Neck Dissection Details
Central Neck Dissection
The most common place for thyroid cancer to spread is to the lymph nodes right around the thyroid and along the windpipe just below the thyroid. This area is called the central neck. Removing lymph nodes in this area to eradicate cancer is known as a "central neck dissection."
In some patients undergoing a thyroidectomy for cancer, a central neck dissection might be performed at the same time as the thyroidectomy. We do this because the lymph nodes in the central neck are a common site of recurrence of thyroid cancer. Removing these lymph nodes at the time of your thyroidectomy may reduce your risk of requiring another operation in the future.
A central neck dissection removes all the lymph nodes from the area just below your voice box (larynx) to the top of your breast bone. Removal of these neck lymph nodes will not impair your immune system’s ability to fight infections.
If you are undergoing a thyroidectomy, the central neck dissection will be performed through the same incision (located in a curve in the skin of the lower neck). If you have already had a thyroidectomy, the previous incision will be used for the neck dissection, but the incision may need to be extended.
The operation usually takes 2 to 3 hours if you have previously had a thyroidectomy. If performed at the same time as a thyroidectomy, the central neck dissections adds about 30-60 minutes to the surgery time.
Care is taken to protect the nerves to the vocal cords as well as the parathyroid glands. Occasionally, this operation requires relocation of the two lower parathyroid glands. When this is necessary, the parathyroid glands are placed into a pocket in one of the muscles of the neck, where they begin to grow again and resume their function. This is known as a parathyroid autotransplant.
Occasionally, a thin plastic tube (drain) may be placed at the time of the surgery and will come out the skin below your collar bone. If placed, this drain will usually be removed prior to your discharge from the hospital.
The scar from the procedure should fade over time. It is often less noticeable than patients expect since the incision is made along a natural crease in the skin of the neck.
Risks of Central Neck Dissection
Two main complications of a central neck dissection are as follows:
1. Hoarseness
The lymph nodes in the central neck are very close to the nerves to the vocal cords (recurrent laryngeal nerves) which run under the thyroid gland on either side of the neck. Injury to one of these nerves can cause hoarseness due to a paralysis of the vocal cord. A permanent vocal cord paralysis occurs in about 1% of patients. Approximately 10-15% of patients will have mild hoarseness resulting from operating around the larynx, but this hoarseness is temporary, lasting days to months.
2. Low Blood Calcium (Hypoparathyroidism)
Approximately 15% of patients experience low calcium directly following a neck-dissection surgery. This can cause a feeling of numbness or “pins and needles” (similar to the sensation you experience when your hand “falls asleep” after you have slept in an awkward position). Low calcium can also lead to muscle spasms. However, only 2-5% of patients will need to take calcium supplements on a long-term basis.
Note: Multiple Operations
If you have had a previous thyroidectomy and are undergoing a central neck dissection for cancer recurrence, there may be scar tissue from the previous operation. This may slightly increase the risk of both nerve injury and parathyroid problems as compared to a central neck dissection performed at the same time as a thyroidectomy.
Modified Radical or Functional Neck Dissection
When an ultrasound-guided FNA has confirmed that a lymph node in the lateral neck area (outside the left or right carotid artery) contains cancer, a lateral neck dissection is necessary.
Lymph nodes that are outside the area bounded by the carotid arteries cannot be removed through the incision used for a thyroidectomy. The incision used for a lateral neck dissection usually extends from the end of the thyroidectomy incision up to just behind the earlobe.
A lateral neck dissection removes all of the lymph nodes along your jugular vein from your jaw bone down to your collar bone. It is referred to as a "modified" or "functional" neck dissection because we remove the lymph nodes without removing any vital nerves, blood vessels, or muscles.
Occasionally, the lymph nodes are stuck to one or more of the following structures, requiring their removal:
- Internal Jugular Vein: The internal jugular veins are large veins on either side of the neck that help to drain blood from the brain and head back to the heart. One jugular vein can be removed without causing any symptoms. About 5% of lateral neck dissections for thyroid cancer require removal of an internal jugular vein.
