Brachycephaly results in an abnormally broad head with a high forehead. It is often associated with other craniofacial abnormalities, including Crouzon syndrome, Apert syndrome, Pfeiffer syndrome, and Saethre-Chotzen syndrome. It also is associated with Down syndrome (trisomy 21).

Trigonocephaly

This type of craniosynostosis involves fusion of the metopic suture that runs from the top of the head toward the nose, which can create a ridge running down the forehead and gives the front of the head a wedge-shaped effect. The eyes also may be close together.

Scaphocephaly (Sagittal Craniosynostosis)

This early fusion involves the sagittal suture that runs from front to back on the top of the skull. The result can be a long, narrow skull.

Positional Nonsyndromic Plagiocephaly (Positional Molding)

Positional nonsyndromic plagiocephaly is a form of craniosynostosis. In 1992, the American Academy of Pediatrics recommended that infants sleep on their backs to reduce the risk of sudden infant death syndrome (SIDS). This successfully reduced the number of infants with SIDS, but also increased the number of infants suffering from positional plagiocephaly due to back sleeping. An infant with positional nonsyndromic plagiocephaly has a flattened skull at the back of the head. This condition is also commonly called positional molding or deformational plagiocephaly.

Demographics

Craniosynostosis occurs in one out of 2,000 live births in the United States. It affects males twice as often as females. Of those affected, 2–8 percent have primary craniosynostosis and the remaining cases are secondary craniosynostosis. Plagiocephaly is the most common form of craniosynostosis. It occurs in approximately one out of every 2,500 live births. Sagittal craniosynostosis is the most common type of single suture craniosynostosis. It is estimated to occur in one in 4,000 to 8,500 live births. Although sagittal craniosynostosis mostly occurs by chance, about 2–6 percent of cases are considered to be inherited.

Frequencies of the types of craniosynostosis based on suture classification include: sagittal (50–58%); coronal (20–29%); metopic (4–10%); and lambdoid (2–4%).

Causes and Symptoms

As of 2004 the exact cause of craniosynostosis is not understood. Many scientists believe it is the result of a defect in the ossification (bone formation) in the bones of the skull. Craniosynostosis usually occurs by chance (sporadic). In some families, however, it is inherited.

Genetic abnormalities such as craniosynostosis are described by the type of chromosome that carries the abnormal gene and whether the gene is recessive or dominant. The autosomal chromosomes are the nonsex chromosomes.

Autosomal Recessive

In order for a child to inherit an autosomal recessive abnormality, both parents have to be carriers of the abnormal gene. When both parents are carriers, there is a 25 percent chance that each child born will inherit the abnormal gene and develop craniosynostosis. The child also has a 50 percent chance of inheriting the abnormal gene and becoming a carrier. Males and females are affected equally.

Autosomal Dominant

When one parent has the abnormal gene and the other parent has normal genes, craniosynostosis can still result. That is because the abnormal gene dominates the normal gene. For an autosomal dominant disorder when one parent is a carrier of the abnormal gene, there is a 50 percent chance each child born will inherit the abnormal gene. Males and females are affected equally.

Other genetic syndromes, such as Crouzon syndrome, Apert syndrome, and Pfeiffer syndrome, are associated with craniosynostosis. All have different patterns of inheritance and chances of recurrence.

The physical symptoms of craniosynostosis depend on the sutures affected. Since other syndromes are associated with craniosynostosis, other symptoms may also be present, including the following:

• Endocrine disorders: Hyperthyroidism (overactivity of the thyroid gland), vitamin D deficiency, renal osteodystrophy (defective bone development), hypercalcemia (high levels of calcium in the blood), and rickets (weakened bones resulting from vitamin D deficiency).
• Hematologic disorders: Bone marrow diseases including sickle cell disease, and thalassemia.
• Inadequate growth of brain: Microcephaly (abnormal smallness of head), and hydrocephalus (abnormal buildup of cerebrospinal fluid in the head).

When to Call the Doctor

Craniosynostosis is a progressive condition that must be treated. The skull and facial asymmetry associated with craniosynostosis are frequently observed by an infant's pediatrician or family physician. Parents may also observe the condition.

Diagnosis

Craniosynostosis may be present at birth or may be observed later when a child has delays in neurological development. It often may be diagnosed by physical examination alone. Craniosynostosis may be suspected when an infant has an abnormally shaped head or a small bony ridge along the skull in various locations. The condition may also be suspected if a baby's fontanel (soft spot) closes off earlier than expected. The physician will do a complete physical exam and take a complete prenatal and birth history of the child, including position in the uterus. Family history of craniosynostosis or other craniofacial abnormalities also will be discussed.

