Key Points
Question
What are the surgical factors and outcomes associated with selective deep lobe parotidectomy (SDLP) vs total parotidectomy for patients with benign deep lobe parotid tumors?
Findings
In this case series of 273 patients, the advantages associated with SDLP included a significantly lower rate of reconstruction for facial asymmetry and a significantly lower rate of complications, such as immediate facial nerve weakness and Frey syndrome. Tumor control was not compromised by SDLP.
Meaning
This study suggests that SDLP can be considered an effective, and even superior, technique for the management of benign tumors in the deep parotid lobe.
Abstract
Importance
Limited literature exists on surgical outcomes after selective deep lobe parotidectomy (SDLP) with preservation of superficial lobe for patients with benign deep lobe tumors.
Objective
To compare the following factors for SDLP vs total parotidectomy for patients with benign tumors in the deep lobe: postoperative complications, including facial nerve paresis or paralysis, Frey syndrome, first bite syndrome, cosmetic defect, sialocele formation, and wound infection; and tumor control and recurrence.
Design, Setting, and Participants
This case series included 273 adults who underwent SDLP (n = 177) or total parotidectomy (n = 96) at a single tertiary care institution for benign parotid tumors located in the deep lobe or deep lobe and parapharynx from January 1, 2000, to December 31, 2020.
Exposure
Selective deep lobe parotidectomy vs total parotidectomy.
Main Outcomes and Measures
Incidence of postoperative complications and tumor recurrence.
Results
Among 273 patients (SDLP, 177 [65%]; 122 women [69%]; median age at surgery, 58 years [IQR, 46-67 years]; total parotidectomy, 96 [35%]; 57 women [59%]; median age at surgery, 59 years [IQR, 40-68 years]), the most common tumor was pleomorphic adenoma (SDLP, 128 of 177 [72%]; total parotidectomy, 62 of 96 [65%]). An abdominal dermal fat graft was less commonly performed for patients who underwent SDLP than those who underwent total parotidectomy (2 of 177 [1%] vs 20 of 96 [21%]; difference, −20% [95% CI, −28% to −11%]). The rate of great auricular nerve preservation was higher in the SDLP group than in the total parotidectomy group (84 of 102 [82%] vs 20 of 34 [59%]; difference, 24% [95% CI, 5%-42%]). No meaningful difference in length of hospital stay was found. The percentage of patients with House-Brackmann grade I immediately after surgery was 48% (85 of 177) in the SDLP group and 21% (20 of 96) in the total parotidectomy group (difference, 28% [95% CI, 16%-40%]). There were no clinically meaningful differences in rates of hematoma, sialocele, seroma, ear numbness, wound infection, or unplanned return to emergency department or operating room. The SDLP group reported a lower rate of Frey syndrome than the total parotidectomy group (1 of 137 [1%] vs 12 of 78 [15%]; difference, −15% [95% CI, −23% to −7%]), as well as a lower rate of facial contour defect (28 of 162 [17%] vs 25 of 84 [30%]; difference, −13% [95% CI, −24% to −1%]) and a higher rate of first bite syndrome (34 of 148 [23%] vs 7 of 78 [9%]; difference, 14% [95% CI, 5%-23%]). The percentage of patients with House-Brackmann grade I at their first follow-up visit was 67% (118 of 177) in the SDLP group compared with 49% (47 of 96) in the total parotidectomy group (difference, 17% [95% CI, 4%-30%]). There was no clinically meaningful difference in House-Brackmann grade after 1 year.
Conclusions and Relevance
Findings of this case series study suggest that SDLP can be considered an effective and even superior technique for management of benign tumors in the deep parotid lobe. Advantages associated with SDLP include reduction in need for reconstruction for facial contour defect and reduction in complications, such as immediate facial nerve weakness and Frey syndrome. The incidence of first bite syndrome was higher in the SDLP group. Tumor control was not compromised by SLDP.
This case series compares selective deep lobe parotidectomy vs total parotidectomy for patients with benign tumors in the deep lobe for postoperative complications and tumor control and recurrence.
