Syndromes of the First and Second Branchial Arches, Part 1: Embryology and Characteristic Defects

Abstract

SUMMARY:A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BAs should begin first by studying a series of isolated defects: CL with or without CP, micrognathia, and EAC atresia, which compose the major features of these syndromes and allow more specific diagnosis. After discussion of these defects and the associated embryology, we proceed to discuss the VCFS, PRS, ACS, TCS, Stickler syndrome, and HFM.ABBREVIATIONS: ACS ϭ auriculocondylar syndrome; BA ϭ branchial arch; CL ϭ cleft lip; CL/P ϭ cleft lip/palate; CP ϭ cleft palate; EAC ϭ external auditory canal; HFM ϭ hemifacial microsomia; MDCT ϭ multidetector CT; PRS ϭ Pierre Robin sequence; TCS ϭ Treacher Collins syndrome; VCFS ϭ velocardiofacial syndrome R adiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions.1 The recent rapid proliferation of MDCT is due, in part, to the increased utility of this technique for multiplanar bone and soft-tissue imaging. The definition of fine bony structure of the craniofacial anatomy on CT images is unmatched by other modalities. There has also been increased demand for treatment planning along with the advances in high-resolution CT evaluation and 3D reconstruction techniques.Knowledge of the genetic basis of human disease and its effect on embryologic development has expanded greatly in recent years. Disorders of the first and second BA are generally thought to result from a combination of inadequate migration and inadequate formation of facial mesenchyma. Because many structures of the head and neck migrate during fetal development, an understanding of embryologic development helps determine the origin and nature of congenital lesions. Familiarity with craniofacial embryology and its associated effects on resultant anatomy also leads to a better understanding of the pathophysiologic basis of craniofacial syndromes. Additionally, it helps to establish a search pattern for characteristic radiologic features of many of these anomalies.Part 1 of this review establishes the embryology, developmental anatomy, clinical symptoms, and characteristic imaging features of the isolated defects that compose some of the major features of the syndromes of the first and second BAs. Part 2 of this review discusses the syndromes and their radiographic features: PRS, HFM, ACS, TCS, Stickler syndrome, and VCFS. When applicable, the disorders number of the public data base of bibliographic information about human genes and genetic disorders-the Online Mendelian Inheritance in Man (http://www.ncbi.nlm.nih....

The syndromic child and anaesthesia

“…Because of the common embryological origin, it should be expected that patients with abnormalities of the ears might have upper airway anomalies. 2 Congenital micrognathia is much more commonly associated with a syndrome (Table 4), than being an isolated anomaly. 10 Obstructive sleep apnoea is a common complication, especially when micrognathia is associated with glossoptosis.…”

“…2 The term "first arch syndrome" applies to conditions with coexisting abnormalities of the eyes, ears, palate and jaw, and include Treacher Collins syndrome and Pierre Robin sequence. 3…”

Identificação de novas variantes causativas e investigação da heterogeneidade clínica da Síndrome aurículo-condilar

“…O primeiro arco faríngeo também dará origem a estruturas como os músculos da mastigação, parte da bigorna (ou incus) e martelo (ou malleus), parte da orelha externa e da língua. Já o segundo arco faríngeo origina, dentre outros, parte da orelha externa, o estribo, processo estilóide e o menor corno do osso hióide, enquanto o corno maior do hióide é derivado do terceiro arco faríngeo (Figura 3) (revisto em Johnson, 2010;Minoux & Rijli, 2010).…”

“…Na quarta semana ocorre a fusão dos dois processos mandibulares, derivados do primeiro arco branquial, na linha média. Enquanto que, na quinta e sexta semanas de gestação, os processos maxilares crescem em direção à linha média resultando em sua fusão entre a sexta e sétima semanas (revisto em Johnson et al, 2010;Garcia & Fernández, 2001). A partir do quinto mês fetal o centro de crescimento do côndilo mandibular será responsável pelo alongamento da mandíbula durante os primeiros 10 anos de vida pós-natal (Garcia & Fernández, 2001 e revisto em Serrano et al, 2011).…”

Refinamento fenotípico da disostose mandibulofacial tipo Bauru

“…As anomalias craniofaciais representam uma das principais causas de mortalidade infantil e constituem grande impacto clínico, requerendo intervenções cirúrgicas, nutricionais, odontológicas, fonoaudiológicas e psicológicas durante toda a infância e adolescência (Murray 2002, Dixon et al 2006, Trainor 2010 e Johnson et al 2011a). Dentre as anomalias craniofaciais, a fissura orofacial é a anomalia mais comum com incidência mundial ao redor de 1:1000 nascidos vivos, podendo variar de acordo com a etnia, origem geográfica e nível socioeconômico com ou sem envolvimento do palato (FL/P) é distinta da fissura de palato (FP) sem envolvimento do lábio.…”