Selective Neck Dissection - Vula - University of Cape Town

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It has been proposed that neck dissectionsbe more logically and precisely describedand classified by naming the structures andthe nodal levels that have been resected.(Ferlito A, Robbins KT, Shah JP, et al.Proposal for a rational classification ofneck dissections. Head Neck 2011 Mar;33(3): 445-50)skin incision can be extended across to theopposite side with bilateral SND, or can beextended superiorly to split the lower lip inthe midline to gain access to the oralcavity, or preauricularly for a parotidectomy(Figure 3). Figure 4 demonstratesthe hockey stick incision.Selective Neck DissectionAnaesthesia, positioning and drapingThe operation is done under generalanaesthesia without muscle relaxation aseliciting muscle contraction on mechanicalor electrical stimulation of the marginalmandibular, hypoglossal (XIIn) andaccessory nerves assists with locating andpreserving these nerves. It is a cleanoperation and antibiotics are therefore notrequired unless the upper aerodigestivetract is entered. With an experiencedsurgeon, blood transfusion is rarelyrequired.The patient is placed in a supine positionwith the neck extended and head turned tothe opposite side. Surgical draping mustpermit monitoring for movement of thelower lip with irritation of the marginalmandibular nerve, and must provide accessto the clavicle inferiorly, the trapeziusmuscle posteriorly, the tip of the earlobesuperiorly and the midline of the neckanteriorly. The drapes are sutured to theskin.Figure 3: Incision for SND (Red)compared to MND (Yellow); dotted linesindicate extensions for parotidectomy andoral tumour resectionsIncisions and flapsIncisions should take into considerationaccess that may be required to resect theprimary tumour, cosmetic factors, and theblood supply to the flaps. A transverse skincrease incision is placed more inferiorlythan with a MND so as to avoid a verticalskin incision and to facilitate dissection oflevels III and IV (Figure 3). The transverseFigure 4: Hockey-stick incision forposterolateral SND combined withparotidectomy2
6The hockey-stick incision may be extendedinto a preauricular skin crease and isparticularly useful for combined posterolateralND and parotidectomy. Care has tobe taken in patients who have beenpreviously irradiated as the posteroinferiorcorner of the flap has a tenuous bloodsupply and may slough and have to heal bysecondary intention.Total laryngectomy with Lateral ND canbe accessed via a wide apron flap (Figure5).overlying the SCM (Figure 6).EJVGr Aur nFigure 6: Note cut edges of platysmamuscle, and the external jugular vein andgreater auricular nerve overlying the SCMFigure 5: Wide apron flapSupraomohyoid SND: Operative steps(Figure 6)The detailed step-by-step description ofneck dissection that follows refers to aright-sided Supraomohyoid ND (Levels I-III). For a Lateral ND, simply skip dissecttionof Level 1 and extend the nodal resectioninferiorly beyond the level of the omohyoidmuscle, either by retracting or dividingthe muscle for access.Initial exposureThe neck is opened via a horizontalincision placed in a skin crease just belowthe level of the hyoid bone. The incision ismade through skin, subcutaneous fat, andplatysma muscle. Identify the externaljugular vein and greater auricular nerveNext the superior skin flap is elevated withcautery in a subplatysmal plane until thesubmandibular salivary gland is identified.The surgeon then uses electrocautery or ascalpel to raise an inferiorly basedsubplatysmal flap, exposing the neck asfollows: anteriorly up to the omohyoidmuscle (the posterior margin of whichcorresponds to the anterior margin of thesupraomohyoid or anterolateral neckdissections) and inferiorly, the lateralsurface of the SCM almost to the clavicleThe only structure to look out for and notinjure during this step of the dissection isthe external jugular vein which lies on thelateral surface of the sternomastoid muscle.The recommended subsequent operativesteps of a supraomohyoid neck dissecttionare illustrated in Figure 7.Step 1 (Figures 7)The surgeon resects fat and lymph nodesfrom the submental triangle (Level Ia).The skin is elevated in a subplatysmalplane up to the opposite anterior belly ofdigastric muscle, looking out for the3
Page 4 and 5: Step 2 (Figure 7)54663Figure 7: Rec
Page 6 and 7: The submandibular ganglion, suspend
Page 8 and 9: shoulder due to mechanical stimulat
Page 10 and 11: CervicalplexusStep 7 (Figure 7)Cont

Selective Neck Dissection - Vula - University of Cape Town

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