Enhancing submandibular gland resection: A retrospective study on the efficacy of the ORBEYE 3D exoscope

Abstract

Purpose

For submandibular gland resection, conventional surgery with the naked eye remains the standard. With its excellent automatic focus and high magnification, the ORBEYE 3D exoscope enables precise submandibular gland resection with less stress. Therefore, we aimed to examine the usefulness of the exoscope in submandibular gland resection.

Methods

This retrospective study involved 12 patients who underwent submandibular gland resection with the ORBEYE exoscope at the Department of Head and Neck Surgery and Otorhinolaryngology at Kansai Medical University from April 2021 to March 2024. Surgical outcomes were retrospectively reviewed.

Results

The mean age of the patients (six women and six men) was 58.5 (23–83) years. The final histopathology showed pleomorphic adenoma in eight patients, non-sebaceous-type lymphadenoma and carcinoma ex pleomorphic adenoma in one patient each, and sialolithiasis with chronic inflammation in two patients. We performed facial artery and vein sparing in all patients except one, in whom level I neck dissection, including submandibular gland excision, was performed. We identified the marginal mandibular branches of the facial, hypoglossal, and lingual nerves, as well as the submandibular duct in all patients. There were no postoperative complications in any of the patients. The mean operative time was 104 (80–129) min. The mean blood volume lost was 20 (5–43) mL.

Conclusion

Using the ORBEYE exoscope in submandibular gland resection will contribute to preserving the mandibular marginal branch of the facial and lingual nerves and facial and artery veins, and visualizing the submandibular ducts, which are important structures surrounding the submandibular gland.

Introduction

Head and neck surgery, including submandibular gland resection performed under magnification, is rare and is performed with the naked eye or, occasionally, with a loupe [1]. The main indications for submandibular gland surgery are chronic sialadenitis based on submandibular gland calculi and tumors. Submandibular gland surgery is essential to avoid damage to the nerves running in the surrounding areas, including the marginal mandibular branch of the facial, hypoglossal, and lingual nerves. Injury to the marginal mandibular branch of the facial nerve is more common than that of the hypoglossal or lingual nerves, with a transient rate of 1–7% and a permanent rate of approximately 2%, compared with < 2% for the hypoglossal and lingual nerves [2–6]. Submandibular duct visibility in level 1 neck dissection, including submandibular gland excision, is as low as 22% [2]. This may pose a challenge if adhesion occurs between the lingual nerve and surrounding tissues, such as the submandibular duct, due to inflammation of the surrounding areas caused by sialolithiasis.

The exoscope is primarily used as an alternative to the microscope in neurosurgery, microvascular surgery, and otologic surgeries [7–9]; however, its use in neck surgery may considerably affect surgical outcomes. ORBEYETM (Olympus, Tokyo, Japan) is a 4K3D exoscope with a small mirror body and excellent autofocus, a valuable function in head and neck surgery to magnify the surgical field and enable precise surgical dissection of the submandibular region to reduce the risk of iatrogenic lesions. Introducing equipment that can provide a magnified field-of-view without stress to preserve the function of the delicate structures mentioned above is necessary. In this study, we investigated, for the first time, the usefulness of the ORBEYE exoscope for submandibular gland surgery.

Materials and methods

This retrospective study of patients who underwent submandibular gland excision using ORBEYE at Kansai Medical University (KMU; Hirakata, Japan) between January 2018 and March 2024 included patients with previously untreated submandibular lesions (Table 1). We targeted 12 consecutive patients clinically diagnosed with submandibular gland tumors or sialoliths in the submandibular glands and examined the surgical outcomes and complications. On postoperative day 1 and several days post-operation, the function of the facial, lingual, and hypoglossal nerves was evaluated by a surgeon different from the one who performed the surgery. We excluded patients with preoperative skin involvement or clinical lymph node metastasis requiring neck dissection other than level I. Two surgeons performed submandibular gland resection using ORBEYE, with one surgeon performing 10 surgeries and the other performing two. To compare surgery times, we calculated the operation times for 24 conventional submandibular gland excisions performed without ORBEYE between January 2019 and December 2020.

Table 1.

Patient demographics and outcome information (submandibular gland excision)

	Age (years)	Sex	Histopathology	Extent of resection	Facial A.V. preservation	Complication	Operation time (min)	Blood loss (mL)
1	65	M	PA	S.E.	Preserved	None	127	30
2	64	F	salivary gland Carcinoma ex PA	S.E. with Level I ND	Sacrificed	None	118	13
3	64	M	Sialolithiasis with chronic inflammation	S.E.	Preserved	None	118	27
4	23	M	PA	S.E.	Preserved	None	129	5
5	35	F	PA	S.E.	Preserved	None	121	31
6	59	F	Lymphadenoma, non-sebaceous type	S.E.	Preserved	None	85	43
7	50	F	PA	S.E.	Preserved	None	104	12
8	72	F	PA	S.E.	Preserved	None	81	6
9	68	M	Sialolithiasis with chronic inflammation	S.E.	Preserved	None	80	13
10	71	M	PA	S.E.	Preserved	None	96	10
11	51	F	PA	S.E.	Preserved	None	80	26
12	83	M	PA	S.E.	Preserved	None	106	24
MEAN	58.75						104	20

A artery; V vein; M male; F female; PA pleomorphic adenoma; SE submandibular gland excision; Level I ND level I lymph node dissection

The KMU Ethics Committee and institutional review board approved this study (2020076). The hospital ethics committee waived the requirement for patient consent because this was a retrospective review and did not include any patient identifiers. However, consent was obtained for the use of images in the text.

