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Complete Bony Syngnathia: Report of a Case and Review

Complete Bony Syngnathia: Report of a Case and Review Congenital fusion of the mandible and maxilla is a rare phenomenon. Cases can be broadly classified as bony fusion or soft tissue synechiae. The more rare bony fusion can be further classified as partial or complete and then as syndromic and nonsyndromic. Although theories as to its etiology exist, the cause of the abnormal joining of the mandible and maxilla remains unknown. Because of the paucity of cases, treatment has been individualized. This is a report of a nonsyndromic case of complete bony syngnathism, including the treatment dilemmas faced and a review of the literature. Report of a case A healthy 21-year-old woman who was gravida 3, para 1, gave birth at 38 weeks to a girl after an uncomplicated pregnancy that was without infection, teratogenic exposure, or trauma. Findings from prenatal ultrasonography at 22 weeks demonstrated fetal micrognathia, and further genetic testing was declined. Findings from fetal magnetic resonance imaging demonstrated a normal mandible. At birth, the child exhibited no respiratory distress and had Apgar scores of 9 and 9 at 1 and 5 minutes, respectively. The initial physical examination of the child revealed fusion of the maxillary and mandibular alveolar ridges. The pediatric otolaryngology service was consulted. The primary issues were establishment of a stable airway and maintenance of long-term nutrition. Al though at the time of our initial evaluation, the child was breathing comfortably through her nose, concerns about future development of nasal edema and secretions were raised. The child also had no nutritional support at the time, and placement of a nasogastric tube could potentially compromise the nasal airway. There was also the potential risk of aspiration because there was no outlet for secretions or nutritional feedings. Also, the child would likely require at least 1 future surgical procedure for repair of the mandible. Finally, fiberoptic nasal intubation in a 2-day-old child presented too great of a risk. After a thorough discussion of all these issues with the intensive care physicians, pediatric anesthesiologist, and other caregivers involved with the child, the patient was taken to the operating room for an awake tracheotomy, which was performed without incident. Further physical examination of the child demonstrated a micrognathic jaw, complete fusion of the mandible and maxilla, an abbreviated buccal vestibule, and mild midface hypoplasia (Figure 1). A flexible fiberoptic examination demonstrated an intact nasal floor and no evidence of a primary or secondary cleft palate; however, examination of the oral cavity proved too difficult to allow assessment of the tongue. The remainder of the examination, including an ultrasonography of her head, revealed no further abnormalities. The computed tomographic scan demonstrated complete bilateral fusion of the maxilla and mandible and normal-appearing temporomandibular joints and zygomatic arches (Figure 2). A gastrostomy tube was also placed, and the craniofacial team began to plan for definitive surgery of the mandible. Figure 1. View LargeDownload Intraoral demonstration of fused gum line. Figure 2. View LargeDownload Three-dimensional construction of computed tomography. A, Bony fusion. B, Lateral view showing right temporomandibular joint and mandibular-maxillary bony fusion. Comment Bony syngnathia is a rare finding. The terminology used to describe this anomaly in the literature is inconsistent, and the descriptions of the associated abnormalities are varied in their detail. Our review of the literature demonstrated 13 articles that provide evidence of complete bony syngnathism (Table). Additional articles were found that discussed cases of syngnathia, but we left them out of this review because on direct examination, we found that the cases described either involved soft tissue connections only or had limited bony involvement. The patient described herein represents the 14th reported case of complete bilateral bony syngnathia and, to our knowledge, only the fourth reported case of isolated syngnathia with no other associated anomalies. Table. View LargeDownload Previously Reported Cases of Complete Bony Syngnathia True bony mandibulo-maxillary fusion was first