- Sternocleidomastoid muscle: This muscle helps you to bend and turn your head. If it is removed, you may have some weakness in your neck and will have a cosmetic defect due to its absence. This muscle is rarely removed for thyroid cancer.
- Spinal accessory nerve: This nerve controls the muscles that allow you to raise your arm above your head. If it is removed, you may be unable to raise your arm above your shoulder and may have pain in the shoulder. This nerve is rarely removed for thyroid cancer.
The operation typically lasts 2-4 hours (in addition to the time required for a thyroidectomy and/or central neck dissection if being done at the same surgery). One or two thin plastic tubes (drains) are placed at the time of the surgery and will come out the skin below your collar bone. A cosmetic skin closure is performed after the tube is removed. It is normal for there to be some numbness of the skin on the jaw, neck, and ear. Most of the time this numbness is temporary, but it can last several months.
Risks of Lateral Neck Dissection
The main complications of a lateral neck dissection involve the numerous nerves which run through the neck. The risk of injury to each nerve is about 1%. The nerves at risk are as follows:
- Spinal accessory nerve: This nerve connects to two muscles in the shoulder, the sternocleidomastoid and trapezius. Injury may result in shoulder pain and/or difficulty in raising the arm above the head.
- Vagus nerve: This nerve gives rise to the nerve to the vocal cord (recurrent laryngeal nerve). Injury to this nerve will result in hoarseness.
- Phrenic nerve: This nerve supplies the diaphragm, which is the muscle that helps you breathe. Most people who have an injury to one phrenic nerve do not experience any major breathing problems. However, if you have lung disease or are an endurance athlete, injury to a phrenic nerve may cause breathing difficulty.
- Hypoglossal nerve: This nerve controls the muscles of the tongue. Injury causes the tongue to deviate to the side when stuck out and may cause difficulty with speech or chewing. These problems usually improve with time.
- Marginal mandibular nerve: This nerve controls the muscles around the corner of the mouth. Injury to this nerve may cause the corner of the mouth to droop.
In addition to injury to nerves, there is a small risk (1% or less) of significant bleeding, infection, leakage of lymph fluid, or shoulder pain. Fluid collection in the neck rarely occurs after the drain is removed.
When a patient is diagnosed with thyroid cancer, it is important to consider the possibility that that the cancer may have spread to lymph nodes in the neck. However, physical symptoms experienced by the patient provide only limited guidance in determining whether this has occurred.
- Enlarged lymph nodes can be a sign that cancer has spread to the lymphatic system, but they can also have other causes, such as inflammation and infection.
- Lymph nodes containing cancer are often not palpable (i.e., cannot be felt by hand) and cause no symptoms.
When cancerous lymph nodes are palpable, they are usually felt as painless, firm lumps at the side of the neck. When symptoms do occur, it is usually due to the enlarged lymph node pressing on surrounding structures such as the esophagus (swallowing difficulty), the windpipe (trouble breathing), or nerves (pain or hoarseness).
Because of the difficulty in determining whether the cancer has spread from symptoms alone, diagnostic tests are usually performed.
Diagnosis begins with a history and physical examination; however, not all cancerous nodes are palpable and a medical history is only a probabilistic guide. One or both of the following tests may be performed depending on your particular case:
Ultrasound
Ultrasound examination uses harmless sound waves to obtain a picture of the tissues of the neck. This technique is much better at detecting abnormal lymph nodes than a physical exam alone.
You may have already had an ultrasound of your thyroid, but this initial ultrasound does not usually include an examination of the lymph nodes. Thus, another full neck ultrasound may need to be performed. This ultrasound will evaluate for abnormal lymph nodes right around your thyroid as well as along the jugular veins which run along the sides of your neck.
Biopsy
Not all abnormal lymph nodes detected through an ultrasound actually contain cancer. The best way to determine if an abnormal lymph node contains cancer is to do a fine-needle aspiration (FNA) biopsy. (You may have already had an FNA of your thyroid.) The skin is prepared and a needle is inserted into the abnormal lymph node by ultrasound guidance. Cells from the lymph node are removed and examined by a pathologist.
This information is provided by the Department of Surgery at the University of Colorado School of Medicine. It is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition.