Salivary Gland Disorders

See also Salivary Gland Tumours.

Saliva is produced by 3 pairs of major salivary glands:

1. The parotid glands - lie below the external auditory meatus between the vertical ramus of the mandible and the mastoid process. The parotid duct crosses masseter and opens via a small papilla on the buccal membrane opposite the crown of the second upper molar. It has an intimate relationship with the facial nerve, which subdivides into its branches as it passes through the parotid.
2. The submandibular glands - is walnut sized, lies beneath and in front of the angle of the jaw, wrapping around the posterior edge of the mylohyoid muscle. Its duct emerges to the floor of the mouth just lateral to the frenulum of the tongue.
3. The sublingual glands - lie below the tongue and open through several ducts into the floor of the mouth.

There are also a large number (600-1000) of minor salivary glands widely distributed throughout the oral mucosa, palate, uvula, floor of the mouth, posterior tongue, retromolar and peritonsillar area, pharynx, larynx and paranasal sinuses.

When assessing salivary gland disorders consider:

• Which gland(s) is affected? Most commonly, it is the parotid. Some conditions affect the parotid more than the submandibular glands e.g. mumps, parotitis, tumours (benign>malignant), and vice versa e.g. stones.
  • Parotid swelling causes loss of the angle of the jaw and may also cause a lump anterior to the ear (related to its accessory lobe).
  • Sublingual gland pathology may cause swelling on the floor of the mouth.
  • Submandibular gland pathology usually involves swelling beneath and anterior to the angle of the jaw. Examine bimanually. Sometimes a stone may be palpated within its duct.
  • Is this swelling a salivary gland? Differentiating a swollen parotid gland and cervical lymphadenopathy may be very difficult clinically. Usually it is possible to feel in front of lymph nodes but it is impossible to get in front of the parotid.
• Uni- or bilateral?
• Pain or painless swelling? Pain may be referred to the ear or throat.
• Duration of symptoms? Has the mass increased in size since it was first noticed?
• Are symptoms affected by eating?
• Are there systemic symptoms e.g. malaise, pyrexia?
• Is there any regional lymphadenopathy?
• Is there facial weakness or asymmetry? This is highly suggestive of malignancy.
• Are the eyes dry? Are there any other features of Sjögren's syndrome? It is often under-diagnosed.¹

• Mumps is the most common cause of salivary gland infection, although its incidence has fallen with widespread immunisation. It usually causes bilateral swelling of the parotids, although the other major salivary glands may also be affected. The swelling lasts 5 to 9 days accompanied by low-grade pyrexia and general malaise.
• Other viruses that may acutely infect the salivary glands include coxsackie virus, parainfluenza, influenza A and herpes.
• Acute bacterial infection of the major salivary glands occurs usually in debilitated or dehydrated patients. Co-morbidity and/or medication may inhibit saliva production, increasing vulnerability. Prior to the advent of antibiotics and intravenous fluid rehydration, bacterial parotitis was often a pre-terminal event with a mortality of over 80%. Infection ascends from the oral cavity, most frequently Staph. aureus.
• Chronic bacterial infection may occur on a background of a gland previously damaged by stones, irradiation or autoimmune disease. Chronic infection destroys the glandular elements of the salivary glands and can impair the protective functions of saliva, leading to dental infections and disease.
  It consequently often first presents to a dentist.⁴
• HIV infection can involve the salivary glands, most frequently in children.
• TB is an uncommon cause of parotitis. However, a quarter will also have pulmonary TB and potentially be infective.

Presentation

• Swelling
• Dry mouth
• Abnormal or foul tastes associated with purulent discharge from salivary duct opening
• Mouth or facial pain, especially associated with eating
• Decreased mouth opening, difficulty talking
• Fever/systemically unwell

Investigation

May include:

• Bloods - FBC, inflammatory markers, U&Es, blood culture, viral serology, HIV test, as appropriate.
• Pus swab for culture and sensitivities
• Sialography - looking for dilation of duct system (sialectasia)
• Ultrasound
• CT/MRI - often to exclude neoplasm
• Fine needle aspirate or incisional biopsy for histology or culture material

Management

• Mumps is a self-limiting condition without serious sequelae in most patients. Supportive treatment is appropriate. It remains a notifiable disease.
• Acute suppurative infection is treated with antibiotics and incision and drainage if an abscess has developed.
• With chronic infections, where duct obstruction is identified, stones or strictures can be removed, promoting saliva flow. Gland excision may sometimes be required where problems become recurrent.

