Preoperative approach and technical considerations in parotid surgery

Introduction

There have been considerable changes in the approach and management paradigms of parotid neoplasms. In most scenarios, there are a multitude of ways that one can choose to manage each patient. The aim of this review is not to attempt to discuss what is “right” vs. “wrong”, but rather, to provide an individual perspective on how these various changes and technical modifications have been incorporated into a clinical practice over the last decade. We present this article in accordance with the SUPER reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-24-318/rc).

Preoperative preparation and requirements

Imaging

The argument and question of the best imaging modality for parotid neoplasms has not been answered, and never will be. In many cases, this is a multifaceted topic, and the optimal modality will be patient, provider, and tumor dependent (1). We have noticed that most patients present to clinic with a computed tomography (CT) scan from the referring provider. Conversely, if an incidental parotid mass is noted on migraine workup, for example, the patient will likely have undergone magnetic resonance imaging (MRI). In terms of cross-sectional imaging, we favor CT and we rarely order MRI (1). While MRI may provide additional soft tissue detail, we typically do not alter our clinical plan based on that information. We also try to consider the inconvenience/impact on the patient given the longer acquisition time and the potential for motion artifact which frequently renders the MRI images of limited utility (2). Occasions during which we consider the addition of MRI to be beneficial for decision-making include: facial paresis out of proportion to exam findings, prior surgery, orbital involvement, or recurrence after prior treatment with suboptimal characterization on CT and/or ultrasound (US).

We perform in-office US at the time of evaluation. For the first several years as we gained US experience, we obtained CT for essentially all parotid patients who presented without cross-sectional imaging. Today, particularly in the case of benign disease, if the lesion is adequately visualized on US in the office, we do not obtain any additional imaging beyond this prior to surgery. Similarly, patients opting for observation will be followed exclusively with serial US examinations in office. Patients have appreciated the reduction in scheduling and cost burden, pre-contrast labs, and the ability to have either reassurance or change in treatment plan, if needed, between interval visits should they feel the lesion has changed in size or character (2). Limitations of US which must be acknowledged include the comparatively poor visualization of the superior aspect of the parapharyngeal space, and in larger gland or habitus patients, poor visualization of the deepest aspect of the deep lobe (3,4). In these situations, as well as in biopsy-proven malignancy, we will obtain CT as part of the preoperative/staging workup. We also find this facilitates easier communication and imaging review during tumor board discussions with the other disciplines who may be less familiar with US interpretation.

Diagnostic workup and treatment decisions

Many patients will arrive with either fine needle aspiration (FNA) or core biopsy already performed. In those who do not already have tissue sampling, we will routinely perform FNA with US-guidance in office during the initial consultation (3–4 passes with 25-gauge needles in formalin for cell block). Treatment recommendations are then based on risk stratification, Milan criteria, and patient preference (5). For incidentally noted masses in patients with low-risk history (e.g., no head/neck skin cancer, no immunosuppression, nonsmoker) and benign clinical exam/US findings, we will often offer observation without FNA with the plan for biopsy should the mass increase in size or new symptoms develop. Additional consideration for elective management is taken in the case of younger patients with lesions suggestive of pleomorphic adenoma (e.g., hypoechoic, post-acoustic enhancement, lobulated border US characteristics) given the risk of malignant transformation, whereas older patients in this situation may favor observation (6,7). In our experience, the majority of patients under 70 years old seem to favor surgery, whereas those aged 80 years and above favor observation. We feel this is reasonable and safe in the majority of cases. We would not say that there is a particular age that, in isolation, serves as a contraindication for parotid surgery (7). In the case of a motivated patient who is experiencing visible tumor growth, discomfort, or another reason to prefer removal, we feel this can still be performed safely with appropriate preoperative risk assessment.

