Congenital causes of limited mouth opening involving fusion of maxilla and mandible (syngnathia) are rare anomalies that often present as part of syndromes such as Van der Woude and popliteal pterygium syndrome. Surgical management involves division of the bony fusion or breakdown of the adhesions in the first few days of life. The authors present a case of maxillo-mandibulo-zygomatic fusion (syngnathia) in an 8-year-old boy, who underwent surgical intervention to achieve adequate jaw function.
Congenital craniofacial disorders represent approximately 20% of all birth defects. Congenital causes of limited mouth opening involving fusion of maxilla and mandible (syngnathia) are rare anomalies that often present as part of syndromes such as Van der Woude and popliteal pterygium syndrome. Maxillo-mandibular fusion (syngnathia) can present a broad spectrum of severity, from simple mucosal strings (syncheia) to extensive bony fusion (synostosis) depending on the amount of mesodermal penetration preventing mouth opening and leading to airway or feeding problems. Proposed embryologic explanations for the syncheia are failure of division (persistant oropharyngeal membrane) or abnormal fusion due to abnormal epithelium. The presence of temporomandibular joint anomalies and mandibular hypoplasia in the bony forms of syngnathia suggest a defect in separation of the maxillary and mandibular components of the first brachial arch during development. Surgical management involves division of the bony fusion or breakdown of the adhesions in the first few days of life.
An 8-year-old boy presented with a congenital facial deformity and inability to open the mouth since birth. His antenatal and obstetric history was not contributory. He was the first child in the family with a full-term normal delivery. Antenatal ultrasonography and X-ray had not been carried out and the mother had not received any medications during her pregnancy. His nutritional status and growth pattern were average. Since birth, his diet had mainly been liquid although it included some semi-solids, which he managed to push through the retromolar space. Physical examination revealed an everted lower lip, facial asymmetry, hemifacial hypoplasia of the left side and an antimongoloid slant of the medial palpebral fissure of the left eye with a classical bird face deformity. There was no mouth opening with the upper and lower arches fused to each other on the left side and the maxillary and mandibular incisors proclined with increased overjet and overbite ( Fig. 1 ). Examination of the palate and tongue could not be achieved preoperatively. No other congenital anomaly was detected on general examination.
A CT scan revealed a hypoplastic left maxilla, fused with the mandible and the zygomatic bone of the left side along with widening and fusion of the left condyloid process ( Fig. 2 ). The left maxillary sinus was hyperpneumatized with the nasal floor sloping downwards. There was asymmetry of the left hemimandible and outward protrusion of the anterior teeth.
Under blind nasoendotracheal intubation, a combination incision (submandibular and retromandibular) was used to approach the fused mass. The dissection was carried out to reach the cleavage on the anterior margin of the fusion of jaws. Concurrently posterior dissection was carried out to reach the anterior aspect of the condyle. The bony cuts were marked from the anterior cleavage up to the anterior margin of the condylar neck ( Fig. 3 ). After completion of the cuts the jaws were separated followed by condylectomy, as the condyle was ankylosed, to achieve adequate mouth opening of 3.2 cm. Postoperative physiotherapy was initiated after 48 h and the patient is regularly followed up to maintain the adequate mouth opening ( Fig. 4 ). The patient was trained to carry out physiotherapy exercises at home with a bunch of wooden spatulas tied together. 1-year postoperatively, he is maintaining adequate mouth opening ( Fig. 5 ).