Supraomohyoid Neck Dissection

Metastatic neck disease is the most important factor in the spread of head and neck squamous cell carcinoma (SCC) from primary sites. The most commonly involved primary sites are the mucosal areas of the upper aerodigestive tract, particularly the larynx, oropharynx, hypopharynx, and oral cavity. Lymph node (LN) metastasis reduces the survival rate of patients with SCC by half. The survival rate is less than 5% in patients who previously underwent surgery and have a recurrent metastasis in the neck. Therefore, control of the neck is one of the most important aspects in the successful management of these particular tumors.

Radical neck dissection is an operation that was created in 1906 to solve the problem of metastatic neck disease. This procedure is a well-designed operation that is relatively easy for the trained head and neck surgeon to learn and to perform. Classic radical neck dissection is still the criterion standard for surgical control of a neck metastasis.

In the last 3 decades, progressive advances have occurred in the understanding of cervical fascial planes, lymphatic drainage patterns, preoperative staging, and extracapsular spread. The necessity to maximize control and to minimize morbidity prompted modifications to the classic neck dissection. One such modification is the preservation of 1 or more nonlymphatic structures (eg, spinal accessory nerve, internal jugular vein [IJV], sternocleidomastoid [SCM] muscle).

Further observations indicated that the pattern of nodal disease depends on the primary site. Therefore, these findings led to another neck dissection modification, which is the selective preservation of 1 or several LN groups. The selected node groups represent the areas of high risk for early metastasis, depending on primary tumor location.

Selective neck dissection types

See the list below:

• Supraomohyoid or anterolateral - Levels I-III

• Lateral - Levels II-IV

• Posterolateral - Levels II-V, postauricular and suboccipital

• Anterior compartment - Level VI

In 1906, Crile was the first person to describe radical neck dissection, which encompasses the surgical removal of neck metastases contained between superficial and deep fascial layers of the neck. In the 1950s, Martin routinely used radical neck dissection for the management of neck metastasis. The main goal of this procedure was to remove, en bloc, all ipsilateral lymphatic structures from the mandible superiorly to the clavicle inferiorly and from the strap muscles to the anterior border of the trapezius.

The resection included the spinal accessory nerve, the IJV, the SCM muscle, and the submandibular gland. The carotid arteries, vagus nerve, hypoglossal nerves, brachial plexus, and phrenic nerve remained. This operation and its oncologic concept remain valid; however, the procedure has been modified to decrease morbidity while maintaining oncologic efficacy. In the 1960s, Suarez and Bocca independently described a more conservative operation that involved removing all the LNs while sparing the spinal accessory nerve, the SCM muscle, and the IJV.[1, 2]

Studies of the lymphatic system determined the likelihood of particular groups of LNs being involved based on the primary site. This ability to predict the location of metastatic disease was found valid and reliable in further studies. Based on that predictability, in the 1970s, surgeons from the MD Anderson Cancer Center designed a neck operation that spared some LN groups and sacrificed others. The main purpose of this neck operation was to create a more conservative and cosmetically oriented surgery without the decrease of oncologic control.

Multiple modifications to the radical neck operation necessitated the coining of neologisms to describe such changes; the terms for the same modification varied from author to author. These new varied and unclear terms created confusion among clinicians from different geographical areas and institutions. Therefore, standardization was necessary. In 1991, the American Academy of Otolaryngology-Head and Neck Surgery (AAOHNS) published an official report that standardized the terminology for different types of neck dissection.[3]

The report was updated and published in 2002 with only a few changes. These dealt with the application of various types of selective neck dissection procedures for oral cavity cancer, pharyngeal and laryngeal cancer, thyroid cancer, and cutaneous malignancies.[4] In addition, 2 new neck sublevels, Va and Vb, were added, for a total of 6 neck levels and 6 neck sublevels. (The 1991 version of the report listed only 4 neck sublevels.) With the exception of the 2 added neck sublevels, the terminology in the updated report is the same as that of the 1991 version.[5]

The Committee for Neck Dissection of the American Head and Neck Society presented a Classification in 2008 based on 4 types of neck dissection, as follows:[6]

• Radical neck dissection: It is considered "the standard neck dissection," including the resection of the lymphatic nodes in levels I, II, III, IV and V, as well as the sternocleidomastoid muscle, the spinal accessory nerve, and the internal jugular vein.

• Modified radical neck dissection: It is considered oncologically as radical as the radical neck dissection, removing the same lymphatic node levels but with preservation of at least 1 of the nonlymphatic structures.[7]

• Extended radical neck dissection: It is considered extended in the sense that additional lymphatic nodes as well nonlymphatic structures are removed.

• Selective neck dissection: It is a neck dissection in which one or more selected lymph node levels are preserved.

In 2010 the American Academy of Otolaryngology Head and Neck Surgery suggested a new terminology, more precise and easier to understand, in order to further standardize and make it easier to compare neck dissections and neck dissection results around the globe. An international effort was made to identify a rational classification format for neck dissections. The consensus was published in 2011.

This new classification system is based on 3 key terms from the new nomenclature. The first term is ND for "neck dissection." The second term is a Roman numeral indicating the lymphatic node level and sublevel removed during the dissection. The third term indicates the nonlymphatic structure included in the dissection.[8, 9]

Lymphatic metastasis is the most important mechanism in the spread of head and neck SCC. The risk of LN involvement by metastasis varies depending on the site of origin, size, histologic grade of the primary tumor, perineural invasion, perivascular invasion, and extracapsular spread. Management of the neck LNs is an integral part of treatment of head and neck cancer. Conversely, no single standardized treatment for cervical metastasis is available.

The indications for and type of neck dissection to be performed in the N+ neck and management of the N0 neck remain controversial. Management is based on personal experience and many retrospective studies.

Radical neck dissection was the first attempt to treat metastatic cervical lymphadenectomy adequately. The classic operation was modified several times to decrease morbidity without decreasing oncologic control. The 2 modifications commonly used today are the modified radical and the selective neck dissections.

Frequency

Incidence of metastatic disease for the upper aerodigestive tract varies from 1-85%, depending on the site, size, and differentiation of the tumor.

In the 1970s, several clinical studies revealed that nodal metastasis to the neck occurs in the following predictable patterns:

• Carcinomas of the oral cavity involve mostly the jugulodigastric and midjugular nodes.

• Lesions in the floor of the mouth or near the midline frequently cause metastasis bilaterally.

• Sites localized in the oral cavity, oral mucosa, oropharynx, hypopharynx, and supraglottis have a higher incidence of metastasis than areas such as the superior gingiva, hard palate, and glottis.

• Anterior portions of the oral cavity are associated with smaller risk of neck metastasis than the posterior portions.

• Young patients with oral carcinoma have a higher risk of nodal metastasis than older patients.

• The larger the primary tumor and/or the greater the depth of penetration, the higher the risk of neck involvement by metastasis.

• Perineural and perivascular invasion are associated with a high risk of nodal metastasis.

• Extracapsular spread carries a high probability for lymphatic spread.

• Poorly differentiated tumors are associated with a higher risk of neck metastasis.

Several retrospective reviews of specimens from radical neck dissections in the 1990s proved that SCCs of the oral cavity most commonly involve nodal levels I-III; level IV is involved 20% of the time, and level V is involved 4% of the time. Furthermore, SCCs at the hypopharyngeal level commonly metastasize to levels II-IV; metastasis to level I occurs 10% of the time, and metastasis to level V occurs 11% of the time. SCCs of the larynx are associated with similar areas and percentages, mostly to levels II-IV (level I, 8%; level V, 5%). Therefore, based on these patterns of nodal metastasis in SCCs, supraomohyoid neck dissection is an adequate node sampling procedure for cancer of the oral cavity.

