4 Surgical Technique
This chapter describes the surgical technique for a complete functional approach to the neck in which all cervical nodal groups are removed. For teaching purposes, the surgical steps are sequentially detailed. However, not every single surgical step of those mentioned must be considered mandatory for every malignant head-and-neck tumor. As previously emphasized in this book, the preservation of selected nodal groups is a valid option that does not modify the basic principle of the functional approach to the neck (i.e., the removal of lymphatic tissue by means of fascial dissection). Surgeons must be able to decide, according to their own personal experience, which nodal groups should be included in the dissection and which can be preserved, then proceed accordingly, skipping the surgical steps that may not be considered necessary.
4.2 Preoperative Preparation and Operating Room Setup
The patient should be prepared as for any major operation. Preoperative evaluation is accomplished by the anesthesiologist prior to surgery. Premedication is used according to the anesthesiologist’s choice. Prophylactic antibiotics are given according to the usual protocol. The patient’s neck and upper chest are shaved and prepared for the operation.
The patient is placed supine on the operating table with a roll or inflatable rubber bag under the shoulders to obtain the proper angle for surgery (Fig. 4‑1). This is generally obtained when the occiput rests against the upper end of the table. Elevating the upper half of the operating table to approximately 30 degrees will decrease the amount of bleeding during surgery. A bloodless field will decrease the operating time and help the identification of neck structures.
The patient’s lower face, ears, neck, shoulders, and upper chest are prepared with surgical solution, and the patient is draped in layers (Fig. 4‑2). Four towels are placed and affixed to the skin. Two of the towels are placed horizontally, one from the chin to the mastoid over the body of the mandible and the other across the upper chest from the shoulder to the midline. The remaining two towels are placed vertically, from the mastoid tip to the shoulder, except for unilateral procedures where the second vertical towel is placed in the midline. A sheet is placed over the patient’s chest and legs, and an open sheet covers the entire patient except for the field of operation. The Mayo stand is secured to the operating table over the thighs of the patient (Fig. 4‑3).
Two assistants are usually present: one in front of the surgeon and the second at the patient’s head. The scrub nurse stands on the right side of the patient facing the head of the table. The ventilator and the anesthetist are placed on the left side of the patient (Fig. 4‑4). Few general instruments are needed for the operation (Fig. 4‑5).
Muscular relaxation is usually avoided to perceive muscle contraction when approaching the main nerves of the neck, especially the spinal-accessory nerve. A nerve stimulator may be useful, although not necessary. We do not routinely perform intraoperative monitoring of the vagus nerve with endolaryngeal electrodes, except when the procedure involves the thyroid gland and the recurrent laryngeal nerve must be identified and preserved.
4.3 Incision and Flaps
The exact location and type of skin incision will depend on the site of the primary tumor and whether a unilateral or bilateral neck dissection is planned. The following are the main goals to be achieved by the skin incision:
Allow adequate exposure of the surgical field.
Assure adequate vascularization of the skin flaps.
Protect the carotid artery if the sternocleidomastoid muscle must be sacrificed.
Include scars from previous procedures (e.g., surgery and biopsy).
Consider the location of the primary tumor.
Facilitate the use of reconstructive techniques.
Contemplate the potential need of postoperative radiotherapy.
Produce acceptable cosmetic results.
A popular incision in our practice is the classic Gluck-Sorenson incision (Fig. 4‑6a), which is basically an apron flap incision. It starts on the mastoid tip, descends vertically through the sternocleidomastoid muscle to the supraclavicular area, and turns medially to cross the midline; the incision is prolonged contralaterally in a symmetrical fashion on bilateral procedures. The incision must be carried along the posterior border of the sternocleidomastoid muscle to facilitate the approach of the supraclavicular area when the lymph nodes in this region have to be removed. This incision allows good exposure when the neck dissection is to be combined with a laryngectomy or a thyroidectomy. When the operation includes a total laryngectomy, the midline is crossed a few centimeters above the suprasternal notch, and the stoma is usually incorporated in the incision. On the other hand, for partial laryngectomies and other tumors requiring temporary tracheostomy, the incision crosses the midline at the level of the cricoid cartilage and a small independent horizontal incision can be made at the level of the tracheostomy.
The single-Y incision (Fig. 4‑6b) is common in our practice for unilateral functional and selective neck dissection that includes the submandibular area and does not need a laryngectomy or a thyroidectomy (e.g., for oropharyngeal cancer). It is also useful when the removal of the primary tumor requires transmandibular approach, which may be accomplished by a chin and labial extension. A well-known disadvantage of this incision is the compromise to the blood supply, especially in the crossing of the incision. Thus, the vertical arm of the incision should be placed posterior to the carotid artery. The cosmetic result is improved by giving the vertical arm a slightly S-shaped curve.
