Novel use of the transparotid approach to the mandible for benign pathology
- Timothy Manzie and
- Emma Lewis
- Oral and Maxillofacial Surgery, Fiona Stanley Hospital, Murdoch, Western Australia, Australia
- Correspondence to Dr Timothy Manzie; tmanzie@gmail.com
Abstract
Access to the mandibular ramus can be difficult. There are a number of described methods for accessing the mandibular ramus and condyle, including a transoral or transcutaneous approach. Access via a transoral approach prevents surgical scars but can result in an excessive amount of bone removal from the anterior mandibular ramus. The transparotid approach has been described and commonly used for the management of mandibular trauma. It allows for direct access to the mandibular ramus and condyle with a number of possible complications, including salivary fistula formation, sialocele and facial nerve injury. Despite these risks, this approach is commonly used in the setting of trauma. This case report describes an additional indication, the successful use of the transparotid approach for the management of benign odontogenic pathology.
Background
Transparotid access to the mandibular condyle has been well described and used for managing mandibular condylar trauma.1 A transparotid approach allows direct access to the lateral mandible with improved visibility to a region that can often be difficult using other approaches. This approach allows for improved access to the mandibular ramus and condyle and allows for adjunctive procedures, such as peripheral ostectomy, to aid in reducing the recurrence of pathology. Multiple studies have reviewed the risk of complications with no long-term incidence of facial nerve weakness with a temporary incidence of 6%–7.5%.2–4 Injury to the parotid gland is another reason clinicians may avoid this approach with the possible risk of sialocele (0%–2%) or salivary fistula formation (0%–7.3%).2 5 Not all of these complications require surgical intervention, salivary fistulas have been documented to resolve within 4 weeks of the initial procedure, requiring pressure dressings in the postoperative period.2 Other complications reported in the literature but appear less common include Frey’s syndrome.2 5 Early identification of these complications and intervention with botulinum toxin will manage most with good effect.6 The resultant scar is often acceptable to the patient.7 8
Access to the mandibular ramus transorally can provide limited access and risk of iatrogenic injury to the inferior alveolar nerve with the advantage of being an improved cosmetic approach.7 To enable access to the lateral and medial aspect, a transoral approach involves removal of a significant portion of the ascending mandibular ramus, removal of or stripping of the temporalis tendon and risks fracturing the coronoid process. When pathology is involved, the transoral approach may also make it difficult to visualise the complete extent of the lesion, decreased access to allow for complete enucleation or ability to perform adjunctive procedures such as the placement of topical chemicals or allow ostectomy of the periphery. No current literature could be identified in using the transparotid approach to manage benign pathology of the mandibular ramus.
Informed consent should be obtained from the patient prior to the procedure. The surgical technique performed under general anaesthesia by the authors followed that described by Ellis.1 The placement of the skin incision can vary from the posterior edge of the mandible to up to 2 cm posterior. The incision is commenced 5 mm inferior to the ear lobe to prevent retraction of the lobule during healing and is 3–3.5 cm in length parallel with the posterior border of the mandible. This incision continues through the skin and subcutaneous tissue to expose the underlying platysma muscle. Following identification of the parotid capsule deep to this thin muscular layer, undermining allows for easier retraction of the overlying skin and subcutaneous tissue during retraction. Sharp incision of the parotid capsule parallel to the skin incision exposes the underlying gland. Blunt dissection in the plane of the facial nerve through the gland and medial parotid capsule using artery forceps or metzenbaum scissors allows for placement of retractors to expose the lateral aspect of the mandibular ramus and condyle. Branches of the facial nerve may be seen during dissection through the gland, however, with blunt dissection and gentle retraction, injury to these structures can be avoided. Further undermining with a periosteal elevator allows for retraction and adequate exposure of the surgical field. There are a number of modifications that can be made, including the anterior–posterior placement of the incision as well as the placement of a stepped incision (parotid capsule incision does not lay directly beneath the skin incision) as well as others, each with a purported advantage.