Fig. 1.

Schematic surgical setup demonstrating the ORBEYE exoscope and screen positions relative to the surgeon, assistant, nurse, and anesthesiologist

Surgical technique

Two surgeons performed the surgical procedures. A horizontal skin incision was made approximately 3 cm caudal to the inferior border of the mandible, and subplatysmal skin flaps were raised. In two patients, the marginal mandibular branch of the facial nerve was identified and magnified (Fig. 2a). In the other 10 patients, the submandibular gland capsule reached the submandibular end, and dissection of the superficial tissue over the submandibular capsule proceeded cephalad, exposing the submandibular gland without identifying the marginal mandibular branch (Fig. 2b). The facial arteries and veins were preserved by ligation or coagulation of the branches of these vessels toward the submandibular glands (Fig. 3). The facial artery and vein were ligated in only one patient (Case 2) because neck dissection was performed at level I. Dissection of the submandibular gland’s deep surface was performed to expose the mylohyoid muscle, and retraction of this muscle exposed the lingual nerve (Fig. 4). The lingual nerve was separated to ligate the submandibular ganglion (Figs. 4 and 5). The submandibular duct was then ligated (Figs. 4 and 5).

Fig. 2.

Identification (a) and non-identification (b) of the mandibular marginal branch of the facial nerve. a Arrowheads indicate the mandibular marginal branch of the facial nerve. b Preservation of the mandibular marginal branch of the facial nerve through dissection of its superficial tissue over the submandibular capsule (arrows).

Fig. 3.

Preservation of the facial artery and vein. a The facial artery (arrowhead) is embedded in the submandibular gland (delineated). b The entire circumference of the facial artery is exposed. c The anterior branch of the facial artery is ligated, and the submandibular gland and facial artery are separated. d Preservation of the facial vein (arrowhead)

Fig. 4.

Lingual nerve and submandibular duct. a Lingual nerve (arrow) and the submandibular ganglion (arrowhead). b Lingual nerve (arrow) and ligation of the submandibular duct (arrowhead)

Fig. 5.

Adhesion between the lingual nerve (arrow) and the submandibular duct (arrowhead) in a patient with sialolithiasis. a Dilated submandibular gland duct due to a stone and adherent lingual nerves. b Ligation was performed while securing the salivary stone in the submandibular gland duct on the resection side, while preserving the lingual nerve

Statistical analysis

Comparative analysis was performed using JMP^® version 13 (SAS Institute, Cary, NC, USA) for Windows 10.0. Statistical significance was set at p ≤ 0.05.

Results

In all patients, we used the ORBEYE exoscope under monitoring throughout the surgical procedure except for skin incision and skin suture; we did not switch to the conventional method in any of the patients. Structures, such as the marginal mandibular, lingual, and hypoglossal nerves, as well as the submandibular duct, were confirmed using the ORBEYE exoscope under monitoring in all patients. The demographic characteristics of the 12 patients are summarized in Table 1.

The mean age of the 12 patients was 58.5 (23–83) years. The final histopathology showed pleomorphic adenoma in eight patients, non-sebaceous-type lymphadenoma in one patient, carcinoma ex pleomorphic adenoma in one patient, and sialolithiasis with chronic inflammation in two patients. The extent of resection was submandibular gland excision in 11 patients and level I lymph node dissection (submental and submandibular nodes), including submandibular excision in one patient (Case 2). We performed facial artery and vein sparing in all patients, except in one patient (Case 2), in whom level I neck dissection, including submandibular gland excision, was performed. In all patients, the marginal mandibular branches of the facial, hypoglossal, and lingual nerves, as well as Warton’s duct, were identified and preserved. None of the patients experienced paralysis of the marginal mandibular branches of the facial, hypoglossal, or lingual nerves, and postoperative bleeding or infection. The mean operative time was 104 (80–129) min. The mean volume of blood lost was 20 (5–43) mL. Between 2019 and 2020, 24 cases of submandibular gland excision were performed, with surgery times ranging from 60 to 182 min and an average of 98.4 min. Of these 24 cases, 11 were submandibular gland calculi, 10 were pleomorphic adenomas, and 3 were malignant tumors (2 cases of pleomorphic adenoma-derived cancer and 1 case of adenoid cystic carcinoma).