demonstrated by Hochstetter1 in 1948; he described a skull from 1877 found in an Austrian ossuary. Sporadic reporting has occurred ever since. Although this condition is usually obvious at birth, there have been reports12,13 of patients with congenital cases of bony fusion presenting as toddlers after they have existed on soft or liquefied diets for prolonged periods of time. Airway management in these children is the most important consideration. Aspiration represents a potentially fatal risk in these patients because there is no direct access to the oral cavity for suctioning and no way to orally intubate. Airway access is therefore limited to fiberoptic or blind nasal intubation or awake tracheotomy. We elected to perform an awake tracheotomy with percutaneous jet ventilation as backup. Even though the child was breathing well through her nose, we did not feel that potential complications of attempted nasal intubation (eg, bleeding and edema) warranted an attempt. Although an awake tracheotomy in a 2-day-old child carries its own challenges, adequate local anesthesia, good positioning, and efficient surgery minimized those challenges. Even with a tracheotomy, however, aspiration is still a significant risk. Of the reviewed cases, death by sudden respiratory arrest occurred in 3 (23%) of 13 patients despite the presence of a tracheotomy. A jejunal tube or gastric tube and Nissen fundoplication are recommended for feeding access and to minimize the possibility of refluxing gastric contents into the airway. Another more drastic option is a temporary laryngotracheal separation if repair of the mandible is to be delayed to reduce the risk of aspiration. One of the 3 children who died of respiratory arrest had undergone a fundoplication.4 Methods of repair of the bony junction between the mandible and maxilla typically involve a transoral or submandibular approach.6,13 Osteotomies are performed, and the exposed bone is then covered with mucosal flaps. In more than 1 case (including ours), however, there was a foreshortened gingival-buccal sulcus, prompting a delayed repair until the child could gain additional weight.6 The absence of a temporomandibular joint may necessitate additional surgery and exposure. Two complications that occurred in the reported cases included synechiae at the surgical sites, resulting in a nonbony syngnathia, and ankylosis of the temporomandibular joint, requiring postoperative exercises and the use of splints.8,9 The etiology of this rare phenomenon has yet to be determined. Studies have found syngnathia in rats that had been exposed to prenatal meclizine hydrochloride, which is also associated with epithelial fusion between the tongue and palate, although exposure to teratogens was not reported in any of the cases found in our review of the literature.14 Given the similarity of syngnathia to hemifacial microsomia, abnormalities of the stapedial artery or early loss of neural crest cells have also been suspected to be possible factors.8 To date, no known genetic associations have been made, although at least 2 syndromes, Dobrow syndrome3 and facio-genito-popliteal syndrome10 (also known as popliteal pterygium syndrome) have been described. Laster et al11 noted that traumatic forces such as head posture or pressure exerted by the mother's pelvis could apply pressure to the mandible, force the tongue upward, and interfere with deglutition and influence the development of a cleft palate and resultant syngnathia. Gartlan et al14 suggested that lack of tongue protrusion (as a result of a cleft palate, aglossia, or impaired neuromuscular development) may allow the prolonged quiescent contact between oral structures and predispose an individual to the development of abnormal fusions. Finally, Sternberg et al15 proposed that the sequence of events begins with a fusion of the gums, resulting in a posterior cleft owing to the failure of the tongue mass to drop. Of the patients with known soft tissue status of the oral cavity, 8 (66%) of the 12 had either an abnormal tongue or a cleft palate or both. Laster et al11 proposed a classification system of syngnathia, a modification of a system by Dawson et al8: Type 1a is a simple anterior syngnathia characterized by bony fusion of the alveolar ridge only and without other congenital deformity in the head and neck. Type 1b is a complex anterior syngnathia characterized by bony fusion