Introduction
Parotidectomy has evolved over the last few decades from extensive resection to more limited resection, particularly for benign tumors.1 In general, parotidectomy for benign tumors in the superficial lobe is changing from superficial parotidectomy to more limited extracapsular dissection.2 Total parotidectomy has been the standard treatment for benign tumors in the deep lobe, although more limited resections consisting of extracapsular dissection and facial nerve identification have been explored.3 Total parotidectomy is used for full visualization of the facial nerve and ease of access to the deep lobe. The value of removing healthy parotid tissue in the superficial lobe to gain access to deep lobe tumors has been questioned. The theoretical advantages of a limited resection include fewer cosmetic defects from gland removal, less frequent cases of Frey syndrome, and preservation of salivary function.4 One potential disadvantage of limited resection is that the final pathologic findings may demonstrate malignant neoplasms, making the extent of resection inadequate and necessitating further operation. Partial deep lobe parotidectomy could also lead to incomplete resection of the tumor and/or tumor spillage, particularly when performed by an inexperienced surgeon.
There is limited literature on selective deep lobe parotidectomy (SDLP) with preservation of the superficial lobe for benign tumors. Although the technique has been described, little is known about potential postoperative complication rates, the course of recovery, and long-term outcomes. In addition, there is little literature on how outcomes after SDLP compare with outcomes after total parotidectomy. In the past 15 years, several small retrospective case series have commented on single-institution experiences with SDLP for patients with benign tumors.3,5,6,7,8,9 Each study reported favorable results with no recurrences, no instances of permanent facial nerve weakness, and no Frey syndrome. However, these studies did not compare the rates of postoperative complications, recurrence, and long-term outcomes between patients undergoing SDLP and those undergoing total parotidectomy.
In this case series study, we aim to review the institutional outcomes of the SDLP experience to better understand the surgical technique, the course of recovery, and the long-term outcomes associated with this relatively novel technique. Our objective was to compare the following factors associated with SDLP vs total parotidectomy for patients with benign tumors in the deep lobe: (1) postoperative complications, including facial nerve paresis or paralysis, Frey syndrome, first bite syndrome, cosmetic defect, sialocele formation, and wound infection; and (2) tumor control and recurrence.
Methods
For this case series, a retrospective review of all patients undergoing parotidectomy at a tertiary care institution between January 1, 2000, and December 31, 2020, was performed. Seven surgeons performed 4207 parotidectomies. Patient medical records were reviewed to identify the tumor pathologic characteristics, the location of the tumor, and the level of parotidectomy performed according to the European Salivary Gland Society (ESGS) classification.10 The ESGS proposes to subdivide the parotid parenchyma into 5 levels: I (lateral superior), II (lateral inferior), III (deep inferior), IV (deep superior), and V (accessory). Parotidectomies are then classified according to the levels removed. Inclusion criteria included tumors involving only the deep lobe of the parotid gland and/or the parapharyngeal space, the surgical approach of either a total parotidectomy (ESGS levels I-IV) or SDLP (defined as ESGS levels III, IV, or III and IV), and benign pathologic characteristics, including pleomorphic adenoma, Warthin tumor, monomorphic adenoma, or oncocytoma. Patients with partial superficial and deep lobe parotidectomy (ESGS levels I or II plus III or IV) were excluded. After application of inclusion and exclusion criteria, 273 patients were identified for the study cohort. This study followed the reporting guideline for case series. The Mayo Clinic institutional review board approved this study; patient consent was not required because patient data were deidentified.
Patient demographic characteristics, medical and social history, presenting signs and symptoms, diagnostic workup, surgical technique, diagnostic pathologic findings, postoperative outcomes, follow-up data, and recurrence data were collected from electronic medical records. Patient demographic characteristics included date of birth and sex assigned at birth. Medical and social history encompassed tobacco and alcohol use as well as history of head and neck malignant neoplasms, tumors, and radiotherapy. Clinical history at presentation included date of consultation visit, mass laterality, symptoms (tenderness, growth, facial numbness, and weakness), examination findings (palpability and mobility of the tumor, tenderness, numbness, and facial nerve function using the House-Brackmann facial nerve grading system). Diagnostic workup included fine-needle aspiration, with date of examination and findings.
Surgical management data included date of surgery, type of incision used, ESGS level of parotidectomy, use of facial nerve monitoring, intraoperative identification of the facial nerve main trunk, greater auricular nerve (GAN) identification and preservation, tumor spillage, resection of skin or masseter muscle, reconstruction, and botulinum toxin injection. Botulinum toxin was injected at the end of surgery at the discretion of the surgeon to decrease the incidence of sialocele or salivary fistula.11 At this institution, the reconstructive method of choice for a facial contour defect after parotidectomy was abdominal dermal fat graft. Postoperative course variables included drain placement details, length of stay, immediate facial nerve function and function at follow-up visits, eye closure, and follow-up timing. Postoperative complications included unplanned return to the emergency department or the operating room, development of hematoma, sialocele, seroma, Frey syndrome, first bite syndrome, facial asymmetry, ear numbness, and wound infection. Development of Frey syndrome was determined to be present if patients reported gustatory sweating. Pathologic diagnosis and recurrence data were recorded as well.
Statistical analysis was performed using SAS, version 9.4 (SAS Institute Inc). Continuous features were summarized with median values and IQRs, and categorical features were summarized with frequencies and percentages. Comparisons of the features under study and the magnitude of the difference between the 2 groups (SDLP and total parotidectomy) were evaluated using appropriate effect size measures; 95% CIs were used to describe the precision of these estimates and whether the results were compatible with clinically meaningful differences.
Results
A total of 273 patients (SDLP, 177 [65%]; 122 women [69%]; median age at surgery, 58 years [IQR, 46-67 years]; total parotidectomy, 96 [35%]; 57 women [59%]; median age at surgery, 59 years [IQR, 40-68 years]) underwent SDLP or total parotidectomy for a benign deep lobe parotid tumor during the study period. Table 1 summarizes the patient demographic characteristics, presenting symptoms, and examination findings. Four patients had abnormal results of facial nerve examinations before surgery. Two patients had vestibular schwanomma resection previously, with abnormal results of examination on the contralateral face. One patient was recovering from Bell palsy and had parotitis associated with temporary weakness of the marginal mandibular branch of the facial nerve. There were no clinically meaningful differences between groups in age, sex, tenderness or firmness on palpation, numbness in the distribution of the trigeminal nerve, or House-Brackmann grade at presentation. There were no clinically meaningful differences in whether a fine-needle aspiration was performed or a diagnosis was made based on fine-needle aspiration between the 2 groups.
Table 1. Preoperative Patient Characteristics.
| Characteristic | Patients, No./total No. (%) | Difference, % (95% CI)a | |
|---|---|---|---|
| SDLP (n = 177) | Total parotidectomy (n = 96) | ||
| Year of surgery, median (IQR) | 2014 (2010 to 2019) | 2008 (2004 to 2014) | 6 (3 to 9) |
| Age at surgery, median (IQR), y | 58 (46 to 67) | 59 (40 to 68) | 0 (−5 to 5) |
| Sex | |||
| Female | 122/177 (69) | 57/96 (59) | 10 (−2 to 22) |
| Male | 55/177 (31) | 39/96 (41) | |
