Neck Dissection and Lymph Node Removal
What are lymph nodes and why are they important?
Lymph nodes are the drainage basins for infections and contaminants that enter the body through mucosal surfaces, skin, glands and dentition in the head and neck. There are over 500 lymph nodes in the body and the head and neck contains a little more than 160. Each of these nodes will gather infection and inflammation, and allow the body a location to create immunity and response to these insults. In children and teenagers, the majority of swollen or inflamed lymph nodes will be related to infection, be they from viruses, bacteria or fungus.
Another problem that may be encountered in lymph nodes is tumors, growths and cancer. The difference between a benign tumor and cancer is the ability of the cells to spread to other locations in the body. The most likely first site of spread or metastasis for cancer is to the regional lymph nodes. For this reason, the lymph nodes may be the first sign that a person has cancer. If a lymph node is larger than is typical for its location and has been large for a considerable amount of time, it may raise the question of a metastatic cancer. Occasionally, the lymph nodes themselves are the source of a type of cancer that is composed of uncontrolled growth of lymphocytes called lymphoma. Therefore, lymph nodes are of great interest in the head and neck when they have grown large and have been present for more than 4 weeks. In this setting they may need to be biopsied or removed. In the setting of known cancer, the lymph nodes may be removed in order to determine if the cancer has spread. This is called a neck dissection.
A neck dissection is divided into 3 different types:
- Selective neck dissection – In which, only the lymph nodes from the most likely drainage basin for that type of cancer are removed.
- Radical neck dissection – All of the lymph nodes on one side of the neck are removed. Additionally, the jugular vein, spinal accessory nerve (which controls the trapezius muscle) and sternocleidomastoid muscle are removed.
- Modified radical neck dissection. All the lymph nodes are removed in a clever way sparing one or all of following: the sternocleidomastoid muscle, spinal accessory nerve and jugular vein.
- Submandibular lymph nodes – An area bordered by the hyoid bone and the digastric muscles.
- Upper jugular chain – Between the jaw and hyoid along the jugular vein
- Mid level jugular chain – Between the hyoid an cricoid level along the jugular chain
- Lower jugular chain – Between the cricoid and clavicle along the jugular chain
- Posterior triangle – Posterior to the sternocleidomastoid muscle
- Central compartment – Under the chin and around the thyroid gland
Now, these areas may sound foreign and are really most important for the surgeon, but they can tell a lot about the tumor and where it is going. For instance, someone with thyroid cancer or cancer of the nasopharynx will likely present with a lymph node in the posterior triangle, while someone with a lymph node in the submandibular triangle that is cancerous likely has the source of cancer in the oral cavity. In this manner it is important to know what lymph nodes have cancer and how many!
How is a neck dissection performed?
After determining a type of cancer the surgeon may want to prophylactically remove the lymph nodes basins that they would typically drain. Alternatively, there may already be obvious manifestations of the cancer in lymph nodes and a therapeutic neck dissection will need to be performed. Based upon the cancer and distribution of the lymph nodes, the surgeon will choose one of the neck dissections described above. The surgery is done under general anesthesia and the area to be treated is sterilized and the patient is positioned for surgery. An incision is made and is usually extended from just under the ear to the lower midline of the neck. This is quite a long incision but heals very well. Often, a year after surgery, the incision is quite well hidden in the creases of the neck.
Next, the surgeon will begin mobilizing important structures such as nerves and muscles to preserve function after the lymph nodes have been removed. For this reason, there is a risk of injuring some of these structures. This can lead to weakness of the lower lip, tongue, shoulder and voice box. Also, the patient can have postoperative hoarseness, problems swallowing, problems breathing or even a collection of fluids in the operated area. After removing the lymph nodes, the incision is closed and drains are placed extending from the incision to prevent fluid collections under the skin. Often the skin is closed with staples, and believe it or not, they can produce some of the absolute best cosmetic results in the neck. The lymph nodes are then sent to the pathologist who counts the number of lymph nodes and looks at each one for cancer and spread.
Do I need my lymph nodes?
Lymph nodes are very important for mounting a response to infection as well as cancer. However we have many lymph nodes in our body to continue this process after a few are removed. Therefore, after removal the patient does not tend to be more or less susceptible to viruses or infection. However, they can develop a condition called lymphedema, where the fluid of the body cannot drain out of the tissues. This is a lot like a swollen ankle after an ankle sprain. The swelling is composed of lymph fluid and usually drains as you elevate for foot. Well, in the head and neck, lymphedema from lymph fluid typically occurs around the chin and cheek region of the face and neck. This most typically occurs in someone who has had radiation therapy and a neck dissection. Overall, after removal of the lymph nodes, your immune system should still work as well as it did before the removal.