Sialolithiasis
Sialolithiasis is the formation of calcified stones (sialoliths) within the salivary gland ducts, most commonly the submandibular gland, leading to obstruction of salivary flow and recurrent gland swelling.
Sialolithiasis
Sialolithiasis (from Greek: sialon = saliva, lithos = stone, -iasis = condition/disease) refers to the formation and presence of calcified stones (calculi) within the salivary glands or their ductal systems [1][2]. It is the most common cause of obstructive salivary gland disease and the most common benign non-neoplastic condition of the salivary glands.
When stones obstruct salivary outflow, this leads to sialadenitis (sialon = saliva, aden = gland, -itis = inflammation) — i.e., inflammation of the salivary gland — which is secondary to ductal obstruction and stasis [2]. So think of sialolithiasis as the primary pathology (the stone) and sialadenitis as its chief complication (the infection/inflammation).
Key Distinction
Sialolithiasis = the stone itself. Sialadenitis = the gland inflammation (which can be caused by stones, autoimmune disease like Sjögren's, or ascending bacterial infection). They are related but distinct entities. The lecture slides emphasize that chronic sialadenitis is most commonly caused by stones [1].
- Prevalence: Sialolithiasis affects approximately 1.2% of the population. It accounts for ~50–60% of all major salivary gland disease [2].
- Age: Typically occurs in individuals aged 30–60 years, with peak incidence in the 4th–6th decades [2].
- Sex: Slight female predominance (some sources say male predominance — exam-wise, know that it is roughly equal with a slight lean depending on the series) [2].
- Only 1 stone in ¾ (75%) of cases — meaning most patients present with a single calculus. Multiple stones occur in ~25% [1].
- Recurrence: Recurrence rate after removal is approximately 10–20%, particularly in the submandibular gland.
Gland-Specific Distribution
| Feature | Submandibular Gland | Parotid Gland | Sublingual / Minor Glands |
|---|---|---|---|
| Frequency | 80% of all sialolithiasis [1][3] | 20% [1] | Rare |
| Stone size | Tend to be larger | Tend to be smaller, multiple | Variable |
| Stone location | More often in the duct (Wharton's duct) | More often within the gland itself | Variable |
| Radiopacity | 90% radiopaque [1] | 90% radiolucent [1] | Variable |
3. Anatomy and Function of the Salivary Glands
Understanding the anatomy is absolutely essential to understanding why stones form where they do.
- The parotid gland is the largest salivary gland, located anterior and inferior to the ear, draped over the posterior ramus of the mandible.
- Its duct is Stensen's duct (parotid duct):
- The facial nerve (CN VII) runs through the substance of the parotid gland, dividing it into superficial and deep lobes. This is critically important surgically — any surgery on the parotid risks facial nerve injury.
- The parotid gland produces serous (watery) saliva.
- The submandibular gland lies in the submandibular triangle, below the floor of the mouth and wraps around the posterior border of the mylohyoid muscle.
- Its duct is Wharton's duct (submandibular duct):
- Runs from the deep part of the gland, coursing anteriorly and superiorly along the floor of the mouth
- Opens at the sublingual caruncle (small papilla on either side of the lingual frenulum) on the floor of the mouth [2]
- The duct is long (~5 cm) and tortuous, and courses upward against gravity from the gland to its opening
- The submandibular gland produces mixed (serous + mucinous) saliva — importantly, the mucinous component makes the saliva more viscous and alkaline.
- The lingual nerve (branch of CN V3) and hypoglossal nerve (CN XII) are in close relation to the gland and duct — relevant for surgical complications.
- Smallest of the major salivary glands, lies beneath the mucosa of the floor of the mouth.
- Drains via multiple small ducts (ducts of Rivinus), some of which join to form the duct of Bartholin, which opens into or near Wharton's duct.
- Produces predominantly mucinous saliva.
Saliva has multiple critical functions:
- Lubrication and facilitation of swallowing
- Antimicrobial (contains IgA, lysozyme, lactoferrin)
- Buffering of oral pH
- Digestive (salivary amylase for starch)
- Remineralisation of teeth (calcium and phosphate)
Normal daily salivary output is approximately 1–1.5 litres/day. The submandibular glands contribute ~70% of resting salivary output. The parotid glands contribute the majority of stimulated salivary output.
4. Etiology and Risk Factors (with Pathophysiology)
This is a favourite exam question. 80% of sialolithiasis occurs in the submandibular gland [1][3] because of four anatomical and physiological reasons:
- Wharton's duct is long and large — a longer ductal system gives more opportunity for stasis and stone formation [2].
- Saliva flow is against gravity — the duct courses superiorly from the gland (below the mylohyoid) to its opening on the floor of the mouth. Gravity works against drainage [2].
- Saliva is more alkaline — the higher pH favours calcium phosphate precipitation [2].
