Apert Syndrome
(acrocephalosyndactyly)
Last Updated: September 4, 2007
1. What Is Apert Syndrome?
Apert syndrome is a genetic disorder involving premature fusion of the bones of the skull. Normally, the junctions between the bones (called “cranial sutures”) are able to move slightly, enabling the skull to flex and grow. If they fuse prematurely during fetal development, the skull is unable to grow properly. Another major symptom of Apert syndrome is fused hands and feet. The syndrome was described in 1906 by Eugène Apert, a French physician. It is also referred to as Apert’s syndrome and acrocephalosyndactyly.
Apert syndrome is similar to Crouzon syndrome, although it is more rarely diagnosed. The major differentiators are the additional presence of fused hands and feet (syndactyly) and more serious levels of cognitive impairment. However, since the syndromes have the same genetic cause, some physicians have suggested that they be grouped together and called Crouzon-Apert syndrome. Symptoms associated with Crouzon syndrome are generally also applicable to Apert syndrome, so readers should search for information using both terms.
2. Symptoms
Depending on how and when the cranial sutures fuse prematurely during fetal development, Apert syndrome manifests itself to various degrees. The classic symptoms are as follows.
- prematurely fused skull bones (craniosynotosis)
- underdeveloped nose and eye sockets (midface hypoplasia)
- vertically compressed nasal passages (a “beaked” nose)
- low-set outer ears (microtia)
- a missing or undersized ear canal (congenital aural atresia)
- conductive and/or sensorineural hearing loss
- fusion of the hands and feet (syndactyly)
- mental retardation
This review focuses on the auditory implications of Apert syndrome. A 1978 study of children with craniofacial disorders found that half of 14 children with Apert syndrome or Crouzon syndrome had some degree of hearing loss. The nature of the loss can be either conductive or sensorineural or both.
Additionally, the patient may also have abnormalities of the outer ear and ear canal. In patients with Apert syndrome, the outer ears are set low on the head, a condition called microtia. This happens because during normal fetal development, the ears begin developing low on the head and travel upward. In Apert syndrome, this process is interrupted.
The degree of microtia is rated on a four-point scale. In Grade 1 microtia, the ears look almost normal but are smaller than average. Grade 2 microtia is characterized by having a curved mass of tissue rather than a formed outer ear. Grade 3, which is the most common form of microtia, consists of having only small bumps of skin. Grade 4, sometimes referred to as “anotia”, consists of having no external ear at all.
Because of the skull development problems, the ear canals are often malformed as well (congenital aural atresia). This results in a significant conductive hearing loss because the bone blocks the passage of sound to the eardrum and inner ear. Furthermore, dead skin cells and earwax cannot drain out of the middle ear in the normal way, leading to severe ear infections (otitis media) and occasionally the formation of benign cysts (cholesteatomas). These infections and cysts can be severe enough to lead to permanent hearing loss.
In some cases, the ear canals are unusually narrow rather than completely closed. This is called canal stenosis. Canal stenosis also causes hearing loss and a higher propensity for developing ear infections.
The presence of microtia, atresia, and canal stenosis are not in themselves indicative of Apert syndrome. It is possible to have these conditions without having Apert syndrome.
Because of the skull development issues, cognitive abilities are often impaired. By one
estimate, Whether the patient’s intelligence is normal or impaired, it is important to ensure that she has as much access to sound as possible to maximize spoken language development. Depending on the circumstances, the family may also wish to explore teaching the child sign language and introducing her to the signing deaf community.
3. Causes
Apert syndrome is caused by mutations in the fibroblast growth factor receptor 2 gene (FGFR2). It is rarer than Crouzon syndrome, although estimates differ of its incidence: 1 in 65,000 according to Chen (2005), and 1 in 160,000 to 1 in 200,000 according to the Children’s Craniofacial Association (2005). The children of a person with Apert syndrome have a fifty percent chance of inheriting the gene. There is no evidence that the gene defect is related to the mother’s actions during pregnancy. It has been suggested, however, that it is more prevalent in children fathered by men over 50.
