King Edward VII's Hospital, London

 

University College London Hospital (NHS base)

        

 

 

Researching, Developing & Teaching Minimally Invasive Head & Neck Surgery 

 

 
 

Salivary Gland Disorders

 
   

Salivary Gland Tumours

   

Benign parotid tumours can be removed safely by a much smaller operation (ECD) than the traditional procedure known as parotidectomy.

What is Extracapsular Dissection? (ECD)

Extracapsular Dissection is a relatively new technique that preserves the gland and greatly reduces facial nerve injury. It was developed by Alan Nicholson (Christie Hospital Manchester) in the 1950s but was overlooked by the surgical community, its use has since been developed by Professor McGurk.

The main advantage of ECD over superficial parotidectomy is that it preserves most or all of the parotid gland and reduces the risk of injury to the facial nerve. Patients leave hospital sooner and the risk of complications and side effects is significantly reduced.  It differs fundamentally from traditional parotidectomy which is described below.

Comparing the Results:

ECD results compared with Superficial Parotidectomy

Published results, peer reviews, meta-analysis and Pubmed reports (Link)

Data analysis shows that ECD is an improvement on Superficial Parotidectomy. It causes less injury and shows no increased risk of disease reoccurrence. (1% - 2%  at ten-year follow up)

 

ECD - detail

With ECD, the facial nerve is not traced and the gland is not separated from the nerve surface as it is with parotidectomy. Instead the nerve is monitored throughout the operation by an electrical facial nerve monitor. Consequently only the tumour area is exposed (smaller incision) and the surgery is limited to careful dissection in a space 2 to 3 mm peripheral to the tumour margin.

Video: ECD Extra Capsular Dissection 

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Parotidectomy

This procedure has remained mostly unchanged since its introduction in the 1940's and it is still the standard procedure in many UK practices for all parotid tumours.

The main risk with parotid surgery is an injury to the facial nerve. This nerve controls the movement of the face and it runs through the area of operation, the parotid gland.

About 2/3 of the gland sits above the nerve and 1/3 below. This can be seen in the video below. With parotidectomy, a large incision is required to expose the whole gland. The facial nerve is then traced through the gland and a portion of the gland is removed. There is a high rate of transient nerve injury as a result. (30%) If the tumour is below the nerve then the nerve has to be lifted from the remaining gland and the gland removed entirely.

Video: Main Salivary Glands and Facial Nerve within the Parotid Gland

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Superficial Parotidectomy 

This is still the standard procedure in many practices. The whole parotid gland needs to be exposed, requiring a large incision. The facial nerve and its many branches are followed through the gland by filleting the upper part of the gland away from the nerve as accurately as can be achieved. The upper 2/3 of the gland is then lifted from the surface of the branching facial nerve.

If the the tumour lies above the nerve, within the upper 2/3 of the parotid, then this upper larger portion of the gland is removed. 

Video: Superficial Parotidectomy 

Full Screen: Run the video and click bottom right corner. Double click or ESC key to return

Total Parotidectomy 

If the tumour is lying below the nerve in the deeper part of the parotid, then the above procedure is extended to include the remaining third of the parotid gland that lies below the facial nerve. The facial nerve has to be further dissected to lift it off the remaining 1/3 portion of the parotid gland. The whole gland is then removed entirely.

 

Radical Parotidectomy  

Malignant tumours that have infiltrated the parotid gland and involve the facial nerve represent aggressive high grade lesions. They are treated by entire parotid gland removal with part or all of the facial nerve in conjunction with a neck dissection. Patients with aggressive or advanced tumours are at particular risk of neck metastasis (spreading of cancer cells to other areas)

With parotidectomy. another set of quite invasive cosmetic operations has been devised to fill the hole left by the extracted parotid gland. 

 

Complications Associated with Parotidectomy

Risks exist to a greater or lesser degree depending on how much of the parotid gland is removed. These risks exist also with the less invasive ECD procedure but to a much lesser degree.

The main risk with parotidectomy is injury to the facial nerve which leads to various post-operative complications depending on how much damage is done. Different branches of the facial nerve control various areas of the face.

