Neck dissection - Professor Stuart Winter



Neck dissection

Neck dissection refers to the removal of lymph nodes and surrounding tissue from the neck. The extent of tissue removal varies depending on the indication for surgery and the clinical circumstances. Several variations of neck dissection are described below.

What are lymph nodes?

The lymphatic system is a network of channels distributed throughout the body. These are similar to blood vessels, but carry lymph (a liquid consisting of white blood cells and serum) from tissues back into the major blood vessels. Along the way, lymph nodes interrupt these channels and act like filters. These filters may swell when an infection is nearby as they remove infected material from the lymph. When a cancer is nearby, the lymph may carry cancer cells. These cancer cells may become trapped and begin to grow within the lymph node. This is known as a lymph node metastasis. Most head and neck cancers appear to spread from the site of origin (in the mouth, throat, salivary gland, or other organ) to the lymph nodes in the neck before spreading to other parts of the body.

What are the types of Neck Dissection?

Radical Neck Dissection

This operation has been used for almost 100 years and describes the removal of all the lymph nodes on one side of the neck. In addition to lymph nodes, this operation removes the submandibular gland, the sternocleidomastoid muscle, the jugular vein and the spinal accessory nerve.

Modified Radical Neck Dissection

This term describes a variety of neck dissections that basically refer to anything that is less than a radical neck dissection. For instance, many times a lymph node metastasis may be present, but all of the lymph nodes at risk can be removed without sacrificing the spinal accessory nerve. This is probably the most common modification of neck dissection. Other situations may present themselves when the sternocleidomastoid muscle, jugular vein or even all three structures (muscle, vein and nerve) can be safely preserved.

Selective Neck Dissection

These neck dissections (another type of modified neck dissection) are procedures that preserve the sternocleidomastoid muscle, the spinal accessory nerve and the jugular vein and also remove less extensive amounts of lymph nodes and surrounding tissue. The type of selective neck dissection (and levels removed) will vary depending on the primary cancer site and the lymph nodes at greatest risk of developing metastases.

Why is this procedure done?

For the most part, the more extensive neck dissections (radical and modified neck dissections) are used when lymph node metastases are present. Less extensive neck dissections (selective neck dissections) are used when metastases are limited, are only suspected, or when pathologic assessment of the lymph nodes is required to decide about further cancer therapy.

How is a neck dissection performed?

The procedure is done under general anesthesia through an incision that runs along a skin crease in the neck. The incision is usually closed with nylon sutures or skin staples that are removed 6-10 days after surgery. If radiation has been given to the neck previously, sutures remain longer than if no previous radiation has been used. One to two drains are also placed which exit the skin of the neck. These are removed 2-6 days after surgery when drainage has ceased.

What are the risks of surgery?

Nerve injury

Weakness of the shoulder muscle is expected after radical neck dissection when the spinal accessory nerve is cut but can also occur even when the nerve is preserved. When the nerve is preserved, recovery can take up to 12 months. Whether this nerve is preserved or sacrificed at surgery, post-operative physiotherapy can help with shoulder discomfort.

A small branch of the facial nerve (marginal mandibular nerve) is encountered just below the jaw line at the top of the neck. This is mobilized and preserved when performing a neck dissection. A temporary or permanent weakness of the lower lip can result from this mobilization.

Numbness of the neck skin is expected after neck dissection and improves over a 12 month period, although often never completely. This occurs because the nerves that provide sensation to the neck skin are cut and need to re-establish connections to the skin. In some cases, the regenerating nerves become trapped in scar tissue and can form a small nodule that is sensitive to the touch. This is a late complication of neck dissection occurring several months to a year after surgery.

Other major nerves in the neck are identified in the course of neck dissection. These include two nerves to the tongue, the lingual (sensation) and the hypoglossal (motion).

Vessel Injury

Many arteries and veins are encountered during neck dissection. Bleeding is a potential complication of any surgery and neck dissection is no exception. Drains are used to remove any oozing blood at the conclusion of surgery. On occasions these can fail to clear the collection of blood and a return to theatre is required.

Lymphatic Leak

Major lymph channels are encountered at the lower aspect of the neck, especially on the left side. These are carefully tied off to prevent lymph drainage into the wound. Occasionally a lymphatic leak occurs despite these efforts. Food in the stomach can increase the amount of lymphatic flow. A diet change and a pressure dressing can usually control this problem, but return to the theatre may be required.

Infection

Wound infections may also occur and can usually be managed in the clinic with antibiotics and minor wound care.

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