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utilized system throughout the world. It is not perfect, however. Not all neck dissections fit perfectly into the classification. Thus, there will be continued discussion and debate concerning the nomenclature used in these situations.
Radical neck dissection
Definition
The radical neck dissection is the gold standard for oncologic treatment of lymph node metastasis in the neck. It involves removal of all lymphatics from levels I-V. In addition, removal of nonlymphatic structures including the spinal accessory nerve, the sternocleidomastoid muscle and the internal jugular vein is carried out. It does not include removal of the postauricular and suboccipital nodes, periparotid nodes except for a few nodes located in the tail of the parotid gland, the perifacial and buccinator nodes, the retropharyngeal nodes, and the paratracheal nodes.
Indications
Decision to perform a radical neck dissection is not always straight forward, and often is determined at the time of surgery. A RND is indicated in patients with extensive cervical lymph node metastasis and/or extension beyond the capsule with invasion into the spinal accessory nerve, IJV, and SCM. Many surgeons will elect to perform a RND if there is extensive disease surrounding the spinal accessory nerve without gross evidence of invasion. Others would elect to perform a MRND. The bottom line is the one should not risk inadequate oncologic resection for the sake of preserving these any of these nonlymphatic structures.
Modified Radical Neck Dissection
Definition
Modified radical neck dissection involves excision of the same lymph node bearing tissues from one side of the neck as is performed in a RND with the preservation of one or more nonlymphatic structure including the spinal accessory nerve, the IJV, or the SCM. As mentioned before, Medina subclassifies the MRND into Types I-III (see Medina’s classifications above). MRND is analogous to the “functional neck dissection” described by Bocca, however they differ in that Bocca originally did not remove the submandibular gland.
Indications
MRND is indicated in patients with gross nodal metastasis to the neck that does not directly infiltrate or adhere to the non-lymphatic structures previously mentioned. Bilateral MRND is indicated when there is contralateral nodal involvement with the above mentioned specifications. In these cases it is important to plan ahead if sacrifice of both IJVs is anticipated because bilateral resection results in massive edema and cases of blindness (ischemic optic neuropathy), stroke, and death have been reported. Preservation of the IJV in MRND results in IJV patency rates of 86-99% excluding patients with compression of the IJV by tumor recurrence. If decision to preserve IJVs is decided on, care should be taken to avoid endothelial damage by atraumatic handling, by tying instead of cauterizing tributaries of the IJV, and by avoiding desiccation. If both veins are involved with tumor, the therapeutic options include staging the second neck dissection, or to proceed with bilateral IJV resection with, or without reconstruction. The IJV may reconstructed in several different ways. Interposition grafts with spiraled saphenous vein is the preferred method. In addition, a segment of the contralateral (resected) IJV, polytetrafluoroethylene (PTFE), or the external jugular vein may be used.
Rationale
Modifications of the classic RND aim to reduce postsurgical neck pain and shoulder dysfunction encountered when the spinal accessory is resected without compromising adequate oncologic treatment. The earliest studies as mentioned previously by Bocca found no difference in those patients treated with MRND vs RND. Many subsequent studies have supported this finding. Anderson and colleagues (1994) found the actuarial 5-year survival and neck failure rates for RND were 63% and 12% respectively compared to 71% and 12% for MRND Type I. These results were not statistically different when controlled for pathologic N stage, presence of extracapsular spread, and pathologic presence of nodes along the spinal accessory nerve. Additionally, there was no difference in the pattern of neck failure.
Sacrifice of the SCM and IJV is less debilitating. SCM preservation, however, improves cosmetic appearance and protects the carotid artery if adjuvant radiotherapy is employed. The oncologic safety of preserving the SCM has been established by pathologic studies. In one study Calearo (1983) found no evidence of SCM invasion in a series of 98 RNDs for oral cancer, despite 73 having pathologic metastases. More recently, Jaehne (1996) looked at of 101 RNDs performed for N+ disease and found that only 12% of cases had SCM invasion. This higher incidence may reflect the trend toward more conservative surgery with RND reserved for cases where there is obvious invasion of nonlymphatic structures. Preserving the IJV becomes more significant in patients requiring bilateral neck dissections. MRND type II is rarely planned, as it is uncommon for metastatic disease to invade the SCM and not the IJV so when gross invasion of the SCM is not seen preservation of both the SCM and IJV should be considered. MRND Type III evolved from work by Suarez (1963) who observed in autopsy and surgical specimens of the larynx and hypopharynx that the lymph nodes were in fibrofatty tissue, and even when near blood vessels but did not share the same adventitia.
Selective Neck Dissection: Supraomohyoid Type (Level I-III)
Definition
The supraomohyoid neck dissection (SOHND) is the most commonly performed selective neck dissection for the treatment of the N0 neck. It involves the en bloc removal of cervical lymph node groups I-III. The posterior limit of this dissection is marked by the cutaneous branches of the cervical plexus and the posterior border of the SCM. The inferior limit is the superior belly of the omohyoid muscle where it crosses the IJV.
Indications
SOHND is indicated in patients with primary tumors arising from the oral cavity without clinical or radiologic evidence of cervical metastasis but who have a high probability of occult lymphatic disease. The oral cavity includes the area between the vermillion border of the lips and the junction of the of the hard and soft palate superiorly and the circumvallate papillae of the tongue inferiorly. Subsites in the oral cavity include the lips, buccal mucosa, upper and lower alveolar ridges, retromolar trigone, hard palate, and anterior two thirds of the tongue, and floor of mouth. Medina recommends SOHND in patients with staged T2-T4N0 or TXN1 when the palpable node is less than 3 cm, clearly mobile, and located in levels I or II.
Bilateral SOHND is indicated in patients who have carcinomas of the anterior tongue or oral tongue and floor of mouth that approach or cross the midline.
SOHND is indicated along with parotidectomy in patients with squamous cell carcinoma, Merkel cell carcinoma, or selected stage I melanomas (thickness between 1.5 and 3.99mm) in the cheek and zygomatic regions of the face.
Rationale
The expectant management of patients with oral cavity tumors and N0 necks has been condemned because of the high incidence of occult nodal metastasis and poor salvage rates. One exception is carcinoma of the lower alveolar ridge, which has a low probability of neck metastasis. Byers does not advocate elective neck dissections in carcinomas of the buccal mucosa no matter what T stage. His series was comprised of ten patients all of whom had elective neck dissections from which no metastatic disease was found. In all patients who are candidates for any selective neck dissection, the decision to proceed with surgery versus radiation is based on the characteristics of the primary tumor, the skill and experience of the physicians involved, and the patient’s wishes and general health.
The basis for which the SOHND was developed for treatment of the N0 neck in patients with oral cavity carcinomas was established by Lindberg’s study in 1972 where he looked at the distribution of lymph node metastasis in head and neck squamous cell carcinomas. He showed that the subdigastric and midjugular nodes were the most likely affected lymphatics. In the absence of involvement of the first echelon node groups (submandibular, subdigastric, and midjugular) oral cavity carcinomas rarely spread to the lower jugular or posterior triangle lymph nodes. In 2001, Hoffman reviewed 5 of the largest series of oral cavity and calculated the mean percent occurrence of oral cavity tumors in all levels of the neck. Many of these studies included N+ necks. The results are a follows: Level I – 30.1%, Level II – 35.7%, Level III – 22.8%, Level IV – 9.1%, and Level V – 2.2%. When factoring in only No necks, the occurrence of occult nodal metastases in both Level IV and Level V was less than 3%. This finding supports the use of the SOHND in treatment of patients with N0 necks with oral cavity carcinoma. |
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