of the alveolar ridges only and associated with other congenital deformity in the head and neck. Type 2a is a simple zygomatico-mandibular syngnathia characterized by bony fusion of the mandible to the zygomatic complex causing only mandibular micrognathia. Type 2b is a complex zygomatico-mandibular syngnathia characterized by bony fusion of the mandible to the zygomatic complex and associated with clefts or temporomandibular joint ankylosis. The patient described herein had zygomatico-mandibular syngnathia without any additional abnormalities and is therefore is classified in the type 2a category. In conclusion, syngnathia is a rare finding, and its etiology has yet to be determined. The lack of oral access makes airway management the highest priority, but close attention should also be paid to feeding and minimizing the risk of aspiration. Repair has not been standardized but should focus on separation of the bones and subsequent soft tissue coverage. Back to top Article Information Correspondence: Kristina W. Rosbe, MD, Department of Otolaryngology–Head and Neck Surgery, University of California, San Francisco, 400 Parnassus Ave, A730, San Francisco, CA 94132-0342 (krosbe@ohns.ucsf.edu). Submitted for Publication: February 1, 2006; final revision received June 8, 2006; accepted July 7, 2006. Author Contributions: Drs Trigg and Rosbe had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Trigg and Rosbe. Acquisition of data: Trigg and Mau. Analysis and interpretation of data: Trigg. Drafting of the manuscript: Trigg. Critical revision of the manuscript for important intellectual content: Trigg, Mau, and Rosbe. Administrative, technical, and material support: Trigg. Study supervision: Rosbe. Financial Disclosure: None reported. References 1. Hochstetter F Uber zwei Falle epithelialer Syngnathie bei menschlichen Keimlingen. Dtsch Med Wochenschr 1948;1081Google Scholar 2. Hoggins GS Aglossia congenital with bony fusion of the jaws. Br J Oral Surg 1969;763- 65Google ScholarCrossref 3. Dobrow B Syndrome identification case report 96: syngnathia and multiple defects. J Clin Dysmorp 1983;15- 7PubMedGoogle Scholar 4. Simpson JRMaves MD Congenital syngnathia or fusion of the gums and jaws. Otolaryngol Head Neck Surg 1985;9396- 99PubMedGoogle Scholar 5. Brown DMMarsh JL Agnathia and associated malformations: a case report. Cleft Palate J 1990;27415- 418Google ScholarCrossref 6. Agrawal KChandra SSSreekumar NS Congenital bilateral intermaxillary bony fusion. Ann Plast Surg 1993;30163- 166PubMedGoogle ScholarCrossref 7. Arshad ARGoh CS Hypoglossia congenita with anterior maxillo-mandibular fusion. Br J Plast Surg 1994;47139- 141Google ScholarCrossref 8. Dawson KHGruss JSMyall RW Congenital bony syngnathia: a proposed classification. Cleft Palate Craniofac J 1997;34141- 146PubMedGoogle ScholarCrossref 9. Ugurlu KTuran TUrganci N et al. Fusion of maxillary and mandibular alveolar process together with a median mandibular cleft: a rare congenital anomaly. J Craniomaxillofac Surg 1999;27105- 108PubMedGoogle ScholarCrossref 10. Yazdi IFakhraee AH Congenital fusion of maxilla and mandible (bony syngnathia): a case report. Arch Iran Med.2000;3. http://pearl.sums.ac.ir/AIM/0033/yazdi0033.html. Accessed: March 30, 2006 Google Scholar 11. Laster ZTemkin DZarfin Y et al. Complete bony fusion of the mandible to the zygomatic complex and maxillary tuberosity: case report and review. Int J Oral Maxillofac Surg 2001;3075- 79PubMedGoogle ScholarCrossref 12. Daniels JS Congential maxillomandibular fusion: a case report and review of the literature. J Craniomaxillofac Surg 2004;32135- 139PubMedGoogle ScholarCrossref 13. Ugurlu KKarsidag SHuthut I et al. Congenital fusion of the maxilla and mandible. J Craniofac Surg 2005;16287- 291PubMedGoogle ScholarCrossref 14. Gartlan MGDavies JSmith RJ Congenital oral synechiae. Ann Otol Rhinol Laryngol 1993;102186- 197PubMedGoogle Scholar 15. Sternberg NSagher UGolan J et al. Congenital fusion of the gums with bilateral fusion of the temporomandibular joints. Plast Reconstr Surg 1983;72385- 387PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology–Head & Neck Surgery American Medical Association

Complete Bony Syngnathia: Report of a Case and Review

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Publisher
American Medical Association
Copyright
Copyright © 2007 American Medical Association. All Rights Reserved.