Supraomohyoid neck dissection carries a recurrence rate of 5% in the N0 neck, 10% in the N+ neck with a single positive node, and 25% when multiple positive nodes or extracapsular spread is present. Supraomohyoid neck dissection is performed for the surgical control of early metastatic neck disease in a selected group of patients with SCCs of the oral cavity and skin cancer of the lip and face.

Metastasis occurs frequently in malignancies. The tumor grows at the primary site by malfunctions in cellular proliferation, differentiation, and death. Mutations due to chemical carcinogens, radiation, or viruses may cause normal cells to allow the activation of oncogenes; multiple genetic mutations, activation of proto-oncogenes, inactivation of tumor suppressor genes, or a combination cause alterations in growth control. Tumor cells move through the basement lamina of the epithelium and the stroma into the lymphatic and vascular channels (ie, cells move from carcinoma in situ to microinvasive tumor). This process is associated with the production of cytokines, enzymes, and growth factors that destroy the basement membrane, thus creating abnormal angiogenesis, which, in turn, triggers neovascularization and growth. The tumor spreads into the regional LNs from the lymphatic and vascular channels and sets up tumors in secondary sites.

Most candidates for supraomohyoid neck dissection present with early stage, (N0 or N1) metastatic neck disease due to SCC of the oral cavity. Usually, the patient is already aware of the primary lesion or it is found easily during physical examination of the upper aerodigestive tract. In 15% of patients, the neck mass is present without an obvious primary lesion.

Nodal classification

The most important prognostic factor in patients with SCC of the head and neck is the status of the neck nodes. The status of the cervical nodes constitutes the N portion of the tumor, node, metastases (TNM) classification by the American Joint Committee on Cancer (AJCC). The AJCC assigns N1-N3 ratings to different degrees of neck adenopathy, with subgroupings of a, b, and c for certain stages. The nodal classification is as follows:

• NX - Cervical neck nodes not assessable

• N0 - No cervical node metastasis

• N1 - Single ipsilateral node metastasis (≤3 cm diameter)

• N2a - Single ipsilateral node (>3 cm but ≤6 cm diameter)

• N2b - Multiple positive ipsilateral nodes (none >6 cm diameter)

• N2c - Bilateral or contralateral positive nodes (none >6 cm diameter)

• N3 - Massive adenopathy (>6 cm diameter)

Palpation

Accuracy of staging relates to the physician's ability to detect cervical adenopathy. Palpation is the technique used most to detect neck metastases. Although palpation is inexpensive and easy to perform, it is not totally reliable.

Sensitivity and specificity of neck examination by palpation range from 60-70%. A short obese neck and/or previous radiation or surgery makes the physical examination more difficult to perform. Negative palpation findings of the neck still indicate a risk of occult metastatic disease. This risk increases according to the site, size, and particular characteristics of the primary lesion.

Imaging

Imaging is an important part of clinical diagnosis and staging. However, imaging is indicated only if results are used in treatment management. Among these techniques are computed tomography (CT) scanning, magnetic resonance imaging (MRI), ultrasonography, and ultrasound-guided aspiration cytology.

CT scan reveals metastatic adenopathy by central necrosis and extracapsular spread by enhancement of the nodal capsule. MRI is less precise than CT scan in identifying tumor necrosis and extracapsular spread, but MRI is better in assessing enlarged LNs that do not necessarily represent metastasis. Both techniques are incapable of detecting lymph nodes smaller than 1 cm. which, on occasion, independently of the size, are involved in metastasis. Ultrasound-guided aspiration cytology has a higher specificity than either CT or MRI in analyzing lymph nodes, particularly in smaller nodes of less than 10 mm. However, the yield of this technique is directly related to the experience of the ultrasonographer and the pathologist.

Positron emission tomography (PET) has been used recently to assist in the diagnosis of LN metastasis. PET provides information about the metabolic activity of the tissues. Tissues with squamous cell carcinoma cells capture18 fluoro-2-deoxy-D-glucose (FDG) at increased rates compared to normal tissues. Therefore, a minimal amount of tumor tissue must be present to be positive and its precision is limited in tumors smaller than 1 cm. The precision of PET is limited to around 5 mm.

Recent literature has demonstrated the higher sensitivity and specificity of the (FDG)–PET compared with ultrasonography, CT scan and MRI in the assessment of metastatic staging of neck carcinomas. This finding could signify a positive role for PET in the identification of metastatic disease in patients with a clinically N0 neck. PET findings could provide early diagnosis of recurrent head and neck cancer, as well as indicate the status of the neck after chemo-radiotherapy.

New challenges have been recognized in the last 15 years with the selection of candidates for neck dissection who were treated initially with organ preservation treatment protocols and who may have persistence of neck disease after the nonoperative management. This group of patients can benefit greatly from the routine use of posttreatment PET/CT during their assessment for subsequent surgical management of the neck.

PET and PET/CT are discussed further in Workup.

Histologic examination

Intraoperative findings are important in the supraomohyoid neck dissection. An intraoperative evaluation by the surgeon or pathologist can alter the course of surgery. The criterion standard for detection of LN metastasis in the neck is careful histologic examination and evaluation of all nodes by the pathologist after the neck dissection is completed.

Detection and accurate staging of neck metastasis are extremely important because staging has major implications for prognosis and treatment. Head and neck surgeons at the Memorial Sloan-Kettering Hospital originally developed the most widely accepted terminology used to define regions of involvement of cervical LN groups. The terminology is as follows:

• Region/level I - Submental and submandibular nodes

  • Ia - Nodes in the submental triangle bound by the anterior belly of the digastric muscle and the hyoid bone

  • Ib - Nodes in the triangle bound by the anterior and posterior bellies of the digastric muscle and body of the mandible

• Region/level II - Upper jugular LNs (including the jugulodigastric nodes)

  • IIa - Nodes in the region anterior to the spinal accessory nerve

  • IIb - Nodes in the region posterior to the spinal accessory nerve

• Region/level III - Nodes from the carotid bifurcation to the omohyoid muscle

• Region/level IV - Nodes of the lower jugular area that extend from the omohyoid to the clavicle

• Region/level V - All LNs within the posterior triangle of the neck

• Region/level VI - Nodes in the anterior compartment group, which includes the LNs that surround the midline structures of the neck (These nodes extend from the hyoid bone superiorly to the suprasternal notch inferiorly.)

The revisions proposed by the American Head and Neck Society and the American Academy of Otolaryngology Head and Neck Surgery Committee and published in 2002 recommended the use of 6 neck levels and 6 sublevels, which added 2 extra sublevels (a and b) at level V. The 6 sublevels are Ia (submental nodes), Ib (submandibular nodes), IIa and IIb (upper jugular nodes), Va (spinal accessory nodes), and Vb (transverse cervical and supraclavicular nodes).[4, 5]

No single set of indications exists for supraomohyoid neck dissection. They vary among authors and institutions around the world. Management strategies discussed in this article are based on recent publications. However, no medical dogma exists and the need for a particular surgery should be based on a case-by-case evaluation that considers the condition of the patient, the surgeon’s expertise and the institution’s capabilities.

