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Crouzon Syndrome

What is Crouzon syndrome?

Crouzon syndrome is a genetic condition with features of craniosynostosis (the early closure of skull sutures) and abnormal development of the eye sockets and midface.

These conditions occur when there is abnormal fusion between some of the bones of the skull and of the face that does not allow the bones to grow normally, affecting the shape of the head, the appearance of the face and the relationship of the teeth.

The features of Crouzon syndrome were first described by the French neurosurgeon Dr. O. Crouzon in 1912.

Crouzon syndrome differs from most other craniosynostosis syndromes because it does not involve abnormalities of the hands and feet.

However, cervical spine abnormalities are fairly common, and a smaller percentage of patients may have subtle elbow, hand, musculoskeletal or internal organ anomalies.

How much experience do you have treating Crouzon syndrome?

Our craniofacial team has significant experience in treating children with Crouzon syndrome. Right now we are treating 23 children.

Each year we have at least two new children come to our Center for treatment for the first time. Each year we perform an average of 13 surgeries for this condition.

Who gets Crouzon syndrome?

Crouzon syndrome is a rare genetic disorder estimated to occur in 1.6 per 100,000 people. About 4.5% of people with craniosynostosis have Crouzon syndrome.

Craniosynostosis in Crouzon syndrome can occur prior to birth or during the first two or three years of life.

Late onset (5 to 10 years old) craniosynostosis has been reported in several children with Crouzon syndrome who suffer from headaches and vision changes with a relatively normal head shape.

Other neurological problems include an increased risk to develop hydrocephalus (excess fluid on the brain) (30%) or Chiari malformation (abnormality of the back of the brain).

About 97% of people with Crouzon syndrome have normal intelligence.

Crouzon syndrome is caused by a genetic change or mutation in one of the fibroblast growth factor receptor (FGFR) genes — FGFR2 on chromosome 10 and FGFR3 on chromosome 4.

Some people inherit the Crouzon syndrome gene mutation from a parent. Crouzon syndrome is an autosomal dominant condition, meaning there is an abnormal gene in one of the first 22 non-sex chromosomes from either parent.

Only one parent needs to have an abnormal gene for the child to inherit the disease. A person with Crouzon syndrome has a 50% chance for each pregnancy of passing this mutation on to the child.

For other people, no one else in the family has a diagnosis of Crouzon syndrome and the condition occurred because of a spontaneous change in one of the genes that cause Crouzon syndrome.

Genetic testing

For parents of a child diagnosed with Crouzon syndrome, a careful family history and genetic evaluation is recommended to provide recurrence risk information.

Genetic testing for mutations in the Crouzon syndrome genes is available.

More than 50% of people with the clinical diagnosis of Crouzon syndrome without acanthosis nigricans have an FGFR2 gene mutation detectable by commercial laboratories.

(Acanthosis nigricans is a skin abnormality that involves the development of patches of darker pigmented (colored), thickened (velvety feeling) skin on the neck and eyelids and around the mouth.)

All people with Crouzon syndrome linked with acanthosis nigricans have a specific mutation (A391E) in the FGFR3 gene. Genetic counseling before testing is recommended.

What does a baby with Crouzon syndrome look like?

The facial features of babies with Crouzon syndrome vary widely.

Some babies with Crouzon syndrome are born with an abnormal head shape (tall and narrow from front to back), wide-set prominent eyes (due to shallow eye sockets), small beak-like nose and small midface.

Some babies with Crouzon syndrome develop craniosynostosis (the early closing of one or more of the sutures that separate the bony plates of the skull) after birth so that the head shape changes over time.

The eye findings are usually apparent at birth. The eye sockets are positioned further apart and are shallow, so the eyes appear to protrude. The eyes may not align properly so the gaze is outward.

Jaw

Slower growth of midface bones results in a progressive difference between the upper and lower jaw. Over time the upper jaw appears smaller and the lower jaw appears to jut outward.

The palate (roof of the mouth) may be very tall and narrow such that the teeth of the upper jaw are crowded and positioned behind the lower jaw during chewing. Rarely there is a cleft palate (gap in the roof of the mouth).

The nose is small and beak-like.

If there is difficulty in breathing the infant may require placement of a surgical tracheostomy (breathing tube in the windpipe).

Hearing

Conductive (bone) hearing impairment is noted in about 55% of people with Crouzon syndrome, with some infants born with a complete absence of ear canals.

Children with Crouzon syndrome may need to wear hearing aids for hearing loss.

