Parotidectomy is the removal of the parotid gland, a salivary gland near the ear.
The parotid gland is the largest of the salivary glands. There are two parotid glands, one on each side of the face, just below and to the front of the ear. A duct through which saliva is secreted runs from each gland to the inside of the cheek.
The main purpose of parotidectomy is to remove abnormal growths (neoplasms) that occur in the parotid gland. Parotid gland neoplasms may be benign (approximately 80%) or malignant. Tumors may spread from other areas of the body, entering the parotid gland by way of the lymphatic system.
Benign parotid gland growths usually appear after the age of 40. Malignant growths most often affect women over the age of 60, while benign tumours affect both sexes equally. Cancer of the salivary glands accounts for only 1% of all cancers, and 7% of all head and neck cancers.
During surgery, two different areas of the parotid gland are identified: the superficial lobe and the deep lobe. Superficial parotidectomy removes just the superficial lobe, while total parotidectomy removes both lobes.
The patient is first placed under general anaesthesia to ensure that no pain is experienced and that all muscles remain relaxed. An incision is made directly to the front or back of the ear and down the jawline. The skin is folded back to expose the parotid gland. The various facial nerves are identified and protected during the surgery so as to avoid permanent facial paralysis or numbness. A superficial or total parotidectomy is then performed, depending on the type and location of a tumour. If a tumour has spread to involve the facial nerve, the operation is expanded to include parts of the bone behind the ear (mastoid) to remove as much tumour as possible. Before the incision is closed, a drain is inserted into the area to collect any leaking saliva, if a superficial parotidectomy was performed. The procedure typically takes from two to five hours to complete, depending on the extent of surgery and the skill of the surgeon.
A complete physical examination and medical history are performed, as are diagnostic tests to help the surgeon better plan for the surgery. Some tests that may be performed include computed tomography (CT) scan, magnetic resonance imaging (MRI), and fine-needle aspiration biopsy (using a thin needle to withdraw fluid and cells from the growth).
After surgery, the patient will remain in the hospital for one to three days. The incision site will be watched closely for signs of infection and heavy bleeding (haemorrhage). The incision site should be kept clean and dry until it is completely healed. If the patient has difficulty smiling, winking, or drinking fluids, the physician should be contacted immediately. These are signs of facial nerve damage.
There are a number of complications that are associated with parotidectomy. Facial nerve paralysis after minor surgery should be minimal. After major surgery, a graft is attempted to restore nerve function to facial muscles. Salivary fistulas can occur when saliva collects in the incision site or drains through the incision. Recurrence of cancer is the single most important consideration for patients who have undergone parotidectomy. Long-term survival rates are largely dependent on the tumour type and the stage of tumour development at the time of the operation.
Other risks include hematoma (collection of blood under the skin) and infection. The most common long-term complication of parotidectomy is redness and sweating on the cheek, known as Frey’s syndrome. Rarely, paralysis may extend throughout all the branches of the facial nervous system.
Although some facial numbness or weakness is normal immediately following parotidectomy, these symptoms usually subside within a few months, with most patients regaining full function within one year. Return of a benign tumour is very rare.
Morbidity and mortality rates
There is a 25–50% risk of temporary facial weakness following parotidectomy, and a 1–2% risk of permanent weakness. Frey’s syndrome may be experienced by up to 90% of patients to some extent and causes perspiration on that side of the face with eating. There is very little or no risk of mortality associated with the surgery. The survival rate of malignant parotid gland tumours depends on their size, location, extension, and if metastasis has occurred. The 10-year survival rate ranges from 32% to 83%.
A benign parotid neoplasm may be managed expectantly (i.e., adhering to a period of watchful waiting) so that the growth is of a larger size before it is removed (the risk of facial nerve damage increases with each subsequent parotidectomy). There is generally no alternative to surgical treatment of parotid gland neoplasms, although radiation therapy may be recommended after the procedure in the case of malignant tumours.