- Higher mucin and Ca²⁺ content — submandibular saliva is mixed seromucinous (more viscous), with higher calcium concentration. This is the key substrate for calculus formation [2].
In contrast, the parotid gland produces serous (watery, low-viscosity) saliva with lower calcium content, and Stensen's duct is shorter and more horizontal — all protective against stone formation.
Exam Must-Know
When asked "Why is sialolithiasis most common in the submandibular gland?", always give these four reasons: (1) long duct, (2) flow against gravity, (3) alkaline saliva, (4) high mucin and calcium content. This is a classic exam answer [2].
Salivary stones are composed largely of calcium phosphate and hydroxyapatite (the same mineral found in bone and teeth), embedded in an organic matrix of glycoproteins and mucopolysaccharides [2]. This is why most submandibular stones (90%) are radiopaque — they are heavily calcified. Parotid stones tend to have more organic matrix and less calcification, which is why 90% are radiolucent [1].
| Category | Risk Factor | Mechanism |
|---|---|---|
| Hydration | Dehydration | Reduced salivary flow → stasis → supersaturation of calcium salts |
| Metabolic | Hypercalcaemia (e.g., hyperparathyroidism) | Increased calcium in saliva → favours stone precipitation |
| Gout (hyperuricaemia) | Uric acid crystals can serve as nidus; altered salivary composition | |
| Nephrolithiasis | Shared metabolic predisposition (hypercalciuria, dehydration) [2] | |
| Oral | Chronic periodontal disease | Local inflammation and debris may serve as a nidus for stone formation |
| Drugs | Anticholinergics | Reduce salivary secretion → stasis → stone formation [2] |
| Diuretics | Cause systemic dehydration → reduced salivary flow | |
| Social | Smoking | Reduces salivary flow; alters saliva composition; chronic inflammation of ducts |
| Trauma | Direct ductal injury → stricture → obstruction → stasis [2] |
Drug History is Key
Always ask about anticholinergics (e.g., antihistamines, tricyclic antidepressants, antipsychotics, oxybutynin) and diuretics. These are common culprits that reduce salivary flow and predispose to stone formation. Post-operative patients who are NPO, intubated, and on anticholinergics are at particular risk [2].
5. Pathophysiology
The fundamental process is:
Step by step:
-
Stagnation: Any factor that reduces salivary flow (dehydration, drugs, anatomical kinking) causes saliva to pool, particularly in the long, gravity-dependent Wharton's duct [2].
-
Supersaturation: The stagnant saliva, already rich in Ca²⁺ and mucin, becomes supersaturated with calcium phosphate.
-
Nucleation: Precipitation occurs around an organic nidus — this can be a mucus plug, desquamated epithelial cells, bacteria, or even foreign material. This is analogous to Randall's plaque in nephrolithiasis (calcium crystals in the interstitial space serving as a nidus) [4].
-
Stone growth: Layers of calcium phosphate and hydroxyapatite are deposited concentrically around the nidus, forming a progressively larger calculus.
-
Obstruction: The stone partially or completely obstructs the duct.
-
Partial obstruction → episodic, meal-related swelling and pain (saliva production increases with eating but cannot drain past the stone → gland swells → pain → as eating stops, gland slowly decompresses → symptoms resolve) [1][2].
-
Complete, chronic obstruction [2]:
- Initially: persistent gland swelling
- Over time: the gland ceases to produce saliva (pressure atrophy of acinar cells)
- The gland becomes firm and fibrosed, and swelling actually regresses
- This can be mistaken for a focal mass/tumour clinically
- Patient becomes asymptomatic — no saliva production means no build-up of pressure
-
Chronic sialadenitis results from destruction of gland tissue after acute infection and blockage of saliva drainage [1].
Clinical Pearl
A firm, non-tender submandibular gland that the patient says "used to swell but doesn't anymore" is classic for chronic obstruction with gland atrophy. Don't mistake it for a tumour. The history of prior episodic meal-related swelling is the key differentiator.
Stagnant saliva behind an obstructing stone is an ideal culture medium for bacteria [3]. Bacteria from the oral cavity can ascend through the duct orifice into the stagnant pool, causing:
- Acute sialadenitis: fever, chills, severe pain, erythema, purulent discharge from the duct orifice [3]
- Abscess formation: if untreated, may threaten the airway (particularly submandibular space infections → Ludwig's angina) [2]
Complications of sialolithiasis include: sialadenitis, ductal ectasia, and stricture [1].
