A proposal for redefining the boundaries of level V in the neck: is dissection of the apex of level V necessary in mucosal squamous cell carcinoma of the head and neck?

In 1991, the Committee for Head and Neck Surgery and Oncology of the American Academy of Otolaryngology-Head and Neck Surgery proposed to define the anatomic boundaries between the lymph node levels in the neck, as initially described by the Memorial Sloan-Kettering Cancer Center (New York, NY). Recently, radiological parameters have been outlined to identify boundaries between various neck levels. The lymphatics of the posterior triangle of the neck are gathered in level V, recently subdivided into 2 subgroups: level Va and level Vb. The superior boundary of level Va is defined by the apex of the convergence of the sternocleidomastoid muscle and trapezius muscle. Based on anatomic evidence and surgical experience, we advocate the subdivision of level Va into 2 sections: the apex of level Va or level Vas (superior) and level Vai (inferior), demarcated by the lower two thirds of the spinal accessory nerve. Dissection of level Vas is not necessary in most head and neck cancers but should be considered only in selected skin cancer of the posterior cephalic area (retroauricular region, occipital scalp)