Surg Radiol Anat DOI 10.1007/s00276-014-1284-8
Original Article
Surgical anatomy of the preauricular anteroparotid approach for mandibular condyle surgery Mathieu Laurentjoye · Alice Veyret · Bruno Ella · André Pierre Uzel · Claire Majoufre‑Lefebvre · Philippe Caix · Anne Sophie Ricard
Received: 24 May 2013 / Accepted: 25 February 2014 © Springer-Verlag France 2014
Abstract Purpose The different surgical approaches used to treat mandibular condyle fractures are carried out in the periparotid skin area and can lead to facial nerve injury. We conducted a preauricular and anteroparotid surgical approach. Our main aim was to show the anatomical relationship between this approach site and the facial nerve branches, and to define cutaneous landmarks to locate the extraparotid facial nerve branches. Method A 2-step dissection of 13 fresh human cadaver semi-heads was performed: a preauricular approach followed by a superficial parotidectomy to visualize the facial nerve. Its course and ramifications were studied and compared to cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed. Results The approach allowed systematically visualising the zygomatic and/or buccal branches. No facial nerve branches were sectioned. In three cases (23 %), a nerve branch was visualized during the approach. The buccal and zygomatic branches were ramified in 77 % of cases. Conclusions During our preauricular anteroparotid approach, the buccal and zygomatic branches were visualized but none was sectioned. Most often the approach was carried out between these two branches (46 % of cases). Cutaneous landmarks used were reliable to define a safe
M. Laurentjoye (*) · B. Ella · A. P. Uzel · P. Caix Medico‑Surgical Anatomy Unit, Bordeaux Ségalen University, 33076 Bordeaux Cedex, France e-mail: [email protected]; Mathieu.laurentjoye@ chu‑bordeaux.fr M. Laurentjoye · A. Veyret · C. Majoufre‑Lefebvre · P. Caix · A. S. Ricard Maxillo Facial Surgery Department, Bordeaux University Hospital, FX Michelet Centre, Pellegrin Hospital, CHU Bordeaux, 33076 Bordeaux Cedex, France
and nerve-free area for dissection. The buccal and zygomatic branches are very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion. Keywords Mandibular fractures · Mandibular condyle · Internal fracture fixation · Facial nerve injury · Facial trauma · Facial nerve anatomy
Introduction Condylar fractures represent 35 % of mandibular fractures. Their treatment can vary depending on surgical teams [1, 7, 18]. Different surgical approaches have been described for their treatment. The Risdon submandibular approach [15], modified by Meyer [12], is the most used in France [18] because it enables a good surgical exposure and is at low risk for the facial nerve. Other approaches can be used, such as the retromandibular transparotid approach described by Hinds [10] and miniaturised by Chossegros et al. [5], the Risdon low submandibular approach [15], the Eckelt preauricular approach [6], intraoral approach or endoscopy (not often used because it requires special equipment and is a difficult technique). The different cutaneous approaches used to access the condyle enter through the periparotid area, where they can lead to direct facial nerve injury or nerve elongation in about 37 % of cases [21]. The extracranial part of the facial nerve begins in the stylomastoid foramen and terminates in the facial muscles where it is involved in their motricity. In the parotid gland, the facial nerve can divide into two or three branches, and terminates into five ramifications: temporal, zygomatic, buccal, mandibular and cervical. Surgical approaches used
13
Surg Radiol Anat
for the treatment of condylar fractures involve frequently the mandibular branch which runs along the mandibular corpus and can be visualized during surgery. It is a fragile branch with a few anastomoses and ramifications [20]. In 2012, Narayanan has published a clinical study describing a retromandibular incision with a preauricular extension and an anteroparotid approach to treat condylar fractures [13]. The rationale for this approach was the presence of a “nerve free window between buccal and marginal mandibular branches of facial nerve” at the anterior edge of the parotid, where they tend to diverge after a course along the intraparotid facial nerve. He has observed no nerve injury with satisfactory healing. We studied anatomically a preauricular and anteroparotid surgical approach. The main aim was to show the anatomical relationship between the approach site and the extracranial facial nerve branches. The secondary aim was to define cutaneous landmarks to locate the extraparotid facial nerve branches.
Materials and methods
Fig. 1 Cutaneous landmarks delineating the zygomatic and buccal facial nerve branches
Five fresh human cadaver heads and three fresh hemi-heads were dissected. There were five women and three men, with an average age of 77 years. All the dissections and measurements were performed by the same surgeon. Cutaneous landmarks for buccal and zygomatic branches were obtained from several anatomical studies [16, 17], and used in association with landmarks already known for temporal and mandibular branches [2, 3]. Before the dissection, cutaneous landmarks were placed to delineate two areas (Figs. 1, 2): –– for the buccal branch, a line from the Tragus to the upper border of the Vermilion (TV), corresponding to the theoretical course of the parotid duct, and a line from the Tragus to the corner of the Lips (TL) to isolate the lower lip and the mandibular branch [16] –– for the zygomatic branch, a line from the Tragus to the external Canthus (TC) to isolate the upper eyelid and the temporal branch, and a line from the Tragus to the Ala Nasi (TN) as a lower limit [17]. Thirteen two-step dissections were performed: a preauricular condylar approach then a superficial parotidectomy to identify the ramifications of the extracranial facial nerve.
