According to history findings [8]:

• A bony face deformity is seen at birth. This is followed later on by other factors of the syndrome.
• The patients often report headache.
• Mental retardation is observed in many patients.
• Convulsions also occur.

The physical findings show the following:

• Fontanels stay unobliterated and pulsating for a long time while coronal and sagittal sutures are obliterated.
• Anteroposterior and lateral flattening of the acrocranium is observed with growth only along the vertical axis.
• The transverse diameter is bigger than the anteroposterior diameter.
• The forehead is often high and wide.
• There is the presence of hypoplastic maxilla producing pseudoprognathism and a wide face.
• Narrowed or obliterated anterior nares and deviation of the nasal septum is present.
• Hypertelorism, falling upper eyelid and divergent squint is also observed.
• The upper lip is often shortened and cleaved in some cases.
• Due to intracranial hypertension, vision impairment occurs due to progressive optic nerve atrophy.
• Disorders of the middle ear brings about impaired hearing.
• Dysphasia, rhinolalia, hypsistaphylia (narrow/high-arched palate), malposed teeth and malocclusion are noted in many cases.
• Characteropathy is a common observation.
• Koilosternia occurs rarely.
• Skin of the individual is darker than normal.
• In childhood, syndromic acanthosis nigricans appears in axillary fossa, on the lips and mouth angular.

• Developmental Delay

  The mental capacity of Crouzon's syndrome patients is usually within the normal range, however, in some cases mental developmental delay has been reported. [skullbaseinstitute.com]

  Type 2 Pfeiffer syndrome is generally associated with the classic “cloverleaf skull,” extreme proptosis, finger and toe abnormalities, elbow ankylosis or synostosis, developmental delay and neurological complications. [entokey.com]

  Most children with Crouzon syndrome have normal developmental and intelligence. However, children who undergo multiple anesthetics and surgical procedures might be at greater risks for potential developmental delays. [thecraniofacialcenter.com]

  Lower amplification efficiencies were obtained from the developmentally delayed embryos. One cell each was biopsied from eight embryos. Of these, amplification of both fragments was observed in three out of eight cells. [academic.oup.com]

• Epilepsy

  Family history of epilepsy is negative. Patient presented with epilepsy at the age of 18. [bib.irb.hr]

  Sleep-related hypermotor epilepsy in a patient with mild Crouzon syndrome. [link.springer.com]

  Central nervous system manifestations include hydrocephalus, headache, epilepsy, dizziness, bilateral jugular foraminal stenosis and conductive hearing impairment. [pubs.sciepub.com]

• Cough

  This ring is C-shaped so that when we cough or breath deeply, it can expand. In Crouzon syndrome sometimes these rings may not open normally, or can be O-shaped (they start out as a “C,” and then close up to form an “O”). [thecraniofacialcenter.com]

  Arnold Chiari malformation Type I is generally asymptomatic during childhood and often manifests itself with headaches which are often aggravated by valsalva maneuvers such as yawning, laying, crying, coughing or sneezing. [omicsonline.org]

• Thrombosis

  This is the first reported case of symptomatic venous thrombosis post-Le Fort III osteotomy and rigid external distraction. Although rare, surgeons should be aware of this potential complication. [ncbi.nlm.nih.gov]

• Hand Deformity

  Associations Chiari I malformations 3: may be present in ~70% of cases hydrocephalus stylohyoid ligament calcification: may be present in ~50% of patients over 4 years old 3 cervical spine abnormalities cervical spine fusion elbow malformations hand deformities [radiopaedia.org]

• Hearing Impairment

  A 24-year-old woman visited our department for evaluation of persistent hearing impairment and absence of an external auditory canal from birth. [ncbi.nlm.nih.gov]

  Hearing impairment may occur. The syndrome varies in severity from mild to very serious. [mun-h-center.se]

