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Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad
ARTICLE IN PRESS
YBJOM-4362; No. of Pages 2
Available online at www.sciencedirect.com
British Journal of Oral and Maxillofacial Surgery xxx (2014) xxx–xxx
Short communication
Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad T. Aldridge ∗ , A. Thomson, V. Ilankovan Poole Hospital NHS Foundation Trust, United Kingdom Accepted 24 September 2014
Abstract The anatomy of the inferior orbital fissure has been well studied, and its reported dimensions vary little. It is encountered during exploration of the orbital floor and when possible is not disturbed. We describe a case of herniation of buccal fat through the inferior orbital fissure that was found during exploration and repair of the orbital floor. © 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.
Keywords: Inferior orbital fissure; Orbital floor fracture; Buccal fat pad
Anatomy The buccal fat pad is an encapsulated mass of specialised fatty tissue. It is located between the buccinator and masseter, and the superficial facial muscles, and allows the masticatory and mimetic muscles to glide. It can be divided into a body and 4 processes, and is fixed by 6 ligaments to the maxilla, posterior zygoma, temporalis tendon, and the inner and outer aspects of the inferior orbital fissure. The inferior orbital fissure transmits the infraorbital and zygomatic branches of the maxillary nerve, the inferior ophthalmic vessels, and orbital branches of the pterygopalatine ganglion. Its length is reported to vary from 25 to 35 mm (mean 29)1 and it lies between the greater wing of the sphenoid bone laterally and the maxillary and palatine bones medially. The anterior margin lies between 6 and 10 mm from the inferior lateral aspect of the infraorbital rim.2,3 Its width has been reported as a mean (SD) of 1.9 mm (1.3)4 to 5 mm anteriorly,
∗
Corresponding author. Tel.: +44 07780682522. E-mail address: t [email protected] (T. Aldridge).
tapering to 2.4 mm posteriorly.1 It communicates inferiorly with the pterygopalatine, infratemporal, and temporal fossas, and the masticator space. In 20 dry skulls of unknown ethnic origin, age and sex, measurements taken (using digital callipers) of the distance from the anterior edge of the infraorbital margin to the anterior edge of the fissure ranged from 11.3 to 23.0 mm (mean 16.1). The widest anterior measurement ranged from 3.05 to 9.32 mm (mean 5.6).
Case report A fit and well 21-year-old man with no previous history of facial trauma presented after an assault. He had sustained a fracture of the left orbital floor and comminuted fractures of the nasal bone. Initial diplopia settled but computed tomography (CT) showed entrapment of the inferior rectus muscle. He was counselled about late onset enophthalmus, and consented to an operation to explore and repair the orbital floor. Exploration through a subciliary incision showed the fracture lateral to the lacrimal groove and medial to the inferior orbital nerve. The trapped muscle was released. Further
http://dx.doi.org/10.1016/j.bjoms.2014.09.020 0266-4356/© 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.
Please cite this article in press as: Aldridge T, et al. Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad. Br J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.bjoms.2014.09.020
YBJOM-4362; No. of Pages 2
2
ARTICLE IN PRESS T. Aldridge et al. / British Journal of Oral and Maxillofacial Surgery xxx (2014) xxx–xxx
Fig. 1. Left orbital floor with alloplastic implant in place.
Fig. 3. Computed tomographic 3-dimensional reconstruction showing abnormal orbital floor defects bilaterally.
Fig. 2. Computed tomogram showing abnormal defect in the orbital floor.
lateral dissection showed herniation of fat into or from a large defect 9 mm from the infraorbital rim. The fat was not related to orbital fat but had a similar morphological structure. Further exploration found that the buccal fat pad had herniated through an abnormal inferior orbital fissure. The edges of the fissure were smooth and were not related to the fractured orbital floor. There was extensive herniation of fat and it was difficult to contain, but it was replaced and the fissure was covered with an alloplastic implant (Fig. 1). The wound was closed and the patient transferred to recovery. Postoperatively, he did not have diplopia or infraorbital paraesthesia. Retrospective review of the CT scan (Figs. 2 and 3) showed the extent of the defect, which had a maximum width of 8.5 mm.
