Trial of IIb Preserving Neck Dissection

Surgery of the cervical lymphatic system has evolved a lot since the introduction of classical radical neck dissection by Crile in 1906, which was later established by Martin (1945). It includes the removal of cervical lymphatic levels I-V along with removal of non-lymphatic structures namely submandibular gland, tail of parotid, omohyoid muscle, cervical plexus of nerves, spinal accessory nerve, internal jugular vein and sternocleidomastoid muscle. The main morbidity of the radical neck dissection was the trapezius muscle dysfunction with shoulder drop, resulting in pain and shoulder dysfunction. The other morbidities of radical neck dissection were cosmetic deformity of neck, painful neuromas, increased facial swelling, numbness of neck and ear.

In the last three decades, many modifications of the classical radical neck dissection (modified radical neck dissections), had been described and are increasingly applied. The main modifications have been the preservation of one or more of the non-lymphatic structures that were removed in classical radical neck dissection mainly the spinal accessory nerve, internal jugular vein, sternocleidomastoid muscle (Bocca and Pignataro, 1967). The reasons for developing these modifications were functional and cosmetic, while preserving the oncological safety of the procedure.

Much later in 1980s, the concept of selective neck dissection, for which Lindberg (1972) and Skolnik (1976) laid down important basis, was introduced. In selective neck dissections only those groups of lymph nodes are removed, which, depending upon the location of the primary tumour, are most likely to contain metastasis (Shah, 1990).

The first selective neck dissection introduced was the supraomohyoid neck dissection, which includes the removal of lymph node levels I-III, while preserving the non-lymphatic structures as functional neck dissection. Medina and Byers in a prospective study have demonstrated the utility of this supraomohyoid neck dissection in patients with clinically negative neck nodes (N0) with malignancies of oral cavity.

The posterolateral neck dissection removes lymph node levels II-V as well as retroauricular and suboccipital nodes, which is used primarily for treatment of tumours of scalp and post auricular skin.

The lateral neck dissection, which includes removal of lymph node levels II-IV, is done for tumours of larynx or hypopharynx with N0 neck.

The anterior compartment neck dissection includes removal of only lymph node level VI which is done in thyroid malignancies when there is no evidence of lateral lymphadenopathy, and is combined with lateral neck dissection(anterolateral) if there are lymphnodes involved.

Recently the concept of superselective neck dissections has been introduced. It is less radical than selective neck dissections, removing lesser number of at-risk lymph nodal groups.

H Coskun (2004) found IIb preserving superselective neck dissection as oncologically safe procedure in N0 laryngeal cancer, with more functional preservation of trapezius muscle and hence negligible shoulder disability. In this study, it was found that even in selective neck dissection, some degree of spinal accessory nerve dysfunction and shoulder disability occurs as a result of retraction of the nerve during the clearance of the lymph nodes posterior and superior to the nerve (IIb). If these lymph nodes were not removed and left in place, there would be no stretching of spinal accessory nerve during the neck dissection and shoulder disability could be avoided