Congenital Zygomatico-Mandibular Fusion (Pseudo-Syngnathia?) in Conjunction with Unilateral Anophthalmia: Review of Terminology and Classification

Abstract

Syngnathia per se is a rare congenital disorder. A literature survey reveals a total of 26 cases of syngnathia in the English literature since 1936, of which only seven cases involved fusion of the ascending ramus of the mandible to the posterior portion of the maxilla and zygomatic complex. The remaining 19 involved fusion of the alveolar ridges of the maxilla and mandible. This is a unique case of fusion of the mandible to the zygomatic complex presenting with a unilateral anophthalmic orbit in an 18-day-old neonate. The use of the term syngnathia has been reviewed and a modification in classification has been suggested.

Separate development of the maxilla and mandible is controlled by regional signaling of the maxillomandibular junction during avian development

“…Several hypotheses about the origin of syngnathia have been suggested, including defect of the embryonic ectoderm (Snijman and Prinsloo, 1966) or exposure to teratogens such as vitamin A (Nanda, 1970). Others have proposed a local loss of neural crest cells (Hegtvedt, 1992), though this may result in hemifacial microsomia, but not syngnathia (Tauro et al, 2011). A recent study raised the possible relationship of syngnathia with Foxc1, which interacts with Fgf8 (Imman et al, 2013), or with Bmp4 (He et al, 2014).…”

Correction of Unilateral Congenital Zygomatico-Mandibular Fusion

“…A review of the literature reveals less than 10 cases involving fusion of the zygomatic complex. 4 Early treatment is essential to allow for feeding, and to protect the airway. 5,6 Early treatment is also essential to facilitate early jaw mobilization and prevent temporomandibular joint (TMJ) ankylosis.…”

Postnatal Diagnosis of a Baby with Multiple Rare Congenital Anomalies Including Syngnathia, Brain Dysmorphism, and Skin Pigmentation

“…It is subdivided into the more common soft tissue fusion or synechiae and the rare bone tissue fusion or synostosis (Subramanian et al, 2010). Recently, “pseudosyngnathia” has also been introduced to describe bone fusion between the mandible and zygoma (Tauro et al, 2012). The severity of syngnathia varies according to the length of fusion involved and is usually diagnosed as soon as feeding attempts are initiated after birth.…”

“…Three classification methods have been proposed based on the anatomical location of the fusion and associated craniofacial anomalies (Dawson et al, 1997; Laster et al, 2001; Tauro et al, 2012). Its etiology is linked to an embryological basis, with several postulated theories including persistence of the buccopharyngeal membrane, amniotic constriction bands, presence of an aberrant stapedial artery, premature loss of embryonic neural crest cells, alveolar fusion predisposed by failure of tongue protrusion or depressed fetal swallowing reflexes, environmental insults, or drug exposure such as meclozine and large doses of vitamin A (Fallahi et al, 2010).…”

“…Common associations reported include anomalies of the tongue, palate, limbs, eyes, ears, and vertebral column. Common syndromes include craniofacial microsomia, Van der Woude syndrome, popliteal pterygium syndrome, cleft palate lateral alveolar synechiae syndrome, and aglossiaadactylia syndrome (Dawson et al, 1997; Tomlinson et al, 2006; Naikmasur et al, 2010; Tauro et al, 2012). The findings in our patient did not meet the criteria of these syndromes.…”