Laboratory Studies

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

Imaging Studies

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.

Other Tests

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.

Diagnostic Procedures

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.

Histologic Findings

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.

Treatment & Management

Suarez O. El problema de las metastasis linfaticas y alejadas del cancer de laringe e hipofaringe. Rev. Otorrinolaringol. 1963. 23:83-99.
Bocca E, Pignataro O. A conservation technique in radical neck dissection. Ann Otol Rhinol Laryngol. 1967 Dec. 76(5):975-87. [QxMD MEDLINE Link].
Robbins KT. Pocket Guide to Neck Dissection Classification and TNM Staging of Head and Neck Cancer. American Academy of Otolaryngology-Head and Neck Surgery Foundation, Inc. 1991:7-9.
Robbins KT. Pocket Guide to Neck Dissection and Classification and TNM Staging of Head and Neck Cancer, American Academy of Otolaryngology-Head and Neck Surgery Foundation, Inc. 2001. 8-38.
Robbins K. T., Clayman G., Levine P. A., Medina J. , Sessions R., Shaha A., et al. Neck Dissection Classification Update: Revisions Proposed by the American Head and Neck Society and the American Academy of Otolaryngology-Head and Neck Surgery. Arch Otolaryngol Head Neck Surg. July 2002. 128 (7):751-758.
Robbins KT, Shaha AR, Medina JE, et al. Consensus statement on the classification and terminology of neck dissection. Arch Otolaryngol Head Neck Surg. 2008 May. 134(5):536-8. [QxMD MEDLINE Link].
Guo CB, Feng Z, Zhang JG, Peng X, Cai ZG, Mao C, et al. Supraomohyoid neck dissection and modified radical neck dissection for clinically node-negative oral squamous cell carcinoma: A prospective study of prognosis, complications and quality of life. J Craniomaxillofac Surg. 2014 Aug 6. [QxMD MEDLINE Link].
Ferlito A, Robbins KT, Shah JP, Medina JE, Silver CE, Al-Tamimi S. Proposal for a rational classification of neck dissections. Head Neck. 2011 Mar. 33(3):445-50. [QxMD MEDLINE Link].
Medina JE, Vasan NR. Neck Dissection. Johnson, Rosen. Bailey's Head and Neck Surgery Otolaryngology. Fifth Edition. Walters Klumer, Lippincott William & Wilkins; 2014. Vol. II: 1807-1838/117.
Kowalski L P, Sanabria A. Elective neck dissection in oral carcinoma: a critical review of the evidence. Acta Otorhinolaryngol. Ital. June 2007. 27 (3):113-117.
Feng Z, Li JN, Niu LX, Guo CB. Supraomohyoid neck dissection in the management of oral squamous cell carcinoma: special consideration for skip metastases at level IV or V. J Oral Maxillofac Surg. 2014 Jun. 72(6):1203-11. [QxMD MEDLINE Link].
Ferlito A, Silver CE, Rinaldo A. Elective management of the neck in oral cavity squamous carcinoma: current concepts supported by prospective studies. Br J Oral Maxillofac Surg. Jan 2009. 47(1):5-9. [QxMD MEDLINE Link].
Civantos FJ, Moffat FL, Goodwin WJ. Lymphatic mapping and sentinel lymphadenectomy for 106 head and neck lesions: contrasts between oral cavity and cutaneous malignancy. Laryngoscope. 2006 Mar. 112(3 Pt 2 Suppl 109):1-15. [QxMD MEDLINE Link].
Pitman KT, Ferlito A, Devaney KO, Shaha AR, Rinaldo A. Sentinel lymph node biopsy in head and neck cancer. Oral Oncol. 2003 Jun. 39(4):343-9. [QxMD MEDLINE Link].
Sebbesen L, Bilde A, Therkildsen M, Mortensen J, Specht L, von Buchwald C. 3 years follow-up of sentinel node negative patients with early oral cavity squamous cell carcinoma. Head Neck. Jun 26 2013.
Seethala RR. Current state of neck dissection in the United States. Head Neck Pathol. Sep 2009. 3(3):238-245. [Full Text].
Patel V, Hood BL, Molinolo AA, Lee NH, Conrads TP, Braisted JC. Proteomic analysis of laser-captured paraffin-embedded tissues: a molecular portrait of head and neck cancer progression. Clin Cancer Res. 2008 Feb 15. 14(4):1002-14. [QxMD MEDLINE Link].
Shores CG, Yin X, Funkhouser W, Yarbrough W. Clinical evaluation of a new molecular method for detection of micrometastases in head and neck squamous cell carcinoma. Arch Otolaryngol Head Neck Surg. 2004 Aug. 130(8):937-42. [QxMD MEDLINE Link].