| Laterality of mass | |||
| Right | 101/177 (57) | 47/96 (49) | 8 (−4 to 20) |
| Left | 76/177 (43) | 49/96 (51) | |
| Duration patient has felt the mass | |||
| Cannot feel it, found incidentally | 96/173 (55) | 18/95 (19) | 37 (26 to 47) |
| <1 mo | 13/173 (8) | 5/95 (5) | |
| 1 to <2 mo | 5/173 (3) | 5/95 (5) | |
| 2 to <3 mo | 8/173 (5) | 14/95 (14) | |
| 3 to <6 mo | 10/173 (6) | 16/95 (16) | |
| 6 to <12 mo | 9/173 (5) | 4/95 (4) | |
| 1 to <2 y | 13/173 (8) | 10/95 (10) | |
| 2 to <5 y | 13/173 (8) | 11/95 (11) | |
| 5 to <10 y | 5/173 (3) | 6/95 (6) | |
| ≥10 y | 1/173 (1) | 6/95 (6) | |
| Mass is tender | 10/160 (6) | 11/94 (12) | −6 (−13 to 2) |
| Mass has grown | |||
| No | 101/138 (73) | 50/89 (56) | 17 (4 to 30) |
| Yes, gradually | 28/138 (20) | 30/89 (34) | |
| Yes, rapidly | 4/138 (3) | 6/89 (7) | |
| Yes, it fluctuates in size | 5/138 (4) | 3/89 (3) | |
| Mass palpated on examination | 106/175 (61) | 80/96 (83) | −23 (−33 to −12) |
| Mass mobile on examination | 51/59 (86) | 63/65 (97) | −10 (−20 to −1) |
| Mass tender on palpation | 4/74 (5) | 4/69 (6) | 0 (−8 to 7) |
| How the mass felt on examination | |||
| Firm | 36/43 (84) | 42/54 (78) | 6 (−10 to 22) |
| Soft | 7 /43(16) | 12/54 (22) | |
| Numbness in distribution of trigeminal nerve | 1/162 (1) | 1/92 (1) | NE |
| House-Brackmann grade at presentation | |||
| I | 169/171 (99) | 91/93 (98) | NE |
| II | 2/171 (1) | 1/93 (1) | |
| III | 0 | 1/93 (1) | |
| FNA performed | 93/177 (53) | 54/96 (56) | −4 (−16 to 9) |
| FNA result | |||
| Nondiagnostic | 12/93 (13) | 10/54 (19) | 2 (−14 to 17) |
| Nonneoplastic | 3/93 (3) | 3/54 (6) | |
| Atypia of undetermined significance | 2/93 (2) | 0 | |
| Benign neoplasm | 67/93 (72) | 38/54 (70) | |
| Salivary neoplasm of uncertain malignant potential | 7/93 (8) | 2/54 (4) | |
| Suspicious for malignant neoplasm | 2/93 (2) | 1/54 (2) | |
Abbreviations: FNA, fine-needle aspiration; NE, not evaluated because there was too little variability in the feature under study (ie, fewer than 5 patients had data that differed from the rest of the cohort); SDLP, selective deep lobe parotidectomy.
Calculated as the difference in median values or the difference in percentages, SDLP minus total parotidectomy. For features with several categories (eg, the duration that the patient has felt the mass), differences and 95% CIs were calculated for the most common category.
Table 2 describes the operative variables. There were no significant differences between groups in the type of incision or the location of the tumor in the deep lobe or deep lobe and parapharynx. There were no significant differences between groups for the use of facial nerve monitoring, identification of the main trunk of the facial nerve, tumor spillage, resection of the masseter muscle or skin, or botulinum toxin injected at the end of surgery. The rate of GAN preservation was higher in the SDLP group than in the total parotidectomy group (84 of 102 [82%] vs 20 of 34 [59%]; difference, 24% [95% CI, 5%-42%]). An abdominal dermal fat graft was less commonly performed for patients who underwent SDLP than for patients who underwent total parotidectomy (2 of 177 [1%] vs 20 of 96 [21%]; difference, −20% [95% CI, −28% to −11%]). A drain was placed for 165 of 177 patients (93%) undergoing SDLP and for 95 of 96 patients (99%) undergoing total parotidectomy (difference, −6% [95% CI, −10% to −2%]).
