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).