N0 neck/squamous cell carcinoma of the oral cavity

The current general opinion is that selective neck dissection is a good alternative for the N0 neck in persons with squamous cell carcinoma (SCC) of the oral cavity.[10] Therefore, supraomohyoid neck dissection is commonly used for this purpose, if the primary lesion is not treated with radiation therapy.[9]

An extended supraomohyoid neck dissection that involves the removal of lymph nodes from levels I through IV has been advocated by certain surgeons if the primary lesion involves the oral tongue subunit. These surgeons have found that approximately 16% of patients with oral tongue lesions develop level IV metastasis, skipping the lower levels. Conversely, other surgeons have found only 2% of patients with metastasis at level IV in T1-T3 N0 oral tongue cancer and they believe in excising level IV only when intraoperative suspicion of metastasis is found at level II or III. Other surgeons believe that if the intraoperative pathology evaluation reveals metastasis at any level an extended supraomohyoid dissection must be performed. However, apart from these differences, most authors agree that supraomohyoid neck dissection for SCC of the oral cavity with an N0 neck is as effective as radical neck dissection.[11]

N+ neck/squamous cell carcinoma of the oral cavity

Indications are less clear in the clinically N+ neck for SCC of the oral cavity. Standardization is lacking.[12] Some authors do not advocate a supraomohyoid neck dissection for the N+ neck. Other authors believe that a supraomohyoid neck dissection is effective for the N1 neck and even the N2a neck in carefully selected patients. Most authors generally agree, however, that the presence of metastatic neck nodes cuts the survival rates by half. In the authors’ institution, in the case of an N+ neck with an oral cavity primary tumor, whenever possible we use the comprehensive neck dissection, which involves dissection of levels I through V.

Possible bilateral neck metastasis/ squamous cell carcinoma of the oral cavity

A consensus believes that a bilateral supraomohyoid neck dissection is indicated when the location of the primary tumor SCC of the oral cavity has a high risk of developing metastasis in both sides of the neck, (eg, floor of the mouth, ventral or midline dorsal tongue) and postoperative radiation therapy is not planned.

Facial carcinoma, squamous cell carcinoma, and basal cell carcinoma

The literature provides no clear consensus regarding nonmelanocytic facial carcinomas. Therefore, treatment depends mostly on the size of the primary tumor. Some authors perform a supraomohyoid neck dissection in the early stages of SCC of the lip and skin of the cheek. A bilateral neck dissection is done if the tumor is close to the midline.

An understanding of the relevant neck anatomy is required to perform a supraomohyoid neck dissection adequately. From the surgical point of view, each side of the neck is divided into 2 cervical triangles (ie, anterior, posterior).

Anterior cervical triangle

The inferior border of the mandible, the SCM muscle, and the strap muscle form the anterior cervical triangle. This triangle is subdivided into 4 smaller triangles (ie, submandibular, submental, muscular, carotid). Understanding and identifying each of these areas guides the surgeon in completely removing the contents of the anterior cervical triangle.

• Submandibular triangle: The inferior border of the mandible and the 2 bellies of the digastric muscle delineate the submandibular triangle. The mylohyoid and hyoglossus muscles form the floor. The submandibular area contains the submandibular gland, lymphatic structures, anterior facial vein, and facial artery. The lingual nerve is above the muscular floor and below the deep layer of the deep cervical fascia.

• Submental triangle: The anterior belly of the digastric muscle, the hyoid bone, and the midline of the neck delineate the submental triangle. The mylohyoid muscle forms the floor of the submental triangle, which contains a few LNs and small tributaries of the anterior jugular vein.

• Muscular triangle/carotid triangle: The omohyoid muscle in the anterior cervical triangle delineates the muscular triangle below and the carotid triangle above.

Posterior cervical triangle

The posterior cervical triangle also is referred to as the lateral cervical triangle. This triangle is limited by the anterior margin of the trapezius muscle, the posterior border of the SCM muscle, and the middle third of the clavicle. The posterior aspect of the omohyoid muscle further subdivides the posterior cervical triangle into 2 smaller triangles: the occipital triangle located above the omohyoid muscle and the supraclavicular triangle located inferiorly to the muscle.

Cervical lymph nodes

Cervical LNs are divided into superficial and deep chains. Superficial LNs are involved in a late stage of cancer; therefore, superficial LNs have less oncologic importance. Deep cervical LNs receive drainage from areas of the mouth, pharynx, larynx, salivary glands, thyroid, and the skin of the head and neck. These deep cervical LNs (ie, superior, middle, inferior) accompany the IJV and its branches.

Oncologically, the superior jugular nodes (the group that lies near the anterosuperior aspect of the accessory nerve) are crucial. These nodes represent the most difficult area in the resection of the deep jugular nodes.

The cervical LNs localized in the posterior triangle of the neck are classified into upper, middle, and inferior cervical nodes. Posterior triangle nodes are located beneath the upper portion of the SCM muscle and run posteriorly along the course of the spinal accessory nerve. This group of lymphatics receives drainage from the nasopharynx and communicates directly with the upper deep nodes from the IJV.

The posterior triangle nodes in the inferior aspect progress anteriorly to the supraclavicular area to join the IJV at the base of the neck. The above groups are easier to understand when divided into levels or zones, as follows:

• level I - Nodal group that involves submental and submandibular regions (also referred to as IA and IB)

• level II - Upper jugular group (IIa nodes in the region anterior to the spinal accessory nerve, IIb nodes in the region posterior to the spinal accessory nerve)

• level III - Middle jugular group

• level IV - Lower jugular group

• level V - Posterior triangle group (Va spinal accessory nodes, Vb transverse cervical and supraclavicular nodes)

• level VI - Central anterior neck group

Platysma muscle

The rectangular and sheetlike platysma muscle extends obliquely from the upper chest to the lower face, from posteroinferior to anterosuperior. Its undersurface creates an ideal plane in which to elevate the skin flaps in neck dissection. The platysma muscle is deficient in the lower anterior midline in the neck and posterior to the external jugular vein (EJV) and greater auricular nerve.

Sternocleidomastoid muscle

The SCM muscle runs from anteroinferior to posterosuperior and attaches to the mastoid tip. The greater auricular nerve and the EJV cross the upper aspect of the muscle. These structures guide the surgeon to the right plane of dissection and should be left on the surface of the SCM during flap elevation. The fascial envelope of the muscle is a key structure for selective neck dissections.

Spinal accessory nerve

The spinal accessory nerve crosses over the IJV in approximately 70% of individuals. The nerve is also medial to the posterior belly of the digastric and stylohyoid muscles. Anatomic variations include the nerve that runs medially to the IJV in 30% of individuals and through the vein in 3% of individuals. Attention to this fact avoids damage to the IJV during the dissection of cranial nerve XI in the upper aspect of the neck. The nerve enters obliquely to the SCM muscle, from superior to inferior, with the exit at the Erb point, which is near the greater auricle nerve at the posteroinferior edge of the SCM muscle.

Digastric muscle

The posterior belly of the digastric muscle is an important landmark. This belly extends from the hyoid bone to the undersurface of the mastoid tip. Important and delicate structures are recognized medial to the muscle. Therefore, the posterior belly of the digastric muscle lies superficial to the external and internal carotid arteries, hypoglossal nerve, and IJV. Lateral to the posterior belly of the digastric muscle, the only structure that requires preservation is the marginal mandibular nerve.

Marginal mandibular nerve

The marginal mandibular nerve is localized deep to the superficial layer of the deep cervical fascia that covers the submandibular gland and lies superficial to the anterior facial vein. The best way to preserve the nerve is to identify it carefully at the above locations. Once the nerve is identified, tissue lateral and inferior to the nerve can be divided to expose the posterior belly of the digastric muscle.

Trapezius muscle

The trapezius muscle extends from the posterior occiput to the lateral third of the clavicle. The anterior border of the trapezius is the posterior edge of level V, or the posterior triangle, of the neck.

Omohyoid muscle

Like the digastric muscle, the omohyoid muscle has 2 bellies. The anterior belly is superficial to the IJV. The posterior belly is superficial to the brachial plexus, phrenic nerve, and transverse cervical artery and vein. Like the digastric muscle, the omohyoid is a key anatomic landmark in radical neck dissection.

Hypoglossal nerve and vagus nerve

The vagus nerve in the neck is intimately associated with the carotid sheath and lies immediately deep to the IJV. Intraoperatively, the vagus nerve can be injured during dissection and division of the lower portion of the IJV. Identification of the vagus nerve before division of the IJV is mandatory.