Step-by-step description

Incision placement

Many surgeons, including ourselves, were taught parotidectomy via modified-Blair incision and with removal of the full superficial parotid lobe in the majority of cases (8). In current practice, we find this incision and extent of surgery to be rarely needed/indicated, particularly in the case of benign disease. This approach is undertaken with the caveat that the surgeon has adequate experience to perform more visually limited and technically demanding approaches and, when in doubt, perform the safest operation (involving a longer incision or more nerve exposure) which is always the best operation. Typically, tumors located in the upper 1/3 of the gland will be approached with a preauricular incision including a retroauricular extension if additional ventral exposure is needed (Figure 1). In these cases, the incision is placed at a 90-degree angle approximately 1 mm away from the attachment of the lobule to the cheek. This eliminates the potential for pixie-ear deformity (9). For tumors located in the mid 1/3 portion, in men the incision is typically located at the posterior aspect of the beard line without a preauricular component. In women, the incision is usually retroauricular with an extension into the posterior hairline as needed. For tumors in the lower 1/3 region, the approach in most men will be an incision inferior to the angle of the mandible/beard line in a skin crease, whereas in female patients depending on age/preference/skin type they will choose between a similar approach vs. a retroauricular/hairline approach with no visible neck incision (8). Patients with relatively thin hair must be given special consideration because longer incisions placed in the hairline may ultimately be more visible than a shorter more direct approach. When designing retroauricular/hairline incisions, we have found that if one visualizes a mirror image of the incision, this will estimate the extent of intraoperative exposure so that preoperative adjustments can be made accordingly (Figure 1).

Figure 1 Retroauricular/hairline incision design resulting in a mirror image extent of intraoperative exposure (vertical line) with elevation (arrows) and reflection of the skin flap (white border demarcates extent of dissection). This image is published with the patient’s consent.

US guidance

In the operating room, US guidance is used to identify the horizontal and vertical planes at the borders of the tumor. Given that gland sparing approaches are quite common, this provides a visual aid to assist in determining where to safely begin the parenchymal cuts (Figure 2).

Figure 2 Preoperative ultrasound guidance is used to demarcate the horizontal and vertical planes at the borders of the tumor which provides a visual aid to assist in determining where to safely begin parenchymal cuts. The anticipated location of the tumor is represented with a circle. This image is published with the patient’s consent.

Nerve dissection

We compartmentalize the tumor into four locations when considering the approach to the facial nerve: lower 1/3 gland, mid 1/3 gland, upper 1/3 gland, and deep lobe. While capsular dissection is an acceptable approach to parotid surgery, we will always find at least the closest nerve branch to the tumor which will give us increased confidence, allow us to determine safe distance for cautery, and to stimulate post-excision to assess for neurophysiologic intactness. For the lower 1/3 tumors [caudal to course of the marginal mandibular nerve (MMN)], these will involve the least amount of nerve dissection. We will identify the MMN as it crosses the angle of the mandible (which is typically a comparatively shallow location in terms of course vs. the main trunk) and retrograde dissect it until the superior border of the tumor, and subsequently reflect the tumor caudally. This eliminates all upper division and midface branch dissection in the majority of cases.

For the mid 1/3 located tumors, the dissection again begins with the MMN which is retrograde dissected until the dorsal aspect of the tumor is able to be visualized. In this location, a midface branch point is often able to be identified proximally, allowing the mass to then be mobilized ventrally. If the mass is obstructing this view, then the midface branches are identified distally and retrograde dissected.

For tumors located in the upper 1/3 of the gland, the proximity to the upper division of the facial nerve often requires comparatively more dissection than those in the lower 1/3 of the gland. In these cases, the extent of the dissection will often be related to the thickness of the gland. In fairly normal size parotid glands, we often will visualize the upper division by first identifying the main trunk at the styloid process. We will then identify the frontal branch in a fairly superficial location as it crosses the zygomatic arch which will then guide the extent of resection. In thicker parotid glands with smaller/shallower tumors, we will rarely identify the main trunk and rely more on distal branch identification given that proximal identification and tracing can require considerably more nerve dissection and division of gland parenchyma prior to approaching the tumor. Particularly in larger gland patients and in large superficial lobe tumors, which have the nerve coursing deep to it, identification of the main trunk will involve a comparatively higher amount of retraction for visualization and thus increased theoretical risk to the nerve. In these cases, identification of the nerve distally either eliminates and/or dramatically reduces the need for traction on the nerve and tumor by allowing the surgeon to work from superficial to deep tissue planes.