Table 2. Operative Variables.
| Variable | Patients, No./total No. (%) | Difference, % (95% CI)a | |
|---|---|---|---|
| SDLP (n = 177) | Total parotidectomy (n = 96) | ||
| Incision | |||
| Modified Blair | 151/176 (86) | 91/96 (95) | −9 (−16 to −2) |
| Facelift incision | 20/176 (11) | 4/96 (4) | |
| Mini parotid incision | 4/176 (2) | 1/96 (1) | |
| Neck | 1/176 (1) | 0 | |
| Intraoperative location | |||
| Deep lobe | 150/177 (85) | 87 /96(91) | −6 (−14 to 2) |
| Deep lobe and parapharynx | 27/177 (15) | 9/96 (9) | |
| Facial nerve monitoring | 90/136 (66) | 27/49 (55) | 11 (−5 to 27) |
| Facial nerve identified | 175/177 (99) | 96/96 (100) | NE |
| Main trunk of facial nerve identified | 168/175 (96) | 95/96 (99) | −3 (−7 to 1) |
| Tumor spillage | 4/175 (2) | 3/96 (3) | −1 (−5 to 3) |
| Great auricular nerve preserved | 84/102 (82) | 20/34 (59) | 24 (5 to 42) |
| Resection of the masseter muscle | 2/176 (1) | 2/96 (2) | NE |
| Resection of skin | 1/177 (1) | 0 | NE |
| Abdominal fat graft performed | 2/177 (1) | 20/96 (21) | −20 (−28 to −11) |
| Botulinum toxin injected at end of surgery | 10/177 (6) | 1/96 (1) | 5 (1 to 9) |
| Drain placed | 165/177 (93) | 95/96 (99) | −6 (−10 to −2) |
Abbreviations: NE, not evaluated because there was too little variability in the feature under study (ie, <5 patients had data that differed from the rest of the cohort); SDLP, selective deep lobe parotidectomy.
Calculated as the difference in percentages, SDLP minus total parotidectomy. For features with several categories (eg, incision), differences and 95% CIs were calculated for the most common category.
Table 3 describes the surgical outcomes. There was no meaningful difference in length of hospital stay. The median length of hospital stay was 1 day (IQR, 1-1 day) for both groups. A total of 22 of 175 patients (13%) in the SDLP group were discharged from the hospital with a drain compared with 4 of 94 patients (4%) in the total parotidectomy group (difference, 8% [95% CI, 2%-15%]). The most common tumor was pleomorphic adenoma (SDLP, 128 of 177 [72%]; total parotidectomy, 62 of 96 [65%]), followed by Warthin tumor (SDLP, 16 of 177 [9%]; total parotidectomy, 6 of 96 [6%]) and oncocytoma (SDLP, 8 of 177 [5%]; total parotidectomy, 7 of 96 [7%]). The percentage of patients with House-Brackmann grade I immediately after surgery was 48% (85 of 177) in the SDLP group and 21% (20 of 96) in the total parotidectomy group (difference, 28% [95% CI, 16%-40%]). There were no clinically meaningful differences in the rate of hematoma, sialocele, seroma, ear numbness, wound infection, or unplanned return to the emergency department or operating room. The SDLP group had a lower rate of Frey syndrome than the total parotidectomy group (1 of 137 [1%] vs 12 of 78 [15%]; difference, −15% [95% CI, −23% to −7%]), as well as a lower rate of facial contour defect (28 of 162 [17%] vs 25 of 84 [30%]; difference, −13% [95% CI, −24% to −1%]) and a higher rate of first bite syndrome (34 of 148 [23%] vs 7 of 78 [9%]; difference, 14% [95% CI, 5%-23%]). The percentage of patients with House-Brackmann grade I at their first follow-up visit was 67% (118 of 177) in the SDLP group compared with 49% (47 of 96) in the total parotidectomy group (difference, 17% [95% CI, 4%-30%]). There was no significant clinically meaningful difference in House-Brackmann grade after 1 year. After a median duration of 65 days (IQR, 22-342 days) of follow-up, only 2 patients developed a recurrence: one who underwent SDLP in 2011 with a locoregional recurrence 9.4 years later and one who underwent total parotidectomy in 2005 with a local recurrence 9.7 years later.
