Crouzon’s syndrome, first described in 1912 by Octave Crouzon, a French neurologist, is a genetic disorder that is closely related to Apert’s syndrome. The skull deformity has the same appearance as that of Apert’s but there is no associated syndactyly (cutaneous and bony fusion) of the fingers and toes. Due to their similarity, some authors connect those two syndromes as one, calling it Crouzon-Apert syndrome, but symptomatologic differentiation makes this classification a difficult or an impractical one.
Crouzon’s and Apert’s syndromes are the most common causes of syndromic craniosynostosis. Crouzon’s syndrome occurs in approximately 1 in every 25,000 live births. Race and sex are not noted as predisposing factors for the occurrence of the syndrome.
Although many of the physical deficiencies associated with Apert’s syndrome are not present in Crouzon’s syndrome, both are thought to have similar genetic origins. Crouzon’s syndrome may appear as a fresh mutation (no affected parents) or may be transmitted as an autosomal dominant genetic disorder to the offspring of a Crouzon’s patient.The chance of inheriting the syndrome is 1 in 2 (or 50%).
Premature fusion of both coronal sutures resulting in a brachycephalic head is the most common calvarial deformity in the Crouzon’s syndrome patient. Quite commonly, other sutures such as the sagittal, metopic and lambdoid, are fused in addition to the coronal and basal sutures. Other forms of skull deformity including oxycephaly, scaphocephaly, trigonocephaly as well as cloverleaf skull deformity have also been observed. The appearance of an infant with Crouzon’s syndrome can vary in severity from a mild presentation with subtle midface characteristics to a severe form with multiple cranial suture fusion and marked midface and eye problems.
The characteristic features of Crouzon’s syndrome are ocular proptosis (exophthalmos), maxillary hypoplasia, excessive distance between both eyes (orbital hypertelorism) and a beaked nose resembling a parrot’s beak. Generally, there is retrusion of both the forehead and the eyebrow, with midface hypoplasia and shallow orbits with bulging eyes (proptosis). Other features may include short stature, abnormalities of the spine, a large protruding lower jaw, misalignment of teeth, and high-arched, narrow or cleft palate. The craniofacial deformities are typically more complex and severe in Apert’s syndrome but the proptosis is usually more prominent in Crouzon’s syndrome.
The nasomaxillary retrusion may cause some degree of nasal airway obstruction due to compression of nasal passages, often causing reduced airflow through the nose and mouth breathing. Unusual resonance and speech patterns can develop from either the small nose, the high arched palate, or the mandibular malocclusion.
Other possible abnormalities in severe or untreated cases of Crouzon’s syndrome include visual disturbances related to an imbalance of the muscles that move the eyes, or progressive optic nerve atrophy in cases of associated intracranial hypertension Exposure keratitis may result from severe ocular proptosis which is typically present in Crouzon’s syndrome and conductive hearing loss may also occur due to repeated middle ear infections.
The mental capacity of Crouzon’s syndrome patients is usually within the normal range, however, in some cases mental developmental delay has been reported. Additionally, in Crouzon’s and Apert’s syndromes synostosis of two or more cranial sutures may be involved, therefore, there is a greater risk for increased intracranial pressure and hydrocephalus.
The condition is usually apparent at birth and, like in Apert’s syndrome, physical examination is usually sufficient to diagnose Crouzon’s syndrome. Plain X-rays, CT scans, 3-dimensional CT scans, and MRI are all helpful in the assessment.
Other tests and methods of evaluation of the Crouzon’s syndrome patient including ophthalmologic and psychological assessment are usually required. Laryngologic, audiologic and speech evaluations are also usually important to monitor speech and language development. Imaging studies of the spine, hands and other body organs are usually necessary to confirm the diagnosis of Crouzon’s syndrome and to detect any associated subtle congenital abnormalities.
As with Apert’s syndrome, treatment is by a multidisciplinary team working in collaboration. A staged treatment plan depending on the severity of the skull deformity and the child’s individual needs is typically required. In the newborn period, surgical release of the synostotic sutures is always prioritized to allow for adequate brain growth and expansion.
Some other potential problems that may need to be addressed in Crouzon’s syndrome patient include respiratory difficulties, feeding problems, neurologic complications such as hydrocephalus, and the potential risk of developmental delay.
Children with Crouzon’s syndrome generally have normal intelligence although occasionally, some reduced intellectual capacity can be seen and in this case referral to an infant stimulation program is included as part of the treatment plan. Early surgery and a proper treatment plan can yield better functional and cosmetic outcomes.
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