Fig. 2 Left lateral schematic view of the CI cutaneous incision carried out during the P preauricular anteroparotid approach. Landmarks can be seen as TC tragus external canthus, TN tragus-ala nasi, TV tragus-upper border fo the vermilion and TL tragus-lip corner lines. We also notice their relationship with the facial nerve branches: fb frontal, zb zygomatic, bb buccal, mb marginal and cb cervical branches
Preauricular anteroparotid approach to the condyle (Fig. 3) A 5–6-cm incision was made from the helix root to the earlobe. A subcutaneous dissection was achieved anteriorly in a 4-cm area. The parotid fascia was incised. Then, the
13
dissection was carried out deeper on the anterior side of the parotid. An atraumatic retractor was placed to move the parotid back and identify the masseter aponeurosis. After passing through this aponeurosis, the muscle was dissected
Surg Radiol Anat
Fig. 3 Schematic preauricular anteroparotid approach to the condyle at the ear level, showing the pre-auricular, subcutaneous and then anteroparotid (P) and transmassteric (MM) dissections carried out to reach the bone. Note the section of the lateral pterygoid muscle (LPM) and the medial pterygoid muscle (MPM)
along the longitudinal fibres, to reach the bone. The muscle was sectioned backwards to visualise the posterior edge of the ramus and simulate osteosynthesis.
branches were sectioned during the procedures. No other facial nerve branches were visualised. The results in Table 1 show the relationship between the facial nerve and the surgical approach site. In 3 out of the 13 cases (23 %), a nerve branch was visualized during the approach. In the ten remaining cases, no ramifications were observed during the surgical approach. The surgical approach was carried out between the zygomatic and buccal branches in six cases (46 %), in contact with the ramifications of the zygomatic and buccal branches in five (39 %) and two cases (15 %), respectively. The mandibular and temporal branches were never involved. Regarding the zygomatic branch anatomy, the nerve course passed along the TN line in nine cases (69 %), between the TN and TC lines in three cases (23 %) and along the TC line in one case (8 %) (Table 2). The zygomatic branch had no ramification in three cases, a bifurcation (Z1, Z2) in eight cases and a trifurcation (Z3) in two cases. Regarding the buccal branch anatomy, the nerve course passed along the TV line in four cases (31 %), between the TV and TL lines in one case (8 %) and along the TL line in four cases (31 %). In four cases (31 %), the branch was identified outside of these lines (one case above the TV line and three cases under the TL line) (Table 3). The buccal branch had no ramification in three cases, a bifurcation (B1, B2) in five cases and a trifurcation (B3) in five cases.
Superficial parotidectomy
Discussion
The cervical incision was extended behind the earlobe and along the anterior edge of the sternocleidomastoid muscle. The facial nerve trunk was identified after subperichondral dissection of the tragus and identification of the posterior belly of the digastric. The facial nerve ramifications were entirely dissected using systematic superficial parotidectomy. The distribution of the facial nerve was studied and compared to the cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed: once the parotidectomy was completed, the mandibular (M), buccal (B), zygomatic (Z) and temporal (T) branches were identified, and their ramifications were marked (B1, B2 and B3; Z1, Z2 and Z3; T and M). We then studied the distance between these branches and the surgical approach site and if they had been sectioned during the procedure.
Our anatomical study has shown that the facial nerve branches visualised during our preauricular anteroparotid approach to the condyle were the buccal and zygomatic branches. The TC and TN lines seemed to be reliable landmarks for the zygomatic branch, whereas the buccal branch course was more variable along the TV and TL lines. Many approaches can be used to treat mandibular condyle fractures. The most used approach nowadays is the modified Risdon approach described by Meyer in 2006, which is really safe for the facial nerve [11] and allows a good surgical access to the condyle. Other approaches can be used, including the retromandibular approach [5], the low submandibular Risdon approach [15] or the preauricular transmasseteric approach recently described by Wilson [19]. Narayanan [13] has described an anteroparotid approach to treat condyle fractures which entered through a “nerve free window between buccal and marginal mandibular branches of facial nerve” at the anterior edge of the parotid where they tended to diverge, whereas they were very close in the parotid. In 7 % of cases, the buccal branch was seen during the approach.