Many other skin incisions have been described and may be used depending on the clinical characteristics of the lesion and the personal preference of the surgeon.
After the incision is completed, the skin flaps are elevated deep to the platysma muscle, preserving the superficial layer of the cervical fascia (Fig. 4‑7). Preservation of the external lymphatic envelope allows further fulfillment of the basic anatomical principle of the functional approach (i.e., the removal of the fascial walls of the lymphatic container along with the lymphatic tissue of the neck).
The limits for a comprehensive functional neck dissection are similar to those of the classic radical neck dissection (Fig. 4‑8). The surgical field should expose superiorly the inferior border of the mandible and the tail of the parotid gland. Inferiorly, the flap should be raised up to the level of the clavicle and the sternal notch. The midline of the neck will be the anterior border of the surgical field for a unilateral neck dissection. Finally, the great auricular nerve and the posterior border of the sternocleidomastoid muscle in the upper part of the surgical field, and the anterior border of the trapezius muscle in the lower half of the neck, constitute the posterior boundary of the dissection. After the flaps have been raised, the underlying neck structures can be seen shining through the superficial layer of the cervical fascia (Fig. 4‑7, Fig. 4‑8).
The skin flaps must be protected by suturing wet surgical sponges on their internal borders (Fig. 4‑9). Pulling from these sponges will help to create tension to the tissues during the procedure. Frequent moistening of the sponges will help to keep the skin flaps in good condition throughout the operation. It should be remembered that this may be a long operation since neck dissection is often performed in conjunction with removal of the primary tumor and, in some instances, reconstructive procedures. Thus, all efforts should be made to preserve the skin in good condition until the end of the procedure.
4.4 Dissection of the Sternocleidomastoid Muscle
Usually, the first step of the operation is the dissection of the fascia that covers the sternocleidomastoid muscle. The goal of this maneuver is to completely unwrap the muscle from its surrounding fascia.
The external jugular vein must be transected during the dissection of the fascia of the sternocleidomastoid muscle. Thus, prior to approaching the fascia, the external jugular vein is usually ligated and divided to facilitate the following maneuvers. Usually, two sections of the external jugular vein are required in functional and selective neck dissection at this stage (Fig. 4‑10): (1) at the posterior border of the sternocleidomastoid muscle, right inferiorly to Erb’s point; and (2) at the tail of the parotid gland, where the external jugular vein begins by the union of the retromandibular and posterior auricular veins. The external jugular vein should be ligated and divided at a third point at a later step of the operation, within the posterior triangle of the neck when this nodal region is included in the dissection.
The dissection of the sternocleidomastoid muscle begins with a longitudinal incision over the fascia, along the entire length of the muscle. This cut is made with a number-10 knife blade and must be placed near the posterior border of the muscle (Fig. 4‑11). The stroke of the knife runs parallel and immediately anterior to the great auricular nerve in the upper half, transects the transverse cervical nerve and the external jugular vein (ligated and divided on a previous step), and follows the posterior border of the muscle in the inferior half. This facilitates the dissection of the sternocleidomastoid muscle because the cleavage plane between the fascia and the muscle is much easier to identify in a forward direction. The external jugular vein is included in the specimen and dissected forward with the fascia of the sternocleidomastoid muscle (Fig. 4‑12). Using several hemostats, one of the assistants retracts the fascia medially while the surgeon carries the dissection toward the anterior margin of the muscle. Fascial retraction should be done with extreme care because the thin superficial layer of the cervical fascia is the only tissue now included in the specimen.
We strongly recommend performing this, as well as most other parts of the operation, using knife dissection. The fascial planes of the neck are mainly avascular and can be easily followed with the scalpel. For knife dissection to be most effective the tissue must be under traction. An important task of the assistants throughout the operation is to apply adequate pressure to the dissected tissue.
When the dissection reaches the anterior border of the sternocleidomastoid muscle, the hemostats that have been used to retract the fascia may be left lying on the medial part of the surgical field hanging toward the opposite side. This will maintain the required amount of traction while freeing the assistants’ hands. Further tension may be applied with a hand and a gauze. Then the muscle is retracted posteriorly to continue the dissection over its medial face. Retraction may be performed by the assistant sited at the head of the patient; or by the main surgeon, while holding the knife with the other hand (Fig. 4‑13).
Until this point, the cleavage plane between the muscle and the fascia is avascular. However, when the deep medial face of the muscle is approached, small perforating vessels are found entering the muscle through the fascia (Fig. 4‑13). The assistant must now cauterize the vessels while the surgeon continues the dissection over the entire medial surface of the sternocleidomastoid muscle. The surgeon must be extremely careful at the upper half of this region, where the spinal accessory nerve enters the muscle. One or more small vessels usually accompany the spinal accessory nerve, which often divides before entering the muscle. The vessels should be cauterized without injuring the nerve, and all branches of the nerve must be preserved to obtain the best shoulder function. More details concerning the dissection of the spinal accessory nerve are given on a later stage of the operation.