Once the tumor is excised, and prior to reconstruction, the specimen is sent for frozen sectioning to confirm consistency with preoperative workup and ensure that no additional resection is required.

Extent of gland resection/reconstruction

In the majority of primary benign cases the goal will be to spare as much normal parotid gland as possible. In the case of deep lobe or deeper superficial lobe tumors with approximately 1 cm of normal gland overlying it, the goal is to preserve the overlying parenchyma and this usually eliminates the need for reconstruction. In cases with deeper positioned tumors, the approach is typically from inferior using the styloid process and the angle of the mandible as reference points for the nerve. In mid or upper positioned masses, the gland overlying the tumor will be divided in a dorsal/ventral plane until the mass can be identified and addressed. After which the capsule can be reapproximated/sutured. In cases where there is a volume defect, the reconstruction is based on the extent of volume/skin loss. In the smallest gland defects, primary parotid capsule closure is assisted by mobilizing the tail from the sternocleidomastoid muscle. This rotation/volume advancement will rarely translate adequately for upper 1/3 defects. Additional volume can often be obtained via free fat with superficial musculoaponeurotic system (SMAS) flap vs. abdominal dermal fat graft. We favor reconstruction with abdominal dermal fat graft given that additional SMAS dissection is not required, the donor site can be closed primarily, and the dermis can be sutured to the remaining capsule which lends to a smooth contour. In cases requiring skin reconstruction as well, various combinations of cervicofacial flap with fat, submental flap, supraclavicular flap, or free flap can also be performed (10,11).

Postoperative considerations and tasks

A mastoid-style or neck wrap pressure dressing is applied, and drains are not used in these cases. The patient will be discharged the same day. Antibiotics are not routinely used postoperatively with one exception; in cases with hairline incisions, we would often notice erythema/tenderness of the ear at the 1-week postoperative visit. We have since changed practice to cover the incision with Dermabond at the conclusion of the case and prescribe a 2–3-day course of cephalexin which has eliminated that occurrence. In instances of sialocele, these are managed by US-guided aspiration in office, pressure dressing, and scopolamine patch.

Tips and pearls

Multi-modality diagnostic workup of parotid neoplasms includes judicious use of cross-sectional imaging, point of care US, and FNA which is crucial to individualizing care based on tumor and patient. This information, coupled with appropriate risk stratification, Milan criteria, and patient preference, lay the groundwork for a thoughtful operative approach. Categorizing tumor location into lower 1/3 gland, mid 1/3 gland, upper 1/3 gland, and deep lobe aids in safe facial nerve dissection which is essential when performing more visually limiting and technically demanding approaches. Preserving normal parotid gland for primary benign cases and overlying parenchyma for deep tumors can considerably reduce or eliminate the need for reconstruction

Discussion

There are numerous ways to navigate the diagnostic workup, approaches, and technical considerations of patients with parotid neoplasms. Conservative management in low-risk patients and minimally invasive approaches to parotidectomy can both be employed in a safe manner. US and a keen understanding of regional anatomy can further aid surgeons in executing a methodical approach to the operation.

Conclusions

Our practice has evolved over the past decade due to the integration of point of care ultrasonography in office and operating room, judicious incision placement, and minimizing extra nerve dissection and tumor manipulation all with excellent results. The aim of this narrative is to provide surgeons with additional technical pearls which can be integrated as needed or if interested into one’s clinical practice.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-24-318/rc

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-24-318/prf

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-24-318/coif). C.E.F. serves as an unpaid editorial board member of Gland Surgery from March 2024 to February 2026. The other author has no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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