Since craniosynostosis may be associated with other neurological and muscular disorders, such as Crouzon syndrome, Apert syndrome, or Pfeiffer syndrome, the physician will also discuss whether there have been any delays in the child's developmental progression.

If craniosynostosis is suspected, an x ray or a CT scan of the child's skull will be taken. In addition, DNA testing can help identify the gene mutations that can cause the condition. Mutations in what are called fibroblast growth factor receptors (FGR1, 2, and 3) and the transcription factor TWIST are responsible for several types of craniosynostosis.

Treatment

For most children with craniosynostosis, facial and skull deformity will be obvious and may be expected to worsen as the child grows. Surgical management by experienced neurosurgeons (brain surgeons) and orthopedic (bone) surgeons will be necessary in most cases. It usually is performed between the ages of six and ten months.

Surgery involves releasing the fused sutures and reshaping the bone of the skull and eye orbit. The fused sutures are excised (removed), and the skull reshaped and replaced with a variety of materials. Surgery usually lasts for three to seven hours, and several days of hospitalization are necessary to monitor and treat any complications of the surgery. When more severe deformities are present, repeat surgery of the skull and eye sockets may be necessary. This will help release and advance the child's mid-face.

In the early 2000s, newer, less invasive techniques are being developed using endoscopes. Endoscopes are narrow tubes that are inserted into the brain through narrow incisions (cuts). They allow surgeons to visualize the brain and pass tiny surgical instruments through the tube to perform surgery to re-open the sutures and allow the brain to grow normally.

Children born with co-existing craniofacial conditions, such as Apert syndrome, which affects the growth of the jaw, may benefit from a technique called mandibular bone lengthening or distraction osteogenesis. This technique was first used in Russia to treat bone problems in the leg and has now been used successfully to correct deformities of the jaw.

Positional Plagiocephaly (Positional Molding, Deformational Plagiocephaly)

Positional plagiocephaly, the result of an infant's back sleeping position, can be treated by varying the infant's sleeping position from back to side sleeping, and providing tummy play time. A wedge-shaped foam pillow sold at many baby stores may help position the infant for side sleeping. The child may also be repositioned in the crib or the crib's location changed. When positional molding is identified at less than three months of age, repositioning is usually successful in stopping the plagiocephaly and reversing the flattening. If the flattening is severe or the condition is not caught until an infant is older, a helmet may be necessary. The helmet is specifically made for the infant by an orthotic specialist, a person who creates devices that provide more normal functioning for impaired people. The infant may wear the helmet for up to 23 hours daily, removing it only during baths. Average length of treatment is three to six months. The helmet gently redirects the skull's growth and is most successful when the skull is most pliable, from about three months to about six months. The plagiocephaly will be monitored throughout this time, and the helmet adjusted as the child grows.

Prognosis

It is important to detect and treat craniosynostosis early. Untreated craniosynostosis will remain the same or worsen as a child grows and can affect a child's mental and physical development. Associated neuromuscular conditions also may affect the child's development. A child with craniosynostosis will require ongoing medical evaluations to ensure that the brain, skull, and facial bones are developing properly.

Prevention

As of 2004 there was no known prevention for craniosynostosis. Nothing that parents did or did not do causes the condition. The exception is positional plagiocephaly, which results from an infant being put to sleep on the back. This can be prevented by varying the infant's sleeping position from back to side sleeping, and providing tummy play time. A wedge-shaped foam pillow sold at many baby stores may help position the infant for side sleeping.

Parents who have an increased likelihood of carrying the genes that result in craniosynostosis may seek genetic counseling to better understand inheritance patterns and chances for reoccurrence.

Parental Concerns

The physical symptoms of an asymmetrical face and head seen when a child has craniosynostosis are readily apparent and may cause the child embarrassment. The pressure a growing brain exerts on a fused suture also can cause a delay in development or, rarely, permanent brain damage. In addition, several conditions exist along with craniosynostosis and need to be evaluated.

A child needs to be carefully evaluated when craniosynostosis is present to distinguish between positional plagiocephaly, caused by back sleeping, and other forms of craniosynostosis. Positional plagiocephaly can be treated by repositioning the infant and perhaps by having the infant wear a helmet. Craniosynostosis must be treated by surgery. The differential diagnosis and treatment of posterior plagiocephaly is a challenging aspect of craniofacial surgery.

