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NECK DISSECTION Presented By – Ryan Fernandes Moderator – Dr B.Ramdas Rai Prof & Unit Chief III Anatomy of Neck SIDE OF NECK • The side of neck is roughly quadrilateral in outline • It is bounded: Anteriorly by the anterior median line Posteriorly by anterior border of trapezius Superiorly by the base of the mandible Inferiorly by the clavicle Cervical Fascia • The cervical fascia is composed of superficial and deep layers. • The superficial fascia is not well developed • The platysma muscle is in the superficial fascia. • It arises inferiorly from the fascia of the pectoralis major muscle and its fibers converge as they ascend to their insertion in the inferior part of the mandibular region • The cutaneous nerves and the superficial veins course below this muscle of facial expression. • The cervical branch of the facial nerve innervates this muscle DEEP CERVICAL FASCIA(FASCIA COLLI) • The deep fascia of the neck is condensed to form: A. Investing layer B. Pretracheal layer C. Carotid Sheath D. Prevertebral layer INVESTING LAYER • Lies deep to the Platysma • Surrounds the neck like a collar ATTACHMENTS SUPERIORLY: a)External occipetal protruberence b)Superior Nuchal Line c)Mastoid Process d)Base of the Mandible INFERIORLY a)Spine of scapula b)Acromion Process c)Clavicle d)Mandible POSTERIORLY a) Ligamentum Nuchae b) Spine of vertebrae C7 ANTERIORLY a)Symphysis Menti b)Hyoid Bone • The investing layer of deep cervical fascia splits to enclose MUSCLES – Trapezius & Sternocleidomastoid SALIVARY GLANDS – Parotid & Submandibular SPACES – Suprasternal & Supraclavicular Pretracheal Fascia • Encloses & suspends the thyroid gland Attachments A)Superiorly – Hydoid bone, oblique line of thyroid cartilage, cricoid cartilage laterally B)Inferiorly – Blends with arch of aorta C)On either side fuses with the front of the carotid sheath PREVERTEBRAL FASCIA • The prevertebral fascia encloses the vertebral column and the attached erector spinae and prevertebral muscles and proximal portions of the cervical and brachial plexuses. • It creates a complete tube. • ATTACHMENTS Superiorly - Base of the skull Inferiorly – Extends into the superior mediastinum & attached to the body of 3rd & 4th thoracic vertebra Anteriorly – Separated from Pharynx by loose areolar tissue Laterally – Lost deep to the trapezius CAROTID FASCIA • It is the condensation of fibroareolar tissue around the main vessels of the neck • Consists of the common carotid artery, internal jugular vein & vagus nerve • The Ansa cervicalis lies embedded in the anterior wall of the carotid sheath Triangles of Neck • The sternocleidomastoid and trapezius muscles divide the neck into anterior and posterior triangles • The triangle is spiral in shape ANTERIOR TRIANGLE • The anterior triangle includes the area between the anterior edges of the sternocleidomastoid muscles. • The superior limit is the mandible and a line drawn from the angle of the mandible to the tip of the mastoid process. • Two double-bellied muscles, omohyoid and digastric, subdivide the triangles. • The inferior belly of the omohyoid muscle attaches to the superior transverse scapular ligament and a portion of the adjacent superior edge of the scapula. It passes superior to the clavicle and enters the lower portion of the posterior triangle. • The intermediate tendon is in the cricoid plane, anterior to the carotid sheath, and is angulated by a fascial sling attached to the clavicle and the manubrium. • The superior belly ascends to the hyoid bone. It is further subdivided into • Digastric triangle (1) • Carotid triangle (2) • Muscular triangle (3) • Submental triangle (4) Muscular Triangle Boundaries • Medially the midline • Inferolaterally Anterior border of the sternocleidomastoid muscle • Superolaterally superior belly of omohyoid • Contents • 1) Infrahyoid muscles (strap muscles). Sternohyoid Sternothyroid Thyrohyoid Omohyoid forming part of the boundary. 2) The anterior jugular veins, run in both sides of the midline. They are joined by the jugular arch at the suprasternal notch. Digastric Triangle Boundaries: • Anterosuperiorly: Inferior border of the mandible. • Inferomedially: Anterior belly of digastric. • Inferolaterally: Posterior belly of digastric. • • • • • • Contents: Submandibular gland Hypoglossal nerve. Mylohyoid nerve. Facial artery and vein. Submandibular lymph nodes CAROTID TRIANGLE Location: Longitudinal interval between cervical viscera (pharynx, esophagus, larynx, trachea and thyroid gland) medially, and prevertebral muscles posteriorly Formation: • Prevertebral fascia behind • Pretracheal fascia medially Posterior Triangle • The boundaries of the posterior triangle are the anterior border of the trapezius muscle and the posterior edge of the sternocleidomastoid muscle, and the middle third of the clavicle is the