View source for Crouzon syndrome

{{Infobox_Disease |
  Name           = {{PAGENAME}} |
  Image          = Tomhead0607.jpg|
  Caption        = An adult with Crouzon syndrome.|
  DiseasesDB     = 3203 |
  ICD10          = {{ICD10|Q|75|1|q|65}} |
  ICD9           = {{ICD9|756.0}} |
  ICDO           = |
  OMIM           = 123500 |
  MedlinePlus    = |
  eMedicineSubj  = ped |
  eMedicineTopic = 511 |
  eMedicine_mult = {{eMedicine2|derm|734}} | 
  MeshID         = D003394 |
}}
{{SI}}
{{CMG}}



'''Crouzon syndrome''' is a genetic disorder known as a [[branchial arch]] syndrome.  Specifically, this syndrome affects the [[first branchial arch|first branchial]] (or pharyngeal) arch, which is the precursor of the [[maxilla]] and [[mandible]]. Since the branchial arches are important developmental features in a growing [[embryo]], disturbances in their development create lasting and widespread effects.

This syndrome is named after [[Octave Crouzon]], a French [[physician]] who first described this disorder. He noted the affected patients were a mother and her daughter, implying a genetic basis.  First called "craniofacial dysostosis", the disorder was characterized by a number of clinical features; as of 2007, the disorder has no known single, initiating defect to account for all of its characteristics.

Breaking down the name, "[[craniofacial]]" refers to the [[skull]] and [[face]], and "dysostosis" refers to [[synostosis]] (a union between adjacent bones or parts of a single bone).

Now known as Crouzon Syndrome, the [[disease]] can be described by the rudimentary meanings of its former name. What occurs in the disease is that an infant's skull and facial bones, while in development, fuse early or are unable to expand. Thus, normal bone growth cannot occur.  Fusion of different sutures leads to different patterns of growth of the skull.  Examples include: [[trigonocephaly]] (fusion of the [[metopic suture]]), [[brachycephaly]] (fusion of the coronal suture), [[dolichocephaly]] (fusion of the [[sagittal suture]]), [[plagiocephaly]] (unilateral premature closure of [[lambdoid]] and [[coronal suture]]s), [[oxycephaly]] (fusion of [[coronal suture|coronal]] and [[lambdoidal suture]]s), Kleeblattschaedel ( premature closure of all sutures).

==Symptoms==

As a very complicating result of the changes to the developing embryo, the symptoms are very pronounced features, especially in the facial areas. Low-set ears is a typical characteristic, as in all of the disorders which are called branchial arch syndromes. The reason for this abnormality is that ears on a fetus are much lower than those on an adult. During normal development, the ears "travel" upward on the head; however, in Crouzon patients, this pattern of development is disrupted.  Ear canal malformations are extremely common, generally resulting in some hearing loss.  In particularly severe cases, [[Ménière's disease]] may occur.

The most notable characteristic of Crouzon Syndrome is cranial synostosis, as described above, but it usually presents as brachycephaly, which results in the appearance of a short and broad head. [[Exophthalmos]] (bulging [[eye]]s due to shallow eye sockets after early fusion of surrounding bones), [[hypertelorism]] (greater than normal distance between the eyes), and psittichorhina (beak-like nose) are also symptoms.  Additionally, a common occurrence is external [[strabismus]], which can be thought of as opposite from the eye position found in [[Down Syndrome]].  Lastly, hypoplastic maxilla (insufficient growth of the midface) results in relative [[mandibular prognathism]] (chin appears to protrude despite normal growth of mandible) and gives the effect of the patient having a concave face.

For reasons that are not entirely clear, most Crouzon patients also have noticeably shorter [[humerus]] and [[femur]] bones, in proportion to the rest of their bodies, than members of the general population.  A small percentage of Crouzon patients also have what is called "Type II" Crouzon Syndrome, distinguished by partial [[syndactyly]].

==Diagnosis==
Diagnosis of Crouzon Syndrome usually can occur at birth by assessing the signs and symptoms of the baby. Further analysis, including radiographs, [[magnetic resonance imaging]] (MRI) scans, genetic testing, X-rays and CT scans can be used to confirm the diagnosis of Crouzon syndrome.

==Incidence==
Incidence of Crouzon Syndrome is currently estimated to occur in 1 out of every 25,000 people out of the general population. Naturally, there is a greater frequency in families with a history of the disorder, but that doesn't mean that everyone in the family is affected (as referred to above).

==Treatment==
[[Image:Cranialband.jpg|thumb|left|200px|A child with Crouzon Syndrome wearing a corrective cranial band.]]

[[Craniofacial surgery|Surgery]] is typically used to prevent the closure of sutures of the skull from damaging the brain's development. Without surgery, blindness and mental retardation are typical outcomes.  To treat the cosmetic troubles, a combination of [[orthodontics|orthodontic]] and orthognathic surgery can be used to relieve some of the midface deficiency. In addition, many patients wear a custom-fitted helmet (or cranial band) for several months after surgery.

Once treated for the cranial vault symptoms, Crouzon patients generally go on to live a normal lifespan.

==Dental significance==
For [[dentist]]s, this disorder is very important to understand since most of the physical abnormalities are presented in the head, and particularly the oral cavity.  Common features are a narrow/high-arched palate, posterior bilateral crossbite, [[hypodontia]] (missing some teeth), and increased spacing between [[tooth|teeth]].  Due to maxillary hypoplasia, Crouzon patients generally have a considerable permanent [[underbite]] and subsequently cannot chew using their incisors.  For this reason, Crouzon patients sometimes eat in an unusual way--eating fried chicken with a fork, for example, or breaking off pieces of a sandwich rather than taking a bite out of it.

== See also ==
* [[Apert syndrome]]
* [[Hearing loss with craniofacial syndromes]]

==External links==
*[http://www.crouzonsupport.org/faq.html Crouzon Syndrome: Frequently Asked Questions] - AboutFace
*[http://rarediseases.about.com/cs/crouzonsyndrome/a/011804.htm Crouzon Syndrome] - About.com
*[http://craniofacial.seattlechildrens.org/conditions_treated/crouzon.asp Crouzon Syndrome] - Seattle Children's Hospital Craniofacial Center
*[http://www.cleftadvocate.org cleftAdvocate] - Non-profit support organization for all craniofacial conditions; on-line and in-person family support, insurance and advocacy assistance, and more.
*[http://www.crouzonsupport.org Crouzon Support Network] - Information, on-line and in-person family support and more.
*[http://www.hopkinsmedicine.org/craniofacial/Education/Article.cfm?ArticleID=65&Source=Physician General Information] at hopkinsmedicine.org


{{Congenital malformations and deformations of musculoskeletal system}}

[[Category:Dental disorders]]
[[Category:Oral and maxillofacial surgery]]
[[Category:Genetic disorders]]
[[Category:Syndromes]]

[[cs:Crouzonův syndrom]]
[[de:Crouzon-Syndrom]]
[[fr:Syndrome de Crouzon]]
[[ko:크루존 증후군]]
[[nl:Syndroom van Crouzon]]
[[pl:Zespół Crouzona]]
[[pt:Síndrome de Crouzon]]

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