Discussion

This retrospective review of 12 cases of submandibular gland resection using an ORBEYE exoscope revealed no postoperative complications, including nerve palsy and vasculature preservation. To our knowledge, this is the first study to examine the usefulness of an exoscope in submandibular gland resection. An exoscope is advantageous because of its superior ergonomics, with reduced fatigue due to its free viewing angle, and its educational significance, as it enables screen sharing with the same surgical field of vision as the surgeon. Moreover, it enables to perform surgery while viewing high-resolution 3D images under magnification [8–11]. In head and neck surgery, usually performed with the naked eye, the ORBEYE exoscope’s excellent autofocus function and small mirror body allow the surgeon to avoid interference from instruments and secure a smooth surgical field without stress. Additionally, its ability to magnify nerves and blood vessels is extremely useful.

In the conventional method, some critical structures for level 1 neck dissection involving submandibular gland excision, such as the marginal mandibular, lingual, and hypoglossal nerves, and the submandibular duct, may not be identified [2]. Paralysis of the mandibular marginal branch of the facial, lingual, and hypoglossal nerves in submandibular gland surgery occurs in 1–7%, 0.5–4.4%, and 0–1.4% of cases, respectively [3–6]. A lack of confirmation can cause these nerve injuries and adhesions between the lingual nerve and the submandibular canal, as observed in sialolithiasis. In the present study, we believe these structures were preserved because they could be clearly visualized under the ORBEYE exoscope.

The facial artery can be preserved by partially burying it in the glandular tissue. This requires careful blunt dissection of the submandibular gland along its course and the division of several small arterial branches from the artery to the gland to free it from the gland. The exoscope helped magnify the surgical field by delicately dissecting the submandibular gland, detaching the artery, and ligating small arterial branches from the artery to the gland. Facial veins rarely run embedded in the submandibular gland [12]. However, the vein requires ligature processing of small venous branches, and the benefit of obtaining magnified views in venous processing, which is prone to vascular collapse, is considered crucial. Cutting and ligating the facial artery are common practices in conventional submandibular surgery; however, facial artery preservation is important because of its role in blood flow to the lower face and platysma muscle. The facial artery should not be routinely ligated and sacrificed because it is a crucial recipient vessel in head and neck reconstructive surgery [12].

Endoscopic and robotic techniques have been reported for submandibular gland surgery, the advantages of which are primarily cosmetic appeal and high magnification [1, 13–19]. However, they are not widely used, possibly because of the complexity of preparation and cost. In contrast, the ORBEYE exoscope does not require special settings or devices other than drapes, such as ultrasonic coagulation devices, and the surgical instruments are almost similar to those used in conventional surgery. Furthermore, the difference in the direction of the field of view compared with that of classical submandibular surgery may also hinder its adoption by surgeons. Therefore, using the exoscope requires familiarity with hand–eye coordination; however, because the direction of the field of view is the same, the hurdle to exoscope adoption may be low. Reports of endoscopic and robotic surgery have generally shown promising results in preserving the mandibular marginal branch and other nerves; however, the facial arteriovenous system is ligated, except for robotic resection through a trans-hairline approach [14–19]. The benefits of preserving the facial arteriovenous system remain unknown; however, preserving large-diameter vessels is not likely to be disadvantageous. To our knowledge, there have been no reports on the use of an exoscope. The ORBEYE™ system is priced at approximately $412,000, which is considered cost-competitive compared to conventional high-end surgical microscopes with equivalent optical and imaging capabilities. Additionally, the system requires minimal recurring expenditure, with disposable sterile drapes being the only consumable item.

This preliminary study provides promising results but has some limitations. The main limitation is the small number of patients included, which may affect the results. Therefore, it will be necessary to conduct a prospective study of submandibular gland surgery, comparing the conventional method with the ORBEYE exoscopic approach in a larger number of patients in the future. Visualization of delicate structures, such as nerves and blood vessels, in greater detail may lead to lower complication rates and educational benefits. Using the ORBEYE exoscope has educational significance for instructors and observers. It is essential to understand anatomical details when learning a surgical technique, and understanding how to handle these structures and surrounding tissues from the surgeon’s perspective can be helpful in improving the technique; ORBEYE makes this possible.

Author contributions

Conceptualization: Masao Yagi. Methodology: Masao Yagi and Takuo Fujisawa. Formal analysis: Kensuke Suzuki. Investigation: Masao Yagi, Mizuki Morita, Toshiki Utsunomiya, and Minaki Shimizu. Data curation: Mizuki Morita and Tomofumi Sakagami. Writing of the original draft: Masao Yagi. Review and editing: Kensuke Suzuki and Tomofumi Sakagami. Supervision: Hiroshi Iwai. Project administration: Masao Yagi and Kensuke Suzuki. All authors read and approved the final manuscript.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Data availability

The data that support the findings of this study are available from the corresponding author on reasonable request.

Declarations

Ethics approval

The KMU Ethics Committee and institutional review board approved this study (2020076).

Consent to participate

The hospital ethics committee waived the requirement for patient consent.

Consent to publish

The authors affirm that human research participants provided informed consent for publication of the images in Fig. 1a, b and c.

Competing interests

The authors declare no competing interests.