Table 3. Operative Outcomes.
| Outcome | Patients, No./total No. (%) | Difference, % (95% CI)a | |
|---|---|---|---|
| SDLP (n = 177) | Total parotidectomy (n = 96) | ||
| Length of hospital stay >2 db | 4/177 (2) | 4/96 (4) | −2 (−6 to 3) |
| Patient discharged with drain | 22/175 (13) | 4/94 (4) | 8 (2 to 15) |
| House-Brackmann grade immediately after surgery | |||
| I | 85/177 (48) | 20/96 (21) | 28 (16 to 40) |
| II | 46/162 (28) | 40/81 (49) | |
| III | 21/162 (13) | 11/81 (14) | |
| IV | 1/162 (1) | 4/81 (5) | |
| V | 5/162 (3) | 5/81 (6) | |
| VI | 4/162 (2) | 1/81 (1) | |
| Patient able to close eye | 150/163 (92) | 69/80 (86) | 6 (−3 to 14) |
| Final pathologic diagnosis | |||
| Pleomorphic adenoma | 128/177 (72) | 62/96 (65) | 8 (−4 to 19) |
| Warthin tumor | 16/177 (9) | 6/96 (6) | |
| Oncocytoma | 8/177 (5) | 7/96 (7) | |
| Lymphoepithelial cyst | 5/177 (3) | 2/96 (2) | |
| Basal cell adenoma | 12/177 (7) | 1/96 (1) | |
| Lymphoma or leukemia | 0 | 1/96 (1) | |
| Monomorphic adenoma | 1/177 (1) | 3/96 (3) | |
| Otherc | 5/177 (3) | 11/96 (11) | |
| Benign cyst (not lymphoepithelial cyst) | 2/177 (1) | 3/96 (3) | |
| Short-term adverse events | |||
| Hematoma | 5/165 (3) | 4/84 (5) | −2 (−7 to 4) |
| Sialocele | 0 | 0 | NE |
| Seroma | 4/165 (2) | 1/82 (1) | 1 (−2 to 5) |
| Frey syndrome | 1/137 (1) | 12/78(15) | −15 (−23 to −7) |
| First bite syndrome | 34/148 (23) | 7/78 (9) | 14 (5 to 23) |
| Facial contour defect | 28/162 (17) | 25/84 (30) | −13 (−24 to −1) |
| Ear numbness | 52/158 (33) | 20/80 (25) | 8 (−4 to 20) |
| Wound infection | 1/153 (1) | 1/84 (1) | NE |
| Unplanned return to the ED | 1/164 (1) | 3/86 (3) | NE |
| Unplanned return to the OR | 2/165 (1) | 3/86 (3) | −2 (−7 to 2) |
| Any of the above | 89/156 (57) | 53/82 (65) | −8 (−21 to 5) |
| House-Brackmann grade at first follow-up visit | |||
| I | 118/177 (67) | 47/96 (49) | 17 (4 to 30) |
| II | 27/157 (17) | 22/81 (27) | |
| III | 5/157 (3) | 4/81 (5) | |
| IV | 3/157 (2) | 5/81 (6) | |
| V | 3/157 (2) | 3/81 (4) | |
| VI | 1/157 (1) | 0 | |
| House-Brackmann grade at ≥1 y | |||
| I | 37/40 (93) | 30/32 (94) | −1 (−13 to 10) |
| II | 3/40 (8) | 2/32 (6) | |
Abbreviations: ED, emergency department; NE, not evaluated because there was too little variability in the feature under study (ie, <5 patients had data that differed from the rest of the cohort); OR, operating room; SDLP, selective deep lobe parotidectomy.
Calculated as the difference in percentages, SDLP minus total parotidectomy. For features with several categories (eg, House-Brackmann grade), differences and 95% CIs were calculated for the most common category.
The median length of hospital stay was 1 day (IQR, 1-1 days) for both groups.
The other pathologic diagnoses included lipoma (1), neurofibroma (1), schwannoma (2), and solitary fibrous tumor (1) for the 5 patients in the SDLP group; and benign peripheral nerve sheath tumor (1), benign simple cyst (1), benign venous malformation (1), cavernous hemangioma (1), hemangioma (1), lymphangioma (1), myoepithelioma (1), plexiform schwannoma (1), schwannoma (1), epithelioid hemangioma (1), and fibrolipoma (1) for the 11 patients in the total parotidectomy group.