Results The approach used for the 13 dissections allowed visualising the zygomatic and/or buccal branches. No facial nerve
13
13 No
Yes (B2)
Within BB
3 Left
TL course
3
Buccal branch landmarks
Divisions
1 Left
1
TL course
2 Left
3
Above TV
3 Left
Table 3 Course and divisions of the buccal branch
1
3
2
Divisions
3 Left
Between TC course TC and TN
2 Left
No
No No
No
2
Under TL
3 Right
2
No
2
Between TV and TL
4 Left
1
No
No
2
1
3
TV course
4 Right
No
No
2
Under TL
5 Left
2
No
No
2
Under TL
6 Right
No
No
Within BB
6 Right
7 Left
No
No
Within BZ
7 Left
7 Right
No
No
Within BZ
7 Right
8 Left
No
No
Within BZ
8 Left
2
2
TV course
6 Left
2
3
TV course
6 Right
3
1
TL course
7 Left
1
TL course
7 Right
2
2
3
TV course
8 Left
TN course TN course Between TN course TN course TC And TN
6 Left
Between BZ and BB
6 Left
5 Right
TN course
5 Right
Between BZ and BB
5 Right
TN course
5 Left
Between BZ and BB
5 Left
TN course
4 Right
Yes (Z2)
Within BZ
4 Right
Between TC and TN
4 Left
Between BZ and BB
4 Left
TN course
3 Right
Between BZ and BB
3 Right
Zygomatic branch TN course landmarks
1 Left
Table 2 Course and divisions of the zygomatic branch
No
Branch section No
Within BZ
No
Between BZ and BB
2 Left
Branch within Yes (Z2) the approach
Approach/ branches
1 Left
Table 1 Relationship between the preauricular anteroparotid approach site and the facial nerve
Surg Radiol Anat
Surg Radiol Anat
He has carried out a preauricular and retromandibular incision below the area where we performed our incision. We limited the procedure to a preauricular incision to hide the scar in a skin fold. During the approach, the zygomatic branch was identified twice and the buccal branch once. Most often, the approach was carried out between these two branches (46 % of cases). During our dissections, no nerves were damaged as previously shown in the clinical study by Narayanan. Clinically, our approach seemed reliable. This result could probably be explained by the numerous ramifications of the buccal and zygomatic branches, as confirmed in the literature. Saylam in 2006 [16] has reported that 55 % of buccal branches had two ramifications, 18 % had three ramifications and the 27 % had a plexiform anatomy. In 2006, the same author has studied the zygomatic branch of 66 facial nerves and confirmed that most nerves had divisions, only 4.5 % of branches lacking ramifications [17]. As a result, this branch was more robust and less vulnerable than other branches with fewer ramifications such as the temporal and mandibular branches [2, 3]. We found in our study that these branches had at least two ramifications in 10 out of the 13 cases. The robustness of the buccal and zygomatic branches could be explained by the numerous anastomoses with each other found in 65–100 % of cases in the literature [4, 19]. In 2005, Farooq [8] conducted an anatomical study in 57 specimens and a literature review to discuss his results on the facial nerve anatomy. In 65 % of the cases, when considering the zygomatic and buccal branches, anastomoses were found between the temporo- and cervicofacial branches. The temporal and mandibular branches had a few connections with the other branches. The zygomatic and buccal branches were therefore likely to be more robust than the mandibular branch where anastomoses were only observed in 15 % of cases [9]. The branches concerned by this anatomical study were thus very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion. Cutaneous landmarks for the facial nerve have often been described for mandibular and temporal branches [2, 3]. However, the anatomy of the buccal and zygomatic branches is less reliable with no precise description. We aimed to define cutaneous landmarks, to predict their courses. During our anatomical study, we have defined TC, TN, TV and TL lines, which could be used as cutaneous landmarks, to delineate the area where the facial nerve branches pass.
Landmarks TC and TN seemed reliable to locate the zygomatic branch which was systematically found between these lines. Saylam [17] has shown that the zygomatic branch was systematically located under a line passing from the tragus to the external canthus, which corresponds to our TC line. This branch course was thus relatively constant. Landmarks TV and TL seemed less reliable to locate the buccal branch. Pogrel [14] has described the buccal branch and its relationship with the parotid duct whose anatomical location is constant and mostly vertical, passing from the tragus to the top of the vermilion (TV line). The buccal branch was located under this line in 75 % of the cases, and was always observed at less than 1 cm from the duct, as in our results (62 %). The buccal branch was only observed once between the TV and TN lines in our study, which makes this area the safest site for dissection. In conclusion, our study has shown that mandibular condyle fractures can be treated with an anteroparotid approach with a simple preauricular incision, without retromandibular wound extension. Compared to Narayanan’s study, our dissection was also performed at the anterior edge of the parotid gland, but in the upper region. This author has shown the clinical safety of this technique. The approach described in our study allowed systematically visualising the buccal and zygomatic facial nerve branches. It should be noted that these nerve branches are more robust than the mandibular branch, as explained by Meyer in his description of the modified Risdon submandibular approach. Furthermore, the delineated preauricular incision makes the scars very discreet while allowing a perfect view of the mandibular condyle for osteosynthesis. Finally, the TV and TN lines are good cutaneous landmarks and the risk of sectioning the facial nerve branches is reduced when surgery is carried out between both lines. We therefore propose this approach as a good alternative to the excellent Risdon modified approach. It seems perfectly adapted to high subcondylar fractures when surgical osteosynthesis is indicated. The scar is well hidden so that the patient has no aesthetic concerns after surgery. A clinical study is ongoing to assess the efficacy of this approach for the treatment of upper mandibular condyle fractures. Conflict of interest The authors declare that they have no conflict of interest.