After all the small vessels entering the sternocleidomastoid muscle have been cauterized, a new avascular fascial plane is entered and the dissection continues posteriorly along the entire length of the muscle. The internal jugular vein can now be seen through the fascia of the carotid sheath (Fig. 4‑14).
The muscle is now almost completely separated from its covering fascia except for a small portion at the posterior border. This part of the muscle will be dissected on a later stage of the procedure. Wet surgical sponges are now introduced in the lower half of the sternocleidomastoid muscle, between the muscle and its dissected fascia. They will serve two purposes: (1) maintain the desired moisture of the dissected tissues while the attention shifts to the upper part of the surgical field; and (2) serve as a reference for the dissection of the fascia that still covers the posterior border of the sternocleidomastoid muscle, on a later stage of the operation.
The surgeon now moves to the upper part of the surgical field to complete the identification of the spinal accessory nerve. For a better understanding of the following steps of the operation, at this point it may help the reader to take a short pause in the technical details to realize how the surgical approach is made with respect to the sternocleidomastoid muscle when the posterior triangle is included in the resection.
4.5 Management of the Sternocleidomastoid Muscle
A comprehensive dissection of the posterior triangle of the neck is facilitated by a combined approach, both posterior and anterior to the sternocleidomastoid muscle (Fig. 4‑15). In the upper half of the neck the dissection is performed anterior to the sternocleidomastoid muscle, whereas in the lower half of the neck the supraclavicular fossa is approached posterior to the sternocleidomastoid muscle.
To better understand this, imagine the surgical field divided in two halves by a plane passing through Erb’s point, the place where the superficial branches of the cervical plexus appear at the posterior border of the sternocleidomastoid muscle. This creates an upper and a lower part of the neck.
The upper half of this division includes the submental and submandibular nodes (area I), the upper part of the posterior triangle of the neck (upper part of area V), and part of the lymphatic chain of the internal jugular vein (area II and part of area III). The dissection of the upper half of this division is performed anteriorly to the sternocleidomastoid muscle. For this purpose, the muscle must be retracted posteriorly throughout the dissection.
The lower half of this imaginary division includes the supraclavicular fossa (lower part of area V), the lower part of the lymphatic chain of the internal jugular vein (area IV and part of area III), and the paratracheal lymph nodes (area VI). These regions will be approached both posterior and anterior to the sternocleidomastoid muscle. The supraclavicular fossa will be dissected from behind the muscle, and the remaining lymph structures of the lower half of the neck will be approached anterior to the sternocleidomastoid muscle.
For the surgical specimen to be removed en bloc, the tissue removed from the supraclavicular fossa will be passed beneath the sternocleidomastoid muscle to meet the remaining part of the specimen.
This maneuver, which has always been difficult to understand, may also be performed anterior to the sternocleidomastoid muscle by strong posterior retraction of the muscle. Thus, the lower part of area V can be approached anterior to the sternocleidomastoid muscle and removed with the rest of the specimen in cases where the location of the primary tumor requires complete removal of the supraclavicular fibrofatty tissue (area V).
Now we shall resume the dissection at the point where we left it. The sternocleidomastoid muscle was almost completely free of its fascia, except for a small part at the posterior edge of the muscle, and the attention of the surgeon was directed to the upper part of the surgical field to identify the spinal accessory nerve on its course between the jugular foramen and the sternocleidomastoid muscle.
4.6 Identification of the Spinal Accessory Nerve
The main goal of this step of the operation is to identify the nerve at the entrance of the sternocleidomastoid muscle. This maneuver is helpful to avoid injuring the nerve while dissecting the fascia of the upper part of the sternocleidomastoid muscle and should be performed before completing the former step. The dissection of the entire course of the nerve between the sternocleidomastoid muscle and the internal jugular vein will be performed in a later step of the procedure.
The spinal accessory nerve enters the sternocleidomastoid muscle approximately at the junction of the upper and middle third of the muscle (Fig. 4‑16). Adequate exposure of the area requires posterior retraction of the sternocleidomastoid muscle. The small vessels that usually go along with the nerve are carefully cauterized and the nerve is examined for divisions that may appear before it enters the muscle. All nerve branches must be preserved to obtain the best shoulder function. Sometimes a branch from the second cervical nerve can be seen joining the spinal accessory nerve before its entrance into the sternocleidomastoid muscle. Although most anatomy books consider this and other branches from the cervical plexus to be mainly sensory, it is our experience that preservation of these branches helps to prevent shoulder dysfunction after the operation.
Once the nerve is identified, wet surgical sponges are introduced between the muscle and the fascia, avoiding excessive pressure and stretching maneuvers that may lead to spinal accessory nerve damage. The dissection now continues along the upper limit of the surgical field.