Of Neck Dissections

The American Academy of Otolaryngology-Head and Neck Surgery and the American Society of Head and Neck Surgery classified neck dissection into four categories: radical, modified radical, extended and selective [99].

Neck dissection is classified primarily by the cervical lymph node groups that are removed, and secondarily on the anatomic structures that may be preserved, such as the spinal accessory nerve, the sternocleidomastoid muscle, and the internal jugular vein [71, 99].

The cervical lymph node groups are referred to using the level system as described by the Sloan-Kettering Memorial Hospital Group (Fig. 9.1). Definition of the anatomic boundaries of the different lymph node groups is beyond the scope of this chapter and can be found in other sources [99, 110].

Table 9.5. Updated classification of neck dissection (extracted from [99]). SCM sternocleidomastoid, IJV internal jugular vein, SAN spinal accessory nerve

Type of dissection

Radical neck dissection Modified radical neck dissection

Selective neck dissection

Extended neck dissection

Lymph node levels removed Non-lymphatic structures resected

Preservation of one or more of the following: I, II, III, IV, V. Brackets are used to denote levels or sublevels removed. (e.g. SND {I, II, III}) Resection of one or more or additional lymph nodes levels routinely not removed by the radical neck dissection (e.g. parapharyngeal)

Preservation of one or more of the following: SCM, IJV, SAN

None

Resection of one or more non-lymphatic structures routinely not removed by the radical neck dissection (e.g. carotid artery)

Radical neck dissection consists of the removal of all five lymph node regions of one side of the neck (levels I-V). This includes removal of the sternocleidomastoid muscle, the internal jugular vein, and the spinal accessory nerve. Modified radical neck dissection refers to excision of all lymph nodes routinely removed by radical neck dissection, with preservation of one or more of the non-lymphatic structures (i.e. spinal accessory nerve, internal jugular vein, and/or sternocleidomastoid muscle).

The term extended radical neck dissection refers to a neck dissection that is extended to include either lymph node groups or non-lymphatic structures that are not routinely removed in a standard radical neck dissection.

Selective neck dissection is any type of cervical lymphadenectomy in which one or more of the lymph node groups that are removed in a radical neck dissection is preserved [13, 71, 99] (Table 9.5).

The following procedure pertains to standard radical neck dissections and needs to be modified for the other three types. When the main anatomic landmarks such as the submandibular gland and internal jugular vein are lacking in a neck dissection specimen, the surgeon must identify and label the lymph node groups. This is especially important in selective and extended neck dissections.

After the neck dissection specimen has been oriented as it appears in vivo, its overall dimensions are measured. The lengths of the sternocleidomastoid muscle and the internal jugular vein are measured separately. The jugular vein should be opened along its entire length. Tumour involvement, including thrombosis, should be noted, described and sampled adequately. Next, the submandibular gland, the sternocleidomastoid muscle, and the internal jugular vein should be divided, and the node-containing fat separated into the five levels:

1. Sublingual and submandibular,

2. Superior jugular,

3. Middle jugular,

4. Inferior jugular,

5. Posterior.

The presence of tumour in soft tissues, submandibular gland and muscle should be described. All lymph nodes visible and palpable are carefully dissected from connective tissue with a rim of perinodal connective tissue or fat. The number of lymph nodes (by level) should be noted; if a tumour is present, the actual size of metastases in centimetres and the presence of extracapsular extension are also noted and recorded. It is generally recognised that most masses larger than 3 cm in diameter are not single nodes but are confluent nodes or tumour in soft tissues [7]. Midline nodes, if found, are considered ipsilateral nodes. The contralateral neck dissection is treated similarly. Nodes larger than 2-3 cm

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