References 1. Abdel-Galil K, Loukota R (2010) Fractures of the mandibular condyle: evidence base and current concepts of management. Br J Oral Maxillofac Surg 48(7):520–526
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2. Babakurban ST, Cakmak O, Kendir S, Elhan A, Quatela VC (2010) Temporal branch of the facial nerve and its relationship to fascial layers. Arch Facial Plast Surg 12(1):16–23 3. Basar R, Sargon MF, Tekdemir Y, Elhan A (1997) The marginal mandibular branch of the facial nerve. Surg Radiol Anat 19(5):311–314 4. Bernstein L, Nelson RH (1984) Surgical anatomy of the extraparotid distribution of the facial nerve. Arch Otolaryngol 110(3):177–183 5. Chossegros C, Cheynet F, Blanc JL, Bourezak Z (1996) Short retromandibular approach of subcondylar fractures: clinical and radiologic long-term evaluation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 82(3):248–252 6. Eckelt U, Gerber S (1981) Draw-screw osteosynthesis with a novel osteosynthesis instrument set in mandibular condyle fractures. Zahn Mund Kieferheilkd Zentralbl 69(6):485–490 7. Eckelt U, Schneider M, Erasmus F, Gerlach KL, Kuhlisch E, Loukota R, Rasse M, Schubert J, Terheyden H (2006) Open versus closed treatment of fractures of the mandibular condylar process-a prospective randomized multi-centre study. J Craniomaxillofac Surg 34(5):306–314 8. Farooq A, Riaz A, Nabila K (2005) Facial Nerve; pattern of distribution in the parotid gland. In: The professional medical journal. http://www.theprofesional.com/vol-12-no-01/. Accessed 18 May 2013 9. Gosain AK (1995) Surgical anatomy of the facial nerve. Clin Plast Surg 22(2):241–251 10. Hinds EC, Girotti WJ (1967) Vertical subcondylar osteotomy: a reappraisal. Oral Surg Oral Med Oral Pathol 24(2):164–170 11. Lutz J-C, Clavert P, Wolfram-Gabel R, Wilk A, Kahn J-L (2010) Is the high submandibular transmasseteric approach to the
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Surg Radiol Anat mandibular condyle safe for the inferior buccal branch? Surg Radiol Anat 32(10):963–969 12. Meyer C, Zink S, Wilk A (2006) Modified Risdon approach for the treatment of subcondylar fractures of the mandible. Rev Stomatol Chir Maxillofac 107(6):449–454 13. Narayanan V, Ramadorai A, Ravi P, Nirvikalpa N (2012) Transmasseteric anterior parotid approach for condylar fractures: experience of 129 cases. Br J Oral Maxillofac Surg 50(5):420–424 14. Pogrel MA, Schmidt B, Ammar A (1996) The relationship of the buccal branch of the facial nerve to the parotid duct. J Oral Maxillofac Surg 54(1):71–73 15. Risdon F (1934) Ankylosis of the temporomaxillary joint. J Am Dent Assoc 21:1933–1937 16. Saylam C, Ucerler H, Orhan M, Ozek C (2006) Anatomic landmarks of the buccal branches of the facial nerve. Surg Radiol Anat 28(5):462–467 17. Saylam C, Ucerler H, Orhan M, Ozek C (2006) Anatomic guides to precisely localize the zygomatic branches of the facial nerve. J Craniofac Surg 17(1):50–53 18. Trost O, Péron J-M (2013) Latest trends in the surgi cal management of mandibular condyle fractures in France, 2005–2012. Rev Stomatol Chir Maxillofac Chir Orale. doi:10.1016/j.revsto.2013.05.004 19. Wilson AW, Ethunandan M, Brennan PA (2005) Transmasseteric antero-parotid approach for open reduction and internal fixation of condylar fractures. Br J Oral Maxillofac Surg 43(1):57–60 20. Woltmann M, de Faveri R, Sgrott EA (2006) Anatomosurgical study of the marginal mandibular branch of the facial nerve for submandibular surgical approach. Braz Dent J 17(1):71–74 21. Zide MF, Kent JN (1983) Indications for open reduction of mandibular condyle fractures. J Oral Maxillofac Surg 41(2):89–98
Original Article
Surgical anatomy of the preauricular anteroparotid approach for mandibular condyle surgery Mathieu Laurentjoye · Alice Veyret · Bruno Ella · André Pierre Uzel · Claire Majoufre‑Lefebvre · Philippe Caix · Anne Sophie Ricard
Received: 24 May 2013 / Accepted: 25 February 2014 © Springer-Verlag France 2014
Abstract Purpose The different surgical approaches used to treat mandibular condyle fractures are carried out in the periparotid skin area and can lead to facial nerve injury. We conducted a preauricular and anteroparotid surgical approach. Our main aim was to show the anatomical relationship between this approach site and the facial nerve branches, and to define cutaneous landmarks to locate the extraparotid facial nerve branches. Method A 2-step dissection of 13 fresh human cadaver semi-heads was performed: a preauricular approach followed by a superficial parotidectomy to visualize the facial nerve. Its course and ramifications were studied and compared to cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed. Results The approach allowed systematically visualising the zygomatic and/or buccal branches. No facial nerve branches were sectioned. In three cases (23 %), a nerve branch was visualized during the approach. The buccal and zygomatic branches were ramified in 77 % of cases. Conclusions During our preauricular anteroparotid approach, the buccal and zygomatic branches were visualized but none was sectioned. Most often the approach was carried out between these two branches (46 % of cases). Cutaneous landmarks used were reliable to define a safe