The hypoglossal nerve in the neck travels under the IJV, passes over the internal and external carotid arteries, and continues inferomedially to the posterior belly of the digastric muscle to enter the tongue musculature. Identification is important to avoid injury.

Brachial plexus and phrenic nerve

The phrenic nerve lies above the anterior scalene muscle and deep to the transverse cervical artery. The brachial plexus exits lower in the neck and then passes between the anterior and middle scalene muscles. Identify anterior and middle scalene muscles before clamping lymphatic structures. Avoid dissection in the supraclavicular area before phrenic and brachial plexus visualization.

Thoracic duct

The thoracic duct, located in the lower left neck, arises posterior to the IJV and anterior to the phrenic and transverse cervical artery. The anatomy varies, and the duct has multiple interdigitated channels.

See Neck Anatomy, Vagus Nerve Anatomy, Brachial Plexus Anatomy, and Thoracic Duct Anatomy for more information.

The contraindications to supraomohyoid neck dissection are obvious once the indications are understood.

In summary:

• The indications to supraomohyoid neck dissection are SCC of the oral cavity, T1-T4, and N0. Supraomohyoid neck dissection is both diagnostic and therapeutic in patients with N0. On this point, authors generally agree.

• However, the treatment role of supraomohyoid neck dissection in patients with positive neck disease (N+) is more controversial. Some authors consider the supraomohyoid neck dissection an adequate treatment for selected N1 and N2a necks. Other authors, however, favor extending the dissection to levels IV and V.

Therefore, the contraindication to supraomohyoid neck dissection is any SCC of the oral cavity in which the clinical neck stage is other than. N0, N1, or N2a.

See the list below:

• CBC count and differential

• Prothrombin time (PT), activated partial thromboplastin time (aPTT), and international normalized ratio (INR) measurements: These studies are especially important in patients with preexisting bleeding diathesis, with hepatitis, or who are taking anticoagulants. Prolonged study results may need to be reversed preoperatively.

• Platelet count

• Electrolyte tests

• Liver enzyme profile

• Glucose test

• BUN and creatinine tests

• Blood type and screen: Because of refinements in the surgical techniques, blood loss has been significantly reduced in these procedures. In situations in which blood loss is expected to be significant, either typing and screening or typing and cross-matching are necessary.

• Urinalysis

An esophagogram can be helpful in evaluating an occult primary tumor.

Perform CT scan and MRI accordingly if they would help to define node status and treatment planning further.

• CT scanning with contrast can depict excellent anatomic details.

• In general, CT scan is the radiologic technique most commonly used to stage the primary lesion; therefore, also include the neck in the examination.

• Criteria for assessing nodal metastases with CT are (1) increased size (>1.5-cm diameter), (2) poorly defined irregular borders or a rounder shape, (3) presence of central necrosis, (4) nodal grouping, and (5) central hypolucency.

• The most accurate CT scan criterion for the presence of metastatic adenopathy is central necrosis. The node periphery is usually thick and enhances with contrast. CT scanning also reveals extracapsular spread by enhancement of the nodal capsule.

• Some radiologists feel that CT scanning demonstrates paratracheal node involvement better than MRI.

• MRI reveals tumor necrosis and extracapsular spread with less precision than CT scan, but MRI is better for assessing enlarged LNs that are not necessarily metastatic.

• MRI may also be used in patients who are allergic to iodinated contrast.

• According to some radiologists, MRI also appears to reveal retropharyngeal node involvement better than CT scan.

Some institutions use ultrasonography and ultrasound-guided aspiration cytology to determine cervical neck metastasis. Ultrasound-guided aspiration cytology has a specificity of nearly 100%.

Positron emission tomography (PET) has recently emerged as an adjunct in the diagnosis of LN metastasis.

• In recent studies, PET has shown positive findings for lymph node metastasis when CT scan and MRI findings were negative. An FDG-PET scan provides physiologic and biochemical data. Glucose metabolism in neoplastic cells produces increased uptake on FDG-PET scanning, which correlates strongly with viable tumor cells. Therefore, FDG-PET may be helpful in the assessment of neck metastasis and even distant metastasis.

• Additionally, PET scanning has shown the ability to differentiate active tumors from chronic fibrotic changes. Therefore, PET may become more useful than CT scan and MRI in the detection of recurrent head and neck cancer. Furthermore, the dual use of the PET and CT scanners produces fused PET and CT scan images, which can further enhance the results of the PET scan. The definitive role of PET and PET/CT scans is evolving and showing great potential in the assessment of metastatic neck disease, the early diagnosis of recurrent head and neck cancer, and the status of the neck after chemoradiotherapy.

• The most recent diagnostic guidelines for the use of PET/CT in head and neck oncology are (1) detection of occult primary tumors, particularly in patients in which the conventional imaging tests are negative; (2) detection and staging of neck metastasis in the negative neck after evaluation with CT or MRI; (3) detection of distant metastasis in patients with advanced metastatic neck disease; and (4) detection of residual or recurrent disease.

Sentinel lymph node biopsy:[13, 14, 15, 16] A sentinel node is the first node of a particular group of nodes to receive the regional lymphatic flow from the primary site. The concept and the procedure for the sentinel lymph node biopsy used in the evaluation of metastatic neck nodes in patients with head and neck squamous cell carcinoma is similar to the one used in the evaluation of nodal disease in skin melanoma. If the sentinel lymph node biopsy is negative, no further lymphadenectomy surgery is necessary. However, the sentinel lymph node biopsy applied to the mucosal cancer of the upper aerodigestive tract is still in the process of evaluation in research trials. Results in this regard are encouraging. Nevertheless, its application in the assessment of neck metastasis is still not established and standardized in the clinical setting.

Biotumor markers and molecular methods:[17, 18] New research techniques have been developed to detect micrometastasis of squamous cell carcinoma by using highly specific biotumor markers and molecular methods. The research is this regard is very active, with goals to impact diagnosis, prognosis, and therapy. However, the practical application, prognosis, and management significance is unknown until further studies are completed in prospective clinical trials.

Perform chest radiography to exclude metastatic disease.

See the list below:

• A complete physical examination is mandatory and includes evaluation of neurologic, cardiovascular, and respiratory status.

  • Palpate the patient's neck to define size, location, mobility, and degree of softness or hardness of any mass.

  • Evaluate the patient's weight and nutritional status.

• Perform ECG as indicated.

• Perform other evaluations, with further medical consultations and recommendations, as indicated.

See the list below:

• Supplement the examination with mirror laryngoscopy, flexible nasopharyngolaryngoscopy, or both.

• When the primary tumor is known, perform a panendoscopy to exclude a second primary tumor. Performing biopsy of the primary lesion is necessary. When the primary tumor is not known, perform panendoscopy to look for the primary tumor. Obtain random biopsy samples of the pyriform sinus, base of tongue, tonsillar area, and nasopharynx to exclude occult malignancies.

• Transnasal esophagoscopy (TNE) can be used in the office to look for primary tumor or tumors and, if found, to take the necessary biopsy or biopsies. TNE can be used to biopsy suspicious lesions in the nasopharynx, glottis, supraglottis, and the esophagus. TNE is done with topical anesthesia in the same fashion as with flexible laryngoscopy. The endoscope used in TNE is fitted with suction and biopsy port to accomplish the same goals as the classic panendoscopy.

• When the patient has a neck mass, a fine-needle aspiration biopsy (FNAB) for pathology evaluation is indicated.

• Open biopsy of the neck is indicated only when results of previous physical examination measures (eg, FNAB, random biopsies, endoscopy) are inconclusive.

• Frozen section can be used intraoperatively to assess neck metastasis of suggestive nodes.