Complications

Abscess formation with spread to the other deep neck spaces of the neck is the most concerning. Trismus may indicate parapharyngeal involvement. Ludwig angina where infection of the submental and sublingual spaces occurs is rare but life-threatening.

Prevention

• To prevent acute suppurative parotitis, consider risk factors, avoid anti-cholinergics and other drugs likely to disrupt saliva flow in the vulnerable and maintain good hydration and mouthcare perioperatively and amongst critically ill patients. Mouth care is an important consideration in the care of the terminally ill.
• A high uptake of MMR vaccine is essential to prevent resurgence of mumps.

• Calculi or stones can form in the major salivary glands and their ducts, causing obstruction of salivary outflow typically with pain and swelling at meal times. This is known as sialolithiasis and is most commonly seen in the submandibular gland and its duct, but may also be seen in the parotid glands. Obstruction is less common in the parotid gland as its secretions are more watery and the duct is wider. Sublingual glands drain into 8-20 ducts so rarely obstruct.
• Obstruction of minor salivary glands also occurs resulting in cyst like swellings in the lips and cheeks.
• The cause of salivary gland stones is unknown - foreign bodies and tooth paste have both been claimed to play a role. Stones are composed of mucus, cellular debris, calcium and magnesium phosphates.
• Parotid gland obstructions are more usually due to stenosis of the opening of the duct rather than stones. This can sometimes be secondary to chronic trauma due to ill-fitting dentures.
• Obstruction of a salivary duct causes inflammation and swelling of the gland.
• If the obstruction is not relieved, the gland becomes damaged and may ultimately require complete excision.

Presentation

• Usually, colicky postprandial swelling of the gland.
• Symptoms typically relapse and remit.

Investigation

• X-ray (AP, lateral, and oblique intraoral occlusal views) - most (70-80%) submandibular calculi are radio-opaque but most parotid stones are radiolucent.
• Sialography provides information about the ductal system and obstruction is indicated by filling defects or strictures.
• Ultrasound - stones appears as markedly hyperechoic lines or points with distal acoustic shadowing.

Management

• Many stones will pass spontaneously so conservative treatment may consist of oral analgesics and antibiotics. Good hydration, warm compresses, and gland massage may assist the stone's passage.
• Surgical management:
  • Proximal submandibular stones may be removed by dilating/incising Wharton's duct and a transoral approach.
  • Calculi in the submandibular duct may be removed by an incision in the floor of the mouth, whilst those in the substance of the gland may require gland excision.
  • Endoscopic and minimally invasive techniques are also increasingly being used.⁶
  • Salivary lithotripsy has not been widely embraced in the Uk although some advocate its use, particularly with smaller stones.⁷

Prevention

Those who had salivary calculi are more likely to produce them again. There are no evidence-based methods of prevention currently. Maintaining good hydration will aid saliva production and may reduce the risk of recurrence.

The most common degenerative disease affecting the salivary glands is Sjögren's syndrome, an autoimmune condition.

• It preferentially affects the parotid gland, but may also affect the submandibular and minor salivary glands. It usually also affects the lacrimal glands. It causes keratoconjunctivitis sicca, xerostomia, salivary gland enlargement.
• Sjögren's syndrome may be accompanied by other systemic diseases such as rheumatoid arthritis, systemic lupus erythematosis or primary biliary sclerosis.
• Approximately 10% of patients with Sjögren's syndrome will develop a non-Hodgkin's lymphoma.⁸
• Sjögren's syndrome has a strong female predominance (9:1) and onset is typically in middle-age.

Causes of sialadenosis (benign salivary gland swelling with glandular hypertrophy and ductal atrophy) include:

• Bulimia
• Diabetes mellitus and hypothyroidism
• Cirrhosis and malabsorption
• Drug induced e.g., thiourea
• Sarcoidosis and Heerfordt syndrome

Investigations

Sjögren's syndrome shows a characteristic sialectasis and parenchymal destruction on sialogram and may be confirmed through many different tests including:
• Biopsy of the labial salivary glands
• Autoantibodies - Sjögren syndrome A (SS-A) and Sjögren syndrome B (SS-B)
• Rheumatoid factor (positive in about 90%)
• Antinuclear antibodies

If sarcoidosis is suspected, CXR may show bilateral hilar lymphadenopathy (BHL).

Management

In patients with Sjögren disease, refer to rheumatology where the diagnosis is suspected. Good dental care is essential to prevent carries. Most treatment is symptomatic e.g. use of artificial tears and saliva. Gland excision is rarely indicated.