Crouzon syndrome is the most common of the craniosynostosis syndromes. It occurs in one of every 25,000 births. The signs of Crouzon syndrome include:
- Wide-set, bulging eyes caused by shallow eye sockets
- Eyes that do not point in the same direction (strabismus)
- A short nose
- An underdeveloped upper jaw causing a flat appearance of the middle portion of the face
- Open bite
The severity of these signs and symptoms varies among affected people. Babies born with Crouzon syndrome are usually of normal intelligence.
Crouzon syndrome is caused by inheriting a gene. Mutations in the FGFR2 gene cause Crouzon syndrome. This is an autosomal dominant syndrome. That means that roughly half of the children of a couple one parent without Crouzon and one parent with Crouzon syndrome can be expected to inherit the syndrome. The parent of a child with Crouzon syndrome may have a milder form of the syndrome and be unaware that they have it.
Babies with Crouzon syndrome usually have craniosynostosis that affects the two coronal sutures. Often, all of the sutures will eventually close prematurely. The usual head shape is short from front to back, tall and wide. Sometimes the eyes may be so prominent as to make it difficult for the eyelids to close fully, and problems with dry eyes can occur. When severe, this can require an operation to help the eyelids close to protect the child’s vision.
The middle portion of the face is flat and the upper jaw is short both vertically and front-to-back, which results in problems with alignment of the upper and lower teeth. The palate is also very narrow. The underdeveloped middle part of the face can result in symptoms of sleep apnea.
Patients with Crouzon syndrome do not have any deformities of the hands or feet. Having normal hands and feet can be used to differentiate these patients from those with Pfeiffer and Apert syndrome, however gentic testing is the standard for diagnosis today.
Patients with Crouzon syndrome are at a high risk for hydrocephalus. This is a build up of the cerebrospinal fluid (CSF) that the brain is surrounded by. This can cause very high pressure in the skull that requires drainage o the CSF using a shunt to protect the health of the brain. These patients are also at a high risk for developing Chiari malformation. This affects the back part of the brain (cerebellum), which is important for balance and coordination. A Chiari malformation is when part of the cerebellum pushes into the opening in the base of the skull where the spinal cord meets the brain (foramen magnum). This can cause a back-up of CSF and increase the blood pressure in the veins draining blood from the brain. Both of these can create high pressure that can harm the brain.
Children with Crouzon syndrome will require an average of 2-3 surgeries on the skull to achieve a normal head shape to treat or prevent increased pressure in the skull. As infants these patients require an operation to reshape and expand the back of the skull with distraction osteogenesis. Later in childhood a fronto-orbital advancement to reshape the forehead and upper portion of the eye sockets is performed. Occasionally the fronto-orbital advancement must be repeated when fully grown. Between ages 5-8 years of age a repositioning of the middle portion of the face forward using distraction osteogenesis is performed to restore normal contour to the middle portion of the face and align the upper and lower jaws. These patients frequently require a surgery once fully grown (in their mid-to-late teens) to align the upper and lower jaws.