Biopsies of the primary site reveal the etiology of the initial mass and the characteristics of the tumor involved (eg, SCC of the upper aerodigestive tract, nasopharyngeal carcinoma, thyroid carcinomas, head and neck skin cancer). FNAB findings of the neck metastasis confirms the pathology findings of the primary tumor. FNAB findings also help determine the etiology of the cervical adenopathy when the patient has a neck metastasis from an occult primary tumor. Frozen section can be used intraoperatively for suggestive nodes to confirm cervical metastasis.

Supraomohyoid neck dissection involves resection of LN groups localized in levels I-III.

Consider and evaluate the following, taking careful documentation:

• Results of physical examination (including head and neck findings)

• Medical history (eg, medication allergies; hypertension, diabetes mellitus, cardiopulmonary disease, and other chronic illnesses; previous surgeries; radiation therapy)

• Medical clearance and recommendations

• All test results, including those of biopsy and FNAB

• Informed consent, with risks and complications fully discussed with the patient

• Summarized problem and treatment plan, including alternatives plans

• Airway and dentition of the patient

• Patient's ability to open the mouth enough for intubation

Additionally, if the patient undergoes a tracheotomy, evaluate its status and that of the airway. On the day of surgery, patients should remain on nothing by mouth (NPO) status after midnight the night before. Patients may be administered usual medications up to midnight before the surgical procedure. Note premedication order on record. Void on call to the operating room. Preoperative antibiotics are required if the procedure involves passage through the neck into the upper aerodigestive tract.

If the airway is obstructed, performing a tracheotomy with the patient under local anesthesia is preferred. Obstructing neoplasms of the upper aerodigestive tract can bleed easily at intubation, which produces a sudden, total obstruction in an already compromised airway. Prevention and planning are mandatory.

If the airway is unobstructed, the anesthesia service can perform an orotracheal or nasotracheal intubation.

In a difficult but not obstructed airway, the anesthetist may perform an awake intubation with the assistance of a flexible nasopharyngolaryngoscopy to accomplish a nasotracheal intubation.

Airway compromise or marginal compromise is not uncommon in patients with head and neck cancer. Therefore, good communication and understanding between the surgeon and the anesthetist is essential.

A Foley catheter is unnecessary during supraomohyoid neck dissection. If the surgery is performed with other procedures that are more complex and prolonged, a Foley catheter is inserted for better control of urine output. Place the patient in the supine position with a shoulder roll to extend the neck. Elevate the upper half of the operating table to a 30° angle. Prepare and drape the patient's neck and upper chest; use staples or sutures to delineate the field. Notify the anesthesia service that the patient cannot be paralyzed during the surgical procedure.

Supraomohyoid neck dissection

Mark the skin incision with methylene blue or a surgical marking pen. Some authors infiltrate the skin incision with 10 mL of lidocaine with 1:100,000 epinephrine to minimize bleeding. (The author's institution does not follow this practice.)

The skin incision varies depending on whether the operation is on a single side of the neck or on both sides and whether the lip needs to be split for access to the oral cavity. Use scratch marks to assist in alignment of flaps at the end of the operation. If an ipsilateral supraomohyoid neck dissection is planned, make a modified apron incision to provide adequate exposure. If bilateral neck dissection is planned, carry the horizontal component across to the other side of the neck. Both of these incisions are adequate for a pull-through operation.

When splitting the lip is essential for exposure into the oral cavity, the unilateral inverted hockey stick incision and the bilateral inverted hockey stick incision, as seen in the image below, are necessary.

The reverse bilateral hockey stick incision is ideal for a wide exposure of all levels of nodes in both sides of the neck. Make scratch marks to assist in alignment of the flaps at the end of the operation.

Make the skin incision through the platysma and elevate the flap in the subplatysmal plane, leaving the external jugular and greater auricular nerve on the SCM muscle. Traction with the surgeon's fingers and countertraction by the assistant with 2 double skin hooks are helpful in this maneuver. Elevation posterior to the SCM muscle is unnecessary. Elevate the subplatysmal flap to the level of the body of the mandible for evaluation of tumor extension. Some surgeons proceed from posteroinferior to anterosuperior; others do the opposite. The author's institution usually proceeds with level I dissection.

The marginal mandibular nerve is identified, elevated, dissected (free from the surrounding tissue), and preserved. Remove the submental fatty tissue with Bovie electrocautery and displace it inferiorly. This reveals the anterior belly of the digastric muscle. Retract and elevate the mylohyoid muscle anteriorly, exposing the submandibular ganglion, lingual nerve, and submandibular duct. Clamp, divide, and ligate the submandibular duct. Ligate the facial artery above the digastric muscle. Careful dissection avoids injury to the hypoglossal and lingual nerves, which are located deep to the fascia on the floor of the submandibular triangle.

Remove the submandibular nodes and the submandibular gland and displace them inferiorly as seen in the image below. As the gland is reflected posteroinferiorly, the facial artery is reencountered and can be ligated. Identify and completely expose the posterior belly of the digastric muscle. level I dissection is completed at this point.

The fascia over the SCM muscle and the ligated EJV are grasped and peeled from the muscle as seen in the image below. The greater auricular nerve is sacrificed in the process of the dissection; however, some surgeons claim preservation. Grasp the fascia with Allis clamps and pull vertically. Using electrocautery, peel the fascia from the SCM muscle. Assistance with traction and countertraction is necessary for this stage. Sharp dissection with a knife also suffices for fascial peeling. Vessels that enter the muscle can be cauterized with a bipolar forceps for hemostasis.

Next, identify the accessory nerve. (This can be accomplished if the patient is not paralyzed and electrocautery is used.) Dissection with an intermediate hemostat placed 2-3 finger breadths below the posterior belly of the digastric muscle, at the point where the accessory nerve enters the SCM muscle, (as seen in the image below) encounters the nerve directly with sight or indirectly with stimulation. Retraction of the SCM muscle and the posterior belly of the digastric muscle is imperative in this maneuver. After identification of the accessory nerve, it can be traced to the posterior belly of the digastric muscle.

Elevate the nerve after dividing the tissue lateral to it. Remember that the nerve is lateral to the IJV in approximately 70% of individuals, as seen in the image below. Therefore, in one third of patients, the accessory nerve passes medial to the IJV and can be traumatized by any technical error. Place attention on the posterior corner formed by the posterior belly of the digastric muscle and the SCM muscle, which are retracted. Retraction is critical in this particular area. Using a Bovie electrocautery unit, grasp the fibroadipose tissue inside the posterior corner with an Allis clamp and retract and dissect inferiorly until the underlying deep cervical muscles are revealed. Pass the fibrofatty tissue under the accessory nerve.

The dissection continues inferiorly with incision of the fibroadipose tissue along the posterior border of the SCM muscle to the level of the omohyoid muscle. When the sensory branches of the cervical plexus are found, the dissection continues in a plane lateral to these nerves. At this point, intraoperative evaluation is extremely important to determine if levels IV and V also must be addressed.

Following the sensory branches of the cervical plexus expedites rolling over the carotid artery from posterior to anterior. If performed incorrectly, in a deeper layer, the dissection runs under the plane of the carotid sheath and IJV. Avoid injury to any of these structures. Being in the right plane is crucial. Watch for the cervical plexus and the phrenic and vagus nerves.

Identify the carotid sheath and vagus nerve as depicted in the images below.

Sharply cut the node-containing tissue above an intermediate hemostat; roll over the carotid axis in an inferior-to-superior direction. Peel the fascia over the IJV. This is best accomplished using a sharp knife with a No.10 surgical blade, cutting with its belly over the vein (in the interface between the fascia and the vein) using gentle traction and countertraction. This particular technique should be taught and discussed with residents in their first cases. Another way to dissect the IJV is to use a vascular forceps with the assistance of scissors, hemostat, or both.