Kos M, Engelke W. Advantages of a new technique of neck dissection using an ultrasonic scalpel. J Craniomaxillofac Surg. Jan 2007. 35(1):10-14. [QxMD MEDLINE Link].
Salami A, Dellepiane M, Bavazzano M, Crippa B, Mora F, Mora R. New trends in head and neck surgery: a prospective evaluation of the Harmonic Scalpel. Med Sci Monit. 2008/05. 14 (5):PI1-5. [QxMD MEDLINE Link].
Byeon HK, Holsinger FC, Koh YW, et al. Endoscopic supraomohyoid neck dissection via a retroauricular or modified facelift approach: preliminary results. Head Neck. 2014 Mar. 36(3):425-30. [QxMD MEDLINE Link].
Byeon HK, Holsinger FC, Koh YW, Ban MJ, Ha JG, Park JJ, et al. Endoscopic supraomohyoid neck dissection via a retroauricular or modified facelift approach: preliminary results. Head Neck. 2014 Mar. 36(3):425-30. [QxMD MEDLINE Link].
Lee HS, Kim WS, Hong HJ, Ban MJ, Lee D, Koh YW, et al. Robot-assisted Supraomohyoid neck dissection via a modified face-lift or retroauricular approach in early-stage cN0 squamous cell carcinoma of the oral cavity: a comparative study with conventional technique. Ann Surg Oncol. 2012 Nov. 19(12):3871-8. [QxMD MEDLINE Link].
Adams S, Baum RP, Stuckensen T, Bitter K, Hör G. Prospective comparison of 18F-FDG PET with conventional imaging modalities (CT, MRI, US) in lymph node staging of head and neck cancer. Eur J Nucl Med. 1998 Sep. 25(9):1255-60. [QxMD MEDLINE Link].
Andersen PE, Warren F, Spiro J, Burningham A, Wong R, Wax MK. Results of selective neck dissection in management of the node-positive neck. Arch Otolaryngol Head Neck Surg. 2002 Oct. 128(10):1180-4. [QxMD MEDLINE Link].
Argiris A, Eng C. Epidemiology, staging, and screening of head and neck cancer. Cancer Treat Res. 2003. 114:15-60. [QxMD MEDLINE Link].
Aygun Nafi, Oliverio PJ, Zinreich S J. Overview of Diagnostic Imaging of the Head and Neck, chapter 2 in Cummings Otolaryngology Head and Neck Surgery. Fourth Edition. Elsevier Mosby; 2005. Volume One: 25-92.
Bier-Laning CM. Surgical Complications of the Neck, chapter 117 in Cummings Otolaryngology Head and Neck Surgery, Fourth Edition, Volume Three. 2005. Elsevier Mosby:2646-2657.
Byers RM, Weber RS, Andrews T, McGill D, Kare R, Wolf P. Frequency and therapeutic implications of "skip metastases" in the neck from squamous carcinoma of the oral tongue. Head Neck. 1997 Jan. 19(1):14-9. [QxMD MEDLINE Link].
Candela FC, Kothari K, Shah JP. Patterns of cervical node metastases from squamous carcinoma of the oropharynx and hypopharynx. Head Neck. 1990 May-Jun. 12(3):197-203. [QxMD MEDLINE Link].
Charron M, Beyer T, Bohnen NN, Kinahan PE, Dachille M, Jerin J. Image analysis in patients with cancer studied with a combined PET and CT scanner. Clin Nucl Med. 2000 Nov. 25(11):905-10. [QxMD MEDLINE Link].
Crean SJ, Hoffman A, Potts J, Fardy MJ. Reduction of occult metastatic disease by extension of the supraomohyoid neck dissection to include level IV. Head Neck. 2003 Sep. 25(9):758-62. [QxMD MEDLINE Link].
Dogan E, Cetinayak HO, Sarioglu S, Erdag TK, Ikiz AO. Patterns of cervical lymph node metastases in oral tongue squamous cell carcinoma: implications for elective and therapeutic neck dissection. J Laryngol Otol. 2014 Mar. 128(3):268-73. [QxMD MEDLINE Link].
Farber LA, Benard F, Machtay M, Smith RJ, Weber RS, Weinstein GS. Detection of recurrent head and neck squamous cell carcinomas after radiation therapy with 2-18F-fluoro-2-deoxy-D-glucose positron emission tomography. Laryngoscope. 1999 Jun. 109(6):970-5. [QxMD MEDLINE Link].
Ferlito A, Rinaldo A, Robbins KT, Silver CE. Neck dissection: past, present and future?. J Laryngol Otol. 2006 Feb. 120(2):87-92. [QxMD MEDLINE Link].
Gavilan C, Gavilan J, Monux. Vaciamiento glanglionar cervical funcional, capitulo XXIV. Gil Carcedo LM, ed. El Abordaje en el Tratamiento Quirúrgico de los Tumores de Cabeza y Cuello. 1992. 361-372.
Gavilan J, Gavilan C, Herranz J. Functional neck dissection: three decades of controversy. Ann Otol Rhinol Laryngol. 1992 Apr. 101(4):339-41. [QxMD MEDLINE Link].
Gavilan J, Herranz J, DeSanto L W, Gavilan C. Functional and Selective Neck Dissection, Thieme Medical Publishers, Inc. 2002. 1-143.