1.  Frey's Syndrome  

The filleting process and removal of parts of the parotid gland can damage part of the nerve network that controls salivary secretion. At the same time, the exposure of the parotid achieved by lifting the skin off its surface inevitably damages a separate set of nerves that control sweating in the skin. In parotidectomy, the skin is laid back over the raw surface of the parotid gland. These nerves try to heal after surgery and they can make incorrect connections with sweat glands on the cheek. This can result in sweating in the operated area while eating, or when anticipating eating.

2.  Facial paralysis and weakness

Although the facial nerves can heal themselves to a large extent, a major risk is permanent injury to the facial nerve. It can cause problems in controlling facial muscles and expression, including the ability to fully close the lips and the eyelid on the operated side.

3. Facial hollowing

The parotid gland is fairly large. If all or part of it is removed, then to some degree it leaves a depression on the upper cheek and neck. For cosmetic reasons, there have been attempts to replace the gland with donated tissue from elsewhere in the body. These have not been completely successful and are quite invasive. They involve fat transfer, rotating muscle or fascia from the scalp or the sternomastoid muscle in the neck.

These masking prodedures are completely unnecessary if ECD is performed.

4. Fistula

After parotid surgery a fistula may develop. This is when the damaged parotid gland leaks saliva into the operative field instead of it being channelled normally into the mouth through the salivary duct. Instead of draining into the mouth, the saliva collects under the skin at the site of surgery. Unless released it will burst through the healing incision on the surface and leak onto the neck and clothes.

It can be very disabling.

 

 

 
 

 

Benign Tumours - How common are they?

About 8 people in every 100,000 will develop a benign salivary tumour each year and 1 in 100,000 will develop a malignant tumour. About 80% of all salivary gland tumours occur in the parotid gland.

 

For every ten tumours (benign & malignant) that occur in the parotid gland, one occurs in the submandibular and another in the minor salivary glands of the mouth.

 

Salivary tumours are so uncommon that most surgeons are not able to gain the experience to change to later techniques. The majority of surgeons have only been trained to provide the traditional parotidectomy procedure described on this page.

A tumour is usually benign if:

  • Surrounding tissues are not invaded but only displaced

  • The mass has regular edges

  • It only grows slowly

  • There are no other clinical symptoms (such as weight loss)

 

Major & Minor Glands

There are two types of salivary gland, minor & major. About a thousand minor salivary glands line the mucosa of the mouth to keep it moist. They secrete continually. The major salivary glands consist of the parotid, submandibular and sublingual glands. (video opposite)

 

 

Typical external appearance of parotid tumour

 

Incision guides for minimally invasive ECD

 

Incision guides for parotidectomy

 

Benign tumour types

The most common benign tumour is called a Benign Mixed Tumour (pleomorphic adenoma) They grow slowly and show few symptoms apart from the swelling itself, therefore they are often tolerated for a while before a diagnosis is sought. The second most common benign tumour, Warthin's Tumour, is more common in the elderly and is linked to cigarette smoking.

All swellings should receive early attention to confirm the diagnosis and avoid missing a more serious condition.

Risks increase with growth of the tumour

 

Malignant  Tumours - Cancer

Fortunately malignant salivary tumours are rare (1 case per 100,000 population each year). In 2014 there were only about 600 malignant salivary gland tumours in England, mostly occurring in the parotid gland. Only about ten of these tumours occurred in young people under 20 years old. 

There are many different types of malignant salivary gland tumours. They pose different problems, therefore treatment has to be tailored to each patient and a general treatment plan is not possible as each tumour is different in nature.  

Key factors in treating malignant tumours are the skills and experience of the practitioner, the size of the tumour (less than 4cm) and whether the tumour has spread (metastasis) to local nodes.

 

Common Diagnostic Techniques

Fine-needle aspiration cytology (FNAC)

FNAC guided by ultrasound imaging (US) This is used to get tissue samples from tumours and the salivary glands.

 

CT or MRI  

Computed Tomography (CT) scanning and Magnetic Resonance Imaging (MRI) are used to obtain images of parotid tumours. Both technologies are very sensitive and can show the entire gland in detail.

CT scanner

 

Sentinel Node Biopsy (SNB)

This is described elsewhere on our site. The procedure identifies very small clusters of cancer cells that would otherwise only be found through exploratory neck dissection.

 

Video  Salivary duct network inside the parotid gland

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Major Salivary Gland Cancer:

Mark McGurk article: target readership: Health professionals

 

 

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