Conceptual Approach to Functional and Selective Neck Dissection

To sum up the essentials of the previous chapters, we may look at the issue of “less than radical” neck dissection under two different standpoints. The American evolution, which is based on the idea of preserving important neck structures that may not be involved by the tumor (e.g., internal jugular vein, spinal accessory nerve, and sternocleidomastoid muscle); and the Latin approach to the problem, which is based on the fascial concept developed by Osvaldo Suárez.

PRESERVING STRUCTURES

The American approach gave rise to the so-called modified radical neck dissections. After some years of debate, the oncological safety of these “less than radical” operations has been widely accepted. A step forward in this evolution resulted in the appearance of “selective” neck dissections in which some nodal regions are preserved according to the location of the primary tumor. This new approach to neck dissection carried a need for a comprehensive classification inclusive of all types of modifications to the radical operation. Because the potential number of modifications is rather large, the resulting classification is complex and difficult to handle on a daily basis.

Selective Neck Dissections: Types and Indications

Supraomohyoid Selective Neck Dissection

This procedure is used for oral cavity cancers. The submental, submandibular, upper, and midjugular groups of nodes are the usual sites of metastases from the oral cancers. Supraomohyoid neck dissection removes levels I, II, III, and at times (oral tongue cancer) level IV. Excluded is level V. Bilateral dissection is recommended for midline tumors (floor of the mouth, ventral surface of the tongue). In patients with significant (N2) nodal metastases in the ipsilateral neck, bilateral dissection or contralateral neck radiation is crucial. It is suggested that if there are metastases in level II, level IV, and V should be dissected. This recommendation suggests that an operation close to a complete functional neck dissection is appropriate for patients with oral cavity cancers with palpable metastases, and something less is acceptable for elective dissection. This approach to cancer codifies and structures of what experienced surgeons have always done: make intraoperative decisions based on operative findings. Martin objected to the selective approach because it lacked a statistical basis. That objection remains valid today.

Lateral Selective Neck Dissection

The lateral dissection removes nodal groups II, III, and IV, leaving levels I and V undissected. The lateral operation is recommended for oropharyngeal, hypopharyngeal, and laryngeal cancers and should be done bilaterally if there are proven metastases to one side of the neck.

Posterolateral Neck Dissection

This operation removes the nodes of levels II, III, IV, and V, the suboccipital, and the postauricular nodal groups. It is recommended for metastases from skin malignancies of the posterior scalp, posterior neck, and some parotid salivary gland cancers that have metastasized posteriorly. The dissection differs from the dissections favored for aerodigestive system metastases. It removes the lymph nodes and lymphatics containing fibrofatty tissue of the posterior neck, the subdermal fat, and fascia between the primary site and nodal compartments where there are no distinct fascial compartments.

Anterior Neck Dissection

There are situations where none of these selective operations will fit a clinical scenario. This requires another category called the extended neck dissection. The extended neck dissection is a defined selective dissection plus something more. The removal of a nonlymphatic structure, such as the internal jugular vein or the sternomastoid muscle. Other extensions that include, in a descriptive bloc, the upper mediastinum, the axilla, or the retropharyngeal space, are examples of the extended neck dissection.

DISSECTING THROUGH FASCIAL SPACES

The Latin approach is based on the anatomical compartmentalization of the neck. The fascial system creates spaces and barriers separating the lymphatic tissue from the remaining neck structures. The lymphatic system of the neck is contained within a fascial envelope, which, under normal conditions, may be removed without taking out other neck structures such as the internal jugular vein, sternocleidomastoid muscle, or spinal accessory nerve. The surgical technique that made this possible was initially referred to as functional neck dissection because it allowed a more functional approach to the neck in head and neck cancer patients. However, as previously emphasized, the most important but less well known fact about functional neck dissection is that it represents a surgical concept with no implications regarding the extent of the surgery. Osvaldo Suárez never performed functional neck dissection as the comprehensive type of neck dissection that some have made of it. In fact, the operation he used for cancer of the larynx did not include the submandibular and submental lymph nodes (area I) in the resection, something that now will be considered a selective neck dissection.

The question that arises at this point is, if functional neck dissection was initially designed as a new approach to the neck regardless of the extent of the surgery, why did we make of it just another type of “modified” radical neck dissection? To understand the reasons for this misinterpretation we must take ourselves to the moment when both trends—American and Latin—merged.

The increasing number of reports from European surgeons in the English literature describing the good results obtained with functional neck dissection drew the attention of American surgeons to this procedure. However, the merging of ideas resembled more a collision than a mixture, and the final result was another modification to radical neck dissection. The operation was accepted as an oncologically safe procedure, but the idea was not understood. The battle of functional neck dissection had been won, but the war of the types of neck dissection, the war of the different ways to approach the neck, was lost.

FUNCTIONAL AS A CONCEPT