M. Laurentjoye (*) · B. Ella · A. P. Uzel · P. Caix Medico‑Surgical Anatomy Unit, Bordeaux Ségalen University, 33076 Bordeaux Cedex, France e-mail: [email protected]; Mathieu.laurentjoye@ chu‑bordeaux.fr M. Laurentjoye · A. Veyret · C. Majoufre‑Lefebvre · P. Caix · A. S. Ricard Maxillo Facial Surgery Department, Bordeaux University Hospital, FX Michelet Centre, Pellegrin Hospital, CHU Bordeaux, 33076 Bordeaux Cedex, France
and nerve-free area for dissection. The buccal and zygomatic branches are very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion. Keywords Mandibular fractures · Mandibular condyle · Internal fracture fixation · Facial nerve injury · Facial trauma · Facial nerve anatomy
Introduction Condylar fractures represent 35 % of mandibular fractures. Their treatment can vary depending on surgical teams [1, 7, 18]. Different surgical approaches have been described for their treatment. The Risdon submandibular approach [15], modified by Meyer [12], is the most used in France [18] because it enables a good surgical exposure and is at low risk for the facial nerve. Other approaches can be used, such as the retromandibular transparotid approach described by Hinds [10] and miniaturised by Chossegros et al. [5], the Risdon low submandibular approach [15], the Eckelt preauricular approach [6], intraoral approach or endoscopy (not often used because it requires special equipment and is a difficult technique). The different cutaneous approaches used to access the condyle enter through the periparotid area, where they can lead to direct facial nerve injury or nerve elongation in about 37 % of cases [21]. The extracranial part of the facial nerve begins in the stylomastoid foramen and terminates in the facial muscles where it is involved in their motricity. In the parotid gland, the facial nerve can divide into two or three branches, and terminates into five ramifications: temporal, zygomatic, buccal, mandibular and cervical. Surgical approaches used
13
Surg Radiol Anat
for the treatment of condylar fractures involve frequently the mandibular branch which runs along the mandibular corpus and can be visualized during surgery. It is a fragile branch with a few anastomoses and ramifications [20]. In 2012, Narayanan has published a clinical study describing a retromandibular incision with a preauricular extension and an anteroparotid approach to treat condylar fractures [13]. The rationale for this approach was the presence of a “nerve free window between buccal and marginal mandibular branches of facial nerve” at the anterior edge of the parotid, where they tend to diverge after a course along the intraparotid facial nerve. He has observed no nerve injury with satisfactory healing. We studied anatomically a preauricular and anteroparotid surgical approach. The main aim was to show the anatomical relationship between the approach site and the extracranial facial nerve branches. The secondary aim was to define cutaneous landmarks to locate the extraparotid facial nerve branches.
Materials and methods
Fig. 1 Cutaneous landmarks delineating the zygomatic and buccal facial nerve branches
Five fresh human cadaver heads and three fresh hemi-heads were dissected. There were five women and three men, with an average age of 77 years. All the dissections and measurements were performed by the same surgeon. Cutaneous landmarks for buccal and zygomatic branches were obtained from several anatomical studies [16, 17], and used in association with landmarks already known for temporal and mandibular branches [2, 3]. Before the dissection, cutaneous landmarks were placed to delineate two areas (Figs. 1, 2): –– for the buccal branch, a line from the Tragus to the upper border of the Vermilion (TV), corresponding to the theoretical course of the parotid duct, and a line from the Tragus to the corner of the Lips (TL) to isolate the lower lip and the mandibular branch [16] –– for the zygomatic branch, a line from the Tragus to the external Canthus (TC) to isolate the upper eyelid and the temporal branch, and a line from the Tragus to the Ala Nasi (TN) as a lower limit [17]. Thirteen two-step dissections were performed: a preauricular condylar approach then a superficial parotidectomy to identify the ramifications of the extracranial facial nerve.