4. Diagnosis
Apert syndrome is usually diagnosed based on the patient’s appearance, hand and foot malformations, and hearing deficits. Genetic testing can be done to detect a mutation in the FGFR2 gene.
5. Treatment
Treatment of Apert syndrome is complex, since there are many aspects of the syndrome to manage. Apert syndrome almost always requires surgery to enable the skull to expand properly and to align the jaws, along with numerous other surgeries to repair face and ear defects. The entire middle portion of the face may be surgically extended forward by a number of surgical techniques such as Rigid External Distraction.
The microtia can be corrected with reconstructive surgery. There are two common methods used to construct an outer ear. One is rib cartilage reconstruction (also called rib grafting), where the surgeon takes cartilage from the patient’s own rib cage, sculpts it into the shape of an ear, and grafts it onto the head. The advantage of this method is that the new ear is made from the patient’s own living tissue and grows along with the rest of the body. The other method is to use a synthetic ear framework using a porous polyethylene material called Medpor. The Medpor technique has the advantage of a fewer number of surgeries and can be done as early as the age of three. Of course, a non-surgical alternative is to use a prosthetic ear, though some prosthetics can be surgically anchored using a titanium abutment. Microtia repair surgery is often done when the patient is between 3 and 6 years of age, although it can be done at any later time.
Congenital aural atresia or canal stenosis can be surgically repaired once the skull has reached a sufficiently large size, generally between ages 3 and 8. The surgery has the goals of allowing proper drainage and enabling sound to reach the eardrum. In cases where the eardrum is absent, that too can be reconstructed. The surgeon drills through the bone to reach the middle ear, and takes skin from elsewhere in the body to line the tunnel so that it becomes an ear canal.
Hearing aids can be effective in giving the patient access to sound. In cases where the ear canal is fully reconstructed, a conventional hearing aid may be used. Another kind of hearing aid that is commonly used is a bone-conduction hearing aid, which bypasses the ear canal by vibrating against the skull behind the ear. The vibrations travel through the skull and stimulate the inner ear, enabling the brain to receive sound. A headband is necessary to press the vibrating component against the skull behind the ear.
A recently developed variant of the bone-conduction hearing aid is the bone-anchored hearing appliance (BAHA), in which the vibrations are transmitted to the skull via a titanium plug surgically implanted behind the ear. (The plug is more technically called a “pedestal” or “abutment”.) A unit containing sound processing circuitry and a vibrating device is attached to the plug; its vibrations are transmitted through the plug to the inner ear. While the plug fuses with the skull after several months in a process called osseointegration, the processor is taken off for sleeping, bathing, and the like. BAHA devices can be more effective and usable than conventional bone-conduction hearing aids because the vibrations aren’t absorbed by the skin, and the patient doesn’t need to wear a headband to anchor the device.
Another device called a Vibrating Ossicular Prosthesis (VORP) may be used. This device consists of a vibrating piston surgically implanted in the middle ear that physically moves the small middle ear bones (ossicles) that normally transmit sound vibrations from the eardrum to the inner ear. An example of a middle-ear hearing aid is the Vibrant Med-El Soundbridge. This device is approved for adults in the United States, and clinical trials are underway to study the use of this device in children between the ages of five and eighteen. The California Ear Institute is part of that clinical trial (for more information, email atresiarepair@calear.com.) A fully implantable middle-ear hearing aid called the Carina is being developed by Otologics, but it is too large for pediatric use.
In cases of profound hearing loss, a cochlear implant may be used. A cochlear implant bypasses all of the mechanisms of the ear and stimulates the auditory nerves directly. It consists of an electrode array surgically inserted into the inner ear. Sound information is sent to it by radio from a device worn on the outer ear like a hearing aid. While cochlear implants do not fully restore hearing, they are often effective enough to allow a child to acquire spoken language normally.
