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Zygomatic exostosis
Int. J. Ora! Surg, 1983: 12: 124-126 (Key words: hyperplasia. osseous; exostosis: zygoma; coronoid process; surgery, oral)
Zygomatic exostosis THOMAS BOLAND AND O. ROSS BEIRNE Department of Oral Medicine and Hospital Dentistry, Division of Oral and Maxillofacial Surgery, School of Dentistry, University of California San Francisco San Francisco, California, USA
ABSTRACT - This report describes a rare case of restricted mandibular opening caused by zygomatic exostosis and hyperplasia of the coronoid process. Computed tomography revealed the presence of a pseudojoint between the exostosis and the enlarged coronoid process; the bony restriction was surgically removed through an intraoral approach. Only 3 similar cases have been reported in the literature.
(Received for publication II August. accepted 10 October 1982)
The patient with restricted mandibular movement can present a difficult diagnostic problem. Limited mandibular movement can be caused by abnormalities in the temporomandibular joint, the muscles of mastication, or the bones or soft tissues surrounding the mandible I -14. This report describes a case of restricted mandibular movement caused by an exostosis from the left zygoma and hyperplasia of the left coronoid process. The patient presented in this report had a unique problem that resembled only 3 other cases described in the literature"•. Computed tomography clearly demonstrated the patient's anatomical abnormality, which was surgically corrected.
Case report A 25-year-old man was referred to the University of California, San Francisco for evaluation of trismus. He had a lO-year history of progressively worsening trismus without pain. He had no history of man-
dibular or maxillary facial fractures and was unable to associate the onset of symptoms with a specific event. At the time of examination, he had a maximum interincisal opening of I em. The right and left condyles moved a small amount in all directions, and the mandible deviated to the right on maximal opening. He had a Class I occlusion and the jaws were normally developed. The dentition was in poor repair, but there was no evidence of acute infection. Radiographic examination included a panographic radiograph, open and closed radiographs of the temporomandibular joint, posterioanterior views of the head, and right and left temporomandibular joint tornographs. The only abnormality was a flattened left condyle with no bony ankylosis (Fig. 1). Because radiography demonstrated no obvious cause for the restricted opening, the temporomandibular joint and surrounding tissues were evaluated by computed tomography. Axial scans using high-resolution review imaging demonstrated a bony exostosis extending from the medial surface of the left zygomatic arch and an enlarged left coronoid process (Fig. 2). There appeared to be soft tissue connecting the exostosis and the coronoid process (Fig. 3). The right zygomatic arch and coronoid process appeared normal (Figs. 2, 3). The patient was admitted to the hospital, and routine history, physical and laboratory examination
ZYGOMATIC EXOSTOSIS
125
weeks after surgery, revealed some restriction of mandibular motion, with a maximum interincisal opening of approximately 2.5 em. Histological examination of the biopsy specimen revealed normal bone with medullary fibrosis.
Discussion
gaveresultswithinnormal limits. He wastaken to the operating room where, under general anesthesia, an intraoral approach over the anterior border of the mandibular ramus was used to perform left and right coronoidectomies - together yielding a maximum interincisalopeningofabout 4.5em- and to removea portion of the zygomatic exostosis for biopsy. The main portion of the exotosis was inaccessible and could not be completely removed without risk of severe hemorrhage, so was left in place pending outcome of the biopsy. Several non-restorable teeth were also removed. 24 h after surgery, the patient's maximum interincisal opening was 2 em. He wasplacedon an active physical therapy program. Follow-up evaluation 8
Restricted mandibular opening from interferences outside the temporomandibular joint can be caused by trauma, unilateral or bilateral hyperplasia of the coronoid process, ankylosis of the coronoid process to the zygomatic arch, presence of a foreign body, infections in the infratemporal space, or neoplasia ,- 3,5,7 -!4. Unilateral hyperplasia of the coronoid process is usually associated with an osteochondroma", Bilateral alterations are commonly developmental in origin",12. A fractured coronoid process can be displaced and ankylose to the zygoma, while a fractured zygomatic arch can hinder movement ofthe mandible by interfering with movement of the coronoid process':", This case report describes an unusual extraarticular bone growth that inhibited mandibular movement. A comprehensive search of the literature revealed only 3 similar cases':". JACOB" described a post-mortem dissection in a 62-year-old male with a maximal incisal opening of2 em. The patient had a bony exostosis on the medial surface of the zygomatic arch with a
Fig. 2. Computerized tomograph demonstrating exostosis from medial portion of left zygoma and enlarged left coronoid.