Discussion
In this study, we compared the surgical outcomes of SDLP and total parotidectomy for patients with benign parotid tumors located in the deep lobe or the deep lobe and parapharynx. We found that, compared with total parotidectomy, SDLP was (1) a safe and effective procedure for patients with benign deep lobe parotid tumors, (2) associated with lower rates of reconstruction for facial asymmetry due to the smaller tissue volume deficit, (3) associated with better immediate facial nerve outcomes, (4) associated with lower rates of Frey syndrome, and (5) associated with higher rates of first bite syndrome. These findings have important implications for preoperative patient counseling and choice of surgical approach for benign tumors in the deep lobe of the parotid gland.
There have been several smaller retrospective single-institution investigations of SDLP that reported low complication rates and no instances of tumor recurrence, permanent facial nerve injury, or postparotidectomy contour defect.3,5,6,7,8,9 Collela et al3 and Roh and Park8 found that the salivary function of the parotid gland was preserved in patients who underwent SDLP. Our findings support the outcomes reported in previous case series for SDLP. In addition, our findings offer unique contributions to the literature by highlighting the advantages and disadvantages associated with SDLP compared with total parotidectomy.
In this study, an abdominal dermal fat graft was more commonly performed for patients who underwent total parotidectomy than for patients who underwent SDLP. Using eye-tracking technology, Anderies et al12 found that the average superficial parotidectomy does not create a significant enough contour deformity to distract casual observer attention, and, in their study, most of the patients did not undergo reconstruction with a fat graft. They suggest that the average total parotidectomy will result in a significant contour deformity that is visually distracting to casual observers and that with abdominal dermal fat graft reconstruction, this visual distraction can be alleviated. Most patients undergoing total parotidectomy in our practice are offered abdominal dermal fat graft reconstruction. Two important variables for the development of a postparotidectomy contour defect are the volume of parotid tissue removed and the patient’s facial structure.12 The superficial lobe accounts for approximately 80% of parotid tissue volume (Figure).13 One significant advantage associated with SDLP is that preservation of the superficial lobe decreases the likelihood of developing a postparotidectomy contour defect and decreases the need for facial reconstruction with an abdominal dermal fat graft.
Figure. Tumor Located in Deep Lobe of Parotid Gland With Superficial Lobe Reflected (A) and Axial T1 Postcontrast Magnetic Resonance Imaging (MRI) Demonstrating Right Deep Lobe Parotid Tumor (B).
Patients in the SDLP group had a lower House-Brackmann grade on postoperative day zero and at their first follow-up appointment approximately 3 months after surgery. Haring et al14 investigated associations between facial nerve monitoring and postoperative facial nerve outcomes. They found that a higher postdissection threshold on facial nerve monitoring and a higher number of intraoperative mechanical events were associated with worse immediate facial nerve outcomes. They describe the extent of surgery as a risk factor for facial nerve injury associated with an increased number of intraoperative mechanical events. Selective deep lobe parotidectomy requires less dissection of the facial nerve than total parotidectomy, which likely accounts for better immediate facial nerve outcomes after SDLP.3,4,5,6,7,8,9
The GAN was preserved for 82% of patients in the SDLP group compared with 59% of patients in the total parotidectomy group. Several studies have shown that the division of the GAN during parotidectomy is associated with sensory and functional deficits and increased risk of neuromas.15,16 In a randomized clinical trial comparing partial parotidectomy vs total parotidectomy, Roh et al17 found that partial parotidectomy was associated with better GAN preservation. In this study, we found that when the superficial lobe of the parotid was preserved for SDLP, there was increased preservation of the GAN compared with total parotidectomy. Anatomically, this is likely due to the association between the GAN and the parotid gland. Anterior branches of the GAN may penetrate the parotid gland, and these branches or the main trunk of the GAN are often sacrificed during complete parotidectomy.18 In a more limited dissection during SDLP, there is a greater likelihood of preserving these branches.