base. • The apex of this triangle is the superior nuchal line. • This triangle, therefore, presents as a spiral as the base is anterior and the apex is posterior. • The triangle is subdivided by the inferior belly of the omohyoid muscle into smaller entities that are named for the blood vessels found in them. There now is a larger, superior, occipital triangle, and the smaller, inferior, subclavian triangle. • The muscular floor of the entire posterior triangle is composed mainly of three muscles whose fibers run inferolaterally. • They are, from above down, the splenius capitis, the levator scapula, and the middle scalene muscles • The muscles of the floor are covered by prevertebral fascia, which creates a fascial carpet. There is also a fascial roof, generated by the investing layer of the deep cervical fascia. The contents of the triangle will be described layer by layer, beginning with the deeper contents found below the fascial carpet in contact with the muscular floor • They include • (a) the occipital artery, • (b) branches of the deep cervical plexus and • (c) portions of the brachial plexus. • The roots of the plexus combine deep to the sternocleidomastoid • Structures that pass between the fascial floor and fascial roof include the transverse cervical and suprascapular (transverse scapular) branches of the thyrocervical trunk, They pass transversely across the anterior aspect of the anterior scalene muscle and are separated from the phrenic nerve by the prevertebral fascia. The spinal accessory nerve (XI) as it traverses the posterior triangle. It is found on the anterior surface of, and runs with, the levator scapula muscle. It will disappear under the trapezius muscle about 2 inches superior to the clavicle. • The external jugular vein, which passes obliquely across the sternocleidomastoid muscle, pierces the deep cervical fascial layers of the subclavian triangle, and ends in the subclavian vein. The transverse cervical, suprascapular, and anterior jugular veins are tributaries of the external jugular vein. The inferior belly of the omohyoid muscle creates the lateral boundary of the subclavian triangle. It is attached inferiorly to the superior surface of the scapula, courses anterosuperiorly, and passes deep to the sternocleidomastoid muscle, where its intermediate tendon is angulated by attachments of deep cervical fascia to the clavicle. The superior belly continues to the hyoid bone. The superficial cervical plexus is created by the ventral rami of C2, C3, and C4. It includes the lesser occipital nerve (C2), which appears at the posterior edge of the sternocleidomastoid muscle just inferior to the spinal accessory nerve. It ascends near the posterior edge of the muscle and will provide sensory innervation to the external ear and the adjacent skin. The superficial cervical plexus also includes the great auricular nerve (C2, C3), which emerges from the cover of the sternocleidomastoid muscle just inferior to the lesser occipital nerve, hooks around the posterior edge of the muscle, and now lies on its superficial surface (Figs. 17, 18). It then passes superiorly toward the parotid region and provides sensory innervation to the overlying skin and a portion of the ear. This nerve can frequently be found just posterior to the external jugular vein as it passes obliquely across the muscle. The transverse cervical nerve (C2, C3) also appears at the posterior edge of the sternocleidomastoid muscle in the vicinity of the other nerves of this plexus. It wraps itself around the posterior edge of the muscle and passes P.273 • transversely across its external surface to reach the anterior triangle. It will then divide into ascending and descending branches that will provide cutaneous sensory innervation to the anterior triangle. • The supraclavicular nerves (C3, C4) first appear in the same area, just below the site of emergence of the other nerves, and then divide into medial, intermediate, and lateral branches. They provide cutaneous sensory innervation to the anterior aspect of the thorax down to the level of the second rib. All branches of the superficial cervical plexus, and the spinal accessory nerve, are quite close to each other as they first appear in the posterior triangle at the edge of the sternocleidomastoid muscle. If one divides the posterior edge of this muscle into thirds, at the junction of the middle and superior third is the site where all these nerves can be found gathered in a small localized area. This is referred to as the nerve point. They will then diverge as they head toward their specific destinations. As the nerves pass through the posterior triangle, it will be seen that the spinal accessory nerve is the most superior of all the nerves that are in the triangle. Therefore, incisions that are made superior to the spinal accessory nerve are not likely to encounter