Abstract
Background and Objectives: The retroauricular hairline approach is increasingly being used for submandibular gland resections because of the excellent cosmetic results. A meta-analysis of studies compared the retroauricular hairline and conventional approaches for submandibular gland excision.
Methods: A meta-analysis of studies identified from the PubMed, Embase, and China National Knowledge Infrastructure databases was performed. Postoperative nerve damage (temporary earlobe numbness and other signs of nerve damage), surgical durations, wound lengths, intraoperative bleeding volumes, postoperative drainage, and lengths of hospital stay were compared.
Results: The retroauricular hairline approach led to greater risk of temporary earlobe numbness (OR: 7.28; 95% CI: 1.57–33.87; P = 0.01), but this resolved during the follow-up. There was no significant difference in the risk of other nerve injuries between the two approaches. The retroauricular hairline group had significantly longer operative times and wound lengths compared to the conventional resection group. There were no significant differences between the two approaches in intraoperative bleeding volumes, postoperative drainage, and lengths of hospital stay.
Conclusions: The retroauricular hairline approach is a safe and efficient alternative to the conventional approach. It provides better cosmetic results and does not increase the risk of long-term neurological complications.
Keywords: retroauricular approach, submandibular gland, aesthetic, gland-preserving surgery
Introduction
In recent decades, head and neck surgery has made great strides with the development and improvement of various minimally-invasive surgical techniques. These procedures have significantly improved survival rates, patient satisfaction, and quality of life. Head and neck surgery has been slow to adopt minimally-invasive surgical techniques because of the complex anatomy, limited operating space, and multiple contiguous layers and cavities in this region1. Technological developments in endoscopic and robotic surgery have led to significant advances in minimally-invasive surgery in all surgical fields, including head and neck surgery2-5. These surgical techniques eliminate the need for large, visible neck incisions and efficiently restore the function. They can also achieve improved aesthetic outcomes with an acceptable cost and complication rates equal to or lower than those for conventional surgery.
Submandibular gland resection is commonly performed for salivary gland tumors, recurrent submandibular adenitis, and salivary sialolithiasis. Traditional submandibular gland resection through a cervical incision is a safe procedure with a low risk of nerve damage, but has the major disadvantage of postoperative scar formation6. Several surgical approaches, including intraoral, endoscopic cervical, and retroauricular hairline approaches, have aimed to improve the cosmetic results of the procedure7-10. Despite perfect cosmetic results, the intraoral approach has been shown to cause lingual nerve palsy and limited tongue movements as a result of scar contracture8, 11. Although the endoscopic neck approach requires a smaller incision, the resultant scar is still visible and there may be pimple formation in keloid patients. The retroauricular hairline approach has a longer incision, but it is perfectly hidden in the hairline behind the ear12.
This study presents our experience with the esthetic and safety aspects of submandibular gland resection through the retroauricular hairline approach. The meta-analysis demonstrates the safety and esthetic advantages of this approach, along with the potential risk of temporary earlobe numbness, which resolves during the follow-up. Submandibular gland excision through the retroauricular hairline approach had a similar incidence of permanent postoperative complications and improved cosmetic results compared to the traditional approach.
Materials and methods
2.1 Search strategy
The PubMed, Embase, and China National Knowledge Infrastructure databases were systematically searched for articles published before January 2023. The following keywords were used to search for comparisons between retroauricular hairline and conventional approaches in submandibular gland excision patients: “submandibular gland”, “submandectomy”, “retroauricular approach”, “aesthetic”, and “gland-preserving surgery”. The search was expanded using the related literature function. All retrieved abstracts, articles, and citations were reviewed regardless of the language of publication.
2.2 Inclusion and exclusion criteria
Studies comparing the retroauricular and conventional approaches in patients undergoing submandibular adenotomy were included if an adequate description of the surgical technique and at least one quantitative outcome metric were reported. Patients with a history of neck surgery or radiotherapy, clinical signs of extra-glandular tumor infiltration, metastatic disease requiring concomitant neck dissection, and those with possible contraindications to surgery or general anesthesia based on the preoperative evaluation were excluded.
2.3 Data extraction
Data were independently extracted by two investigators who read the abstracts and full texts to identify the studies that met the inclusion criteria. Disagreements between the investigators were resolved through discussion. The following data were collected from each study: first author, year of publication, type of study, number of patients for each procedure, and complications.
2.4 Quality assessment
Study quality was assessed using the Newcastle-Ottawa Scale (NOS), which is based on three factors: patient selection, comparability of study groups, and number of reported outcomes. Study quality was indicated using the NOS star system. Each item received a maximum of one star, except items related to comparability, which could receive two stars. NOS scores range from 0 to 9 stars, with scores > 4 indicating high-quality studies13.
2.5 Statistical analysis
Meta-analyses were performed by using Review Manager version 5.2 (Cochrane Collaboration) and Stata SE version 12.0 (StataCorp LLC, College Station, TX, USA). Heterogeneity between groups was assessed using the χ2 test and I2 statistics, and the values were reported as degrees of freedom (df). Heterogeneity was considered significant if the p-value was < 0.10 or the I² value was > 50%. This was followed by a random effects or fixed effects model analysis, whichever was appropriate. Bilateral p-values < 0.05 were considered significant [14]. Subgroup and sensitivity analyses were further performed when the heterogeneity was large.
Publication bias was detected using Begg’s test and funnel plot analysis. Bilateral p-values < 0.05 were considered significant. Continuity variables were compared using the weighted mean difference (WMD), and reported with 95% confidence intervals (CIs). Dichotomous variables were compared using odds ratios (ORs), and reported with 95% CIs. An OR < 1 favored the retroauricular approach. If the 95% CI did not include the value of 1, point estimates were considered statistically significant at p < 0.0514.
Results
A total of 294 relevant studies were identified using the PubMed, Embase, and China National Knowledge Infrastructure databases, and were imported into the Endnote X8 software (Clarivate PLC, London, UK). After a review of the titles and abstracts, 56 studies were selected for in-depth assessment of the full texts. Eight of the studies met the eligibility criteria and were included in the meta-analysis15-22. The selection process for the studies included in the meta-analysis is shown in Fig 1. This study was conducted strictly in accordance with the PRISMA guidelines.
The studies included four prospective15, 17-19and four retrospective16, 20-22studies, with a total of 330 patients (186 and 144 for the conventional and retroauricular hairline approaches, respectively). The main outcome indicators were postoperative nerve damage, including temporary earlobe numbness (n = 4)15, 16, 18, 21 and other signs of nerve damage (n = 7)15-21. The secondary outcome indicators were duration of surgery (n = 8)15-22, wound length (n = 8)15-17, 22, intraoperative bleeding volume (n = 2)16, 22, postoperative drainage (n = 3)18, 19, 22, length of hospital stay (n = 5)15, 17-19, 22. Because of the good comparability and clear outcomes of the included studies, all NOS scores were > 4 stars (Table 1).