Discussion Management of the inferior orbital fissure is a critical step in the repair of an orbital defect, and is particularly important for the prevention of late onset enophthalmus. The fissure is a linear defect with a reported width of about 5 mm anteriorly, tapering to about 2.4 mm posteriorly.1 In our case the width
was 5.6 mm, and its anterior margin was 16.2 mm from the infraorbital rim. These are consistent with the measurements reported previously. We identified a circular defect with well rounded edges, which was clearly an anatomical abnormality. Herniation of the buccal fat pad into the orbit through the inferior orbital fissure is rare. Morphological studies have shown that this fat is similar to orbital fat,5 and clinically it was confusing. Failure to recognise that it was buccal fat may have led to further mobilisation into the orbit and would have hindered repair of the orbital floor. To our knowledge this is the first reported case of abnormal anatomy of the inferior orbital fissure with herniation of the buccal fat pad.
Conflict of interest We have no conflicts of interest.
Ethics statement/confirmation of patient permission The patient is unavailable to give consent at present.
References 1. De Battista JC, Zimmer LA, Theodosopoulos PV, et al. Anatomy of the inferior orbital fissure: implications of endoscopic cranial base surgery. J Neurol Surg B Skull Base 2012;73:132–8. 2. Balasubramanian T. Anatomy of orbit. Available from URL: http://www.drtbalu.co.in/orbit.html 3. Turvey TA, Golden BA. Orbital anatomy for the surgeon. Oral Maxillofac Surg Clin North Am 2012;24:525–36. 4. Ozer MA, Celik S, Govsa F. A morphometric study of the inferior orbital fissure using three-dimensional anatomical landmarks: application to orbital surgery. Clin Anat 2009;22:649–54. 5. Ilankovan V, Soames JV. Morphometric analysis of orbital, buccal and subcutaneous fats: their potential in the treatment of enophthalmos. Br J Oral Maxillofacial Surg 1995;33:40–2.
Please cite this article in press as: Aldridge T, et al. Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad. Br J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.bjoms.2014.09.020
YBJOM-4362; No. of Pages 2
Available online at www.sciencedirect.com
British Journal of Oral and Maxillofacial Surgery xxx (2014) xxx–xxx
Short communication
Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad T. Aldridge ∗ , A. Thomson, V. Ilankovan Poole Hospital NHS Foundation Trust, United Kingdom Accepted 24 September 2014
Abstract The anatomy of the inferior orbital fissure has been well studied, and its reported dimensions vary little. It is encountered during exploration of the orbital floor and when possible is not disturbed. We describe a case of herniation of buccal fat through the inferior orbital fissure that was found during exploration and repair of the orbital floor. © 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.
Keywords: Inferior orbital fissure; Orbital floor fracture; Buccal fat pad
Anatomy The buccal fat pad is an encapsulated mass of specialised fatty tissue. It is located between the buccinator and masseter, and the superficial facial muscles, and allows the masticatory and mimetic muscles to glide. It can be divided into a body and 4 processes, and is fixed by 6 ligaments to the maxilla, posterior zygoma, temporalis tendon, and the inner and outer aspects of the inferior orbital fissure. The inferior orbital fissure transmits the infraorbital and zygomatic branches of the maxillary nerve, the inferior ophthalmic vessels, and orbital branches of the pterygopalatine ganglion. Its length is reported to vary from 25 to 35 mm (mean 29)1 and it lies between the greater wing of the sphenoid bone laterally and the maxillary and palatine bones medially. The anterior margin lies between 6 and 10 mm from the inferior lateral aspect of the infraorbital rim.2,3 Its width has been reported as a mean (SD) of 1.9 mm (1.3)4 to 5 mm anteriorly,
∗
Corresponding author. Tel.: +44 07780682522. E-mail address: t [email protected] (T. Aldridge).
tapering to 2.4 mm posteriorly.1 It communicates inferiorly with the pterygopalatine, infratemporal, and temporal fossas, and the masticator space. In 20 dry skulls of unknown ethnic origin, age and sex, measurements taken (using digital callipers) of the distance from the anterior edge of the infraorbital margin to the anterior edge of the fissure ranged from 11.3 to 23.0 mm (mean 16.1). The widest anterior measurement ranged from 3.05 to 9.32 mm (mean 5.6).
Case report A fit and well 21-year-old man with no previous history of facial trauma presented after an assault. He had sustained a fracture of the left orbital floor and comminuted fractures of the nasal bone. Initial diplopia settled but computed tomography (CT) showed entrapment of the inferior rectus muscle. He was counselled about late onset enophthalmus, and consented to an operation to explore and repair the orbital floor. Exploration through a subciliary incision showed the fracture lateral to the lacrimal groove and medial to the inferior orbital nerve. The trapped muscle was released. Further
http://dx.doi.org/10.1016/j.bjoms.2014.09.020 0266-4356/© 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.
Please cite this article in press as: Aldridge T, et al. Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad. Br J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.bjoms.2014.09.020
YBJOM-4362; No. of Pages 2
2
ARTICLE IN PRESS T. Aldridge et al. / British Journal of Oral and Maxillofacial Surgery xxx (2014) xxx–xxx
Fig. 1. Left orbital floor with alloplastic implant in place.
Fig. 3. Computed tomographic 3-dimensional reconstruction showing abnormal orbital floor defects bilaterally.
Fig. 2. Computed tomogram showing abnormal defect in the orbital floor.
lateral dissection showed herniation of fat into or from a large defect 9 mm from the infraorbital rim. The fat was not related to orbital fat but had a similar morphological structure. Further exploration found that the buccal fat pad had herniated through an abnormal inferior orbital fissure. The edges of the fissure were smooth and were not related to the fractured orbital floor. There was extensive herniation of fat and it was difficult to contain, but it was replaced and the fissure was covered with an alloplastic implant (Fig. 1). The wound was closed and the patient transferred to recovery. Postoperatively, he did not have diplopia or infraorbital paraesthesia. Retrospective review of the CT scan (Figs. 2 and 3) showed the extent of the defect, which had a maximum width of 8.5 mm.
Discussion Management of the inferior orbital fissure is a critical step in the repair of an orbital defect, and is particularly important for the prevention of late onset enophthalmus. The fissure is a linear defect with a reported width of about 5 mm anteriorly, tapering to about 2.4 mm posteriorly.1 In our case the width
was 5.6 mm, and its anterior margin was 16.2 mm from the infraorbital rim. These are consistent with the measurements reported previously. We identified a circular defect with well rounded edges, which was clearly an anatomical abnormality. Herniation of the buccal fat pad into the orbit through the inferior orbital fissure is rare. Morphological studies have shown that this fat is similar to orbital fat,5 and clinically it was confusing. Failure to recognise that it was buccal fat may have led to further mobilisation into the orbit and would have hindered repair of the orbital floor. To our knowledge this is the first reported case of abnormal anatomy of the inferior orbital fissure with herniation of the buccal fat pad.
Conflict of interest We have no conflicts of interest.
Ethics statement/confirmation of patient permission The patient is unavailable to give consent at present.
References 1. De Battista JC, Zimmer LA, Theodosopoulos PV, et al. Anatomy of the inferior orbital fissure: implications of endoscopic cranial base surgery. J Neurol Surg B Skull Base 2012;73:132–8. 2. Balasubramanian T. Anatomy of orbit. Available from URL: http://www.drtbalu.co.in/orbit.html 3. Turvey TA, Golden BA. Orbital anatomy for the surgeon. Oral Maxillofac Surg Clin North Am 2012;24:525–36. 4. Ozer MA, Celik S, Govsa F. A morphometric study of the inferior orbital fissure using three-dimensional anatomical landmarks: application to orbital surgery. Clin Anat 2009;22:649–54. 5. Ilankovan V, Soames JV. Morphometric analysis of orbital, buccal and subcutaneous fats: their potential in the treatment of enophthalmos. Br J Oral Maxillofacial Surg 1995;33:40–2.
Please cite this article in press as: Aldridge T, et al. Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad. Br J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.bjoms.2014.09.020