Resources

Periodicals

Coumoul, Xavier, and Deng Chu-Xia. "Roles of FGF receptors in mammalian development and congenital diseases." Birth Defects Research Part C: Embryo Today: Reviews 69 (2003): 286–304.

Jimenez, David, et al. "Endoscopy-assisted wide-vertex craniectomy, barrel stave osteotomies, and postoperative helmet molding therapy in the management of sagittal suture craniosynostosis." Journal of Neurosurgery (Pediatrics 5) 100 (2002): 407–17.

Kabbani, H., and T. S. Raghuveer. "Craniosynostosis." American Family Physician 69 (June 15, 2004): 2863–70.

Panchal, Jayesh, and Venus Uttchin. "Management of Craniosynostosis." Plastic & Reconstructive Surgery 111 (May 2003): 2032–49.

Organizations

Crouzon Support Network. PO Box 1272, Edmonds, WA 98020. Web site: www.crouzon.org/.

FACES: The National Craniofacial Association. PO Box 11082, Chattanooga, TN 37401. Web site: www.facescranio.org/.

National Association for Rare Disorders. 55 Kenosia Avenue, PO Box 1968, Danbury, CT 06813–1968. Web site: www.rarediseases.org/info/contact.html.

Web Sites

"Autosomal dominant." MedlinePlus, June 15, 2003. Available online at www.nlm.nih.gov/medlineplus/ency/article/002049.htm (accessed December 9, 2004).

"Autosomal recessive." MedlinePlus, June 15, 2003. Available online at www.nlm.nih.gov/medlineplus/ency/article/002052.htm (accessed December 9, 2004).

"Craniofacial Anomalies." The Children's Hospital of Philadelphia, 2002. Available online at www.chop.edu/consumer/your_child/condition_section_index.jsp?id=-9703 (accessed December 9, 2004).

"Craniosynostosis: A new less, invasion treatment." Craniosynostosis Net, July 15, 2003. Available online at www.craniosynostosis.net/about.html (accessed December 9, 2004).

"NINDS Craniosynostosis Information Page." National Institute of Neurological Disorders and Stroke, 2004. Available online at www.ninds.nih.gov/health_and_medical/disorders/craniosytosis_doc.htm (accessed December 9, 2004)

[Article by: Christine Kuehn Kelly]

Premature closure of the cranial sutures.

Craniosynostosis
Classification and external resources
Child with premature closure (craniosynostosis) of the lambdoid suture. Notice the swelling on the right side of the head
ICD-10	Q75.0
ICD-9	756.0
OMIM	218500
DiseasesDB	3160
eMedicine	med/2897
MeSH	D003398

Craniosynostosis,^[1] is a medical condition in which some or all of the sutures in the skull of an infant or child close too early,^[2] causing problems with normal brain and skull growth. It can result in craniostenosis, which is the skull deformity caused by the premature closure of the cranial sutures. Also intracranial pressure can be increased.

Contents 1 Normal skull development 2 Pathophysiology 3 Diagnosis 3.1 Syndromes 3.2 Differential diagnosis 4 Treatment 5 Epidemiology 6 See also 7 References 8 External links

Normal skull development

In humans, the adult skull is normally made up of 28 bones. The flat bones making up the cranial vault are joined together by sutures: rigid articulations permitting very little movement.

At birth, the human skull is made up of 45 separate bony elements. As growth occurs, many of these bony elements gradually fuse together into solid bone (for example, the frontal bones).

The bones of the roof of the skull are initially separated by regions of dense connective tissue. At birth these regions are fibrous and moveable, necessary for birth and later growth. Larger regions of connective tissue, called fontanelles, occur where certain bony elements meet. As growth and ossification progress, the connective tissue of the fontanelles is invaded and replaced by bone. The posterior fontanelle usually closes by eight weeks, but the anterior fontanelle can remain up to eighteen months.

Pathophysiology

When one or more sutures fuse prematurely, skull growth can be restricted perpendicular to the suture. If multiple sutures fuse while the brain is still increasing in size, intracranial pressure can increase.

Primary craniosynostosis is believed to be a result of primary defect in the mesenchymal layer ossification in the cranial bones. Secondary craniosynostosis is a result of primary failure of brain growth.