6. Consequences of Avoiding Treatment
Apert syndrome requires skull surgery to enable the growing brain to expand normally. Failure to do so creates pressure on the brain, resulting in severe neurological disorders. Jaw problems may result in a restrictive diet and malnutrition, and issues with the eyelids may lead to subsequent vision problems. Without hearing assistance, individuals with full bilateral microtia and atresia will not able to acquire normal spoken language.
7. Who Should Treat This?
A large team of professionals is necessary to treat all of the issues associated with Apert syndrome. Expert audiological treatment and ear surgery are often required.
The California Ear Institute is a leading global center for microtia and atresia repair. Dr. Joseph Roberson, a board certified neurotologist, has performed hundreds of successful atresia repair surgeries on children and adults from dozens of countries. Dr. Roberson's atresia repair surgery is compatible with all forms of outer ear reconstruction - Medpor, Rib Graft, and Prosthetics.
8. Additional Notes
Patients searching the internet for information about Apert syndrome or any other medical issue should know that generally it is the patients with the severest cases who take the time to write up their experiences for online reading. As a result, it is easy become overly alarmed and assume the worst. Patients should keep this in mind as they explore the available resources. As with all medical conditions, prompt treatment by experienced medical personnel give the best chance for a positive outcome.
For more information on Apert Syndrome
9. Useful Readings
Apert International. http://www.apert-international.org.
Bergstrom, La Vonne (1978 Jul). “Congenital and Acquired Deafness in Clefting and Craniofacial Syndromes” Cleft Palate Craniofacial Journal 15(3): pp. 254-261.
Brent, B. (1999). “Technical advances in ear reconstruction with autogenous rib cartilage grafts—a personal review of 1,200 cases.” Plast. Reconstr. Surg 104: 3 “A19.
Chen, Harold. (2005). “Apert syndrome.” eMedicine website. http://www.emedicine.com/ped/topic122.htm.
Children’s Craniofacial Association (2005). “A Guide to Understanding Apert syndrome.” (PDF). http://www.ccakids.com/Syndrome/Apert.pdf.
Grealy, Lucy (1994). Autobiography of a Face. New York: HarperCollins.
Kaplan, Lawrence C. (1991 April). “Clinical Assessment and Multispecialty Management of Apert Syndrome.” Clinics in Plastic Surgery 18:2 (217-25).
Kiefer, J., Arnold, W., & Staudenmaier, R. (2006 Oct). “Round Window Stimulation with an Implantable Hearing Aid (Soundbridge®) Combined with Autogenous Reconstruction of the Auricle - A New Approach.” ORL: Journal for Oto - Rhino - Laryngology and Its Related Specialties. Vol. 68, Iss. 6; pg. 378.
Posnick J.C., Ruiz R.L. (2000). “The craniofacial dysostosis syndromes: current surgical thinking and future directions.” Cleft Palate Craniofacial Journal 37(5): 433.
Kugler, Mary. (2007). “Apert Syndrome.” About.com website.
http://rarediseases.about.com/cs/musclesbonesjoints/a/040503.htm
“Teeter’s Page.” http://www.apert.org.
Young, Nancy M. (1996). “Congenital aural atresia.” http://www.childsdoc.org/fall96/young/conatresia.asp.
1http://www.hopkinsmedicine.org/craniofacial/Education/Article.cfm?ArticleID=65&Source=Physician
2Bergstrom, La Vonne (1978). “Congenital and Acquired Deafness in Clefting and Craniofacial Syndromes” Cleft Palate Craniofac J 1978 Jul; 15(3): pp. 254-261.
3Chen, Harold (2006).
4Posnick JC; Ruiz RL (2000). The craniofacial dysostosis syndromes: current surgical thinking and future directions. Cleft Palate Craniofac J. 37(5):433.
5Chen, 2005.