  The child's pediatrician and psychologist had diagnosed her with Crouzon's syndrome, and bilateral profound speech and hearing impairment with borderline intelligence (75 IQ). [jorr.org]

  impairment Breathing problems Diagnosis Diagnosis of Crouzon syndrome requires a combination of measures. [ana-neurosurgery.com]

  The condition may also affect internal structures, which causes varying degrees of hearing impairment. In 5 to 10 percent of the cases, children also have dark, roughened folds of skin located in the armpits or groin. [craniofacial.net]

• Strabismus

  Optokinetic nystagmus is reduced in CS without strabismus owing to binocular position disparities and in CS with strabismus is likely due to cortical suppression associated with cross-axis orientation and exotropia. [ncbi.nlm.nih.gov]

• Blue Sclera

  Other associations are aniridia, blue sclera, cataract, coloboma, ectopia lentis and optic nerve hypoplasia. No medical treatment exists for craniosynostosis. [casereports.bmj.com]

  Ophthalmic Anti- Mongoloid Slant, Shallow Orbits, Proptosis, Exotropia, Hypertelorism Keratoconus, Ectopic Lens, Glaucoma, Staphyloma Exophthalmos, Spontaneous luxation, ‘v’ Exotropia Hypertelorism, Nystagmus, Corneal malformation, Cataract, Aniridia, Blue [bhj.org.in]

  There also have been rare occurances of nystagmus, iris coloboma, aniridia, anisocoria, microcornea, megalocornea, cataract, ectopia lentis, blue sclera, glaucoma and luxation of the eye ( Bowling and Burstein, 2006 ). [scialert.net]

  There rarely may occur nystagmus, coloboma of the iris, anisocoria, microcornea or megalocornea, cataract, blue sclerae, glaucoma and globe luxation (6). [arquivosdeorl.org.br]

• Headache

  A 25-year-old man with Crouzon syndrome complicated by pseudotumor cerebri and multiple shunt failures presented with progressive back and neck pain, intermittent headaches, and associated vomiting secondary to shunt infection. [ncbi.nlm.nih.gov]

  The boy also complained of recurrent headaches and transient visual obscurations. The patient did not have any digital abnormalities or hearing deficit. [scialert.net]

• Nystagmus

  Optokinetic nystagmus gains were reduced in both CS groups (P < 0.02) but were lower in subjects with strabismus. [ncbi.nlm.nih.gov]

  […] lateral ventricles, Ballooning of Fronto-Parietal bones Ophthalmic Anti- Mongoloid Slant, Shallow Orbits, Proptosis, Exotropia, Hypertelorism Keratoconus, Ectopic Lens, Glaucoma, Staphyloma Exophthalmos, Spontaneous luxation, ‘v’ Exotropia Hypertelorism, Nystagmus [bhj.org.in]

  There also have been rare occurances of nystagmus, iris coloboma, aniridia, anisocoria, microcornea, megalocornea, cataract, ectopia lentis, blue sclera, glaucoma and luxation of the eye ( Bowling and Burstein, 2006 ). [scialert.net]

  Figure 1: Crouzon syndrome showing bilateral proptosis and convergent squint Click here to view Hypertelorism, pendular nystagmus, and convergent squint were noted. Lagophthalmos was present in her right eye [Figure 2]. [mjdrdypu.org]

• Papilledema

  We present a case of a 5-year-old girl with Crouzon syndrome displaying classic facial abnormalities along with proptosis and papilledema. The child's condition was improved dramatically after a monoblock advancement procedure. [ncbi.nlm.nih.gov]

  On fundus examination, chronic papilledema features were present. Other systems examination was normal On radiological examination, skull X- ray revealed an abnormal skull shape with hypoplasia of the maxilla and zygoma. [pubs.sciepub.com]

  Correlation between Papilledema and Intracranial Hypertension in Crouzon Syndrome: A Case Report and Review of the Literature. Pediatr Neurosurg. 2019 Jul 3. 1-5. [Medline]. Posnick JC, Ruiz RL. [emedicine.medscape.com]