Fig. 3. Computerized tomograph demonstrating soft tissue connecting zygomatic exostosis with left coronoid process (arrow).
Fig. 1. Tomograph of left temporomandibular joint demonstrating flattened condylar head.
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BOLAND AND BEIRNE
false joint between a normal-sized coronoid process and the exostosis. The maxillary sinus was also diminished in size. The diagnosis in 1899 could only be made by post-mortem dissection. In 1958, BERCHER4 presented 2 cases of restricted mandibular movement caused by a zygomatic exostosis associated with a coronoid abnormality. By means of tomography, the coronoid abnormality was noted and corrected surgically. The trismus described in this report was relieved by doing left and right coronoidectomies through an intraoral approach. This approach was used because it is better cosmetically and less likely to cause damage to nerves or vessels than an extraoral approach. The specifics of this approach have been reviewed
previously':'. Routine radiographic examination of the patient described in this report failed to reveal the zygomatic exostosis. However, computed tomography demonstrated the anatomical abnormality clearly. The difficulties in diagnosing restriction of mandibular movement caused by coronoid and zygomatic abnormalities can be significantly reduced with the use of computed tomography.
References I. ALLIsON, M. L., WALLACE, W. R. & VON WYL, H.; Coronoid abnormalities causing limitation of mandibular movement. J. Oral Surg. 1969: 27: 229-233. 2. ALLAN, I. M. B. & REID, W. H.: Unilateral exostosis of the coronoid process of the mandible: a report of 2 cases. Br. J. Oral Surg, 1969; 5; 2Q....24. 3. ARCHER, W. H.: Oral and maxillofacial surgery, 5th edition. W. B. Saunders Company, Philadelphia 1975,pp. 1045-1061.
4. BERCHER, J.: La maladie de O. Jacob. Exostose du malaire et anamolie de l'apophyse coronoide. Cah.Odontostomatol. 1958: 8: 17-33. 5. GRIDLEY, M. S,: Abnormal bony connections between the skull and the mandible. Oral Surg, 1954; 7; 954-959. 6. JACOB, O. : Un cas de constriction permanente des machoires. Bulletins et Memoires de la Societe d'Anatomie de Paris. 1899. 7. JAVID, B.: Unilateral hyperplasia of the coronoid process of the mandible. Int. J. Oral Surg, 1981; 10: 145-147. 8. MEYER, R. A.: Osteochondroma of coronoid process of mandible; report of case. J. Oral Surg, 1972: 30; 297-300. 9. MOHNAC, A. M.: Bilateral coronoid osteochondromas. J. Oral Surg. 1962: 20: 50Q....506. 10. REVZIN, M. & MONACO, F.: Persistent trismus caused by a foreign body; report of 2 cases. J, Oral Surg. 1956: 14: 243-246. 11. ROWE, N. L.: Bilateral developmental hyperplasia of the mandibular coronoid process: a report of 2 cases. Br. J. Oral Surg, 1963: 1; 9Q.... 104. 12. RUSCONI, L. & BRUSATI, R.: Restricted opening of the mouth from symmetrical bilateral hyperplasia of the coronoid processes. J. Oral Surg. 1974: 32: 452-456. 13. SCHWARTZ, H. C. & KAGAN, A. R.: Zygomaticcoronoid ankylosis secondary to heterotopic bone formation: combined treatment by surgery and radiation therapy - a case report. J. Maxillofac. Surg. 1979: 7: 158-161. 14. TROYER, S. H.; Ankylosis of the coronoid process of the mandible to the zygomatic arch subsequent to the surgical correction of prognathism; case report. J. Hasp. Dent. Prac. 1971: 5; 19-34.