Case presentation
A 30-year-old man was seen in an outpatient Oral and Maxillofacial Clinic with concerns for recurrence of an odontogenic keratocyst. The patient had previously undergone biopsy and decompression in 2014 followed by enucleation of the lesion in 2016, he had represented due to concerns on surveillance imaging without new symptoms. Based on his history of previous treatment, this was presumed recurrence. Resection of a recurrent odontogenic keratocyst can be advocated; however, the patient elected for a conservative approach, primarily to preserve function of the inferior alveolar nerve.9 10 The benefits and risks of the surgical approach were discussed with the patient electing to undergo a transparotid approach.
Investigations
The surveillance orthopantomogram (OPG; figure 1) demonstrated a lesion in the right mandibular ramus. Subsequent CT was performed for operative planning (figures 2 and 3) further delineated the lesion demonstrating a non-expansile unicystic lesion at the height of the mandibular foramen.
Surveillance orthopantomogram demonstrating a lesion to the right mandibular ramus.
Axial CT image demonstrating the lesion at the right mandibular ramus (preoperative).
Sagittal CT image demonstrating the lesion at the right mandibular ramus (preoperative).
Treatment
The patient, under a general anaesthetic, underwent transparotid enucleation of the lesion with the placement of Carnoy’s solution and peripheral ostectomy. The approach and length of incision are seen in figure 4. Use of Carnoy’s solution and peripheral ostectomy has been demonstrated to reduce the risk of recurrence of these lesions.11 With a small amount of bone removal, the use of the transparotid approach allowed for direct access and visualisation to the cystic cavity with sufficient access to allow for adjunctive treatment. The inferior alveolar nerve was able to be identified on the medial aspect with preservation. Immediately postoperatively, the patient had preserved facial and trigeminal nerve function. The patient was discharged home on the day of surgery. A postoperative OPG was taken on the day of surgery to establish a new baseline and to allow for comparison with subsequent imaging (figure 5).
Clinical photograph demonstrating incision through to parotid gland.
Orthopantomogram demonstrating the lesion to the right mandibular ramus (postoperative).
Outcome and follow-up
Subsequent to the procedure, the patient has undergone regular follow-up in the outpatient clinic for 6 months since the procedure. He has had no postoperative complications with minimal requirement for analgesics. Histological examination of the lesion demonstrated features consistent with a recurrent odontogenic keratocyst. He has further follow-up for 6 months and repeats imaging arranged for 12 months. Given the recurrent nature of this lesion, he will have an ongoing follow-up for a minimum of 5 years.11
Discussion
The transparotid approach has been previously described to manage mandibular fractures.1 No previous studies could be identified by the authors in the literature where this approach has been used to manage benign pathology of the mandible. The approach has previously been reported to have been used for resection of a pleomorphic rhabdomyosarcoma associated with the masseter thus lateral to the mandible.12 Several variations differ between this case and the former; we did not require identification of the main trunk of the facial nerve given benign pathology and resection without a surgical margin was not required. Use of the transparotid approach allows for access and sufficient visibility to an area that can often be difficult by a transoral approach. No motor or sensory nerve dysfunction, salivary gland or infective complications were identified in the postoperative period. The approach allowed for direct access to the lesion, prevented any with the resultant scar acceptable to the patient. While this technique has been described in the trauma setting, this case report demonstrates its ability to be used for alternative purposes, such as benign pathology. This is the first case identified by the authors whereby the transparotid approach has been used for benign odontogenic pathology. Given the successful use, in this case, we suggest this approach be considered for localised bony pathology to the mandibular ramus or condyle. This approach is recommended for surgeons with experience in parotid gland surgery or previous experience with this technique.
Learning points
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The transparotid approach can be used to improve access to the mandibular condyle and ramus for a number of indications, including benign pathology.
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The greatest morbidity associated with the transparotid approach is salivary gland injury (sialocele or fistula formation) or facial nerve injury.
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The resultant scar from the approach is acceptable to the patient with an overall low risk of complication.
Footnotes
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Contributors EL and TM conceived the idea of the surgical technique and planned the case. TM was the primary surgeon for the procedure with EL overseeing the case as the consultant in charge. TM collated the clinical pictures and medical imaging. TM, with guidance from EL, produced the initial draft presentation. EL reviewed the draft and further modified the draft. Both the authors discussed the results and contributed to the final manuscript.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Patient consent for publication Obtained.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.
References
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