Fig. 2 Left lateral schematic view of the CI cutaneous incision carried out during the P preauricular anteroparotid approach. Landmarks can be seen as TC tragus external canthus, TN tragus-ala nasi, TV tragus-upper border fo the vermilion and TL tragus-lip corner lines. We also notice their relationship with the facial nerve branches: fb frontal, zb zygomatic, bb buccal, mb marginal and cb cervical branches
Preauricular anteroparotid approach to the condyle (Fig. 3) A 5–6-cm incision was made from the helix root to the earlobe. A subcutaneous dissection was achieved anteriorly in a 4-cm area. The parotid fascia was incised. Then, the
13
dissection was carried out deeper on the anterior side of the parotid. An atraumatic retractor was placed to move the parotid back and identify the masseter aponeurosis. After passing through this aponeurosis, the muscle was dissected
Surg Radiol Anat
Fig. 3 Schematic preauricular anteroparotid approach to the condyle at the ear level, showing the pre-auricular, subcutaneous and then anteroparotid (P) and transmassteric (MM) dissections carried out to reach the bone. Note the section of the lateral pterygoid muscle (LPM) and the medial pterygoid muscle (MPM)
along the longitudinal fibres, to reach the bone. The muscle was sectioned backwards to visualise the posterior edge of the ramus and simulate osteosynthesis.
branches were sectioned during the procedures. No other facial nerve branches were visualised. The results in Table 1 show the relationship between the facial nerve and the surgical approach site. In 3 out of the 13 cases (23 %), a nerve branch was visualized during the approach. In the ten remaining cases, no ramifications were observed during the surgical approach. The surgical approach was carried out between the zygomatic and buccal branches in six cases (46 %), in contact with the ramifications of the zygomatic and buccal branches in five (39 %) and two cases (15 %), respectively. The mandibular and temporal branches were never involved. Regarding the zygomatic branch anatomy, the nerve course passed along the TN line in nine cases (69 %), between the TN and TC lines in three cases (23 %) and along the TC line in one case (8 %) (Table 2). The zygomatic branch had no ramification in three cases, a bifurcation (Z1, Z2) in eight cases and a trifurcation (Z3) in two cases. Regarding the buccal branch anatomy, the nerve course passed along the TV line in four cases (31 %), between the TV and TL lines in one case (8 %) and along the TL line in four cases (31 %). In four cases (31 %), the branch was identified outside of these lines (one case above the TV line and three cases under the TL line) (Table 3). The buccal branch had no ramification in three cases, a bifurcation (B1, B2) in five cases and a trifurcation (B3) in five cases.
Superficial parotidectomy
Discussion
The cervical incision was extended behind the earlobe and along the anterior edge of the sternocleidomastoid muscle. The facial nerve trunk was identified after subperichondral dissection of the tragus and identification of the posterior belly of the digastric. The facial nerve ramifications were entirely dissected using systematic superficial parotidectomy. The distribution of the facial nerve was studied and compared to the cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed: once the parotidectomy was completed, the mandibular (M), buccal (B), zygomatic (Z) and temporal (T) branches were identified, and their ramifications were marked (B1, B2 and B3; Z1, Z2 and Z3; T and M). We then studied the distance between these branches and the surgical approach site and if they had been sectioned during the procedure.
Our anatomical study has shown that the facial nerve branches visualised during our preauricular anteroparotid approach to the condyle were the buccal and zygomatic branches. The TC and TN lines seemed to be reliable landmarks for the zygomatic branch, whereas the buccal branch course was more variable along the TV and TL lines. Many approaches can be used to treat mandibular condyle fractures. The most used approach nowadays is the modified Risdon approach described by Meyer in 2006, which is really safe for the facial nerve [11] and allows a good surgical access to the condyle. Other approaches can be used, including the retromandibular approach [5], the low submandibular Risdon approach [15] or the preauricular transmasseteric approach recently described by Wilson [19]. Narayanan [13] has described an anteroparotid approach to treat condyle fractures which entered through a “nerve free window between buccal and marginal mandibular branches of facial nerve” at the anterior edge of the parotid where they tended to diverge, whereas they were very close in the parotid. In 7 % of cases, the buccal branch was seen during the approach.