Ligate the tributary veins with 3-0 silk, since fasciae over the IJV are unfolded. Occasionally, the common facial vein must be divided; this is accomplished by preserving a stump of the IJV to avoid a narrowing of the main vein. Follow the superior belly of the omohyoid muscle to the hyoid bone. Divide and ligate the ranine veins. Preserve the superior thyroid artery and the hypoglossal nerve. Continue until the dissection posteriorly reaches anteriorly. Complete the dissection at this point by removing the specimen.

In the last year, the use of the harmonic scalpel in the execution of the supraomohyoid neck dissection has been introduced.[19, 20] Its progressive use has displaced most other, more conventional, intraoperative techniques used for providing hemostasis, such as clamping, tying, and electrocauterization. The major advantage is shortening of the operative time.

Resection of the primary lesion follows. In the image below, the final aspect of the surgical wound after removal of the operative specimen is seen. Irrigate with isotonic sodium chloride solution at the end of the operation. Maintain hemostasis. Insert 0.125-in Hemovac or Jackson-Pratt drains, usually 2 for each side of the neck.

Table 1. Surgical Steps in Supraomohyoid Neck Dissection (Open Table in a new window)

Wound closure

Use 3-0 Vicryl through the platysmal flaps and staples or 4-0 nylon for the skin. No compressive dressings are used for bilateral neck dissections; however, some surgeons use a compression dressing for unilateral neck dissection.

Pathology specimen

Plastic plates with a life-size drawing of the different neck areas are recommended for orientation. Place the unfixed specimen as it appears in the patient and transfer to the pathology department from the operating room. The type of dissection performed should be clearly indicated on the requisition slip.

Surgical technique modification

The main difficulty in the learning process for the head and neck surgeon is neck orientation. Tridimensional and depth perception in the different planes are difficult to master. Therefore, the authors have found that the learning process is easier if the resident can approach the supraomohyoid neck dissection from 2 different angles that meet at the exposed carotid-jugular axis. The exposure and identification of the carotid-internal jugular axis helps the resident to understand depth perception in the different planes. In other words, complete level I first and displace it inferiorly, which exposes both bellies of the digastric muscle. Then, expose the anterior belly of the omohyoid, and, from above, dissect the carotid triangle below the digastric muscle.

Carefully ligate the ranine veins. Preserve the superior thyroid artery and the superior laryngeal nerve. The plane of the carotid-internal jugular axis is identified anteriorly. The surgical technique is depicted in the image below.

As described previously, dissection then proceeds from lateral to medial as seen in the image below.

Current Procedural Terminology code (CPT coding)

38724, Supraomohyoid Neck Dissection (same code used for extended supraomohyoid neck dissection)

Endoscopic and robotic neck dissections

Minimally invasive surgery with the assistance of endoscopic and robotic instrumentation has been tried in head and neck cancer management, including neck dissection for cervical metastatic disease.[21, 22] The viability of neck dissection has been demonstrated using this armamentarium; however, its oncological application in the management of neck metastasis versus the classic open approach remains to be seen.

Supraomohyoid neck dissection in the clinically N0 neck has been also tried using endoscopic and robotic instrumentation with better cosmetic results and similar oncological effectivity.[23]

Further assessment and follow-up are needed prior to the use of endoscopic and robotic dissections in routine oncological practice.

Other associated surgeries

Bilateral supraomohyoid neck dissection does not require tracheotomy. Other surgeries directed to the primary tumor vary according to size and location of the tumor. The patient may need a tracheotomy to control the airway, depending on the amount of tissue resected at the primary site, type of reconstruction, and the need to maintain the airway patent in the immediate postoperative period.

See the list below:

• Maintain NPO status for at least the first 24 hours postoperatively.

• Most patients have a nasogastric tube (NGT). Start feeding through the NGT on a schedule corresponding to the patient's condition and tolerance.

• Maintain head elevation at a 30° angle.

• Monitor vital signs, intake, and output every 4 hours.

• Administer pain medications as needed.

• Ensure that Hemovac suction tubes or drains function properly.

• Ensure that drains are maintained continuously on suction and that they do not clot.

• Maintain drains until they drain less than 20-25 mL in 24 hours.

• Administer antibiotics for 24 hours if the surgery involved opening the neck and the upper aerodigestive tract.

• Monitor for fever, bleeding, or hematoma in the postoperative period.

• Avoid atelectasis. Encourage deep breathing and early ambulation with assistance.

• Monitor for possible fistula if the oral or upper digestive tract was opened, particularly during postoperative days (PODs) 3 and 4.

Discharge criteria

See the list below:

• Shoulder physical therapy has been ordered if needed.

• Drains have been removed (usually on POD 4 or 5).

• The surgical wound has healed satisfactorily.

• No evidence of bleeding or infection has been observed.

• Adequate airway and nutrition have been achieved.

• Hemodynamic stability has been achieved.

• Adequate family or home care support has been arranged.

• If other surgical procedures were performed in addition to supraomohyoid neck dissection, the discharge day varies according to the progress and condition of the patient.

See the list below:

• Call the patient at home to check the patient's condition.

• Arrange for the patient to return to clinic (RTC) in 7-10 days. Check the pathology report for complete resection and free margins. Check the pathology status of the neck. Evaluate for further consultations and adjunctive treatment as needed.

• Remove sutures or clips at 7-14 days. When radiation therapy has been administered, sutures or clips should remain in place for at least 10 PODs.

• If necessary, continue with shoulder physical therapy.

• Follow-up care is mandatory to check for recurrent tumor or development of a second primary tumor. Therefore, see the patient every month for the first year, particularly if no primary lesion was initially found. Thereafter, see the patient every 2-4 months for up to 5 years. After this interval, the patient can be seen yearly.

• Advise the patient to call for an immediate appointment if the patient's condition suddenly changes.

• For excellent patient education resources, see eMedicineHealth's patient education article Cancer of the Mouth and Throat.

When the supraomohyoid neck dissection is performed without opening the oral cavity or aerodigestive tract, major complications are unlikely.

However, previous radiation therapy is associated with a high complication rate. Other factors, such as poor general health, chronic malnutrition, alcoholism, diabetes mellitus, advanced age, and systemic illness, increase the percentage rate of complications.

Intraoperative complications

See the list below:

• Hemorrhage

  • Severe blood loss is an uncommon complication for an experienced head and neck surgeon. The average blood loss in the realization of a selective neck dissection is 200 mL or less. This amount varies slightly according to the surgical technique and the surgeon. Careful attention to anatomy, hemostasis with an electrocautery unit or bipolar forceps, and use of clamps and suture ligation has allowed an almost bloodless neck operation. The recent addition of the harmonic scalpel in the armamentarium has allowed a significant shortening of the operative time.[19, 20]

  • Today, major vessel trauma, laceration, tear, or transection (eg, IJV, junction of IJV and subclavian and/or carotid arteries) is a rare occurrence. Immediately repair injury to the carotid arteries. Consultation with a vascular surgeon may be useful depending on intraoperative findings. A small tear or laceration requires primary closure with a 6-0 continuous vascular suture. Other injuries may require ligation or reconstruction. Injury to the IJV at the upper or lower ends can be a serious problem.

  • If the lower end of the jugular vein bleeds excessively, pressure is the first aid, followed by adequate visualization and suctioning until the stump is identified, dissected, and ligated properly. Infrequently, bleeding cannot be controlled and requires the assistance of a thoracic surgeon to enter the superior mediastinum.

  • If the distal end of the vein bleeds excessively and the stump has retracted into the temporal bone, packing the jugular foramen with large pieces of Surgicel, plicating with the posterior belly of the digastric muscle, or both suffices to solve the problem.

  • In most instances, injury along the axis of the IJV is less problematic. Small fissures of the IJV are rare when the scalpel blade is used (understanding the technique is necessary), and the fissures usually stop bleeding with gentle pressure or with a tiny suture ligation using 3-0 silk (while holding the break with the tip of the small hemostat). On the few occasions when the vein is torn, it can be salvaged using a 6-0 vascular suture.

