The Thoracic Duct

The large lymphatic channels that terminate at the base of the neck are the thoracic duct on the left and the right lymphatic duct on the right. The right lymphatic duct is not a common source of problems during neck dissection. However, injuring the thoracic duct during the operation results in persistent chylous leak that may be extremely difficult to solve in patients with a functional approach. Preservation of the sternocleidomastoid muscle in these patients decreases the efficacy of the usual compressive maneuvers that are used to stop chylous leak. Thus, early recognition of lymphatic leakage during the operation is crucial in order to repair the injury before closure. Precise knowledge of the cervical course of the thoracic duct is fundamental to avoid postoperative problems.

The exact end point of the thoracic duct is variable because it may open into the internal jugular vein, the subclavian vein, or the angle of junction between them. Also, the termination of the duct

Figure 5-30 Repair of an injured thoracic duct requires the use of muscle, fascia, or adipose tissue to surround the fragile wall of this major lymph duct. td, thoracic duct; IJ, internal jugular vein; SC, sternocleidomastoid muscle; tm, trapezius muscle; oh, omohyoid muscle.

may be doubled, tripled, or even quadrupled. All these variations, along with the frail thin walls of the duct, facilitate its injury at surgery.

The best way to avoid injuring the thoracic duct is by not approaching the base of the neck on the left side unless it is absolutely necessary. When the operation must proceed to the lowest part of the left side of the neck, the surgeon must be aware of the variable anatomy of the thoracic duct when approaching the junction of the internal jugular and subclavian veins. If the duct is to be ligated to include in the dissection the tissue at the level of the final portion of the internal jugular vein, additional tissue must be included in the ligature to avoid sectioning the thin wall of the thoracic duct with the suture. Thus, the area of the duct is surrounded by muscle, fascia, or adipose tissue before being sutured with 3-0 atraumatic silk (Fig. 5-30).

When the duct is inadvertently sectioned, the lymph drains overtly at the base of the neck. This situation must be recognized and repaired during the operation. The typical transparent, slightly yellow liquid with particles of fat positively identifies the presence of lymphorrhea from a cut thoracic duct. In such instances the ruptured opening of the duct must be identified and repaired, including additional tissue in the ligature, as mentioned before. It is not uncommon after involuntary section of the thoracic duct that the open end of the vessel cannot be identified. In these cases the area where the lymph appears at the base of the neck must be sutured, including enough tissue to stop the leak. Attentive examination of the area must be performed after repair to assure the cessation of the leak. Asking the anesthetist to momentarily increase the thoracic pressure may help in the identification of the cut end of the duct and to assess the resolution of the lymphorrhea.

Although the right lymphatic duct is seldom a problem, the same principles must be applied in case of a right chylous leak.

CHAPTER 6

Complications

Postoperative complications after neck surgery have a significant impact on morbidity and health care cost, leading to prolonged hospitalizations, further operations, permanent sequelae, and sometimes, fatal outcome. Aging, poor nutritional status, and chronic diseases of the respiratory, cardiovascular, and other systems (due to alcohol and tobacco abuse) are common factors in most patients with tumors of the upper aerodigestive tract. Salvage surgery after radiation therapy has also been related to higher incidence of complications.

Concerning neck dissection, it is difficult to identify the complications directly related to the procedure and separate them from those associated with removal of the primary tumor because both surgeries are usually performed at the same time. Tables 6-1 and 6-2 summarize the complications that can be more specifically related to neck dissection and will be addressed in this chapter.

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