Diagnosis

Physicians diagnose craniosynostosis through physical examination, plain x-rays, and CT scans. ^[3]

Syndromes

Craniosynostosis often occurs alone, however about 20% of cases are associated with syndromes. A syndrome is diagnosed by considering the presence of a variety of features, signs, and symptoms throughout the body. Genetic testing may be available to confirm the diagnosis of a specific syndrome. A family history of abnormal head shape can sometimes be found with genetic syndromes, though many syndromes are caused by new genetic mutations, and there is no family history of the disorder. ^[3]

The most common causes of syndromic craniosynostosis are Crouzon syndrome and Apert syndrome. However, there are over 150 syndromes associated with craniosynostosis. ^[3] The following table lists some of the craniosynostosis syndromes, as well as prominent additional symptoms that are found in these syndromes — this is not a comprehensive list of all symptoms that could occur within each syndrome. There is considerable overlap of symptoms between many of these syndromes, and clinical evaluation by a geneticist may be necessary to determine the most appropriate diagnosis.

The following syndromes are associated with fibroblast growth factor receptors:

Name of syndrome	Other signs and symptoms (along with craniosynostosis; may not all be present)	OMIM reference	Gene
Crouzon syndrome	wide-set, bulging eyes • beaked nose • flat face	123500	FGFR2, FGFR3
Apert syndrome	fused fingers or toes • flat midface	101200	FGFR2
Crouzonodermoskeletal syndrome	wide-set, bulging eyes • beaked nose • flat face • dark, velvety skin folds • spine abnormalities • benign growths in the jaw	134934	FGFR3
Jackson-Weiss syndrome	enlarged, bent big toes • flat midface	123150	FGFR1, FGFR2
Muenke syndrome	coronal synostosis • skeletal abnormalities of the hands or feet • hearing loss	602849	FGFR3
Pfeiffer syndrome	broad, short thumbs or big toes • webbed or fused fingers or toes	101600	FGFR1, FGFR2

In addition, the following syndromes have been identified:

Name of syndrome	Other signs and symptoms (along with craniosynostosis; may not all be present)	OMIM reference	Gene
Loeys-Dietz syndrome	wide-set eyes • split uvula or cleft palate • arterial tortuosity • aneurysms	609192	TGFBR1
Saethre-Chotzen syndrome	facial asymmetry • low frontal hairline • drooping eyelids • webbed fingers or toes • broad big toes	101400	TWIST1
Shprintzen-Goldberg syndrome	bulging eyes • flat face • hernias • long, thin fingers • developmental delay • mental retardation	182212	FBN1

Differential diagnosis

A separate cause of abnormal head shape is positional plagiocephaly — flattened or misshapen areas on the head that may develop due to sleeping position. While the appearance may look rather similar to craniosynostosis, the distinction is important. Positional plagiocephaly does not require surgery^[4] — treatment can be as simple as occasionally repositioning the child's head while sleeping or, in some cases, wearing a cranial band to mold the skull. ^[3] It has recently been discovered that using certain prescription drugs during pregnancy may lead to this disorder. (sertraline)

A child wearing a cranial helmet.

Treatment

Surgery is typically used to separate the fused sutures of the skull as well as to reshape the skull. To treat the cosmetic troubles, a combination of orthodontic and orthognathic surgery can be used to relieve some of the midface deficiency.

Typical surgery begins with a zigzag incision from ear to ear across the top of the head. The scar left by this type of incision makes the hair look more natural than that left by a straight incision would. Leroy clips are typically used to curtail bleeding, as cauterization would not result in an aesthetically pleasing result upon healing. Once the scalp is peeled back, pilot holes are drilled through the skull. These pilot holes are then connected, separating the skull into several pieces. Once reshaped, these pieces are placed back on the head (typically in an altered configuration) and held together by a combination of dissolving sutures, plates, and screws. These plates and screws are typically made of a copolymer composed of polyglycolic and polylactic acid and will break down into water and carbon dioxide within a year. Demineralized bone matrix or bone morphogenetic proteins are often used to fill gaps left by the expanded skull, encouraging the body to grow new bone in a process called intramembranous ossification. Once the hemostatic scalp clips are removed, sutures are again used to close the incision.

Newer approaches include minimally invasive endoscopic assisted removal of the closed suture followed by treatment with custom made molding helmets. These surgeries are associated with significantly less blood loss, swelling, hospital length of stay and pain. The results have been excellent in the majority of patients treated this way. Endoscopic surgery, however, is indicated only for very young infants(< 6 months of age). Older children require the more extensive surgery described above.

