Key points
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Branchial arch syndromes present with variable expressivity.
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Management necessitates a multidisciplinary approach.
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Features corroborate a disorder with first and second branchial arch derivatives.
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Treatment should be performed early for vital functional impairments and delayed for esthetic concerns.
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Möbius syndrome is a rare congenital palsy of the sixth and seventh cranial nerves.
Treacher Collins syndrome
Genetics (including inheritance patterns and frequency)
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Autosomal dominant inheritance pattern (a small percentage has autosomal recessive inheritance)
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Affects 1 in 50,000 live births
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Up to 60% of cases result from new or sporadic mutations
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There are 3 recognized gene mutations:
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TCOF1 and POLR1D : autosomal dominant
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POLRIC : autosomal recessive
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The result of these mutations is an aberrant production of ribosomal RNA that is important in the structural development of the face, and more specifically the first and second branchial arches
Clinical features
The clinical features of Treacher Collin syndrome (TCS) consist of bilaterally symmetric, abnormal development of the structures arising from the first and second branchial arches. This abnormal development contributes to deficient generation of the lower two-thirds of the face ( Fig. 1 ).
The first branchial arch is involved with the growth of the mandible and the zygomaticomaxillary complex and the second arch or hyoid arch is involved with development of the middle ear. The classically presented patient accordingly has a convex facial profile with gross hypoplasia or incomplete formation of the zygoma, maxilla, and mandible in all 3 dimensions. These individuals also have normal intelligence. These facial features are summarized in Table 1 .
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Differential diagnosis:
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Craniofacial microsomia: features are asymmetric and usually unilateral
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Pierre Robin sequence: children born with severe hypoplasia of the mandible, high arching cleft palate, and a relative macroglossia
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Stickler syndrome comprises a group of hereditary conditions involving eye, ear, and joint deformities plus Pierre Robin sequence
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Nager syndrome includes malformed upper limbs as well as cleft palate and severe palatal hypoplasia
| Eyes | Downward slanting of palpebral fissures Colobomata Lower lid hypoplasia and partial absence of eyelid cilia Dystopia |
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| Ears | Microtia or absent external ear Middle ear or ossicle hypoplasia Conductive deafness Atresia |
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| Nose | Prominent nasal dorsum Choanal atresia or stenosis |
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| Mouth | Cleft palate ± lip Malocclusion (Angel class II, anterior open bite, steep clockwise rotation of the maxillomandibular complex) Dental abnormalities (enamel opacities, dental agenesis, eruption disturbances) |
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| Musculoskeletal | Skeleton | Mandibular hypoplasia Microgenia Hypoplastic glenoid fossa Maxillary hypoplasia |
| Muscles | Muscular hypoplasia (muscles of mastication) | |
| Joint | Absent, hypoplastic, or deformed TMJ | |
Treatment considerations for the oral and maxillofacial surgeon
The treatment strategy for patients should prioritize procedures that result in functional improvement while delaying those with cosmetic goals until growth maturity. The following functional categories may necessitate early intervention: airway, feeding, hearing, speech, vision, and socialization.
Airway
Maxillary and mandibular hypoplasia can contribute to a compromised airway. Choanal atresia or stenosis can compound this problem, which may require immediate intervention ranging from observation with pulse oximetry and positioning to mandibular advancement with distraction osteogenesis, or tracheotomy ( Fig. 2 ).
Feeding
An incompetent lip seal or cleft lip and or palate may compromise adequate nutrition. Considerations to cleft treatment algorithms or G-tube placement may be necessary.
Hearing
Pediatric otolaryngology consultation and formal audiology testing is required early in order to establish successful hearing.
Vision
Pediatric ophthalmologist should be consulted to evaluate for any extra ocular muscle (EOM) dysfunction or deficits in visual acuity. When the lateral and inferior orbital supporting structures are hypoplastic or missing the corneas are unprotected, which may necessitate earlier reconstruction of the orbital and zygomatic structures.
Speech
Correction of a cleft palate should follow the standard cleft treatment recommendations.
Secondary treatment strategy should take place at the end of skeletal maturity and include orthognathic surgery and zygomatic-orbital reconstruction.
Malar and orbital reconstruction uses a full-thickness calvarium bone graft through a coronal incision and exposure. It is recommended that this procedure be performed after the age of 6 years, for skeletal maturity of the midface, as well as the ability to reconstruct the donor calvarium site with a local split-thickness calvarium graft.
Maxillomandibular reconstruction is best approached with traditional orthognathic surgery at 13 to 15 years of age, at the time of early skeletal maturity. Le Fort I and rami osteotomies with sliding genioplasty are usually indicated.
When the deformity results in absent ramus, condyle, or glenoid fossa, then reconstruction may be performed at the time of malar and orbital reconstruction. The use of costochondral bone graft to reconstruct the ramus-condyle is advocated. A second reconstruction with conventional osteotomies is almost certain to be warranted after skeletal maturity.
As with conventional orthognathic surgery, nasal reconstruction should be performed as the final reconstructive procedure when indicated.
Treacher Collins syndrome
Genetics (including inheritance patterns and frequency)
- •
Autosomal dominant inheritance pattern (a small percentage has autosomal recessive inheritance)
- •
Affects 1 in 50,000 live births
- •
Up to 60% of cases result from new or sporadic mutations
- •
There are 3 recognized gene mutations:
- ○
TCOF1 and POLR1D : autosomal dominant
- ○
POLRIC : autosomal recessive
- ○
- •
The result of these mutations is an aberrant production of ribosomal RNA that is important in the structural development of the face, and more specifically the first and second branchial arches
Clinical features
The clinical features of Treacher Collin syndrome (TCS) consist of bilaterally symmetric, abnormal development of the structures arising from the first and second branchial arches. This abnormal development contributes to deficient generation of the lower two-thirds of the face ( Fig. 1 ).