ISSN
0886-4470
DOI
10.1001/archotol.133.2.187
pmid
17309989
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Abstract

Congenital fusion of the mandible and maxilla is a rare phenomenon. Cases can be broadly classified as bony fusion or soft tissue synechiae. The more rare bony fusion can be further classified as partial or complete and then as syndromic and nonsyndromic. Although theories as to its etiology exist, the cause of the abnormal joining of the mandible and maxilla remains unknown. Because of the paucity of cases, treatment has been individualized. This is a report of a nonsyndromic case of complete bony syngnathism, including the treatment dilemmas faced and a review of the literature. Report of a case A healthy 21-year-old woman who was gravida 3, para 1, gave birth at 38 weeks to a girl after an uncomplicated pregnancy that was without infection, teratogenic exposure, or trauma. Findings from prenatal ultrasonography at 22 weeks demonstrated fetal micrognathia, and further genetic testing was declined. Findings from fetal magnetic resonance imaging demonstrated a normal mandible. At birth, the child exhibited no respiratory distress and had Apgar scores of 9 and 9 at 1 and 5 minutes, respectively. The initial physical examination of the child revealed fusion of the maxillary and mandibular alveolar ridges. The pediatric otolaryngology service was consulted. The primary issues were establishment of a stable airway and maintenance of long-term nutrition. Al though at the time of our initial evaluation, the child was breathing comfortably through her nose, concerns about future development of nasal edema and secretions were raised. The child also had no nutritional support at the time, and placement of a nasogastric tube could potentially compromise the nasal airway. There was also the potential risk of aspiration because there was no outlet for secretions or nutritional feedings. Also, the child would likely require at least 1 future surgical procedure for repair of the mandible. Finally, fiberoptic nasal intubation in a 2-day-old child presented too great of a risk. After a thorough discussion of all these issues with the intensive care physicians, pediatric anesthesiologist, and other caregivers involved with the child, the patient was taken to the operating room for an awake tracheotomy, which was performed without incident. Further physical examination of the child demonstrated a micrognathic jaw, complete fusion of the mandible and maxilla, an abbreviated buccal vestibule, and mild midface hypoplasia (Figure 1). A flexible fiberoptic examination demonstrated an intact nasal floor and no evidence of a primary or secondary cleft palate; however, examination of the oral cavity proved too difficult to allow assessment of the tongue. The remainder of the examination, including an ultrasonography of her head, revealed no further abnormalities. The computed tomographic scan demonstrated complete bilateral fusion of the maxilla and mandible and normal-appearing temporomandibular joints and zygomatic arches (Figure 2). A gastrostomy tube was also placed, and the craniofacial team began to plan for definitive surgery of the mandible. Figure 1. View LargeDownload Intraoral demonstration of fused gum line. Figure 2. View LargeDownload Three-dimensional construction of computed tomography. A, Bony fusion. B, Lateral view showing right temporomandibular joint and mandibular-maxillary bony fusion. Comment Bony syngnathia is a rare finding. The terminology used to describe this anomaly in the literature is inconsistent, and the descriptions of the associated abnormalities are varied in their detail. Our review of the literature demonstrated 13 articles that provide evidence of complete bony syngnathism (Table). Additional articles were found that discussed cases of syngnathia, but we left them out of this review because on direct examination, we found that the cases described either involved soft tissue connections only or had limited bony involvement. The patient described herein represents the 14th reported case of complete bilateral bony syngnathia and, to our knowledge, only the fourth reported case of isolated syngnathia with no other associated anomalies. Table. View LargeDownload Previously Reported Cases of Complete Bony Syngnathia True bony mandibulo-maxillary