When comparing postoperative complications, there was no clinically meaningful difference between the 2 groups in the length of hospital stay or the rate of most postoperative complications, such as hematoma, sialocele, seroma, ear numbness, wound infection, or unplanned return to the emergency department or operating room. The SDLP group reported a lower rate of Frey syndrome. Frey syndrome, also known as gustatory sweating, is a result of the regeneration of the postganglionic parasympathetic nerve fibers in relation to the severed postganglionic sympathetic fibers.19 Martin et al20 describe a greater incidence of Frey syndrome with superficial parotidectomy compared with extracapsular dissection. The reduced risk of Frey syndrome after extracapsular dissection may be associated with the reduced disruption of the parotid gland parenchyma and its auriculotemporal innervation compared with superficial parotidectomy.20 Similarly, preservation of the superficial lobe during SDLP likely minimizes disruption of auriculotemporal nerve fibers in the superficial lobe of the parotid, which is associated with less aberrant regeneration of these postganglionic parasympathetic fibers and, therefore, a lower rate of Frey syndrome for SDLP compared with total parotidectomy, as seen in this study.
There was a higher rate of first bite syndrome in the SDLP group compared with the total parotidectomy group. First bite syndrome is facial pain and cramping in the parotid region that occurs on the first bite of a meal and diminishes with each subsequent bite.21 It is thought to be secondary to unopposed parasympathetic innervation of the parotid gland after disruption of the sympathetic innervation during dissection of the carotid artery.22 This unopposed parasympathetic innervation can lead to excessive contraction of the remaining parotid salivary system upon eating. There are 2 possible mechanisms that may explain why SDLP is associated with a higher rate of first bite syndrome. First, any partial parotidectomy procedure leaves more functional salivary tissue, and SDLP leaves much more functional salivary tissue to produce first bite syndrome compared with total parotidectomy.8 In addition, access to deep lobe parotid tumors via an SDLP approach often uses the external carotid artery as a surgical landmark, identifying the vessel just above the posterior belly of the digastric muscle and following it distally as it enters the deep lobe of the parotid gland to identify the location of the tumor. In the transoral robotic surgery literature, prophylactic ligation of external carotid artery branches to decrease the incidence of postoperative bleeding after resection of oropharynx cancers has been associated with the development of first bite syndrome.23 Our findings are similar to those reported by Linkov et al,21 who showed that 38.4% of patients undergoing isolated deep lobe parotid resection developed first bite syndrome compared with 0.8% of patients undergoing total parotidectomy. Fortunately, most patients will have a gradual decrease in the intensity and frequency of the pain episodes associated with first bite syndrome.23
Limitations
This study had some limitations, including that most patients in this study had less than 1 year of follow-up. The median follow-up was longer for patients undergoing total parotidectomy than for those undergoing SDLP. These limitations in the follow-up period may be associated with the difficulty in accurately assessing recurrence rates (especially given that the 2 reported recurrences occurred close to 10 years after surgery) and Frey syndrome and less likely assessing short-term adverse event rates. Skill set and level of mastery varies by physician, which may lead clinicians toward a certain procedure over another. Similarly, rates of complications and outcomes may differ from surgeon to surgeon depending on their level of comfort with SDLP.
Conclusion
This case series study suggests that SDLP can be considered an effective technique for the management of benign tumors in the deep parotid lobe. The major advantages associated with this procedure include a reduction in the need for volume reconstruction and a reduction in complications, such as temporary facial nerve palsy and Frey syndrome. The disadvantages include a higher rate of first bite syndrome. We believe that SDLP is a safe approach for patients with benign tumors in the deep parotid lobe, and patients should be offered this technique if the surgeon is experienced. Patients should be counseled on the advantages and disadvantages of SDLP, including the risk of first bite syndrome, which typically resolves without intervention but may require botulinum toxin injection in some cases.
Data Sharing Statement
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