Epidemiology

The incidence of craniosynostosis has been described as 1 in 2500 live births.^[5] The earliest known case is a child dated to 530,000 BP found in Atapuerca Spain.^[6]

See also

• Cephalic disorder
• Positional plagiocephaly (flattened head syndrome)

References

1. ^ Silva, Sandra; Philippe Jeanty (1999-06-07). "Cloverleaf skull or kleeblattschadel". TheFetus.net. MacroMedia. http://www.thefetus.net/page.php?id=340. Retrieved 2007-02-03. 
2. ^ Panchal J, Uttchin V (May 2003). "Management of craniosynostosis". Plast. Reconstr. Surg. 111 (6): 2032–48; quiz 2049. doi:10.1097/01.PRS.0000056839.94034.47. PMID 12711969. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0032-1052&volume=111&issue=6&spage=2032. 
3. ^ ^{a b c d} Kabbani H; Raghuveer TS (2004-06-15). "Craniosynostosis". American Family Physician 69 (12): 2863–70. PMID 15222651. http://www.aafp.org/afp/20040615/2863.html. 
4. ^ Liu Y, Kadlub N, da Silva Freitas R, Persing JA, Duncan C, Shin JH (January 2008). "The misdiagnosis of craniosynostosis as deformational plagiocephaly". J Craniofac Surg 19 (1): 132–6. doi:10.1097/SCS.0b013e3181655314. PMID 18216678. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00001665-200801000-00022. 
5. ^ Stenirri S, Restagno G, Ferrero GB, et al. (October 2007). "Integrated strategy for fast and automated molecular characterization of genes involved in craniosynostosis". Clin. Chem. 53 (10): 1767–74. doi:10.1373/clinchem.2007.089292. PMID 17693524. http://www.clinchem.org/cgi/pmidlookup?view=long&pmid=17693524. 
6. ^ Gracia A, Arsuaga JL, Martínez I, Lorenzo C, Carretero JM, Bermúdez de Castro JM, Carbonell E. (2009). Craniosynostosis in the Middle Pleistocene human Cranium 14 from the Sima de los Huesos, Atapuerca, Spain. Proc Natl Acad Sci U S A. 2106(16):6573-8. PMID 19332773

External links

• Information and support Cranio Kids- Families sharing and supporting
• Information and support Childrens Craniofacial Association

• Overview of craniosynostosis from Children's Hospital Boston
• Craniosynostosis — comprehensive overview (American Family Physician)
• Single Suture Craniosynostoses (The Craniofacial Center in Dallas, Texas)
• Craniosynostosis Photo Gallery at the University of Missouri Children's Hospital
• Information from CAPPS
• Information from Headlines]
• GeneReview/NIH/UW entry on FGFR-Related Craniosynostosis Syndromes

v • d • e Congenital malformations and deformations of musculoskeletal system / musculoskeletal abnormality (Q65-Q76, 754-756.3) Limb/ dysmelia Upper clavicle/shoulder: Cleidocranial dysostosis · Sprengel's deformity · Wallis Zieff Goldblatt syndrome hand deformity: Madelung's deformity · Clinodactyly Lower hip: Dislocation of hip/Hip dysplasia · Upington disease · Coxa valga · Coxa vara knee: Genu valgum · Genu varum foot deformity: Club foot · Flat feet · Pes cavus · Rocker bottom foot Either/both dactyly/digit: Polydactyly/Syndactyly (Webbed toes) · Arachnodactyly · Cenani Lenz syndactylism · Ectrodactyly · Brachydactyly reduction deficits/limb: Acheiropodia · ectromelia (Phocomelia, Amelia, Hemimelia) multiple joints: Arthrogryposis · Larsen syndrome · Rapadilino syndrome Craniofacial Craniosynostosis: Scaphocephaly · Oxycephaly · Trigonocephaly Craniofacial dysostosis: Crouzon syndrome · Hypertelorism · Hallermann-Streiff syndrome · Treacher Collins syndrome other: Macrocephaly · Platybasia · Craniodiaphyseal dysplasia · Dolichocephaly · Greig cephalopolysyndactyly syndrome · Plagiocephaly · Saddle nose Other axial spine: spinal curvature (Scoliosis) · Klippel-Feil syndrome · Spondylolisthesis · Spina bifida occulta ribs: Cervical rib · Bifid rib sternum: Pectus excavatum · Pectus carinatum joint navs: anat, non-congenital arthropathies/deformities/dorsopathies/soft tissue arthropathy/congenital, eponymous signs, proc

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