Results The approach used for the 13 dissections allowed visualising the zygomatic and/or buccal branches. No facial nerve
13
13 No
Yes (B2)
Within BB
3 Left
TL course
3
Buccal branch landmarks
Divisions
1 Left
1
TL course
2 Left
3
Above TV
3 Left
Table 3 Course and divisions of the buccal branch
1
3
2
Divisions
3 Left
Between TC course TC and TN
2 Left
No
No No
No
2
Under TL
3 Right
2
No
2
Between TV and TL
4 Left
1
No
No
2
1
3
TV course
4 Right
No
No
2
Under TL
5 Left
2
No
No
2
Under TL
6 Right
No
No
Within BB
6 Right
7 Left
No
No
Within BZ
7 Left
7 Right
No
No
Within BZ
7 Right
8 Left
No
No
Within BZ
8 Left
2
2
TV course
6 Left
2
3
TV course
6 Right
3
1
TL course
7 Left
1
TL course
7 Right
2
2
3
TV course
8 Left
TN course TN course Between TN course TN course TC And TN
6 Left
Between BZ and BB
6 Left
5 Right
TN course
5 Right
Between BZ and BB
5 Right
TN course
5 Left
Between BZ and BB
5 Left
TN course
4 Right
Yes (Z2)
Within BZ
4 Right
Between TC and TN
4 Left
Between BZ and BB
4 Left
TN course
3 Right
Between BZ and BB
3 Right
Zygomatic branch TN course landmarks
1 Left
Table 2 Course and divisions of the zygomatic branch
No
Branch section No
Within BZ
No
Between BZ and BB
2 Left
Branch within Yes (Z2) the approach
Approach/ branches
1 Left
Table 1 Relationship between the preauricular anteroparotid approach site and the facial nerve
Surg Radiol Anat
Surg Radiol Anat
He has carried out a preauricular and retromandibular incision below the area where we performed our incision. We limited the procedure to a preauricular incision to hide the scar in a skin fold. During the approach, the zygomatic branch was identified twice and the buccal branch once. Most often, the approach was carried out between these two branches (46 % of cases). During our dissections, no nerves were damaged as previously shown in the clinical study by Narayanan. Clinically, our approach seemed reliable. This result could probably be explained by the numerous ramifications of the buccal and zygomatic branches, as confirmed in the literature. Saylam in 2006 [16] has reported that 55 % of buccal branches had two ramifications, 18 % had three ramifications and the 27 % had a plexiform anatomy. In 2006, the same author has studied the zygomatic branch of 66 facial nerves and confirmed that most nerves had divisions, only 4.5 % of branches lacking ramifications [17]. As a result, this branch was more robust and less vulnerable than other branches with fewer ramifications such as the temporal and mandibular branches [2, 3]. We found in our study that these branches had at least two ramifications in 10 out of the 13 cases. The robustness of the buccal and zygomatic branches could be explained by the numerous anastomoses with each other found in 65–100 % of cases in the literature [4, 19]. In 2005, Farooq [8] conducted an anatomical study in 57 specimens and a literature review to discuss his results on the facial nerve anatomy. In 65 % of the cases, when considering the zygomatic and buccal branches, anastomoses were found between the temporo- and cervicofacial branches. The temporal and mandibular branches had a few connections with the other branches. The zygomatic and buccal branches were therefore likely to be more robust than the mandibular branch where anastomoses were only observed in 15 % of cases [9]. The branches concerned by this anatomical study were thus very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion. Cutaneous landmarks for the facial nerve have often been described for mandibular and temporal branches [2, 3]. However, the anatomy of the buccal and zygomatic branches is less reliable with no precise description. We aimed to define cutaneous landmarks, to predict their courses. During our anatomical study, we have defined TC, TN, TV and TL lines, which could be used as cutaneous landmarks, to delineate the area where the facial nerve branches pass.
Landmarks TC and TN seemed reliable to locate the zygomatic branch which was systematically found between these lines. Saylam [17] has shown that the zygomatic branch was systematically located under a line passing from the tragus to the external canthus, which corresponds to our TC line. This branch course was thus relatively constant. Landmarks TV and TL seemed less reliable to locate the buccal branch. Pogrel [14] has described the buccal branch and its relationship with the parotid duct whose anatomical location is constant and mostly vertical, passing from the tragus to the top of the vermilion (TV line). The buccal branch was located under this line in 75 % of the cases, and was always observed at less than 1 cm from the duct, as in our results (62 %). The buccal branch was only observed once between the TV and TN lines in our study, which makes this area the safest site for dissection. In conclusion, our study has shown that mandibular condyle fractures can be treated with an anteroparotid approach with a simple preauricular incision, without retromandibular wound extension. Compared to Narayanan’s study, our dissection was also performed at the anterior edge of the parotid gland, but in the upper region. This author has shown the clinical safety of this technique. The approach described in our study allowed systematically visualising the buccal and zygomatic facial nerve branches. It should be noted that these nerve branches are more robust than the mandibular branch, as explained by Meyer in his description of the modified Risdon submandibular approach. Furthermore, the delineated preauricular incision makes the scars very discreet while allowing a perfect view of the mandibular condyle for osteosynthesis. Finally, the TV and TN lines are good cutaneous landmarks and the risk of sectioning the facial nerve branches is reduced when surgery is carried out between both lines. We therefore propose this approach as a good alternative to the excellent Risdon modified approach. It seems perfectly adapted to high subcondylar fractures when surgical osteosynthesis is indicated. The scar is well hidden so that the patient has no aesthetic concerns after surgery. A clinical study is ongoing to assess the efficacy of this approach for the treatment of upper mandibular condyle fractures. Conflict of interest The authors declare that they have no conflict of interest.