Address; O. Ross Beirne School of Dentistry Division of Oral and Maxillofacial Surgery, 8653 University of California, San Francisco San Francisco, California 94143 USA
Zygomatic exostosis THOMAS BOLAND AND O. ROSS BEIRNE Department of Oral Medicine and Hospital Dentistry, Division of Oral and Maxillofacial Surgery, School of Dentistry, University of California San Francisco San Francisco, California, USA
ABSTRACT - This report describes a rare case of restricted mandibular opening caused by zygomatic exostosis and hyperplasia of the coronoid process. Computed tomography revealed the presence of a pseudojoint between the exostosis and the enlarged coronoid process; the bony restriction was surgically removed through an intraoral approach. Only 3 similar cases have been reported in the literature.
(Received for publication II August. accepted 10 October 1982)
The patient with restricted mandibular movement can present a difficult diagnostic problem. Limited mandibular movement can be caused by abnormalities in the temporomandibular joint, the muscles of mastication, or the bones or soft tissues surrounding the mandible I -14. This report describes a case of restricted mandibular movement caused by an exostosis from the left zygoma and hyperplasia of the left coronoid process. The patient presented in this report had a unique problem that resembled only 3 other cases described in the literature"•. Computed tomography clearly demonstrated the patient's anatomical abnormality, which was surgically corrected.
Case report A 25-year-old man was referred to the University of California, San Francisco for evaluation of trismus. He had a lO-year history of progressively worsening trismus without pain. He had no history of man-
dibular or maxillary facial fractures and was unable to associate the onset of symptoms with a specific event. At the time of examination, he had a maximum interincisal opening of I em. The right and left condyles moved a small amount in all directions, and the mandible deviated to the right on maximal opening. He had a Class I occlusion and the jaws were normally developed. The dentition was in poor repair, but there was no evidence of acute infection. Radiographic examination included a panographic radiograph, open and closed radiographs of the temporomandibular joint, posterioanterior views of the head, and right and left temporomandibular joint tornographs. The only abnormality was a flattened left condyle with no bony ankylosis (Fig. 1). Because radiography demonstrated no obvious cause for the restricted opening, the temporomandibular joint and surrounding tissues were evaluated by computed tomography. Axial scans using high-resolution review imaging demonstrated a bony exostosis extending from the medial surface of the left zygomatic arch and an enlarged left coronoid process (Fig. 2). There appeared to be soft tissue connecting the exostosis and the coronoid process (Fig. 3). The right zygomatic arch and coronoid process appeared normal (Figs. 2, 3). The patient was admitted to the hospital, and routine history, physical and laboratory examination
ZYGOMATIC EXOSTOSIS
125
weeks after surgery, revealed some restriction of mandibular motion, with a maximum interincisal opening of approximately 2.5 em. Histological examination of the biopsy specimen revealed normal bone with medullary fibrosis.
Discussion
gaveresultswithinnormal limits. He wastaken to the operating room where, under general anesthesia, an intraoral approach over the anterior border of the mandibular ramus was used to perform left and right coronoidectomies - together yielding a maximum interincisalopeningofabout 4.5em- and to removea portion of the zygomatic exostosis for biopsy. The main portion of the exotosis was inaccessible and could not be completely removed without risk of severe hemorrhage, so was left in place pending outcome of the biopsy. Several non-restorable teeth were also removed. 24 h after surgery, the patient's maximum interincisal opening was 2 em. He wasplacedon an active physical therapy program. Follow-up evaluation 8
Restricted mandibular opening from interferences outside the temporomandibular joint can be caused by trauma, unilateral or bilateral hyperplasia of the coronoid process, ankylosis of the coronoid process to the zygomatic arch, presence of a foreign body, infections in the infratemporal space, or neoplasia ,- 3,5,7 -!4. Unilateral hyperplasia of the coronoid process is usually associated with an osteochondroma", Bilateral alterations are commonly developmental in origin",12. A fractured coronoid process can be displaced and ankylose to the zygoma, while a fractured zygomatic arch can hinder movement ofthe mandible by interfering with movement of the coronoid process':", This case report describes an unusual extraarticular bone growth that inhibited mandibular movement. A comprehensive search of the literature revealed only 3 similar cases':". JACOB" described a post-mortem dissection in a 62-year-old male with a maximal incisal opening of2 em. The patient had a bony exostosis on the medial surface of the zygomatic arch with a
Fig. 2. Computerized tomograph demonstrating exostosis from medial portion of left zygoma and enlarged left coronoid.
