Neck Dissection - MU

Neck Dissection Definition

• Surgery performed to examine and remove lymph nodes in the neck.

Types of Neck Dissection

• Radical block dissection.
• Modified radical neck dissection.
• Functional neck dissection.
• Extended radical neck dissection.
• Bilateral block dissection.
• Selective neck dissection.

Selective Neck Dissection Subtypes

• Suprahyoid block dissection: Involves level I-II lymph nodes.
• Supraomohyoid neck dissection: Involves level I-III lymph nodes.
• Extended supraomohyoid dissection: Involves level I-IV lymph nodes.
• Lateral neck dissection: Involves levels II-IV lymph nodes.
• Posterolateral neck dissection: Involves level II-V lymph nodes.
• The anterior compartment neck dissection: Involves level VI lymph nodes.
• Superior mediastinum dissection: Involves level VII lymph nodes.

Radical Block Dissection Indications

• For all carcinomas of the head and neck, except cancer of the lip.
• Removal of lymph nodes of the anterior and posterior triangles of the neck.
• Other structures are removed to simplify the removal of lymph glands.

Structures Removed during Radical Block Dissection

• Sternomastoid: Removed to expose the internal jugular vein.
• Internal jugular vein: Removed to simplify the removal of upper and lower deep cervical lymph nodes; removed from the base of the skull to its root in the neck.
• Spinal accessory nerve.
• Cervical fascia: Removed from the jaw to the clavicle.
• Submandibular salivary gland: Removed for easier removal of submandibular lymph nodes.
• Lower part of the parotid gland: Removed because it contains lymph nodes.

Structures Preserved during Radical Block Dissection

• Carotid arteries
• Vagus nerve
• Sympathetic trunk
• Phrenic nerve
• Hypoglossal nerve

Incisions for Radical Block Dissection

• Goblet incision (Crile's incision).
• Hockey stick incision (Apron incision).
• Ladder incision.
• Macfee incision (2 incisions, 2cm apart).
• Inverted L shaped incision.

Goblet Incision (Crile's incision) Details

• Transverse incision: From angle of jaw, forwards & downwards.
• Vertical incision: From the center of the transverse incision downward.
• Extends from the Level of the hyoid bone, then forward & upwards to the chin, to the clavicle.
• Sloughing & necrosis: Occurs at the center part of the incision due to least blood supply.
• Exposure of internal carotid artery can lead to: Infection, hemorrhage and potentially death.

Surgical Steps

• An inflatable pillow is placed behind the patient’s back, and the head is extended and supported by a head ring.
• The course of the spinal accessory nerve is marked on the patient's skin.
• The most commonly employed incision for thyroid cancer is a continuation of a Kocher incision along the posterior border of the sternocleidomastoid muscle.
• The incision extends superiorly to approximately 1 inch below the ipsilateral ear lobe.
• Subplatysmal flaps are developed anteriorly and posteriorly.
• The greater auricular and spinal accessory nerves have been identified and preserved.
• The sternocleidomastoid muscle and external jugular vein are visualized.
• The external jugular vein is ligated superiorly, and the fascial sheath covering the sternocleidomastoid muscle is unwrapped. -Lymph nodes along great vessels of the neck are commonly encountered at this point.
• A Penrose drain is placed around the sternocleidomastoid muscle and is pulled anteriorly.
• The omohyoid muscle is preserved, and the carotid sheath is identified.
• The cervical fat pad containing lymphatics & nodes is mobilized from below the clavicle and pulled superiorly.
• The thoracic duct, phrenic nerve, & brachial plexus are protected.
• During mobilization, the specimen is passed under the omohyoid muscle & traction is applied superiorly.
• The specimen is passed from its lateral position underneath the sternocleidomastoid muscle & is pulled from an inferiomedial direction.
• A thyroid retractor is used to pull the mandible superiorly & the digastric muscle is identified.
• The hypoglossal & proximal spinal accessory nerves are identified & preserved.
• Cervical fat tissues with contained lymphatics are resected in continuity as the specimen is pulled off great vessels.

Modified Radical Neck Dissection Definition

• Involves the excision of all lymph node groups removed during a radical neck dissection, but with the preservation of one or more of the following structures:
  • Spinal accessory nerve.
  • Internal jugular vein.
  • Sternomastoid muscle.

Modified Radical Neck Dissection Types

• Type I: Preserves the spinal accessory nerve.
• Type II: Preserves the spinal accessory nerve and the internal jugular vein.
• Type III: Preserves the spinal accessory nerve, internal jugular vein, and sternomastoid muscle.
  • Also known as Functional neck dissection.

Functional Neck Dissection Definition

• Excision of all lymph node groups removed during a radical neck dissection with preservation of all of the following structures:
  • Spinal accessory nerve
  • Internal jugular vein
  • Sternomastoid muscle

Extended Radical Neck Dissection

• Radical neck dissection ++ involves both lymphatic and non-lymphatic structures
• Lymphatic Structures:
• Parapharyngeal LNs
• Superior mediastinal LNs
• Paratracheal LNs
• Non-lymphatic structures
  • Carotid artery
  • Hypoglossal nerve
  • Vagus nerve
  • Para-spinal muscles

Bilateral Block Dissection

• The dissection of the 2nd side is carried out after 4-6 weeks to allow venous collaterals to develop.

Selective Neck Dissection Definition

• Involves any type of lymph node removal where there is preservation of one or more lymph node groups removed by radical neck dissection.

Suprahyoid Block Dissection (Level I-II)

• Structures Removed:
  • Upper deep cervical lymph nodes.
  • Parotid lymph nodes, specifically the lower part of the parotid gland.
  • Submandibular lymph nodes and salivary glands.
  • Submental LN, with fat and deep fascia removed as one block.
• Indication:
  • Carcinoma of the lower lip.
• Incision:
  • A curved incision from mastoid process of one side to opposite mastoid reaching down to hyoid.
  • Also referred to as Visor incision.
• Limits of Dissection:
  • Posterior Limit: Cutaneous branches of cervical plexus & posterior border of sternomastoid muscle
  • Inferior Limit: Superior belly of omohyoid muscle where it crosses internal jugular vein

Supraomohyoid Neck Dissection (Level I-III)

• Involves removal of lymph nodes from levels I, II, and III.
• Indication: Oral cavity malignancy

Extended Supraomohyoid Dissection (Level I-IV)

Lateral Neck Dissection (Levels II-IV)

• Structures Removed: LNs in levels II, III, and IV
• Indication: Cancer of the larynx

Posterolateral Neck Dissection (Level II-V)

• Structures Removed: LNs in levels II, III, IV, and V
• Indication: Cutaneous melanoma of posterior scalp & neck

The Anterior Compartment Neck Dissection (Level VI)

• Structures Removed: LNs from the anterior triangle of the neck, specifically level VI.

Superior Mediastinum Dissection (Level VII)

Anatomical Considerations

• En bloc dissection of internal jugular vein (IJV) lymph nodes & exposure of floor of neck.
• ASM indicates anterior scalene muscle; BP, brachial plexus; CCA, common carotid artery; MSM, middle scalene muscles; PN, phrenic nerve; SCM, sternocleidomastoid muscle; SCV, subclavian vein; TD, thoracic duct.