any important nerves. This area has been referred to as the carefree area; whereas, an incision made below this nerve can injure major structures and is called the careful area. INTRODUCTION • The single most important factor affecting the prognosis of squamous cell carcinoma of the head & neck is the status of cervical lymph nodes • Metastasis to regional lymph nodes reduces the 5 year survival rate by 50% compared with that of patients with early stage disease • Therefore management of cervical lymph nodes is an important component in the overall treatment plan for patients with squamous cell carcinoma of head & neck Anatomy of the Cervical Lymphatics • Cervical lymph nodes are classified according to the system developed at Memorial Sloan-Kettering Cancer Center in the 1930s. • This system divides the lymph nodes in the lateral aspect of the neck into five nodal levels, I through V, • In addition, lymph nodes in the central compartment are categorized into level VI and those in the superior mediastinum as level VII • Recently, level I, II, and V nodes were subclassified into levels IA and IB, IIA and IIB, and VA and VB.. • Level IA includes the submental lymph nodes, whereas level IB includes the submandibular lymph nodes. • Level IIA includes lymph nodes below the accessory nerve, whereas IIB includes nodes above the accessory nerve. • The posterior triangle has been subdivided into levels VA and VB, with the dividing line being the accessory nerve in the posterior triangle. • This subdivision is based on patterns of lymph node spread from various primaries. s NODAL FACTORS AFFECTING PROGNOSIS • Characteristics of regional nodes that affect prognosis include 1. the presence of pathologically positive nodes, 2. size of the metastatic lymph node, 3. the number of lymph nodes involved, and 4. the location of the lymph nodes. Involvement of the lower cervical nodes (level IV) and the lower posterior triangle lymph nodes has a very poor prognosis. Another important prognostic factor is the presence of extranodal spread where the capsule of the lymph node is ruptured, resulting in invasion of the surrounding soft tissues. RISK FACTORS FOR NODAL METASTASIS • The risk for cervical node metastases is influenced by characteristics of the primary tumor such as location, size, and histology. • The risk for lymph node metastases increases for more posteriorly located tumors, i.e., lips, oral cavity, oropharynx, and hypopharynx. • For example, oropharyngeal cancers are at higher risk than oral cavity tumors. • Lesions of the tonsil and base of tongue have a very high incidence of nodal metastases. • Tumors of the hypopharynx universally have lymph node metastases. • The greater the T size of the primary tumor, the greater the probability of having lymph node metastases PATTERNS OF NODAL METASTASIS ASSESSMENT OF CERVICAL LYMPHADENOPATHY • CLINICAL EXAMINATION- 77% accuracy • FNAC • ULTRASOUND SCAN - 77 -90% no absolute criteria for benign / malignancy ( absence of hilar echoes and increase in short axial length) • CT scan-: High diagnostic accuracy Criteria – lymph node short axis, diameter larger than 1 cm cluster of 3 / more borderline enlarged node nodal necrosis/ patchy enhancement with in node • MRI -: Similar accuracy Better in N0 neck and presence of deep invasion • CT PET scan-: To detect occult metastasis, residual /recurrent following surgery/ radiation. • Open biopsy SENTINAL NODE SENTINAL NODE BIOPSY CLASSIFICATION OF NECK DISSECTION • The Classical operation of Radical Neck Dissection was 1st performed by George Washington Crile • The operation was popularised by Hayes Martin • Oswald Suarez from Argentina was the 1st to describe functional neck dissection in 1963, now called Modified Radical Neck Dissection COMPREHENSIVE NECK DISSECTION • Comprehensive neck dissections involve the removal of all lymphatic tissue in the lateral neck (levels I to V) and are generally carried out for the clinically positive neck (N+). • They can be classified into radical and modified radical neck dissection • Radical neck dissection involves the removal of lymph nodes in levels I to V, but also the sternocleidomastoid muscle, internal jugular vein, spinal accessory nerve, and submandibular salivary gland. • Modified radical neck dissection (MRND) is divided into type I, II, or III, depending on the structures that are preserved. Type I MRND involves preservation of one structure, the spinal accessory nerve. Type II involves preservation of two structures, the spinal accessory nerve and the sternocleidomastoid muscle. Type III involves preservation of the spinal accessory nerve, internal jugular vein, and the sternocleidomastoid muscle. SELECTIVE NECK DISSECTION • Selective neck dissection spares all nonlymphatic tissue, including the sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve. • However, it does not