Salivary glands types, Inflammations of the parotid gland and Cat scratch disease

Salivary glands are exocrine glands in the mouth that produce saliva, which is essential for lubricating food for easier swallowing, beginning digestion of carbohydrates (via the enzyme amylase), maintaining oral hygiene by controlling bacterial growth, and moistening the mouth for speech and comfort.

Major Salivary Glands 

1. Parotid gland

It is a wedge-shaped, well-encapsulated gland on the lateral side of the face, that secretes serous secretion. It has 2 lobes; superficial & deep. connected by an isthmus. The deep lobe (segment) is lodged between the mastoid process posteriorly, the external auditory meatus (superiorly), and the ramus of the mandible anteriorly. Medially, it reaches the styloid process. Anteriorly, the parotid gland overlaps the masseter muscle, while posteriorly, it overlaps the sternomastoid muscle.

Parotid Duct (Stenson’s Duct) runs over the masseter, pierces the buccal pad of fat, and opens in the vestibule of the mouth behind the upper second molar tooth.

Structures Within the Parotid Gland

• ECA (it gives the posterior auricular artery just before entering the gland), with its 2 terminal branches: superficial temporal & maxillary artery.
• Retro-mandibular Vein (Posterior facial vein with its tributaries).
• Facial Nerve: It enters the deep surface of the gland close to the stylomastoid foramen and gives 5 branches inside the gland, radiating forwards superficial to the vein and artery.
• Parotid Lymph Nodes.

Surface Anatomy of the Parotid Gland

• Upper Border: From the tragus to the mastoid process.
• Anterior Border: From the tragus to the posterior border of the masseter opposite the angle of the mouth.
• Inferior Border: From the anterior border to below & behind the angle of the mandible.
• Posterior Border: From the mastoid process to the inferior border.

Surface Anatomy of the Parotid Duct: The parotid ducts correspond to the middle 1/3 of an imaginary line from the tragus of the ear to the mid-portion of the upper lip.

Facial nerve anatomy

Resection of the parotid tumors may be followed by recurrence due to fear of injury to the facial nerve.

The facial nerve arises from the stylomastoid foramen midway between the bases of the mastoid and styloid processes, about 1.5 cm deep from the external surface of the mastoid process, the nerve is about 1 cm in length outside the gland then pierces the gland and runs through for another 1 cm, where it divides into 2 branches which then give 5 branches:

1. Temprofacial: Temporal, Zygomatic, and Buccal.
2. Cervicofacial: Mandibular, and Cervical

So we have 5 branches that leave the gland at its anterior border, adherent to the surface of the masseter muscle. The parotid is divided by an imaginary plane passing through the plane of the facial nerve and its branches into superficial and deep lobes. This plane is called the faciovenous plane.

Function of the parotid gland: The parotid gland is made up almost entirely of serous acini, which produce about 25% of the daily saliva. Stimulation of the gland is mainly via the parasympathetics of the lesser petrosal nerve, which is a branch of the glossopharyngeal nerve. Stimulation produces watery, amylase-rich saliva. On the other hand, sympathetic stimulation produces thicker glycoprotein-rich saliva. The main function is that it aids food digestion and teeth protection.

Inflammations of the parotid gland

Acute Inflammation (Acute Parotitis = Acute Sialadenitis)

Mumps (Acute Epidemic Parotitis):

• Etiology: Specific acute viral infection.
• Clinical Picture: It usually affects children, incubation period is 3 weeks. It starts unilateral, but in a few days it affects the other side, preceded by a prodromal influenza-like syndrome. It causes fever & painful swelling, which is soft & tender. There is difficulty in mastication. I never suppurates.
• It may be complicated by pancreatitis &/or orchitis.
• Treatment: It is a self-limited disease that requires rest & symptomatic R/ only (no specific R/).

Acute Suppurative Parotitis (Parotid Abscess):

• Etiology: The infective organism is usually staph aureus, and the usual predisposing factor is infected dry mouth.
• Infection spreads from the mouth through the duct into the gland i.e. retrograde, or blood-borne.
• The parotid gland, being enclosed in a dense capsule, is liable to fulminating inflammation & necrosis due to increased tension within the tightly closed fascial compartment.

Causes include the following:

1. Following the obstruction of Stenson’s duct by a stone.
2. Postoperative parotitis due to dehydration & electrolyte imbalance.
3. As a complication of debilitating diseases as typhoid, cholera, and uremia due to dehydration & reduced resistance to infection.
4. As a complication of septicemia & bad oral hygiene.
5. Idiopathic.

Clinical Picture:

1. General Manifestations: Fever, tachycardia, insomnia, anorexia & loss of weight.
2. Local Manifestations:

• Skin Over is red & edematous, and tethered to the swelling.
• Size: The swollen gland may be 3-4 times larger than a normal gland.
• Tenderness & Temperature: The swelling is very tender and hot with throbbing pain.
• Consistency: Brawny i.e. firm but indentable. It is not compressible.
• Fluctuation is difficult to elicit & is never waited for. Pus may exudate from the duct orifice on palpation of the gland (diagnostic). A culture should be done.
• Relations: It can not be moved over the deep structures, and becomes more prominent when the patient clenches his teeth by contracting the masseter muscles.
• Lymph Drainage: The upper deep cervical L.Ns will be enlarged & tender.
• Movements of the temporo-mandibular joint are restricted.
• The facial nerve is intact. If neglected, pus tracks its way to the external auditory meatus.

Complications

• Fistula formation, chronicity.
• Local spread causing cellulitis.
• Systemic spread of infection causing septicemia.
• It may rupture into the external auditory meatus.
• It may burrow its way along the carotid sheath.

Investigations: Leukocytosis – Culture & Sensitivity from the pus.

Treatment:

• Prophylactic: Good oral hygiene + correction of fluid & electrolyte imbalance.
• Medical Treatment: In early cases, warm fomentation, antibiotics, and analgesics.
• Surgical Treatment: Decompression of the parotid (Hilton’s method): Do not wait for fluctuation. Under general anesthesia, a vertical incision is done in the skin down to the parotid capsule. The capsule is incised transversely along the course branches of the facial nerve to avoid their injury. Pus is evacuated, a drain is put in the lower part, and then closure is achieved. Complications of this procedure include parotid fistula & facial nerve injury.

Chronic Inflammation (Chronic Sialadenitis):

• Chronic Endemic Parotitis: It occurs in male farmers suffering from ancylostomiasis.
• Chronic Pyogenic Parotitis: It results from improper treatment of acute parotitis, presence of stones in the duct, or stenosis of the Stenson’s duct.

Chronic Recurrent Parotitis:

• It occurs in children & young adults, especially women.
• Etiology is unknown, but it may be allergic or autoimmune.
• Patients present with recurrent attacks of pain & parotid swelling at meal times, and a gush of purulent saliva may come out from the orifice of the duct on pressure.
• Sialography may show sialectasia (dilated ductules and acini) and stenosis.
• Treatment includes good oral hygiene, antihistaminics, and catheterization of the parotid duct & injection of antiseptic solutions.

Mikulicz Syndrome

• Chronic, symmetrical, bilateral enlargement of all salivary glands & lacrimal glands.
• It is an autoimmune disease.
• It may accompany sarcoidosis, reticulosis, TB & Sjogren’s syndrome.

Sjogren’s Syndrome:

Primary:

• It is similar to Mikulicz syndrome but associated with xerostomia & xerophthalmia.
• The gland is hard & nodular.
• Massive lymphocytic infiltration with a high incidence of lymphomatous infiltration.

Secondary:

• Similar to the primary type, but in addition, there are manifestations of connective tissue disease as RA.
• It predisposes to lymphoma of the parotid gland, but in a smaller % than in primary.

Other rare chronic inflammatory conditions of the parotid:

Tuberculosis:

• It mostly affects the parotid or submandibular from a nearby LN.
• It may be associated with systemic manifestations of TB as fever, night sweating & anemia.
• The gland is firm & nodular but may become cystic with sinuses
• R. Specific therapy of TB for 1 year + SAN regimen.

Sarcoidosis:

• Resembles TB but with no cascation.
• Other sites of affection include the mediastinum.

Actinomycosis:

Characterized by sulphur granules.

Cat scratch disease:

A disease caused by infection with a gram-negative bacillus called Bartonella henslae from contact with cats, though it was previously thought to be a fungal infection.

Complications of Chronic Parotitis:

• Acute exacerbations.
• Stone formation.
• Sialodesis (persistent infection).
• Fistula formation: Infection causes desquamation of organic debris leading to deposition of calcium bicarbonate & calcium phosphate, resulting in Stone formation.

Treatment:

• Good oral hygiene & antibiotics.
• Removal of the offending cause e.g. stone.
• Injection of antiseptic solutions through the duct.
• In refractory cases, we can do tympanic neurectomy, stopping the parasympathetic flow to the gland, which then dries up.
• Parotidectomy.

Frey’s syndrome

It is a syndrome that may complicate the incision of parotid abscess due to the injury of the auriculo-temporal nerve.

Clinical presentation:

• When the patient eats, the cheek becomes red, hot & painful. This is followed by beads of perspiration (sweating).
• Starch-iodine test (B&L).

Pathogenesis:

The severed axis cylinders conveying secretory impulses grow down the sheath of the cutaneous elements of the nerve; thus, a stimulus intended for saliva stimulation, (evokes) hyperesthesia & sweating.

Treatment:

• Nerve avulsion of auriculo-temporal nerve &/or tympanic neurectomy.
• Injection of Botulinum toxin into the skin of the affected area.

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