• Delayed Milestone

  The child had a history of delayed milestones and was of short stature. The parents gave a history suggestive of obstructive sleep apnea. The child had undergone adenotonsillectomy 1 year back at a peripheral center. [aeronline.org]

• Stroke

  Case of Ferumoxytol (Feraheme®) Prompting Critical Modification to Our Patient Prebreast Magnetic Resonance Imaging Questionnaire Naziya Samreen, Asha A Bhatt, James Glockner, Christine U Lee J Clin Imaging Sci 9 (6) 1-3 (28 March 2019) Case report: Stroke [clinicalimagingscience.org]

Histopathologic examination of changes in the skin will often reveal acanthosis nigricans [9]. To confirm the diagnosis, hand, spine and skull radiography is often required. The skull radiography will reveal the following:

• Underdeveloped lateral nasal sinuses
• Shortened anterior cranial fossa
• Presence of Turkish saddle which is deepened with osseous sternum which connects the anterior and posterior clinoid processes.
• Shallow eye sockets (exophthalmous) and deep digitate impression.
• Obliterated sutures (usually the sagittal and coronal) and Oxycephaly-Acrocranium

On radiography of the spine, lumbarization and the presence of bifid spinous process is seen. Some cases show signs of achondroplasia too. Achondroplasia is also established by looking through a radiographic examination of the metacarpal bones and fingers.

Other tests can also be carried out to further confirm diagnosis. These tests include:

• Psychiatric examinations and psychological testing
• Stomatologic examination
• Laryngologic examinations with audiography
• Ophthalmologic examination with ophthalmoscopy
• Genetic testing
• General physical examination with ECG
• EEG - Low-voltage, increased convulsive excitability

Histologic findings

Papillomatosis, acanthosis and hyperkeratosis are all histologic features of acanthosis nigricans. The amount of pigment cells is also increased in the upper dermis of the basal layer. There is no difference between the histologic features of acanthosis nigricans in its symptomatic, benign or malignant forms.

Surgical interventions are aimed to preventing complications and correcting the craniofacial dysmorphy which can be of great benefit.

Individuals with the crouzon syndrome can expect to live a normal life with any life expectancy reductions.

An ophthalmologist is expected to monitor the cornea of the eye to ensure it isn’t allowed to dry out. Any dental problems can be treated successfully [10].

The Crouzon syndrome is often inherited in an autosomal pattern. Associations with mutations in the genes FGFR2 and FGFR3 have been identified in many cases [5].

Dental significance

This disorder is of interest to dentists because many of the abnormalities recorded physically are present in the head and mostly the oral cavity. The common features are crowding of teeth, hypodontia (missing some teeth), posterior lateral crossbite and narrow/high-arched palate.

Crouzon patients have permanent underbite and thus they will not be able to chew using their incisors. The permanent underbite is as a result of maxillary hypoplasia. It is for this reason that many Crouzon patients have to eat in a way that can be deemed as unusual. Breaking off pieces of sandwich instead of taking a bite into it and eating fried chicken with a fork are some of these unusual eating habits [6].

The prevalence of this condition is very low as Crouzon syndrome is very rare across the world. It is currently estimated that it occurs in 1 out of 25,000 individuals in the general population across the world [4].

Mortality/morbidity

When there is high intracranial pressure, death may occur. High intracranial pressure is brought about by disproportion between brain growth and craniostenosis.

Race

There is no difference recorded between races.

Sex

Sex does not play any role in the distribution of this condition.

Age

The deformation of bony face is readily visible just at birth and other factors linked to this syndrome become visible with time.

All dysplasias of the skeleton which includes craniofacial dysostosis are caused by the malformations of the ectoderm and mesenchyme. This is also taking into account the unknown teratogenic factors.

