Trial Information

Randomized Controlled Trial of IIb Preserving Neck Dissection VS Neck Dissections Involving IIb Removal (Selective/Functional) in Patients With N0 Neck With Oral Cavity Malignancies

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