Chapter
5:
Treacher Collins Syndrome
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Chapter
5: |
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Treacher Collins Syndrome
Treacher Collins Syndrome
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Treacher Collins syndrome (also called
mandibulofacial dysostosis and Franceschetti Syndrome) is a highly
complex disease process. The basic etiology is unknown, but it is
generally thought to be inherited as an autosomal dominant trait with
variable penetrance. It is characterized by hypoplasia of the facial
bones, especially the zygoma and the mandible. Facial clefting causes
this hypoplastic appearance, with possible deformities or deficiencies
of the ear, orbital, midface, and lower jaw regions. The clinical
appearance is a result of the zygoma (malar bone) failing to fuse with
the maxilla, frontal, and temporal bones. Highly variant degrees of
involvement (complete, incomplete, and abortive forms) can be seen, but
common facial features may include:
The craniofacial team's geneticist should evaluate all Treacher Collins patients and their families to determine if the disease has been caused by inheritance of a family trait or as the result of a spontaneous gene mutation. If the disease has been inherited by one child in a family, there is a 50% chance that the parents will give birth to another involved child. If neither parents nor other family members are affected and a child is born with the condition, then a mutation has occurred. There is a 50% chance that this child will pass the trait on to future generations. Fortunately, genetic advances and careful prenatal screening have made Treacher Collins syndrome extremely rare.
An extensive array of complications can affect treatment. Because of the small jaw and airway, combined with the normal size of the tongue, breathing problems can occur at birth and during sleep for a child with Treacher Collins syndrome when the base of the tongue obstructs the small hypopharynx. This situation can cause serious problems during the induction of general anesthesia. Consequently, a tracheostomy may be required to adequately control the airway. Learning and speech difficulties can also occur depending on the degree of conductive hearing loss common in the syndrome. Learning disabilities can potentially create a significant social stigma for the child. As with other disfiguring conditions, assessing and treating the psychological needs of the Treacher Collins patient is a vital function of the true craniofacial center. Treatment of the hard and soft tissues of the face can require a number of surgical interventions, the first being the correction of eyelid coloboma in the first years of life (depending on the severity). The next stage is orbital reconstruction with calvarial bone grafts and correction of the lateral canthal displacement. Multi-stage ear reconstruction follows at about 5-7 years of age. Correcting the lower face and jaws involves close coordination between the craniofacial surgeon and the pedodontist/orthodontist, with orthodontic intervention beginning with the eruption of the patient's permanent teeth. After the teeth are aligned to their proper axis (or as closely as is possible), treatment of the lower face then involves orthognathic surgery to reposition the mandible and the maxilla, usually done during the patient's teen years. This can be a one- or two-step procedure. The combined procedure involves rotating the midfacial segment around a transverse axis at the frontonasal angle (for severe maxillary hypoplasia) and lengethening the mandibular ramus. For less severe cases, a LeFort I type osteotomy technique is used to lower the maxillary tuberosities along with the ramus lengthening procedure for the mandible. As the child's face continues to grow, additional procedures may be required to correct any developing deformities. Complimentary procedures such as rib cartilage grafts on the zygoma, closure of macrostomia, and secondary genioplasties are performed according to individual cases. A well-planned treatment regimen can produce excellent results with the ultimate goal being the complete restoration of form and function, thus enabling the patient to adapt to a "normal" way of life.
The Tennessee Craniofacial
Center, part of the Erlanger Health System, is located in Chattanooga,
Tennessee. The Center, led Larry A. Sargent, M.D., specializes in the
evaluation and treatment of patients of all ages with craniofacial deformities.
Location:
975 East Third Street. Chattanooga, Tennessee 37403
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