Hanasono MM, Kunda LD, Segall GM, Ku GH, Terris DJ. Uses and limitations of FDG positron emission tomography in patients with head and neck cancer. Laryngoscope. 1999 Jun. 109(6):880-5. [QxMD MEDLINE Link].
Johnson J. Cervical metastases. Gludkman, Gullane, Johnson, eds. Practical Approach to Head and Neck Tumors. Raven Book; 1994. chap 4.
Khafif A, Lopez-Garza JR, Medina JE. Is dissection of level IV necessary in patients with T1-T3 N0 tongue cancer?. Laryngoscope. 2001 Jun. 111(6):1088-90. [QxMD MEDLINE Link].
Kowalski LP, Carvalho AL. Feasibility of supraomohyoid neck dissection in N1 and N2a oral cancer patients. Head Neck. 2002 Oct. 24(10):921-4. [QxMD MEDLINE Link].
Lonneux M, Lawson G, Ide C, Bausart R, Remacle M, Pauwels S. Positron emission tomography with fluorodeoxyglucose for suspected head and neck tumor recurrence in the symptomatic patient. Laryngoscope. 2000 Sep. 110(9):1493-7. [QxMD MEDLINE Link].
Lowe VJ, Boyd JH, Dunphy FR, Kim H, Dunleavy T, Collins BT. Surveillance for recurrent head and neck cancer using positron emission tomography. J Clin Oncol. 2000 Feb. 18(3):651-8. [QxMD MEDLINE Link].
Lowe VJ, Stack Jr BC, Watson Jr RE. Head and Neck Cancer Imaging, chapter 3 in Head and Neck Cancer, Emerging Perspectives (Ensley J. F, Gutkind J.S., Jacobs J. R., Lippman S. M., editors). 2003. 23-33.
Medina J E. Management of the Neck in Squamous Cell Carcinomas of the Head and Neck, chapter 22 in Head and Neck Cancer, Emerging Perspectives (Ensley J. F, Gutkind J.S., Jacobs J. R., Lippman S. M., editors). 2003. 317-327.
Medina J E, Houck Jr JR, O'Malley B B. Management of Cervical Lymph Nodes in Squamous Cell Carcinoma of the Head and Neck, chapter 16, Head and Neck Cancer, A Multidisciplinary Approach (Harrison L. B., Sessions R. B., Hong W. K., editors). 1999. 353-377:
Medina JE. A rational classification of neck dissections. Otolaryngol Head Neck Surg. 1989 Mar. 100(3):169-76. [QxMD MEDLINE Link].
Medina JE. Neck Dissection, chapter 113, in Head & Neck Surgery-Otolryngology, (Bailey B.J. & Johnson J. T.,editors),. Fourth Edition. Lippincoott Williams & Wilkins; 2006. Volume Two: 1585-1609.
Medina JE. Selective Neck Dissection [videotape]. Continuing Education with Television (CETV). 1987.
Medina JE, Byers RM. Supraomohyoid neck dissection: rationale, indications, and surgical technique. Head Neck. 1989 Mar-Apr. 11(2):111-22. [QxMD MEDLINE Link].
Medina JE, Lore Jr J M. The Neck, chapter 16 in An Atlas of Head and Neck Surgery, (Lore & Medina, editor), Fourth Edition. Elsevier Saunders, 2005. 780-817.
Medina JE, Weisman RA. The Otolaryngology Clinics of North America. Vol 1. August 1998. 585-686.
Myers EN. Chapter 78, Neck Dissection. Operative Otolaryngology Head and Neck Surgery. 2nd Edition. Elsevier; 2008. Vol 1: 679-708.
Myers LL, Wax MK, Nabi H, Simpson GT, Lamonica D. Positron emission tomography in the evaluation of the N0 neck. Laryngoscope. 1998 Feb. 108(2):232-6. [QxMD MEDLINE Link].
Rassekh CH, Johnson JT, Myers EN. Accuracy of intraoperative staging of the NO neck in squamous cell carcinoma. Laryngoscope. 1995 Dec. 105(12 Pt 1):1334-6. [QxMD MEDLINE Link].
Robbins K T. Neck Dissection, chapter 116 in Cummings Otolaryngology Head and Neck Surgery. Fourth Edition. Elsevier Mosby,; 2005. Volume Three: 2614-2645.
Robbins KT. Neck Dissection. Cummings, Fredrickson, Harker, Krause, Richardson, Schuller. Otolaryngology Head Neck Surgery. 3rd ed. Mosby Book; 1998. Vol 3: 1787-1810.
Shah JP. Patterns of cervical lymph node metastasis from squamous carcinomas of the upper aerodigestive tract. Am J Surg. 1990 Oct. 160(4):405-9. [QxMD MEDLINE Link].
Shah JP, Andersen PE. The impact of patterns of nodal metastasis on modifications of neck dissection. Ann Surg Oncol. 1994 Nov. 1(6):521-32. [QxMD MEDLINE Link].
Shockley WW, Pillsbury III HC. The Neck: Diagnosis and Surgery. Mosby Book; 1994. 413-429.
Stokkel MP, Terhaard CH, Hordijk GJ, van Rijk PP. The detection of local recurrent head and neck cancer with fluorine-18 fluorodeoxyglucose dual-head positron emission tomography. Eur J Nucl Med. 1999 Jul. 26(7):767-73. [QxMD MEDLINE Link].