fusion was first demonstrated by Hochstetter1 in 1948; he described a skull from 1877 found in an Austrian ossuary. Sporadic reporting has occurred ever since. Although this condition is usually obvious at birth, there have been reports12,13 of patients with congenital cases of bony fusion presenting as toddlers after they have existed on soft or liquefied diets for prolonged periods of time. Airway management in these children is the most important consideration. Aspiration represents a potentially fatal risk in these patients because there is no direct access to the oral cavity for suctioning and no way to orally intubate. Airway access is therefore limited to fiberoptic or blind nasal intubation or awake tracheotomy. We elected to perform an awake tracheotomy with percutaneous jet ventilation as backup. Even though the child was breathing well through her nose, we did not feel that potential complications of attempted nasal intubation (eg, bleeding and edema) warranted an attempt. Although an awake tracheotomy in a 2-day-old child carries its own challenges, adequate local anesthesia, good positioning, and efficient surgery minimized those challenges. Even with a tracheotomy, however, aspiration is still a significant risk. Of the reviewed cases, death by sudden respiratory arrest occurred in 3 (23%) of 13 patients despite the presence of a tracheotomy. A jejunal tube or gastric tube and Nissen fundoplication are recommended for feeding access and to minimize the possibility of refluxing gastric contents into the airway. Another more drastic option is a temporary laryngotracheal separation if repair of the mandible is to be delayed to reduce the risk of aspiration. One of the 3 children who died of respiratory arrest had undergone a fundoplication.4 Methods of repair of the bony junction between the mandible and maxilla typically involve a transoral or submandibular approach.6,13 Osteotomies are performed, and the exposed bone is then covered with mucosal flaps. In more than 1 case (including ours), however, there was a foreshortened gingival-buccal sulcus, prompting a delayed repair until the child could gain additional weight.6 The absence of a temporomandibular joint may necessitate additional surgery and exposure. Two complications that occurred in the reported cases included synechiae at the surgical sites, resulting in a nonbony syngnathia, and ankylosis of the temporomandibular joint, requiring postoperative exercises and the use of splints.8,9 The etiology of this rare phenomenon has yet to be determined. Studies have found syngnathia in rats that had been exposed to prenatal meclizine hydrochloride, which is also associated with epithelial fusion between the tongue and palate, although exposure to teratogens was not reported in any of the cases found in our review of the literature.14 Given the similarity of syngnathia to hemifacial microsomia, abnormalities of the stapedial artery or early loss of neural crest cells have also been suspected to be possible factors.8 To date, no known genetic associations have been made, although at least 2 syndromes, Dobrow syndrome3 and facio-genito-popliteal syndrome10 (also known as popliteal pterygium syndrome) have been described. Laster et al11 noted that traumatic forces such as head posture or pressure exerted by the mother's pelvis could apply pressure to the mandible, force the tongue upward, and interfere with deglutition and influence the development of a cleft palate and resultant syngnathia. Gartlan et al14 suggested that lack of tongue protrusion (as a result of a cleft palate, aglossia, or impaired neuromuscular development) may allow the prolonged quiescent contact between oral structures and predispose an individual to the development of abnormal fusions. Finally, Sternberg et al15 proposed that the sequence of events begins with a fusion of the gums, resulting in a posterior cleft owing to the failure of the tongue mass to drop. Of the patients with known soft tissue status of the oral cavity, 8 (66%) of the 12 had either an abnormal tongue or a cleft palate or both. Laster et al11 proposed a classification system of syngnathia, a modification of a system by Dawson et al8: Type 1a is a simple anterior syngnathia characterized by bony fusion of the alveolar ridge only and without other congenital deformity in the head