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2. Babakurban ST, Cakmak O, Kendir S, Elhan A, Quatela VC (2010) Temporal branch of the facial nerve and its relationship to fascial layers. Arch Facial Plast Surg 12(1):16–23 3. Basar R, Sargon MF, Tekdemir Y, Elhan A (1997) The marginal mandibular branch of the facial nerve. Surg Radiol Anat 19(5):311–314 4. Bernstein L, Nelson RH (1984) Surgical anatomy of the extraparotid distribution of the facial nerve. Arch Otolaryngol 110(3):177–183 5. Chossegros C, Cheynet F, Blanc JL, Bourezak Z (1996) Short retromandibular approach of subcondylar fractures: clinical and radiologic long-term evaluation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 82(3):248–252 6. Eckelt U, Gerber S (1981) Draw-screw osteosynthesis with a novel osteosynthesis instrument set in mandibular condyle fractures. Zahn Mund Kieferheilkd Zentralbl 69(6):485–490 7. Eckelt U, Schneider M, Erasmus F, Gerlach KL, Kuhlisch E, Loukota R, Rasse M, Schubert J, Terheyden H (2006) Open versus closed treatment of fractures of the mandibular condylar process-a prospective randomized multi-centre study. J Craniomaxillofac Surg 34(5):306–314 8. Farooq A, Riaz A, Nabila K (2005) Facial Nerve; pattern of distribution in the parotid gland. In: The professional medical journal. http://www.theprofesional.com/vol-12-no-01/. Accessed 18 May 2013 9. Gosain AK (1995) Surgical anatomy of the facial nerve. Clin Plast Surg 22(2):241–251 10. Hinds EC, Girotti WJ (1967) Vertical subcondylar osteotomy: a reappraisal. Oral Surg Oral Med Oral Pathol 24(2):164–170 11. Lutz J-C, Clavert P, Wolfram-Gabel R, Wilk A, Kahn J-L (2010) Is the high submandibular transmasseteric approach to the
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Surg Radiol Anat mandibular condyle safe for the inferior buccal branch? Surg Radiol Anat 32(10):963–969 12. Meyer C, Zink S, Wilk A (2006) Modified Risdon approach for the treatment of subcondylar fractures of the mandible. Rev Stomatol Chir Maxillofac 107(6):449–454 13. Narayanan V, Ramadorai A, Ravi P, Nirvikalpa N (2012) Transmasseteric anterior parotid approach for condylar fractures: experience of 129 cases. Br J Oral Maxillofac Surg 50(5):420–424 14. Pogrel MA, Schmidt B, Ammar A (1996) The relationship of the buccal branch of the facial nerve to the parotid duct. J Oral Maxillofac Surg 54(1):71–73 15. Risdon F (1934) Ankylosis of the temporomaxillary joint. J Am Dent Assoc 21:1933–1937 16. Saylam C, Ucerler H, Orhan M, Ozek C (2006) Anatomic landmarks of the buccal branches of the facial nerve. Surg Radiol Anat 28(5):462–467 17. Saylam C, Ucerler H, Orhan M, Ozek C (2006) Anatomic guides to precisely localize the zygomatic branches of the facial nerve. J Craniofac Surg 17(1):50–53 18. Trost O, Péron J-M (2013) Latest trends in the surgi cal management of mandibular condyle fractures in France, 2005–2012. Rev Stomatol Chir Maxillofac Chir Orale. doi:10.1016/j.revsto.2013.05.004 19. Wilson AW, Ethunandan M, Brennan PA (2005) Transmasseteric antero-parotid approach for open reduction and internal fixation of condylar fractures. Br J Oral Maxillofac Surg 43(1):57–60 20. Woltmann M, de Faveri R, Sgrott EA (2006) Anatomosurgical study of the marginal mandibular branch of the facial nerve for submandibular surgical approach. Braz Dent J 17(1):71–74 21. Zide MF, Kent JN (1983) Indications for open reduction of mandibular condyle fractures. J Oral Maxillofac Surg 41(2):89–98