Fig. 3. Computerized tomograph demonstrating soft tissue connecting zygomatic exostosis with left coronoid process (arrow).
Fig. 1. Tomograph of left temporomandibular joint demonstrating flattened condylar head.
126
BOLAND AND BEIRNE
false joint between a normal-sized coronoid process and the exostosis. The maxillary sinus was also diminished in size. The diagnosis in 1899 could only be made by post-mortem dissection. In 1958, BERCHER4 presented 2 cases of restricted mandibular movement caused by a zygomatic exostosis associated with a coronoid abnormality. By means of tomography, the coronoid abnormality was noted and corrected surgically. The trismus described in this report was relieved by doing left and right coronoidectomies through an intraoral approach. This approach was used because it is better cosmetically and less likely to cause damage to nerves or vessels than an extraoral approach. The specifics of this approach have been reviewed
previously':'. Routine radiographic examination of the patient described in this report failed to reveal the zygomatic exostosis. However, computed tomography demonstrated the anatomical abnormality clearly. The difficulties in diagnosing restriction of mandibular movement caused by coronoid and zygomatic abnormalities can be significantly reduced with the use of computed tomography.
References I. ALLIsON, M. L., WALLACE, W. R. & VON WYL, H.; Coronoid abnormalities causing limitation of mandibular movement. J. Oral Surg. 1969: 27: 229-233. 2. ALLAN, I. M. B. & REID, W. H.: Unilateral exostosis of the coronoid process of the mandible: a report of 2 cases. Br. J. Oral Surg, 1969; 5; 2Q....24. 3. ARCHER, W. H.: Oral and maxillofacial surgery, 5th edition. W. B. Saunders Company, Philadelphia 1975,pp. 1045-1061.
4. BERCHER, J.: La maladie de O. Jacob. Exostose du malaire et anamolie de l'apophyse coronoide. Cah.Odontostomatol. 1958: 8: 17-33. 5. GRIDLEY, M. S,: Abnormal bony connections between the skull and the mandible. Oral Surg, 1954; 7; 954-959. 6. JACOB, O. : Un cas de constriction permanente des machoires. Bulletins et Memoires de la Societe d'Anatomie de Paris. 1899. 7. JAVID, B.: Unilateral hyperplasia of the coronoid process of the mandible. Int. J. Oral Surg, 1981; 10: 145-147. 8. MEYER, R. A.: Osteochondroma of coronoid process of mandible; report of case. J. Oral Surg, 1972: 30; 297-300. 9. MOHNAC, A. M.: Bilateral coronoid osteochondromas. J. Oral Surg. 1962: 20: 50Q....506. 10. REVZIN, M. & MONACO, F.: Persistent trismus caused by a foreign body; report of 2 cases. J, Oral Surg. 1956: 14: 243-246. 11. ROWE, N. L.: Bilateral developmental hyperplasia of the mandibular coronoid process: a report of 2 cases. Br. J. Oral Surg, 1963: 1; 9Q.... 104. 12. RUSCONI, L. & BRUSATI, R.: Restricted opening of the mouth from symmetrical bilateral hyperplasia of the coronoid processes. J. Oral Surg. 1974: 32: 452-456. 13. SCHWARTZ, H. C. & KAGAN, A. R.: Zygomaticcoronoid ankylosis secondary to heterotopic bone formation: combined treatment by surgery and radiation therapy - a case report. J. Maxillofac. Surg. 1979: 7: 158-161. 14. TROYER, S. H.; Ankylosis of the coronoid process of the mandible to the zygomatic arch subsequent to the surgical correction of prognathism; case report. J. Hasp. Dent. Prac. 1971: 5; 19-34.
Address; O. Ross Beirne School of Dentistry Division of Oral and Maxillofacial Surgery, 8653 University of California, San Francisco San Francisco, California 94143 USA