remove all the lymphatic tissue on the involved side of the neck as does a comprehensive neck dissection, but rather uses the selective removal of nodal regions at risk. • This is determined by the predictive pattern of metastases based on the location of the primary tumor. • It is based on the clinical observation that squamous cell carcinoma of the upper aerodigestive tract metastasizes in a predictable and sequential pattern. • Selective neck dissections are therefore generally carried out for the neck with clinically negative disease (N0), where there is at least a 15% to 20% risk of occult metastatic disease. • Common selective neck dissections include The supraomohyoid neck dissection, in which lymph nodes in levels I to III and the submandibular salivary gland are removed The extended supraomohyoid neck dissection, in which lymph nodes in levels I to IV and the submandibular gland are removed T he anterolateral neck dissection (LND), in which lymph nodes in levels II to IV are removed Posterolateral neck dissection (PLND), in which lymph nodes in levels II to V and also the suboccipital and retroauricular lymph nodes are removed and Central or anterior compartment neck dissection, in which lymph nodes in the prelaryngeal, pretracheal, and paratracheal regions are removed SUPRAOMOHYOID NECK DISSECTION • Supraomohyoid neck dissection (SOHND) is recommended for squamous cell carcinoma of the oral cavity with a high risk of micrometastases in a neck that is clinically negative for disease. • Extended supraomohyoid neck dissection is recommended for squamous cell carcinoma of the lateral tongue. This is based on the observation that patients with primary carcinoma of the lateral border of the oral tongue have a small but increased risk of skip metastases to level IV compared with other sites in the oral cavity. Therefore, selective treatment of the N0 neck in lateral tongue cancer should include level IV. • Anterolateral neck dissection (LND) is recommended for squamous cell carcinoma of the larynx or pharynx with a high risk of micrometastases in a neck that is clinically negative for disease. If the primary tumor crosses the midline, this procedure is carried out bilaterally. • LND is indicated for cancer of the oropharynx when the primary tumor is treated with surgery in a neck that is clinically negative for disease. • If postoperative radiation therapy is indicated, it is not necessary to perform bilateral LND because radiation alone is effective in treating the node-negative contralateral neck. • Posterolateral neck dissection (PLND) is recommended for primary cutaneous malignancies of the posterior scalp (e.g., melanoma and squamous cell carcinoma). • Central compartment neck dissection is recommended for differentiated thyroid carcinoma in which the disease is limited to the pretracheal and paratracheal nodes. Classification of Different Types Of Neck Dissection PREOPERATIVE PREPARATION • Patient consent • Medical fitness • Tracheostomy • Planned treatment • Antibiotic coverage POSTION OF THE PATIENT • • • • Head is turned to the opposite side Hyperextended resting on a head ring A sandbag is placed under the shoulder Upper end of the table is elevated to approximately 30 degrees • When draping, the following surgical landmarks must be visible Mastoid tip Ear lobe Body of the Mandible Midline of the Chin Suprasternal notch Clavicle Region of Trapezius muscle insertion TYPE OF INCISION • MAIN GOALS – 1. Assure adequate vascularisation of the flaps 2. Adequate exposure of the surgical field 3. Consider the localisation of the primary tumor 4. Adequate protection of the major vessels if the sternocleidomastoid muscle is resected 5. Preoperative factors such as previous radiotherapy 6. Include previous surgical fields(scars, incisions for biopsies) 7. Produce accepatable cosmetic results • APPROACHES-: 1.Tri-radiate incision and its modification 2.Hayes Martin double ‘Y’ incision 3.McFee incision 4.Apron flap incision 5.J incision 6.Hockey stick incisions and its modifications Tri-radiate incision Advantage Provides good exposure to surgical site Disadvantage Flap necrosis is high due to disruption of vasculature of skin flaps Occurrence of flap separation at the trifurcation site. Modification of Tri-radiate • Schobinger (1957) • Cramer & Culf (1969) • Conley (1970) Schobinger (1957) Conley (1970) • Suggested a posteriorly curving vertical incision Cramer and culf • ‘S’ shaped vertical incision • avoid over the carotid Hayes Martin Incision • a paired ‘Y’ incision • This flap most often gets cyanosed. • Flap necrosis and carotid exposure is more in this type of incision. McFee Incision • It avoids a vertical limb. • Two horizontal incisions are used one in submandibular region and other in the suprasclavicular region. • IRRADIATED NECK Apron flaps • Described by Latyschevsky and Freund 