Townsend Courtney M.Jr., Evers B. Mark. Atlas of General Surgical Techniques: Expert Consult

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CHAPTER 2 • Modiﬁ ed Radical Neck Dissection Preserving Spinal Accessory Nerve 25

Facial vessels

Marginal mandibular nerve

FIGURE 2 –3

Incision is over the hyoid bone

Submental fibro-fatty tissue

Anterior belly of digastric muscle

FIGURE 2 –4

26 Section I • Head and Neck and Endocrine Procedures

◆ The periosteum overlying the inferior border of the mandibular body is incised with

electrocautery, and the tissue in the submandibular triangle is retracted inferiorly. The facial

vessels are ligated at the lower border of the body of the mandible (Figure 2-5).

◆ The posterior border of the mylohyoid muscle is identiﬁ ed during this dissection

(Figure 2-6).

Nerve to mylohyoid

Facial artery and vein

Marginal mandibular nerve

FIGURE 2 –5

Submandibular gland

and tissue

Mylohyoid muscle

FIGURE 2 –6

CHAPTER 2 • Modiﬁ ed Radical Neck Dissection Preserving Spinal Accessory Nerve 27

◆ An Army-Navy retractor is placed under the posterior aspect of the mylohyoid muscle, and

it is retracted cephalad. The lingual nerve, submandibular ganglion, and submandibular

duct are identiﬁ ed (Figure 2-7, A).

◆ A clamp is placed below the submandibular ganglion, and the postganglionic ﬁ bers are

transected and ligated. This releases the lingual nerve (Figure 2-7, B-C).

◆ The submandibular duct is located medial to the ganglion; it is transected and ligated

(Figure 2-7, B-C).

Submandibular ganglion

Submandibular duct

Lingual nerve

FIGURE 2 –7

28 Section I • Head and Neck and Endocrine Procedures

◆ Inferior retraction of the submandibular contents reveals the facial vessels as they cross the

superior aspect of the posterior belly of the digastric muscle. The vessels are clamped, tran-

sected, and ligated. The posterior belly of the digastric muscle is isolated in its entirety. This

muscle belly provides a landmark for levels I and II and the carotid sheath. The contents of

the submental and submandibular triangles, including the prevascular nodes, are pedicled

at the level of the hyoid bone (Figure 2-8).

◆ Attention is now directed to the posterior skin ﬂ ap. Elevation of the ﬂ ap proceeds in a sub-

cutaneous plane until the anterior border of the trapezius muscle is reached (Figure 2-9).

The platysma is deﬁ cient in this area, and care must be taken to not “button hole” the skin

ﬂ ap by dissecting too superﬁ cially or to injure the SAN by dissecting too deeply; the SAN

lies superﬁ cial in the posterior triangle. The use of electrocautery may stimulate the SAN

and cause the shoulder to “jump.”

Facial artery and vein

Submandibular gland

Marginal mandibular nerve

External jugular vein

Greater

auricular nerve

Tail of

parotid gland

FIGURE 2 –8

External jugular vein

Greater auricular nerve

Lesser occipital nerve

FIGURE 2 –9

CHAPTER 2 • Modiﬁ ed Radical Neck Dissection Preserving Spinal Accessory Nerve 29

◆ The SAN is identiﬁ ed in the posterior triangle as it enters the trapezius muscle. A spreading

technique using a ﬁ ne hemostat or Metzenbaum scissors is used to dissect the soft tissue

and fascia overlying the nerve. The nerve is traced as it passes from the trapezius muscle to

the SCM muscle (Figure 2-10).

◆ The SAN exits the SCM muscle and dissection continues anteriorly and superiorly to the

skull base, transecting the overlying muscle with the nerve constantly in view. This divides

the SCM muscle in two (Figure 2-11). The posterior belly of the digastric muscle is

retracted superiorly for exposure of the nerve and the IJV at the skull base. The relationship

of the SAN to the IJV is noted during this dissection.

◆ The nerve is sharply dissected from the underlying tissue. The branch to the SCM muscle

must be divided to mobilize the nerve. A nerve hook or vein retractor can be used to

retract the nerve as it is being skeletonized to minimize trauma.

Accessory nerve

FIGURE 2 –10

Accessory nerve

Trapezius muscle

FIGURE 2 –11

30 Section I • Head and Neck and Endocrine Procedures

◆ The IJV at the skull base is isolated circumferentially from the surrounding tissue so that it

can be ligated at a later time.

