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Treacher Collins Syndrome

What Is Treacher Collins Syndrome?

Treacher Collins syndrome (sometimes referred to as TCS) is a rare genetic disorder where the face and skull form incorrectly during fetal development. It affects the patient in many ways, including incorrect development of the outer ear, ear canal, and middle ear, frequently resulting in substantial hearing impairment. The syndrome is named after Edward Treacher Collins, the English surgeon and ophthalmologist who described it in 1900. (It is sometimes called Treacher-Collins syndrome using a hyphen, but this is incorrect.)

Treacher Collins syndrome is sometimes called Franceschetti-Zwahlen-Klein syndrome or mandibulofacial dysostosis.

 

Symptoms

Treacher Collins manifests itself in degrees ranging from nearly unnoticeable to severe. The most visible facial manifestations are:

  • eyes that slant downward away from the nose
  • a small jaw (micrognathia)
  • underdeveloped cheekbones
  • unilateral or bilateral microtia and atresia

The most obvious auditory manifestation is microtia that is, small, abnormally shaped, or missing outer ears. 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.

In Treacher Collins, individuals with microtia almost always have congenital aural atresia as well, that is, missing or extremely narrow ear canals. The missing ear canal 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 (cholesteatoma). These infections and cysts can be severe enough to lead to permanent hearing loss. The presence of microtia and congenital aural atresia are not, in themselves, indicative of Treacher Collins; it is possible to have either of these conditions without having Treacher Collins.

In some cases, the ear canal is 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.

In 40-50% of Treacher Collins patients, the middle ear bones (ossicles) are malformed as well, resulting in additional conductive hearing loss because sound cannot be efficiently transmitted from the eardrum to the inner ear. However, these malformed ossicles can be repaired or replaced at the time the atresia repair surgery is performed..

Despite all these conductive hearing loss issues, individuals with Treacher Collins Syndrome generally have normal inner function. This is important because it gives hope for restoring hearing through a variety of means (see “Treatment.”)

Since most Treacher Collins patients have a hearing loss, they may appear to have a cognitive deficit. However, only about 5% of Treacher Collins patients have cognitive deficits. Therefore, since the patient’s intelligence is likely to be normal, it is important to ensure that they have 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.

Causes

Treacher Collins syndrome occurs in approximately 1 in every 50,000 births. It is caused by a mutation of the TCOF1 gene. The mutation may be inherited from the parents, or it may occur spontaneously. Treacher Collins syndrome is an autosomal dominant disorder. Therefore, individuals who have the TCOF1 mutation have a 50% chance of passing it on to their children. For this reason, Treacher Collins often runs in families. In cases of non-inherited Treacher Collins, there is no evidence that the mother’s actions during pregnancy contributed to the condition.

Diagnosis

Treacher Collins is usually diagnosed based on the patient’s appearance and hearing deficits. If necessary, genetic testing can be performed to distinguish Treacher Collins from similar disorders and to determine whether it is spontaneous or inherited.

Treatment

Treatment of Treacher Collins is complex, since there are many aspects of the syndrome to manage. In addition to surgeries associated with restoring hearing, Treacher Collins patients often require reconstructive surgery of the jaw and skull, tracheotomies to enable them to breathe, and repair of cleft palates and notched eyelids.

Microtia can be corrected with reconstructive surgery. There are two common methods used to construct an outer ear. One is rib cartilage reconstruction, 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 in place of the rib. 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 reconstructed once the skull has reached a sufficiently large size, generally between age three and eight. California Ear Institute performs this surgery any time after age three with excellent results, in the belief that restoring hearing before the window of neural plasticity for language development closes at age five creates substantially better results for the child. The surgery has the goals of allowing proper drainage and enabling sound to reach the eardrum. In cases where the eardrum or one or more of the middle ear bones is absent, those too can be replaced. 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. Click here to see actual atresia repair surgery video.

Since the inner ear is rarely affected by Treacher Collins, external hearing aids as well as implanted hearing aids such as the Baha and VORP devices can be effective in giving the patient access to sound. 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 bone-conduction hearing aids is the bone-anchored hearing appliance (BAHA), in which the vibrations are transmitted to the skull via a titanium screw, known as an “abutment” which is surgically implanted behind the ear. A unit containing sound processing circuitry and a vibrating device is attached to the abutment and the vibrations are transmitted through the abutment to the inner ear. BAHA devices can be more effective and usable than conventional bone-conduction hearing aids because the vibrations aren’t absorbed by the skin and hair, and the patient doesn’t need to wear a headband to anchor the device.

A middle-ear implantable prosthetic may also be an option. 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, e-mail atresia repair@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.

Consequences of Avoiding Treatment

Treacher Collins affects many aspects of the patient’s life and requires immediate intervention from birth. For example, the patient may suffer from severe obstructive sleep apnea due to airway abnormalities. 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 Treacher Collins Syndrome with full bilateral microtia and Atresia will not able to acquire normal spoken language.

Who Should Treat This?

A large team of professionals is necessary to treat all of the issues associated with Treacher Collins Syndrome. Expert audiological treatment and ear surgery are almost always required.

The California Ear Institute is a leading global center for atresia repair. Dr. Joseph Roberson, a board certified neurotologist, has performed hundreds of successful atresia repair surgeries on children and adults, including many with Treacher Collins Syndrome, from dozens of countries, creating functional ear canals and restoring hearing to within normal limits. Dr. Roberson's atresia repair surgery is compatible with all forms of outer ear reconstruction - Medpor, Rib Graft, and Prosthetics.

Additional Notes

Patients searching the internet for information about Treacher Collins 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.

 

 

 

 


 
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