Media Gallery

Bilateral inverted hockey stick incision. This skin incision is ideal for a wide exposure of all levels of nodes in both sides of the neck. The skin incision is made through the platysma, and the flap is elevated in the subplatysmal plane, leaving the external jugular vein (EJV) and the greater auricular nerve on the sternocleidomastoid (SCM) muscle. Elevation posterior to the SCM muscle is unnecessary. The subplatysmal flap is elevated to the level of the body of the mandible. The marginal mandibular nerve is identified (circle).
The submental fatty tissue, submandibular nodes, and submandibular gland are dissected and displaced inferiorly. The mylohyoid muscle is retracted and elevated anteriorly. The anterior belly of the digastric muscle is exposed.
The fascia over the sternocleidomastoid (SCM) muscle, along with the ligated external jugular vein (EJV), is grasped and peeled from the muscle. The accessory nerve is localized in the upper portion of the SCM muscle during the peeling maneuver.
View of the upper portion of the sternocleidomastoid (SCM) muscle and the accessory nerve during dissection.
A close view of the relationship between the accessory nerve and the upper portion of the internal jugular vein (IJV). In one third of patients, the accessory nerve passes medial to the IJV.
The carotid sheath and vagus are identified. The node-containing tissue is peeled over the carotid axis in an inferior-to-superior direction. Rolling over the fascia of the internal jugular vein (IJV) is best performed using a sharp knife with a No. 10 surgical blade. Traction and countertraction are crucial.
View of the upper and midportion of the sternocleidomastoid (SCM) and the accessory nerve (rectangle) during dissection. The carotid sheath (C) and the internal jugular vein (IJV) are seen in the picture.
The sternocleidomastoid muscle (SCM) is retracted. The carotid sheath (C), the vagus (V), and the accessory nerve (rectangle) are identified. The node-containing tissue is peeled over the carotid axis in an inferior-to-superior direction. The peeling of the nodal tissue over the internal jugular vein (IJV) has been partially done in the picture. Traction and countertraction are crucial during the peeling maneuver.
The final aspect of the surgical wound after removal of the operative specimen.
Surgical technique modification. The level I dissection is completed first and displaced inferiorly. The carotid triangle is then dissected. The ranine veins are carefully ligated. The superior thyroid artery and the superior laryngeal nerve are preserved. The exposure and identification of the carotid-internal jugular axis help in understanding the depth perception in the different planes (arrow 1). The dissection then proceeds as described previously from lateral to medial (arrow 2).
Surgical technique modification. Exposure and identification of the carotid-internal jugular axis has been accomplished. Finally, the dissection proceeds in the usual fashion, from lateral to medial, until the entire specimen is removed.