• Carotid sinus reflux: Hypotension due to carotid sinus reflux may occur upon dissection around the carotid bifurcation. Temporarily, this situation can be avoided by careful dissection at this level without manipulation, injection of 2 mL of local anesthetic into the adventitia at the carotid bifurcation between the internal and external carotid arteries, or both.

• Pneumothorax

  • Pneumothorax involves a sudden compromise of the respiratory and circulatory system and manifests as difficult breathing, bronchospasm, and decrease in oxygen saturation. The pressure of the anesthetic bag does not cause normal expansion of the thorax.

  • Pneumothorax is rare today. To minimize chances of this complication, carefully dissect in the paratracheal area and base of the neck with good hemostasis, adequate visualization, and precise dissection of the tissues close to the apex of lung.

  • If the pneumothorax is small, the wound can be closed with an airtight seal. Follow-up with conservative management controls the situation without sequelae. However, a large pleural leak with a tension pneumothorax requires immediate aspiration with a No. 14 or No. 16 needle in the upper anterior thorax, placement of a chest tube with an underwater drainage, or both.

• Air embolism

  • Air embolism is also rare today. This complication can occur when a large vein is inadvertently opened. A large volume of air rapidly enters the open vein by negative pressure and passes directly into the right atrium, causing a sudden alteration of the central circulation, which leads to tamponade of the heart and even death.

  • Clinically, cyanosis, hypotension, and a loud churning noise over the precordial area suddenly manifest, and the peripheral pulse disappears. Treatment requires immediately packing or clamping the offending vein and turning the patient onto the left side with the head down. Cardiac arrest can occur, requiring aspiration of the air from the heart, massage, and standard resuscitation procedures. Prevention, with careful identification and clamping of the major veins of the neck, is best. Adequate ligations and transfixion sutures are mandatory.

• Embolism: Embolism leading to stroke can occur. Most patients with cancer are of the age at which arterial cerebrovascular disease is common. Careful handling of the carotid arterial system in the neck with gentle retraction, ligation, and manipulation prevents dislodgment of arteriosclerotic plaques from the internal carotid system.

• Nerve damage

  • The neck area has multiple sensory nerves that are sacrificed during supraomohyoid neck dissection. Therefore, loss of sensation occurs in multiple areas (eg, neck, posterior occiput, external ear, mandibular region, lateral shoulder, deltoid area, upper pectoral area). Occasionally, the formation of a neuroma at the end of a cut nerve may cause paresthesias and pain.

  • The ramus mandibularis is preserved in most neck dissections unless it is involved by metastatic disease. The transection of the marginal mandibular branch of the facial nerve produces lower lip weakness. If the tail of the parotid is resected, follow the nerve into the parotid tissue before removal of this tissue. Sacrifice of the cervical sympathetic chain produces Horner syndrome, which involves ptosis, anhidrosis, and miosis.

  • The spinal accessory nerve is preserved in the supraomohyoid neck dissection. However, damage to the nerve by stretching or devascularization produces shoulder dysfunction, limitation in the range of motion of the arm and shoulder, and local pain in the affected area. Most patients tolerate this disability well and improve markedly with physical therapy within 1 year.

  • Unilateral resection of the hypoglossal nerve is usually well tolerated without serious sequelae; however, bilateral hypoglossal nerve resection causes severe disability with serious difficulties in feeding, swallowing, and speaking. A feeding gastrostomy tube is sometimes recommended for adequate nutrition.

  • Damage in the lower or middle neck to the vagus nerve, which carries motor and sensory branches to the larynx and pharynx, causes vocal cord paralysis. Damage to the brachial plexus is rare in the supraomohyoid neck dissection and can be avoided by proper identification of anatomic planes. If damage occurs, reapproximate the sectioned brachial plexus with 8-0 or 9-0 nylon monofilament or silk.

• Poor wound healing after radiation therapy: Patients who have received radiation therapy before supraomohyoid neck dissection tend to have increased postoperative complications such as wound infection, fistula, flap necrosis, osteoradionecrosis, and carotid artery rupture. Few institutions reserve surgery for salvage after radiotherapy failure in the treatment of cancer of the head and neck.

• Chylous fistula: Chylous fistula is a rare complication of supraomohyoid neck dissection that may occur during dissection of the thoracic duct region. Most chylous fistulas occur on the left side. If a chylous fistula is found, ligate the thoracic duct. Reinspect the area before completing the surgery. Ask the anesthesiologist to apply positive pressure to determine if further leaking is present. A small leak can be identified with assistance of the microscope. Ligation is mandatory. A suture ligation with a figure 8 using 4-0 silk is usually satisfactory. Hemostat clips have also been used when the leakage is clearly visualized.

Postoperative complications

See the list below:

• Hematoma

  • Meticulous hemostasis during the surgical procedure is mandatory. Use suction drains to avoid accumulation of blood under the skin flap and to prevent hematoma formation.

  • Some surgeons also use a floppy, moderately compressive dressing in addition to the suctioning system mentioned above. This is disadvantageous because the compressive dressing leaves flaps unavailable for inspection, which is the best way to monitor for hematoma formation.

  • A hematoma usually manifests in the first few postoperative hours. Sudden bleeding in the postoperative period indicates that an untied vessel has opened or that a ligature has slipped from the vessel. Blood under the flap accumulates rapidly. Treat by opening and elevating the neck flaps to evacuate the hematoma. Irrigate the surgical field with isotonic sodium chloride solution, and, if any source of bleeding is found, ligate, suture, or electrocauterize to achieve hemostasis. If the hematoma is recognized and treated early, no adverse consequences ensue. However, if found late, airway compromise, infection, or flap necrosis can occur.

• Wound infection

  • When supraomohyoid neck dissection is performed without opening the oral cavity or aerodigestive tract, wound infection is unlikely. However, the potential for wound infection increases markedly when supraomohyoid dissection is performed in combination with the opening of the oral cavity as part of a composite resection. Salivary contamination from the oral cavity is possible, causing bacterial invasion and wound infection.

  • All irradiated tissues are more susceptible to infection because of ischemia and hypoxemia. Other factors that increase possibilities of wound infection are malnutrition, chemotherapy, anemia, diabetes mellitus, and advanced tumor mass.

  • If wound infection develops, open the flap, evacuate and culture the pus, and irrigate the wound. Administer antibiotics that cover gram-positive and gram-negative organisms. Carefully debride necrotic tissue. Local care with frequent dressing changes, salivary fistula control, and wound irrigation is critical. Once the infection is under control and necrotic tissue is removed, healthy granulation tissue appears.

• Skin flap loss

  • Skin flap necrosis can have several causes, such as design errors, elevation, poor handling, or improper postoperative care. Preexisting scars, prior radiation therapy, hematoma, infection, and poor nutrition can contribute to skin flap loss. If skin flap necrosis occurs and the carotid is not exposed, a conservative approach is mandatory. Carefully and progressively trim necrotic tissue and frequently change wound dressings.

  • In the supraomohyoid neck dissection, the carotid artery is covered by the SCM muscle. Therefore, carotid exposure is unlikely unless major tissue necrosis and skin loss occurs.

  • Skin necrosis, infection, and accumulation of pus adjacent to the carotid wall alert the surgeon to a potential carotid artery rupture. Management is on a patient-by-patient basis; however, initially, control of infection, wound cleansing, and local care are priorities. The decision between flap coverage and secondary healing is then made.

• Salivary fistula

  • Salivary fistula occurs more frequently when a patient previously has received radiation therapy and the oral cavity, pharynx, or cervical esophagus has been opened in association with the neck dissection.

  • Good surgical technique with double-layer closures and watertight closures without tension minimize this complication. Use Vicryl or Dexon sutures in high-risk patients. Low-suction drainage is recommended; do not place Hemovac drains over carotid arteries.

