Neck Dissection Levels I to III (Supraomohyoid Dissection)
10.1055/b-0034-99054
Neck Dissection Levels I to III (Supraomohyoid Dissection)
Preliminary Considerations and Recommended Procedure
There is no evidence-based clinical benefit in resecting the neck dissection specimen en bloc. Splitting the neck dissection levels into stages A to E is therefore preferred, as illustrated in Fig. 2.8 and the following photo series “Technique of neck dissection” (Fig. 2.9 to 2.26). This approach facilitates the postoperative tumor board review discussion, especially with the pathologist. Exact pinpointing of cervical metastasis for adjuvant radiotherapy is alleviated.
Stages A to E of neck dissection levels I–III.
Technique of Neck Dissection Levels I to III
Patient positioned with neck extended, appropriate draping, and antiseptic skin preparation. Incision line is marked 2 cm caudal to the mandibular margin.Infiltration of 5 mL local anaesthetic with 1:200,000 adrenaline.Incision of skin and subcutaneous fatty tissue down to the platysma muscle. Posterior extent of the incision: point at which the greater auricular nerve crosses the posterior border of the SCM muscle. Anterior extent of incision: contralateral anterior belly of the digastric muscle.Division of the platysma muscle and definition of the anterior margin of the SCM muscle.Reflection of the platysma muscle cranially and caudally. Fixation of the skin–platysma flaps with sutures superiorly and inferiorly. Exposure of the ipsilateral anterior belly of digastric muscle down to the hyoid bone.Definition of the muscle landmarks: (1) Exposure of the posterior belly of the digastric muscle in anteroposterior direction to the point at which it is crossed by the facial vein; (2) exposure of the omohyoid muscle from the hyoid bone to the point at which it reaches the SCM muscle; and (3) exposure of the anterior border of the SCM muscle from its cranial origin to the point at which it is crossed by the omohyoid muscle.Ligation of the facial vein and exposure of the posterior belly of the digastric muscle to the mastoid process.Start removal of block A (Fig. 2.8). Facultative circumferential dissection of the IJV (lateral, anterior, and medial surfaces have to be dissected necessarily). Inferior limit of dissection of the IJV: the level of omohyoid and SCM muscle crossing (*). Superior limit of dissection of the IJV: the point at which the IJV is crossed by the posterior belly of the digastric muscle (X).Block A (Fig. 2.8)—the fatty/lymphoid tissue overlying the carotid artery and the superior thyroid artery—is removed. The tissue block is bounded by an anatomic triangle formed by the IJV, the omohyoid muscle, and the posterior belly of the digastric muscle.Identification of the SAN, which can be found in close proximity to the meeting point of the IJV and the posterior belly of the digastric muscle. The nerve runs along the line, bisecting the right angle formed by the IJV and the posterior belly of the digastric muscle. Dissection of the SAN deep to the SCM muscle.Removal of block B (Fig. 2.8), the fatty/lymphoid tissue located caudal to the SAN, posterior of the IJV, and cranial to the crossing point of the omohyoid/SCM muscles. Removal of the fatty/lymphoid tissue located caudal to the mastoid process, cranial to the SAN, and anterior to the SCM muscle (block C, Fig. 2.8); beware of bleeding from the occipital artery.Ligation of the facial vein and artery (can be palpated at the mandibular margin). The mandibular marginal branch (highlighted by dotting) of the facial nerve can be protected by retracting the ligated facial vessels in a cranial direction. Dissection of the contents of the submandibular triangle (block D, Fig. 2.8) from the periosteum of the mandible.Blunt dissection of the submandibular triangle contents from the mylohyoid muscle anteriorly and from the posterior belly of the digastric muscle caudally.Dissection of the loop of the lingual nerve and identification of the parasympathetic fibers to the submandibular gland.Parasympathetic fibers to the submandibular gland are highlighted by a yellow vessel loop. The proximally pedicled facial artery is highlighted by a red vessel loop. Ligation of both of the structures and removal of the block D (Fig. 2.8) contents.Appearance following removal of levels Ib, II, and III (blocks A to D, Fig. 2.8) contents.Finally, block E (Fig. 2.8), which is located between the anterior bellies of the digastric muscles, the mylohyoid muscle, and the hyoid bone, is resected.Final appearance after resection of lymphatic and fatty tissue block E (Fig. 2.8).
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