of 11

Table 1. Surgical Steps in Supraomohyoid Neck Dissection

Table 1. Surgical Steps in Supraomohyoid Neck Dissection

Procedure Step	Surgical Steps and Pearls
Supraomohyoid neck dissection/definition	It is also called anterolateral neck dissection. It consists of removal of cervical lymphatic nodes contained in neck levels I, II and III. It is generally used as a selective neck dissection in patients with squamous cell carcinoma of the oral cavity, T1-T4 and N0, if the primary lesion is not to be treated with radiation therapy. In this manner, the supraomohyoid neck dissection is both diagnostic and therapeutic. In the N+ neck, standardization is lacking; see text for a detailed description of indications and contraindications.
Incision design	Try not to use trifurcation incisions. The recommended incisions for unilateral neck dissection are the modified apron incision or the inverted hockey stick incision. The recommended incisions for bilateral neck dissection are the apron incision or the bilateral inverted hockey stick incision.
Skin incision and skin and subplatysmal flap elevation	Elevate the skin and subplatysmal flap to the level of the body of the mandible. Expose the anatomy of the submandibular, submental, and carotid triangles. Leave the external jugular vein and the greater auricular nerve on the SCM muscle. Elevation posterior to the SCM muscles is unnecessary.
level I dissection	Identify the mandibular nerve and elevate it, along with the surrounding tissue, in its own plane. Remove the submental fatty tissue and identify the anterior belly of the digastric muscle. Follow the anterior belly of the digastric muscle and identify the mylohyoid muscle. Retract anteriorly the mylohyoid and expose the submandibular ganglion, lingual nerve, and submandibular duct. Divide and ligate the submandibular duct. Clamp, divide, and ligate the facial artery. Remove the submandibular gland and the submandibular lymph nodes. Identify the hypoglossal nerve deep into the fascia of the submandibular triangle. Identify and expose completely the posterior belly of the digastric muscle up to the mastoid tip. If the facial artery is reencountered at this point, tie it and ligate it. After completion of all of the above, dissect and displace inferiorly the submental fatty tissue, submandibular nodes, and submandibular gland.
Fascial peeling of SCM	Ligate the external jugular vein. Grasp the fascia over the SCM and peel it from the muscle. The accessory nerve is encountered in the upper portion of the SCM during the peeling maneuver. Identify the accessory nerve directly by sight or indirectly with nerve stimulation.
Dissection posterior and inferior to the SCM	Continue inferiorly the dissection of fibroadipose tissue along the posterior border of the SCM muscle to the level of the omohyoid muscle. Identify and follow the sensory branches of the cervical plexus and continue the dissection lateral to these nerves. Follow the sensory branches of the cervical plexus from posterior to anterior in order to reach the carotid sheath. Identify and protect the cervical plexus and the phrenic and vagus nerves.
Carotid sheath, vagus nerve, internal jugular vein	Identify the carotid sheath, the vagus nerve, and the internal jugular vein. Unwrap the carotid sheath, freeing it of tissue containing nodes, working in an inferior to superior direction. Identify the vagus nerve and preserve it. Do the same with the internal jugular vein. Identify, clamp, and ligate the branches of the internal jugular vein.
Completion and removal of specimen	Follow the superior belly of the omohyoid muscle to the hyoid bone. Divide and ligate the ranine veins. Identify and preserve the superior thyroid artery and the hypoglossal nerve. Complete the dissection at this point by removing the specimen.