Joints

People with Crouzon syndrome do not have the abnormalities of the hands and feet noted in other craniosynostosis syndromes, though sometimes they will have restricted elbow movement.

Cervical spine (neck) abnormalities have been noted in 30% of people with Crouzon syndrome.

Skin

Some people with Crouzon syndrome develop a skin abnormality called acanthosis nigricans.

This involves the development of patches of darker pigmented (colored), thickened (velvety feeling) skin on the neck and eyelids and around the mouth.

The abnormal facial features of a child with Crouzon syndrome typically become more apparent with growth.

How is Crouzon syndrome treated?

CT Scan

Infants and children should be checked for possible craniosynostosis with computed tomography imaging.

A CT scan is an X-ray procedure that takes a computer-enhanced cross-sectional view of the body. The timing and recommendations for cranial vault expansion and reshaping (surgery to remove the closed sutures and expand and reshape the skull) is based upon the type and number of closed sutures.

Infants with multiple-suture synostosis resulting in a severe skull deformity may require cranioplasty surgery early in the first year of life.

Most times, 10 to 20% of children with early cranial vault expansion will require a second cranioplasty.

Eyes

Children with Crouzon syndrome have an abnormal position and shape of their eye sockets.

They are at risk for visual impairment for several reasons including the misalignment of the eyes and increased intracranial pressure.

Children should visit an ophthalmologist on a regular basis for these concerns. Early orbital advancement may be needed for children with extremely shallow orbits resulting in incomplete eyelid closure and risk of keratitis (corneal irritation).

Brain

Because craniosynostosis can occur with normal head shape and symptoms of increased intracranial pressure in older children, evaluation of severe recurrent headaches is warranted.

Some people with Crouzon syndrome do not develop craniosynostosis or symptoms requiring cranial surgery.

Infants and children with Crouzon syndrome should be checked for signs and symptoms of hydrocephalus (excess fluid in the brain). Symptoms in infants include bulging anterior fontanelle (soft spot), irritability (feeling cranky) or lethargy (feeling sluggish) and rapidly increasing head size.

In older children, symptoms include headaches (worse in the morning), vomiting, vision impairment and declining school performance.

Some infants and children with hydrocephalus will require surgery to place a ventriculoperitoneal shunt (tube draining excess fluid from areas surrounding the brain to the abdomen).

Some children with Crouzon syndrome have a Chiari malformation (abnormality in the back of the brain) because of an abnormal shape of the base of the skull.

Sometimes the brain is compressed by the base of the skull, resulting in headaches or other neurological symptoms. Surgery to widen the base of the skull is performed on a subset of children with this disorder.

Hearing

Some children with Crouzon syndrome have conductive (bone) hearing loss or abnormalities of the ear canal. An initial hearing check and periodic follow-up is recommended.

Speech difficulties can occur as a result of hearing difficulties, the abnormally high arched palate or the small nasal cavity. If needed, a team speech pathologist will recommend speech therapy.

Breathing

Infants with Crouzon syndrome may have difficulty breathing through their nose. This can represent a major problem as babies can only breathe through their nose.

Some infants with Crouzon syndrome who have severe breathing difficulty will require placement of a surgical tracheostomy (a breathing tube in the windpipe).

Older children with Crouzon syndrome may develop sleep apnea symptoms or snoring when the combination of the small nose and poor midface growth result in a too-small airway.

A midface advancement, or LeFort III osteotomy (surgery to move the middle portion of the face forward), to align the upper and lower jaw and create a larger airway is considered in childhood.

The timing of midface advancement is a team decision based on age, degree of jaw misalignment (chewing and speech difficulties) and symptoms of obstructive sleep apnea (based on an overnight sleep study).

Midface advancements may need to be repeated because the lower jaw will continue to grow, eventually passing the upper jaw again.

Midface advancements can be done with a single surgery or over a period of several months through distraction osteogenesis, a technique that uses a device to pull the midface slowly forward after surgery and move it further forward than a single surgery can.

Other surgical options for children with sleep apnea include adenoidectomy, a procedure to remove adenoids or lymphoid tissue in the back of the nose, or tracheostomy.

Teeth

All children with Crouzon syndrome are seen on a regular basis by a team orthodontist due to crowding of the teeth and jaw misalignment.

Because of the small upper jaw, some upper teeth may need to be extracted to relieve crowding as the child develops.

Placement of orthodontic braces to expand the palate and align the teeth is coordinated as needed with jaw surgery. To provide a normal bite, final jaw surgery and braces must often wait until after facial growth is finished.