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Overview
Apert's syndrome, named after the French physician Eugene Apert, who first described the syndrome in 1906, is a condition primarily characterized by craniosynostosis, craniofacial anomalies, and symmetrical syndactyly (cutaneous and bony fusion) of the fingers and toes in varying degrees.
Apert's syndrome is relatively uncommon, it occurs with a frequency of one in every 160,000 to 200,000 live births and accounts for approximately 4.5% of all cases of craniosynostosis (Crouzon's and Apert's syndromes are the most common of the craniosynostosis syndromes). In the United States, its prevalence is estimated to be almost one in every 65,000 live births. There is no sexual predilection for the syndrome but it is more prevalent in certain races with the highest prevalence in Asians and the lowest in Hispanics. The reported incidence of mental retardation in patients with Apert's syndrome is between 20% and 30% while a lower incidence (approx. 10-20%) has been reported with Crouzon's syndrome.
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Causes
Apert's syndrome results from a genetic defect (mutation) that occurs early in pregnancy, it is a rare autosomal dominant disorder that falls under the broad classification of craniofacial/limb anomalies. The condition may be passed on to the offspring of an affected adult with a frequency of approximately 1 in 2 (50%), or may develop as a spontaneous new genetic mutation.
Symptoms
Apert's syndrome is detected early in the newborn period due to the craniosynostosis and associated findings of webbed digits (syndactyly) in the hands and feet. Syndactyly always involves fusion of the soft tissues of the first, middle and ring fingers. The thumb may be fused with the rest or may be free. Bicoronal synostosis, or brachycephaly, is the suture fusion found most often in Apert's (and Crouzon's) syndromes, these children also often have fusion of the sutures of the skull base. The skull is prematurely fused and unable to grow normally; the midface appears retruded or sunken; the orbits are shallow and thus the eyes appear protruded. As synostosis of two or more cranial sutures may be involved, there is a higher risk for increased intracranial pressure.
Physical characteristics of Apert's include:
- Skull: short from back to front, wide on the sides
- Eyes: bulging, eyelids tilt downward abnormally at the sides
- Face: mid-face has a sunken-in appearance, the upper jaw slopes backward, lower teeth project in front of the upper teeth
- Hands and feet: webbing and/or fusion including finger bones, toe bones, and joints of fingers and toes
In addition to the physical characteristics common to Apert's syndrome, other associated abnormalities may include visual disturbances related to an imbalance of the muscles that move the eyes, cardiac anomalies, gastrointestinal malformations, cleft palate, hearing deficits due to recurrent ear infections, and varying degrees of acne. There can be a reduced intellectual capacity in these patients which may be secondary to cerebral cortical atrophy due to intracranial hypertension in some individuals, but many children have normal intelligence. Noisy breathing or sleep apnea may occur due to upper airway compromise that may result from small nasopharyngeal and oropharyngeal dimensions in the Apert craniofacial configuration.
Additionally, children with Apert's syndrome may have unusual speech characteristics. They often have hyponasal resonance due to an under-developed midface, small nose, and excessively long soft palate. If there is a cleft palate, they may also have hypernasal resonance. Articulation of speech sounds is often distorted due to the malocclusion and high arched palate. Impaired hearing or a general developmental delay will also affect speech and language development.
Diagnosis
Radiographic evaluation of the skull and brain may include plain X-rays, computed tomography (CT) scans and magnetic resonance imaging (MRI) to evaluate the craniosynostosis which usually involves the coronal sutures and is associated with a hypoplastic maxilla and shallow orbits. CT scan with three-dimensional reconstruction of the calvarium and cranial base allows precise identification of the pathological anatomy of the skull and helps determine the specific operative plan. MRI does not accurately depict the bony anatomy, but its main importance lies in demonstrating the anatomy of the soft-tissue structures and the brain.
Other radiographic investigations may be performed on the hands and feet to evaluate for cutaneous and osseous syndactyly and on the limbs and spine to detect any subtle associated congental abnormalities. In addition, further methods of evaluation may include psychometric evaluation, hearing and visual assessment, psychological counseling, and genetic counseling.
Treatment
The treatment plan should involve a multidisciplinary teamwork and multi-staged surgery based on the identification of the child's individual needs. The best time for release of the fused sutures is between three and six months of age. This early surgery allows the child's brain to have plenty of room to grow.
Besides release of the prematurely fused sutures, the traditional surgery involves repositioning (usually advancing) the frontal bones, correcting the bulging eyes and upper facial deformities including the "retrusion" or hypoplasia of the midface.
Depending on the severity of Apert's syndrome and the associated congenital abnormalities, other operations such as rhinoplasty - plastic surgery of the nose, genioplasty - plastic surgery of the chin, eye muscle surgery to correct strabismus or eyelid surgery to correct the abnormal downward tilt, and surgical separation of the fingers and/or toes are performed according to a staged treatment plan.
Prognosis
Early surgery relieves the pressure on the brain and eyes by allowing the bone plates of the skull to be detached from one another. Even in severe cases of Apert's syndrome a significant cosmetic and functional improvement is possible and a decreased risk of optic difficulties or blindness secondary to orbital hypoplasia can be achieved.
Related Links:
Plagiocephaly
Scaphocephaly
Trigonocephaly
Crouzon's Syndrome
Pfeiffer's Syndrome
Craniosynostosis
Articles:
- Mathiasen R, Eby J, Jarrahy R, Shahinian HK, Margulies D: A Dedicated Craniofacial and Skull Base Trauma Team Improves Efficacy and Reduces Cost.
- Katzen JT, Jarrahy R, Eby J, Mathiasen R, Margulies D, Shahinian HK: Craniofacial and Skull Base Trauma.
- Shahinian HK, Jaekle R, Suh R, Jarrahy R, Aguilar V, Soojian M: Obstetrical Factors Governing the Etiopathogenesis of Lambdoid Synostosis.
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