Prof. Domenico Napolitano, Chief of Otorilaringology, Cardarelli Hospital, Napoli he neck dissection is a surgical procedure for control of neck lymph node metastasis. This can be done for clinically or radiologically evident lymph nodes or as part of curative surgery where risk of occult nodal metastasis is deemed sufficiently high. The aim of the procedure is to remove lymph nodes from the neck into which cancer cells may have migrated. Metastasis of tumours into the lymph nodes of the neck is one of the strongest prognostic indicators for head and neck cancer. The metastases may originate from tumours of the upper aerodigestive tract, including the oral cavity, tongue, nasopharynx, oropharynx, hypopharynx, and larynx, as well as the thyroid, parotid and posterior scalp. Neck nodal metastasis can sometimes also originate from lung cancer or intra-abdominal malignancy. However, neck dissection is rarely performed for such purposes. Lymph nodes in a particular region are numerous and generally referred to in groups. It is impossible to dissect through all the soft tissue to remove individual lymph nodes. As such the neck dissection is the en-bloc resection of all soft tissue in the region including all the lymph nodes and structures passing through them. In the case of a neck dissection, this entails the resection of everything within the superficial layer of deep cervical fascia (also known as the investing layer of cervical fascia). Where deemed excessively morbid, the structures within are conserved. These include the carotid and in some instances the three structures - IJV, SCM and Accessory Nerve. Memorial Sloan-Kettering Cancer Center developed the lymph node regional definitions most widely used today. To describe the lymph nodes of the neck for neck dissection, the neck is divided into 6 areas called Levels. The levels are identified by Roman numeral, increasing towards the chest. A further Level VII to denote lymph node groups in the superior mediastinum is no longer used. Instead, lymph nodes in other non-neck regions are referred to by the name of their specific nodal groups. Region I: Submental and submandibular triangles. Ia is the submental triangle bound by the anterior bellies of the digastric and the mylohyoid. Ib is the triangle formed by the anterior and posterior bellies of the digastric and body of mandible. Region II, III, IV: nodes associated with the IJV; fibroadipose tissue located medial to the posterior border of SCM and lateral to the border of the sternohyoid. Region II: upper third including the upper jugular and jugulodigastric nodes and the upper posterior cervical nodes. Region bound by the digastric muscle superiorly and the hyoid bone (clinical landmark), or the carotid bifurcation (surgical landmark) inferiorly. IIa contains nodes in the region anterior to the spinal accessory nerve and IIb postero-superior to the nerve. Region III: middle third jugular nodes extending from the carotid bifurcation superiorly to the cricothyroid notch (clinical landmark), or inferior edge of cricoid cartilage (radiological landmark), or omohyoid muscle (surgical landmark). Region IV: lower jugular nodes extending from the omohyoid muscle superiorly to the clavicle inferiorly. Region V: posterior triangle group of lymph nodes located along the lower half of the spinal accessory nerve and the transverse cervical artery. The supraclavicular nodes are also included in this group. The posterior boundary is the anterior border of the trapezius muscle, the anterior boundary is the posterior border of the sternocleidomastoid muscle, and the inferior boundary is the clavicle. Region VI: anterior compartment group comprises lymph nodes surrounding the midline visceral structures of the neck extending from the level of the hyoid bone superiorly to the suprasternal notch inferiorly. On each side, the lateral boundary is the medial border of the carotid sheath. Located within this compartment are the perithyroidal lymph nodes, paratracheal lymph nodes, lymph nodes along the recurrent laryngeal nerves, and precricoid lymph nodes.
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