1960. • Advantages - Carotid artery is well protected - Protects the descending arterial recovery • Disadvantages -It will damage the ascending arterial and venous recovery -Venous congestion and oedema Hockey stick incision • Lahey et al (1940) described. • Modified for RND by Eckert & Byars 1952. • It has a longitudinal and transverse incision • B/L hockey stick incision allows the deglovement of the whole neck. • Tracheostomy along with bilateral neck dissection Generic Steps for All Neck Dissections • Desired incision is marked using ink • Incision is made with No. 10 blade through skin down to platysma • Skin flaps are elevated keeping the platysma as identification Four areas of special attention during neck dissection • Lower end of internal jugular vein • Junction of lateral border of clavicle with lower edge of trapezius • Upper end of internal jugular vein • Submandibular triangle MODIFIED RADICAL NECK DISSECTION • Incision For MRND type I, a single trifurcate neck incision is the most frequently employed incision Procedure • The dissection begins with elevation of the posterior skin flap. • Skin is incised & the incision is deepened through the subcutaneous tissue and then through the platysma muscle. • The posterior flap is then raised in the subplatysmal plane by applying traction and countertraction • The flap is elevated up to the anterior border of the trapezius muscle. • During this elevation, care is taken not to enter the posterior triangle fat pad to prevent any injury to the spinal accessory nerve • The anterior border of trapezius muscle is skeletonized and then care is taken to identify the spinal accessory nerve • This can be done either by identifying it as it passes onto the undersurface of the trapezius muscle in the lower part of the neck, or by identifying it 1 cm superior to Erb's point (which is a plexus of cervical cutaneous nerves on the posterior border of the sternocleidomastoid muscle approximately 6 cm from the inferior lobule of the ear). • Once identified, the nerve is dissected out from its entry in the trapezius muscle up to the posterior border of sternocleidomastoid muscle. • The nerve is then followed up through the sternocleidomastoid muscle, dividing the muscle • The nerve is then carefully dissected out in a cephalad direction along the lateral border of the internal jugular vein up to its exit from the jugular foramen at the skull base under the posterior belly of the digastric muscle. • Once this is done, the nerve is then carefully separated from underlying tissue • The superior attachment of the sternocleidomastoid muscle is then detached from the mastoid process, and fibrofatty tissue lying in the supra-accessory triangle is dissected off the muscular floor, working from a lateral-to-medial direction. • The tissue is sequentially dissected off the splenius capitis muscle, followed by the levator scapulae muscle. • Working in a lateral-to-medial direction, the anterior border of each subsequent muscle is exposed. • The posterior scalene muscle is exposed and then the inferior belly of omohyoid muscle is divided at its attachment on the scapula. • The specimen to be retracted medially, allowing further dissection of the muscular floor, first exposing the middle scalene muscle and then the anterior scalene muscle with the brachial plexus in between. • On the anterior surface of the anterior scalene muscle, the phrenic nerve is identified passing in a lateral-to-medial direction • Once the phrenic nerve is identified and preserved, the dissection then continues in a cephalad • The specimen is further retracted medially to expose the internal jugular vein, common carotid artery, and the vagus nerve. • Attention is then turned to the anterior skin flap. • The transverse skin incision is completed from the trifurcation point up to its medial end. • The skin, subcutaneous tissue, and platysma muscle are divided, and an anterior subplatysmal flap is elevated up to the midline superiorly and to the medial end of the sternocleidomastoid muscle at its attachment to the sternum inferiorly. • The sternal and clavicular heads of sternocleidomastoid muscle are divided. • The muscle is then retracted in a cephalad direction and loose areolar tissue is dissected to expose the carotid sheath. • The lateral border of the strap muscles are retracted medially, allowing the carotid sheath to be fully exposed. • The sheath is opened and the common carotid artery, vagus nerve, and internal jugular vein identified and dissected. • The internal jugular vein is then divided between clamps and doubly ligated with 2-0 silk ties . • A 3-0 chromic catgut transfixion suture is used to secure the distal end of the vein. • Lymphatic tissue lying lateral to the internal jugular vein encompassing the thoracic duct on the left side and unnamed lymphatics on the right hand side of the