Selective Neck Dissection

The MD Anderson University of Texas Cancer Center and the Memorial Sloan-Kettering group popularized the concept of selective neck dissection. It evolved from the modified dissection, which preserved the spinal accessory nerve. Of lesser influence in North America was the concept of the functional neck dissection of Suarez, popularized in the English-speaking world by Bocca. Data assured surgeons that neck recurrence rates with pathologically negative necks and low-staged clinically positive necks were similar regardless if the accessory nerve was sacrificed or not. The long-term functional consequences of accessory nerve sacrifice were described in the 1960s as the shoulder syndrome. Shoulder droop, diminished range of motion, shoulder abduction, and external rotation and pain led to reconsideration of routine nerve sacrifice. Modified neck dissection that preserved the accessory nerve was a logical first modification. It later became obvious that preserving the nerve, by dissecting it free, was not always followed by normal nerve function. Surgical trauma during dissection left some with variations of the shoulder syndrome. Questionnaires about shoulder function were reassuring but electromyography and careful clinical evaluation by experts documented that preserving the accessory nerve is not always enough. However, careful nerve preservation is more rational than routine sacrifice of the nerve.

The loss of contour after removal of the sternomastoid muscle led to reconsideration of that practice. The muscle does not contain lymphatics or lymph nodes, but its removal does make neck dissection easier. Routine sacrifice of the jugular vein adds no oncological safety in the clinically negative and low-stage clinically positive neck situations. These observations, among others, led to selective neck dissection being accepted as a staging operation.

Lymph Node Groups

The concept of radical and modified neck dissection considers the cervical lymph nodes as a unified system divided into anatomical areas such as upper, lower, posterior, and submandibular. The selective dissection movement in the United States focuses more on the subgroups than the system as a whole. The selective dissection model uses retrospective studies that support the idea that metastases from the various sites in the head and neck have predictable patterns in early stages. The movement is a logical outgrowth of the concept of conservation surgery and a movement away from the ''more is better'' philosophy.

The most popular terminology for subdividing the lymph node groups is that used by the head and neck service at the Memorial Sloan-Kettering Hospital. This classification divides the neck into five levels in each side of the neck. A sixth zone describes the anterior compartments of the neck. A complete description of level and boundaries of lymph node groups is provided in the next chapter.

Using the Selective Neck Dissections

The idea of selective neck dissection appears to have started for neck management of lip cancer at the MD Anderson Hospital. Jesse and Fletcher raised the question of radical versus modified neck dissection in 1978. At the Mayo Clinic surgeons were performing a modified neck dissection with preservation of the accessory nerve from the early 1960s when Ward et al reported on this modification.

Selective neck dissections are used on patients with known limited disease or a probability of limited disease. The operations are based on the predictability of metastatic patterns depending on the primary site. Level or levels of nodes removed depend on the location of the primary tumor. Selectivity in neck dissection depends on the principle that, in the early stages, metastatic patterns are predictable in previously untreated cancers.

Information concerning the metastatic pattern from different head and neck primary sites has allowed a more selective type of neck dissection. The issue is why? The removal of nonlymphatic structures causes the morbidity of neck dissection. One can question the rationale for saving proximate nodal groups that merge into one another. In the United States, the concept of selective neck dissection is popular, but difficult to use. Selective dissections are recommended only for early and previously untreated cancer. With the popularity of so-called organ preservation programs in clinical studies and the community, the treatment of previously untreated cancers by the surgeon is not as common as when the concept of selective neck dissection was evolving.

Selective Neck Dissection: Final Issues

A surgeon from somewhere other than the United States might wonder what purpose is served by trying to classify what surgeons have always done. The importance may be more nononcological than oncological. We perceive the selective classification's role as part of the medical reimbursement system of the United States. Insurance companies and government health care funding systems prefer categorical descriptions of what they are paying for by codifying selective procedures as much as is possible. This motive is seldom stated. There are unanticipated consequences of this manipulation of the nomenclature. Major cancer center guidelines separate the head and neck oncological specialists in the community from those in the cancer centers. This may have been an unstated goal rather than an unintended consequence. With seven or more primary sites, four primary stages, three or more neck disease stages, seven or more kinds of neck dissections, and two sides of the neck, the practitioner has to choose among so many permutations and combinations that the neck may be undertreated, overtreated, or not treated at all. Out of frustration, the patient may be referred to the medical center. The experienced surgeon may well be comfortable with intuitively picking and choosing among options. The community surgeon, who is less comfortable with so many options, may give up, and refer away, radiate the neck, or not treat the neck nodes in the elective situation. As educators who listened to more than one hundred resident physicians discuss their ideas about proper neck treatment strategies, we have perceived their confusion. An experienced surgeon can use selective neck dissections in selective situations. The decision is usually intuitive and based on the conviction that bilateral neck dissections are at times important. Martin's caution remains about the absence of infallibility and the certainty that there are no reliable statistical data to support many of these decisions. The whole concept of selective neck dissection may well be rendered moot in the United States because so much more surgery for neck metastases is being done after chemoradiotherapy either in a planned sequence in advanced (N2 and N3) neck metastatic disease or in the salvage at recurrence after chemor-adiotherapy failure.

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