  • Usually, the fistula appears within 4-5 days of surgery; however, fistulas can develop after an interval of 2-3 weeks, particularly after irradiation. Fistulas may range from a small leak that is well managed by conservative measures (eg, frequent dressing changes, local care) to a large leak that involves infection of the whole neck with flap necrosis. Patients with large leaks require enteral or parenteral feeding, controlled exteriorization of the fistula, and local care before closure of local skin or myocutaneous flaps.

• Chylous fistula: Chylous fistula is rare in supraomohyoid neck dissection. Chyle can be identified by a milky appearance in the Hemovac tubes. Chyle accumulation under the flap can cause redness and swelling of the flap with induration of the surrounding tissues. If the leak is minimal, it usually can be controlled by aspiration, pressure dressings, and a low-fat diet. Ligation of the offending thoracic duct is required when the leak is extensive (ie, >500 mL of drainage for 5 d without improvement with conservative management).

• Facial edema: Facial edema can occur even if a single IJV remains, particularly in patients with previous irradiation therapy. Edema reaches a maximum at POD 7 and progressively decreases in a few weeks with conservative management. Facial edema is increased with synchronous bilateral radical neck dissections.

• Electrolyte disturbances: The most common electrolyte disturbance in the postoperative period is hyponatremia. Although usually dilutional, this condition can be related to inappropriate antidiuretic hormone secretion. Clinically, hyponatremia can manifest as mental changes, including depression and hallucinations. Occasionally, hypernatremia, hypokalemia, hypercalcemia, and hypophosphatemia are also associated with neck operations.

• Carotid artery rupture

  • Carotid artery rupture is rare after supraomohyoid neck dissection. Incidence of this complication ranges from 3-7%. The precipitating factors of carotid artery rupture are as follows:

    • Radiation therapy

    • Infection and salivary fistula

    • Suction catheters that cause erosion of the vessel wall

    • Exposure by dehiscence of the suture line or necrosis of the dermis

  • Rupture occurs in patients who underwent neck surgery with exposure of the carotid artery and one or more of the precipitating factors listed above. Most patients have prodromal bleeding (ie, sentinel bleed) within 48 hours of carotid artery rupture. Therefore, initial bleeding indicates that serious complications can be avoided with elective ligation of the offending artery. Immediate treatment for carotid artery rupture includes the following measures:

    • Apply direct and firm pressure to the affected area. Prepare the operating room for neck surgery. Suctioning, good illumination, and adequate instrumentation are imperative.

    • With a large-bore catheter, cannulize a peripheral vein in each arm for immediate administration of fluids (eg, Ringer lactate, isotonic sodium chloride solution). Controlling blood pressure and blood volume before ligation is important.

    • The airway should be adequate and stable. If the patient does not undergo a tracheotomy, orotracheal intubation may be necessary.

    • Blood is typed and cross-matched for 4-6 units of blood.

    • Move the patient to the operating room.

    • If bleeding cannot be controlled with pressure, clamp the common carotid artery as an emergency procedure after blood pressure and pulse are within the reference range.

  • Definitive treatment for carotid artery rupture includes the following measures:

    • Ligate the carotid artery. Avoid repair or diversion in infected areas.

    • Use general endotracheal anesthesia.

    • Ensure adequate instrumentation is prepared.

    • Adequate exposure (both proximally and distally) to the source of bleeding and contaminated or infected areas helps prevent a second rupture.

    • Accomplish ligation with 1-0 silk suture. Reinforce this suture, distally and proximally, with 2-0 silk suture. Then, bury the ligated stump in surrounding healthy tissue.

    • Occasionally, ligating the carotid artery beneath the clavicle is necessary. Resection of the medial half of the clavicle is necessary for exposure if the ligation must be performed inferior to the supraclavicular triangle.

  • Prophylaxis for carotid artery rupture includes the following measures:

    • Do not traumatize the carotid vessel. Careful handling of the carotid artery and preservation of the adventitia are most important.

    • Avoid suction catheters that lie adjacent to the carotid artery.

    • If a fistula is present, divert it from the carotid area.

    • Use adequate dressings that retain moisture.

    • Cover the carotid artery with a dermal graft using the levator scapulae muscle or posterior scalene muscle.

    • Aggressively treat infection with drainage, culture, and appropriate antibiotics.

Supraomohyoid neck dissection, with the primary tumor under control, has resulted in recurrence rates as follows:

• In a neck with negative histologic findings, the recurrence rate is 4-6%.

• In a neck with single node metastasis without capsular spread, the recurrence rate is 10%.

• In a neck with multiple node metastasis or extracapsular spread, the recurrence rate is 12-25%.

Because of a high risk of recurrence, radiation therapy is recommended for patients who have positive histologic findings in the neck and multiple node metastasis or extracapsular spread.

Generally, the following characteristics of nodal metastasis affect prognosis in the supraomohyoid neck dissection:

• Extracapsular spread: This condition adversely affects the prognosis. The pathologist looks systematically for extracapsular spread, which is commonly encountered. Tumor spread beyond the capsule of an LN is the most important prognostic factor related to recurrence in the neck.

• Sites of nodal involvement: The prognosis and survival rates are poor when multiple levels of neck nodes are involved. If the contralateral side is involved, prognosis is poor.

• Number of nodes: A greater number of involved LNs portends a poorer prognosis. Additionally, risk of recurrence and poor survival rate increases.

• Node fixation: In general, fixation occurs with large masses, and prognosis is poor. Supraomohyoid neck dissection is not indicated in fixed masses.

• Degree of differentiation: The risk of cervical metastasis correlates with the grade of tumor differentiation at the primary site. Poorly differentiated tumors are more aggressive and carry a poor prognosis.

• Involvement of the surgical margin: A positive surgical margin at the primary tumor site carries a poor prognosis.

Once the neck has metastatic disease, adequate treatment is essential. Preoperatively, no method can be used to identify all metastatic disease clearly. Therefore, false-positive and false-negative results are common. The pathologist's examination of LNs removed during surgery is the optimum standard for detection of occult metastasis.

Accordingly, the decision to treat the neck electively depends on the risk of occult metastatic disease associated with a particular primary tumor. Treat patients who have a 20% or higher possibility of harboring metastasis.

Elective management of the neck can be accomplished with surgery or radiation therapy. Surgery is probably selected when the primary tumor is treated with surgery and postoperative radiation therapy is not planned. Furthermore, pathology results define the actual status of neck nodes and serve to guide further treatment. Management is not standardized and varies according to institution, geographical area, and surgeon.

Selection of treatment modality is a controversial subject because the decision to preserve a particular group of nodes remains intraoperative and is based on the surgeon's or pathologist's findings. Although general opinion holds that selective neck dissection is a good alternative for the N0 neck, other alternatives are available (eg, elective treatment, waiting and observing, surgery, radiation).

Because indications are not standardized, the question of comprehensive neck dissection versus selective neck dissection depends on the surgeon. This lack of standardization places the onus of deciding whether to remove levels I-V or to remove a particular group of nodes on the surgeon.

In the future, surgeons worldwide must accomplish the following:

• Develop better techniques for evaluation of neck metastasis.

• Define and standardize indications for preoperative and postoperative radiation therapy of the neck.

• Define and standardize clinical criteria for selective and comprehensive neck dissection.

• Define and standardize indications for the N0 neck.

• Define and standardize indications for the N0 neck after using chemotherapy/radiation for the primary tumor.

• Define and standardize indications for the N+ neck.

• Define and standardize the role of PET/CT in the assessment and identification of neck metastasis.

• Further investigate and analyze prognostic indicators.

• Continue clinical research in these areas.

Special acknowledgment

The authors wish to acknowledge Joan Flaherty, RN, for her editorial assistance and Gustavo Díaz, MD, for taking the digital surgical photos.