neck are carefully divided in clamps and ligated with silk ties to prevent chyle leakage. • The middle thyroid vein needs to be identified, divided, and ligated with 3-0 silk as it enters the medial aspect of the internal jugular vein. • Working in a cephalad direction, the hypoglossal nerve is then identified beyond the bifurcation of the carotid artery. • The anteromedial limit of the dissection is the anterior belly of the omohyoid muscle. • This is incorporated into the specimen by dissecting it up to its attachment to the hyoid bone, where it is then detached. • Careful dissection at this level allows identification of the superior thyroid vessels. • The superior thyroid vein is divided and ligated and the superior thyroid artery is preserved. • The soft tissue from the submental triangle is then dissected off the ipsilateral anterior belly of the digastric muscle, followed by the mylohyoid muscle. • The submandibular duct is dissected, divided, and ligated. • Care is taken not to enter the fascia of the hyoglossus muscle as it is in this plane that the hypoglossal nerve is located. • The submandibular gland is now retracted laterally and separated from the posterior belly of the digastric muscle. • The proximal portion of the facial artery is then identified on the posteromedial aspect of the posterior belly of the digastric muscle. It is divided in clamps and ligated with 3-0 silk • The tail of parotid is retracted cephalad, allowing access to the posterior belly of the digastric muscle. • After this, the posterior belly of the digastric muscle is retracted cephalad with a deep right-angled retractor. • The occipital artery and vein lying superficial to the internal jugular vein are divided and ligated, allowing exposure of the upper end of the internal jugular vein at the base of the skull. • The vein is then skeletonized circumferentially and then doubly ligated with 2-0 silk . • The specimen is then able to be delivered. • Meticulous hemostasis is then secured with ligation or electrocautery and the wound irrigated with a plentiful amount of saline. • Large suction drains are inserted through stab incisions in the lower skin flaps . • One drain is placed along the anterior border of the trapezius muscle and held in position with a loop of chromic catgut suture. • An anterior drain is placed along the strap muscles, medial to the carotid artery, and again secured in place with a loop of chromic catgut suture. • Both drains are secured to skin with a purse-string silk suture. The incision is then closed in two layers using 3-0 chromic catgut interrupted sutures for the platysma muscle and 5-0 nylon for skin. • Suction on the drains is maintained while the wound is being closed. An airtight closure is required to ensure adherence between the skin and deep structures of the neck. The drains remain in place for 4 to 7 days and are removed only once minimal serous drainage is present. Selective Neck Dissection Supraomohyoid Neck Dissection (SOHND) • The skin incision used for the SOHND is in a skin crease approximately two fingerbreadths below the inferior border of the mandible • The superior flap is raised first in the subplatysmal plane. • Fascia overlying the submandibular gland containing the marginal branch of the facial nerve is incised and this layer is raised along with the superior skin flap • Dissection of the submental and submandibular triangles is then carried out in an identical fashion to that described for MRND type I. • . • • • • • • • • • Dissection then proceeds to level II and III lymph nodes. An inferior skin flap is raised in the subplatysmal plane down to the posterior edge of the sternocleidomastoid muscle laterally and the sternal attachments of sternocleidomastoid muscle inferiorly. Fascia on the anterior border of the sternocleidomastoid muscle is incised, and the fascial attachments between the tail of parotid gland and sternocleidomastoid muscle are dissected, allowing exposure of the posterior belly of the digastric muscle. Next, the spinal accessory nerve is identified as it pierces the upper third of the sternocleidomastoid muscle. The nerve is dissected out, up toward the proximal end of internal jugular vein and posterior belly of the digastric muscle. The fat pad and lymph nodes lying in level IIb are then carefully dissected out This tissue is then passed under the spinal accessory nerve and retracted in a medial direction using a clamp. With the sternocleidomastoid muscle retracted laterally the tissue overlying the cervical plexus of nerves is divided. Clamps are placed on the soft tissue and retracted medially, allowing the underlying nerves from the cervical plexus to be visualized • • • • • • • • • • • • Dissection then proceeds in a lateral-to-medial direction in a plane just superficial to these nerves. The lower limit of the dissection is the