9 Robotic-Assisted Neck Dissection
Key Landmarks
Sternocleidomastoid muscle
Mandible angle
Clavicle
Key Vascular Structures
External jugular vein
Internal jugular vein
Facial artery
Key Nervous Structures
Great auricular nerve
Spinal accessory nerve
Hypoglossal nerve
Background
Since the introduction of the robotic system to the field of surgery, transoral robotic surgery (TORS) has been chosen by many surgeons from all over the world as a promising method in extirpating the primary lesions of head and neck carcinoma. On the basis of this achievement, the application of robotic surgery has been extrapolated to various minimally invasive head and neck surgery including neck dissection. Robot-assisted neck dissection (RAND) was first described by Kang et al, who presented their technique of robot-assisted selective neck dissection (SND) including levels IIA, III, IV, and VB in thyroid papillary carcinoma with lateral neck node metastasis. However, the upper cervical level I and posterior cervical levels IIB and VA were not easy to approach with this procedure as a consequence of the limited axis of view and instrumentation. Comprehensive neck dissection is frequently required in the neck management of head and neck carcinoma, so we have developed a novel retroauricular approach that could provide access to the upper and posterior cervical levels. Since 2010, we have developed and steadily performed robot-assisted neck dissection (RAND) for patients with cN+ necks as well as cN0 necks. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 In this chapter, our novel surgical technique of RAND via a retroauricular approach is introduced in detail, with special focus on the surgical anatomy.
Indications
Indications for robot-assisted neck dissection are as follows: (1) biopsy-proven cancer of the head and neck requiring elective neck dissection (cN0) or therapeutic neck dissection (cN+), (2) no previous treatment for head and neck cancer. For beginners, robot-assisted neck dissection should be attempted mainly in elective neck dissection for the cN0 neck; however, reflecting our surgical experience, the procedure can be competently performed on therapeutic neck dissection for the cN+ neck without overt extracapsular spread of the metastatic node. 1 Contraindications for this procedure are as follows: (1) patients expressing refusal of the procedure, (2) chemoradiation for primary definitive treatment due to refusal of surgery, (3) salvage neck surgery, (4) inoperable state due to distant metastasis, (5) unresectable metastatic cervical nodes with overt extracapsular spread, (6) advanced nodal stage more than N2, (7) patients who require cervical skin incision for removal of advanced primary cancers, (8) patients who require free flap reconstruction, or (9) history of neck surgery of any kind. We have recently begun and have been actively performing simultaneous robot-assisted neck dissection and free flap reconstruction via the same retroauricular approach, so the necessity for free flap reconstruction would be a relative contraindication. 7 The length and circumference of the patient′s neck are important determinants of good exposure for robot-assisted neck dissection. A patient who has a slender, long neck provides the best exposure, yet the robot-assisted neck dissection has been successfully managed as well in less favorable situations. The somatometry is not an absolute contraindication.
Surgical Anatomy
The relevant surgical anatomy will be discussed and illustrated according to two distinct types of neck dissection.
Selective Neck Dissection (Levels I–III) 2 , 3 , 4 , 6 , 9 , 10
Skin Incision Design
A retroauricular (RA) or modified facelift (MFL) incision is adopted with respect to the type and extent of surgery. The RA incision is placed at the retroauricular sulcus, where it is curved posteriorly at the level of the midpoint of the sulcus to angulate smoothly downward 0.5 cm inside and along the hairline ( Fig. 9.1a ). The MFL incision is similar to the RA incision except that it has an additional preauricular limb, so that the incision is extended along the ear lobule to the natural preauricular fold and behind the tragus ( Fig. 9.1b ).
Skin Flap Elevation
A subplatysmal skin flap is elevated just above the sternocleidomastoid (SCM) muscle using a monopolar electrocautery under direct vision. The great auricular nerve (GAN) and external jugular vein (EJV) can be identified, which are located superficial to the SCM muscle ( Fig. 9.2 ). The skin flap is elevated so that its anterior extent is the midline of the anterior neck, its superior extent the inferior border of the mandible, and its inferior extent the level of the omohyoid muscle. Skin flap elevation below the mandible should be conducted with caution so as not to damage the nearby marginal mandibular branch of the facial nerve. After identifying the contour of the submandibular gland (SMG), the lateral borders of the strap muscles are noted medially and the superior belly of the omohyoid muscle can be visualized inferiorly. Two assistant surgeons are needed to hold up the skin flap with an Army-Navy retractor or a right-angle breast retractor. After achievement of an adequate working space, a self-retaining retractor is applied ( Fig. 9.2 ).
Upper Neck Dissection under Direct Vision: Pre–Robotic Surgical Procedure
Before robotic arms are docked, neck dissection of fibrofatty tissues accessible under direct vision is conducted using the conventional technique. First of all, the marginal mandibular branch of the facial nerve is identified using the distal facial artery and vein as reference landmarks, which are located along the inferior border of the mandible ( Fig. 9.3 ). The marginal mandibular branch is preserved by careful dissection from the surrounding fibroadipose tissues containing the perifacial lymph nodes, which should be meticulously retrieved. Then the parotid tail is divided from the fibrofatty tissue using a Bovie coagulator. Dissecting the inferior border of the SMG reveals the posterior belly of the digastric muscle underneath ( Fig. 9.4 ). Dissecting the area between the inferior border of the digastric muscle and the anterior border of the SCM muscle enables the visualization of the internal jugular vein (IJV) contour. The transverse process of the atlas, which can be a reliable landmark to localize the spinal accessory nerve (SAN), can be palpated at this area. The SAN is identified and dissected, and level IIb is consequently dissected ( Fig. 9.5 ). The specimen is directed anteriorly toward the carotid sheath, combining the fibroadipose tissues of levels IIa and III while preserving the cervical plexus.
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