Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

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STEP 2: PREOPERATIVE CONSIDERATIONS

Selection of a surgical option for local control of breast cancer is a complex decision based on the tumor features, the body habitus, and individual choice. Interdisciplinary discussion with radiation oncologists, medical oncologists, and plastic surgeons, in addition to the oncologic surgeon, provides a comprehensive understanding of the options available to the patient.

Lumpectomy with axillary lymph node dissection may be an alternative procedure to a modified radical mastectomy for many women, especially in the current era of mammographic screening and identification of early stage disease and with the use of induction chemotherapy to reduce the size of the primary tumor.

Discussion of the planned procedure with the anesthesiologist is critical.

Long-acting paralytic agents should be avoided when an axillary dissection is planned to detect intact motor nerve function.

STEP 3: OPERATIVE STEPS

1.INCISION

The patient is placed in the supine position, close to the edge of the operating table for ease of exposure of the axilla, with the arm extended on a padded arm board with or without a wedge. The arm may be prepped out separately and covered in a sterile stockinette to allow free rotation of the arm medially to relax the pectoralis major and minor muscles.

Many incisions have been used for axillary dissection. The transverse incision approximately 1 cm below the hair-bearing area extending from the latissimus dorsi to the pectoralis major medially results in the most cosmetically attractive incision. Other incisions may be perpendicular to the axilla or S-shaped incisions.

A marking pen is used to draw the planned incision. The skin is incised and extended through the dermis into the subcutaneous adipose tissue to expose the investing fascia of the axilla (Figure 100-3). The thickness of the flaps will vary according to body mass index. In heavyset individuals, the flaps will be thick and may cave into the axilla, making dissection difficult. Adequate exposure is essential to avoid injury to important structures.

C H A P T E R 100 • Axillary Node Dissection 1113

Pectoralis major muscle retracted

Axillary fat and lymph nodes

FIGURE 100–3

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2. DISSECTION

Dissection is initiated by elevating the skin flaps with skin hooks or Freeman face lift retractors with electrocautery.

As the flaps are elevated, the assistant holds upward tension on the skin flaps while the surgeon uses countertraction on the axillary fat pad.

The skin flaps are raised circumferentially and retracted with medium Richardson retractors to expose the axillary fat and lymph nodes (see Figure 100-3).

Dissection is initiated along the pectoralis major muscle medially from superior to inferior. Care must be exercised to avoid injury to the medial anterior thoracic nerve (medial pectoral nerve), which may penetrate both pectoral muscles and emerge medially or may course along the lateral aspect of the pectoralis minor. Injury to this nerve may lead to atrophy of part of the pectoralis major muscle.

The fascia along the pectoralis major is incised and retracted medially with a small or medium Richardson retractor, exposing the underlying pectoralis minor. The clavipectoral fascia along the pectoralis minor is then incised and the retractor is replaced, exposing the level II nodes posterior to the pectoralis minor. The arm may now be rotated medially to take tension off the pectoral muscles and expose the axillary contents. Care must be taken to avoid traction of the extremity and the brachial plexus in the anesthetized patient.

The inferior reflection of the axillary fascia is identified, and dissection is continued from medial to lateral on the serratus anterior muscle to the latissimus dorsi muscle laterally.

Dissection is continued along the lateral aspect of the latissimus dorsi muscle to the level of its tendinous insertion (Figure 100-4). This marks the location of the overlying axillary vein. Dissection along the ventral aspect of the latissimus dorsi should be avoided until the thoracodorsal nerve, artery, and vein are identified, visualized, and maintained in view during dissection.

Dissection from the tendinous insertion of the latissimus dorsi proceeds medially, inferior to the axillary vein.

The superior extent of the axillary dissection should begin approximately 5 mm below the axillary vein to preserve the lymphatics of the arm and reduce the likelihood of upper extremity lymphedema (see Figure 100-4). This tissue is rich in lymphatics and blood vessels, which should be ligated with fine silk ties or Weck Hemoclips.

C H A P T E R 100 • Axillary Node Dissection 1115

Axillary vein

Latissimus dorsi muscle

FIGURE 100–4

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The thoracodorsal artery and vein with the thoracodorsal nerve medially will be identified in the lateral third of the axillary artery (Figure 100-5). The thoracodorsal trunk courses on the medial aspect of the latissimus dorsi. Transection of the thoracodorsal nerve leads to weakened shoulder adduction.

Once the thoracodorsal trunk is identified, lateral dissection is safe as long as the intercostalbrachial cutaneous nerve is visualized as it emerges from the axillary fat pad approximately halfway up the latissimus dorsi muscle, coursing toward the arm.

The intercostalbrachial cutaneous nerve may be identified coursing transversely below the axillary vein and should be preserved if free of matted tumor-laden nodes to prevent bothersome sensory dysesthesias along the medial aspect of the upper arm.

Dissection medially should be cautious, with attention to the long thoracic nerve, which lies on the serratus anterior muscle beneath the fascia (see Figure 100-5). Retraction of the fascia off the chest wall will pull the long thoracic nerve off the chest wall and place it at risk of injury. The nerve can be identified deep to the intercostalbrachial nerve or higher, inferior to the axillary vein on the chest wall, where it is less likely to have been pulled away from the serratus anterior into the axillary fat. The nerve should be protected and preserved. The function can be confirmed by very gentle compression and demonstration of contraction of the serratus muscle in the unparalyzed individual. Injury to the long thoracic nerve causes a winged scapula.

After the axillary boundaries and important structures are identified, resection of the axillary contents is carried out from superior to inferior, maintaining visualization of the nerves at risk. As the fatty tissue is swept inferiorly, lymphatics and blood vessels are ligated or clipped and transected.

The axillary contents are oriented to identify the apex of the axilla.

The axilla devoid of lymphatics and the chest wall are visualized (see Figure 100-5). The cavity is irrigated with warm saline. Any residual bleeding vessels are cauterized or ligated.

C H A P T E R 100 • Axillary Node Dissection 1117

Axillary artery and vein

Long thoracic nerve

Thoracodorsal artery and vein

Latissimus dorsi muscle

FIGURE 100–5