Dyspalsias are inherited in an autosomal dominant pattern. The condition is believed to stem from the mutation of the gene for fibroblast growth factor receptor 2 (FGFR2) [7]. However, mutation in the transmembrane region of the FGFR3 has been detected as a possible cause of this syndrome. It has been observed in cases where acanthosis nigricans was exisiting alongside the condition.

There are no guidelines for prevention of Crouzon syndrome.

Also known as branchial arch syndrome, Crouzon syndrome is a genetic disorder which specifically targets the first pharyngeal (branchial) arch [1]. This arch is the precursor of the maxilla and mandible.

Disturbances in the development of the arch often have lasting and widespread effect because the branchial arches are very important developmental features in a growing embryo.

Crouzon syndrome was first discovered in 1912 as one of the types of craniofacial dysotosis. The dysostosis is brought about by premature obliteration and subsequent ossification of two sutures or more. The sutures mostly affected are the sagittal and coronal. The term craniostenosis was introduced by Virchow [2]. The type of craniostenosis is determined by the type of obliterated sutures. The differentiations are, oblique head, wedge skull, scaphocephaly, and oxycephaly. The most common occurences of dysostosis involve Crouzon syndrome with Oxycephaly and Apert Syndrome with oxycephaly.

The syndrome is named after a French physician Octave Crouzon who was the first to describe this disorder. According to him, there affected patients were a mother and daughter and this implied genetic bias. It was first called craniofocal dysostosis and it is a disorder that was characterised by numerous clinical features. The syndrome occurs where there is a mutation in the fibroblast growth factor receptor II which is located on chromosome 10 [3].

To further break down the name, “dysostosis” refers to malformation of the bone while “craniofocal” refers to the skull and face.

Patients with Crouzon syndrome are expected to have regular appointments with an Ophthalmologist and a neurologist.

1. Reardon W, Winter RM, Rutland P, Pulleyn LJ, Jones BM, Malcolm S (September 1994). "Mutations in the fibroblast growth factor receptor 2 gene cause Crouzon syndrome". Nat. Genet. 8 (1): 98–103.
2. Rutland P, Pulleyn LJ, Reardon W, et al. Identical mutations in the FGFR2 gene cause both Pfeiffer and Crouzon syndrome phenotypes. Nat Genet 1995; 9:173.
3. Reardon W, Winter RM, Rutland P, et al. Mutations in the fibroblast growth factor receptor 2 gene cause Crouzon syndrome. Nat Genet 1994; 8:98.
4. Park WJ, Meyers GA, Li X, et al. Novel FGFR2 mutations in Crouzon and Jackson-Weiss syndromes show allelic heterogeneity and phenotypic variability. Hum Mol Genet 1995; 4:1229.
5. Vajo Z, Francomano CA, Wilkin DJ. (February 2000). "The molecular and genetic basis of fibroblast growth factor receptor 3 disorders: the achondroplasia family of skeletal dysplasias, Muenke craniosynostosis, and Crouzon syndrome with acanthosis nigricans". Endocrine Reviews 21 (1): 23–39.
6. L. E. O. Crouzon. Dysostose cranio-faciale héréditaire. Bulletin de la Société des Médecins des Hôpitaux de Paris, 1912, 33: 545-555.
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8. Maeda T, Hatakenaka M, Muta H, Nakayama M, Nakazaki Y, Hiroyama T, et al. Clinically mild, atypical, and aged craniofacial syndrome is diagnosed as Crouzon syndrome by identification of a point mutation in the fibroblast growth factor receptor 2 gene (FGFR2). Intern Med. May 2004;43(5):432-5.
9. Miklaszewska M. Dysostosis cranio-facialis hederitaria. In: Miklaszewska M, Wasik F, eds. Dermatologia Pediatryczna. Vol 2. Wrocaw, Poland: Volumed; 2000:650-4.
10. Miklaszewska M, Racawska A, Ziarkiewicz M. Syndroma Crouzon and syndromal acanthosis nigricans. Demonstration of case on the meeting of Polish Dermatological Society; February 1990.