◆ The sternal and clavicular heads of the SCM muscle are transected one ﬁ ngerbreadth

above the clavicle (Figure 2-12). Upward traction is placed on the muscle with a sponge,

and the layers of the muscle are carefully transected so as not to injure the contents of the

carotid sheath that lie immediately deep to the muscle.

◆ Once the SCM muscle is divided inferiorly, the posterior belly of the omohyoid muscle is

visualized. The tissue overlying the muscle posteriorly is incised (Figure 2-13).

Sternocleidomastoid muscle

(clavicular head)

FIGURE 2 –12

Fascia covering

Omohyoid muscle

(posterior belly)

Sternocleidomastoid

muscle

Carotid sheath

FIGURE 2 –13

CHAPTER 2 • Modiﬁ ed Radical Neck Dissection Preserving Spinal Accessory Nerve 31

◆ The muscle belly itself is transected near its origin at the scapula (Figure 2-14) and elevated

anteriorly to its attachment at the hyoid bone. The anterior jugular veins will be encountered

at this point and should be ligated. This deﬁ nes the anterior limit of the neck dissection.

◆ The fascia underlying the posterior belly of the omohyoid muscle is incised horizontally. The

supraclavicular fat pad is then opened using blunt dissection exposing the brachial plexus

and phrenic nerve, which lies on the surface of the anterior scalene muscle (Figure 2-15). The

dissection should not continue until the brachial plexus and phrenic nerve are identiﬁ ed,

because injury to these structures can be catastrophic. The transverse cervical vessels will also

be seen in this area. It is not always necessary to divide these vessels.

Omohyoid muscle

Sternocleidomastoid

muscle

FIGURE 2 –14

Brachial plexus

External jugular vein

Cut edge of fascia

Anterior scalene muscle

Phrenic nerve

FIGURE 2 –15

32 Section I • Head and Neck and Endocrine Procedures

◆ The ﬁ bro-fatty tissue between the brachial plexus and the anterior border of the trapezius

muscle (supraclavicular fat pad) is clamped and ligated. The brachial plexus must be

directly visualized while the clamps are being placed. This tissue can be bluntly dissected

using a ﬁ nger. This area is known as the “bloody gulch,” and bleeding will occur if the

tissue is not ligated (Figure 2-16).

◆ Dissection is then carried superiorly along the anterior border of the trapezius muscle until the

SAN is encountered. The SAN is retracted anteriorly to avoid injury during this dissection. The

SCM muscle is transected just inferior to the mastoid tip, and the fascia is incised at its poste-

rior aspect (Figure 2-17). This allows the specimen to be retracted medially.

Incise through

fascia

Transverse

cervical vessels

Accessory nerve

FIGURE 2 –17

Brachial plexus

Accessory nerve

Phrenic nerve

FIGURE 2 –16

CHAPTER 2 • Modiﬁ ed Radical Neck Dissection Preserving Spinal Accessory Nerve 33

◆ The specimen, including the ﬁ bro-fatty and lymphatic tissue in level V, as well as the

superior aspect of the SCM muscle, is dissected in a posterior to anterior direction. The

specimen is passed underneath the SAN, gently retracting the SAN laterally (Figure 2-18).

◆ The deep limit of dissection is the fascia of the deep cervical muscles; the dissection proceeds

along the medial aspect of the levator scapulae and the scalene muscles. The rootlets of the

cervical plexus are exposed. The cutaneous branches are transected and removed with the

specimen. Care must be taken to preserve the nerve supply to the posterior compartment

musculature and the contributions to the phrenic nerve. This is done by transecting the

cervical rootlets approximately 1 cm anterior to the takeoff of the phrenic nerve, that is, “high”

in the specimen. Vessels typically accompany the rootlets and should be controlled using

bipolar cautery or suture ligation. In addition, care must be taken to avoid direct injury to the

phrenic nerve by lifting it off the anterior scalene muscle with the specimen (Figure 2-19).

Accessory nerve

Fibro-fatty tissue

Phrenic nerve

FIGURE 2 –18

Cervical rootlets

Phrenic nerve

FIGURE 2 –19

34 Section I • Head and Neck and Endocrine Procedures

◆ Mobilization of the specimen continues until the IJV is exposed in its full length

(Figure 2-20).

Splenius muscle

Carotid sheath

Internal jugular vein

FIGURE 2 –20