and neck. Type 1b is a complex anterior syngnathia characterized by bony fusion of the alveolar ridges only and associated with other congenital deformity in the head and neck. Type 2a is a simple zygomatico-mandibular syngnathia characterized by bony fusion of the mandible to the zygomatic complex causing only mandibular micrognathia. Type 2b is a complex zygomatico-mandibular syngnathia characterized by bony fusion of the mandible to the zygomatic complex and associated with clefts or temporomandibular joint ankylosis. The patient described herein had zygomatico-mandibular syngnathia without any additional abnormalities and is therefore is classified in the type 2a category. In conclusion, syngnathia is a rare finding, and its etiology has yet to be determined. The lack of oral access makes airway management the highest priority, but close attention should also be paid to feeding and minimizing the risk of aspiration. Repair has not been standardized but should focus on separation of the bones and subsequent soft tissue coverage. Back to top Article Information Correspondence: Kristina W. Rosbe, MD, Department of Otolaryngology–Head and Neck Surgery, University of California, San Francisco, 400 Parnassus Ave, A730, San Francisco, CA 94132-0342 (krosbe@ohns.ucsf.edu). Submitted for Publication: February 1, 2006; final revision received June 8, 2006; accepted July 7, 2006. Author Contributions: Drs Trigg and Rosbe had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Trigg and Rosbe. Acquisition of data: Trigg and Mau. Analysis and interpretation of data: Trigg. Drafting of the manuscript: Trigg. Critical revision of the manuscript for important intellectual content: Trigg, Mau, and Rosbe. Administrative, technical, and material support: Trigg. Study supervision: Rosbe. Financial Disclosure: None reported. References 1. Hochstetter F Uber zwei Falle epithelialer Syngnathie bei menschlichen Keimlingen. Dtsch Med Wochenschr 1948;1081Google Scholar 2. Hoggins GS Aglossia congenital with bony fusion of the jaws. Br J Oral Surg 1969;763- 65Google ScholarCrossref 3. Dobrow B Syndrome identification case report 96: syngnathia and multiple defects. J Clin Dysmorp 1983;15- 7PubMedGoogle Scholar 4. Simpson JRMaves MD Congenital syngnathia or fusion of the gums and jaws. Otolaryngol Head Neck Surg 1985;9396- 99PubMedGoogle Scholar 5. Brown DMMarsh JL Agnathia and associated malformations: a case report. Cleft Palate J 1990;27415- 418Google ScholarCrossref 6. Agrawal KChandra SSSreekumar NS Congenital bilateral intermaxillary bony fusion. Ann Plast Surg 1993;30163- 166PubMedGoogle ScholarCrossref 7. Arshad ARGoh CS Hypoglossia congenita with anterior maxillo-mandibular fusion. Br J Plast Surg 1994;47139- 141Google ScholarCrossref 8. Dawson KHGruss JSMyall RW Congenital bony syngnathia: a proposed classification. Cleft Palate Craniofac J 1997;34141- 146PubMedGoogle ScholarCrossref 9. Ugurlu KTuran TUrganci N et al. Fusion of maxillary and mandibular alveolar process together with a median mandibular cleft: a rare congenital anomaly. J Craniomaxillofac Surg 1999;27105- 108PubMedGoogle ScholarCrossref 10. Yazdi IFakhraee AH Congenital fusion of maxilla and mandible (bony syngnathia): a case report. Arch Iran Med.2000;3. http://pearl.sums.ac.ir/AIM/0033/yazdi0033.html. Accessed: March 30, 2006 Google Scholar 11. Laster ZTemkin DZarfin Y et al. Complete bony fusion of the mandible to the zygomatic complex and maxillary tuberosity: case report and review. Int J Oral Maxillofac Surg 2001;3075- 79PubMedGoogle ScholarCrossref 12. Daniels JS Congential maxillomandibular fusion: a case report and review of the literature. J Craniomaxillofac Surg 2004;32135- 139PubMedGoogle ScholarCrossref 13. Ugurlu KKarsidag SHuthut I et al. Congenital fusion of the maxilla and mandible. J Craniofac Surg 2005;16287- 291PubMedGoogle ScholarCrossref 14. Gartlan MGDavies JSmith RJ Congenital oral synechiae. Ann Otol Rhinol Laryngol 1993;102186- 197PubMedGoogle Scholar 15. Sternberg NSagher UGolan J et al. Congenital fusion of the gums with bilateral fusion of the temporomandibular joints. Plast Reconstr Surg 1983;72385- 387PubMedGoogle ScholarCrossref

Journal

Archives of Otolaryngology–Head & Neck Surgery – American Medical Association

Published: Feb 1, 2007

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