inferior belly of the omohyoid muscle The phrenic nerve is then identified on the anterior scalene muscle and carefully preserved. The carotid sheath fascia is divided, Working from a lateral-to-medial direction, the soft tissue encompassing levels II and III lymph nodes are dissected off the internal jugular vein. The anteromedial limit of the dissection is the superior belly of the omohyoid muscle. The soft tissue containing lymph nodes from the midjugular chain is then retracted in a cephalad direction and dissected off the internal jugular vein and superior belly of omohyoid muscle. The superior thyroid artery is preserved but the vein needs to be divided and ligated Superiorly, the common facial vein is then identified on the medial aspect of the internal jugular vein and divided in clamps and ligated with 3-0 silk. The hypoglossal nerve is identified and tissue lying lateral and inferior to it dissected. The specimen encompassing levels I, II, and III is then delivered. The incision is closed in two layers with interrupted 3-0 chromic catgut for the platysma muscle and 5-0 nylon for skin. Anterolateral Neck Dissection • This dissection is usually carried out as a staging procedure in conjunction with excision of primary carcinoma of the larynx or pharynx in a patient with a neck with clinically negative disease. • This involves dissection of lymph nodes from levels II to IV. • The incision is therefore planned according to resection of the primary tumor. • This is usually a transverse incision at the level of the thyrohyoid membrane from the posterior border of one sternocleidomastoid muscle to the midline • Upper and lower skin flaps are raised in the subplatysmal plane. • Fascia on the anterior border of the sternocleidomastoid muscle is incised and elevated medially to expose the underlying jugular lymph nodes • The omohyoid muscle is divided inferiorly to allow dissection of level IV nodes. • As in the SOHND, the accessory nerve is identified as it pierces the medial aspect of the sternocleidomastoid muscle and is traced superiorly. • Lymph nodes in level IIb superior and lateral to the nerve are dissected as described for the SOHND. • Dissection again proceeds lateral to medial, identifying the anterior scalene muscle, phrenic nerve, and roots of the cervical plexus. • The carotid sheath is opened to identify the vagus nerve, carotid artery and internal jugular vein. • Middle thyroid, superior thyroid, and common facial veins on the medial aspect of the internal jugular vein are divided and ligated with 3-0 silk to allow the specimen to be reflected medially. • The specimen may be left attached to the primary tumor or may be removed separately. Insertion of drains and wound closure are as described previously. Posterolateral Neck Dissection • This is carried out for clinically negative neck disease for either melanoma or squamous cell carcinoma of the posterior scalp. • It involves the removal of lymph nodes in levels II to V, including the suboccipital and retroauricular lymph nodes. • A hockey-stick incision is used (Fig. 9D), extending from the mastoid tip along the anterior border of the trapezius muscle and then curving anteriorly just superior to the clavicle. • An anterior skin flap is elevated in the subplatysmal plane up to the anterior border of the sternocleidomastoid muscle. • • • • • • • The spinal accessory P.333 nerve is identified in the posterior triangle as described previously and dissected out from the inferior aspect of the trapezius muscle up to the posterior border of the sternocleidomastoid muscle. Dissection of the posterior triangle lymph nodes proceeds as described previously. To dissect out the upper, middle, and lower jugular lymph nodes, the sternocleidomastoid muscle is retracted medially. The fascia of the carotid sheath is divided, identifying the carotid artery, vagus nerve, and internal jugular vein. Dissection of level II to IV lymph nodes proceeds in a caudal-to-cephalad fashion, and the specimen including the posterior triangle soft tissue is delivered. In order to include the postauricular and suboccipital lymph nodes, a lateral extension of the P.334 upper end of the skin incision from the mastoid process to the occipital tubercle is carried out. The trapezius muscle is then detached from its nuchal attachment, allowing exposure of lymph nodes in the suboccipital triangle, which are then removed as a separate specimen. COMPLICATIONS • Cervical Complications-: -: Local Complications Infection Serohematoma Wound dehiscence Chylous fistula -: Vascular Complications Hemorrhage Vascular blowout -: Neural Complications Spinal accessory nerve Phrenic nerve Hypoglossal nerve Vagus nerve Sympathetic trunk Mandibular branch of CN VII Brachial plexus • General Complications -: Pulmonary Complications Pneumonia Pulmonary embolism -: Stress ulcer -: Sepsis Other