6. Classification
Sialolithiasis can be classified by several axes:
- Intraductal (within the duct) — more common in submandibular stones; more amenable to transoral removal or sialoendoscopy
- Intraglandular (within the gland parenchyma) — more common in parotid stones; often requires gland excision if symptomatic
- Single stone: ~75% of cases [1]
- Multiple stones: ~25%
- Acute — episodic meal-related swelling and pain (partial obstruction)
- Chronic — persistent swelling, fibrosed gland, possible superinfection
- Complicated — sialadenitis, abscess, stricture, ductal ectasia
7. Clinical Features
| Symptom | Description | Pathophysiological Basis |
|---|---|---|
| Recurrent swelling of the affected gland | Episodic gland enlargement, often worse with eating or even anticipation of eating [1][2] | Eating stimulates salivary secretion (via parasympathetic stimulation). If the duct is obstructed by a stone, saliva accumulates behind it → gland distends → swelling. Between meals, secretion rate drops and saliva slowly seeps past the stone → gland decompresses. |
| Pain ("salivary colic") | Colicky postprandial glandular pain [3] — sharp, cramping pain in the region of the gland, worse with eating [1] | Same mechanism as above. Distension of the gland capsule and duct by trapped saliva stimulates nociceptors → pain. Analogous to biliary colic (gallstone obstructing bile duct during fat digestion). |
| Waxing and waning symptoms | Symptoms come and go, often with meals | Partial obstruction: stone acts as a ball-valve, intermittently blocking and then allowing flow [2]. |
| Painless swelling (30%) | 30% of patients with submandibular sialolithiasis present with painless swelling [2] | Slow, progressive obstruction → gradual gland enlargement without acute distension → less pain. Or chronic obstruction → gland atrophy → firm, non-tender mass. |
| Salty or foul taste in mouth | Intermittent bad taste | Stagnant, infected saliva occasionally draining past the stone into the mouth. |
| Dry mouth (if bilateral or severe) | Reduced salivary output | Obstructed gland cannot contribute to oral moisture. |
Symptoms of Superimposed Sialadenitis
| Symptom | Pathophysiological Basis |
|---|---|
| Fever and chills | Systemic inflammatory response to bacterial infection in the obstructed gland [2] |
| Worsening pain | Inflammatory oedema and pus within the gland capsule → increased pressure → more pain |
| Purulent taste | Pus draining from the duct orifice into the mouth |
| Sign | Description | Pathophysiological Basis |
|---|---|---|
| Gland enlargement | Visible/palpable swelling in the submandibular triangle (submandibular stones) or pre-auricular/angle of jaw region (parotid stones) | Accumulation of saliva behind the obstructing stone → glandular distension |
| Gland tenderness | Tender on palpation, especially during or after meals | Ductal distension stretching the gland capsule → nociceptor activation |
| Firm, non-tender gland (chronic) | In chronic obstruction, gland is firm and rubbery | Gland fibrosis and atrophy from prolonged obstruction; may mimic a tumour [2] |
| Palpable stone | A hard, smooth or irregular structure palpable in the floor of the mouth (Wharton's duct) or buccal mucosa (Stensen's duct) | Direct palpation of the calcified calculus within the duct |
| Visible stone at duct orifice | Small stones may be visible at the sublingual caruncle or parotid papilla, moving in and out of view with gland compression [2] | Stone at the distal end of the duct, partially extruding through the orifice |
| Erythema and swelling over the gland | Red, swollen, warm skin over the gland | Acute sialadenitis: inflammatory vasodilatation and oedema |
| Purulent discharge from the duct | Pus expressed from the ductal orifice when the gland is milked [1][3] | Bacterial infection in stagnant saliva → suppuration → pus drains along the duct |
| Absent or reduced saliva flow | When gland is compressed/milked, no clear saliva is seen flowing from the duct | Duct is obstructed → saliva cannot reach the orifice |
| Trismus (if parotid abscess) | Difficulty opening the mouth | Parotid abscess spreading to involve the masseter or medial pterygoid → muscle spasm |
| Induration of the floor of mouth | Firm swelling of the floor of mouth | Large Wharton's duct stone or associated submandibular abscess |
Examination of salivary glands and ducts [2]:
Bimanual palpation is the key technique:
-
For Wharton's duct (submandibular):
- Palpate the floor of mouth in a posterior-to-anterior direction
- One finger intraorally on the floor of the mouth, other hand externally on the submandibular triangle
- Have the patient close their mouth slightly to relax the musculature of the floor of mouth — this facilitates examination [2]
- Stones are typically rock hard, small, smooth or irregular, mostly felt within the ductal system [2]
-
For Stensen's duct (parotid):
-
General principles:
Exam Tip — Bimanual Palpation
Bimanual palpation of the floor of the mouth is the single most important clinical skill for detecting submandibular stones. One finger inside the mouth, one hand outside. Roll the tissues between your fingers. A stone feels like a hard pebble in the duct. If you can express pus from the orifice, that confirms secondary sialadenitis.
| Pathophysiology | → Clinical Consequence |
|---|---|
| Partial ductal obstruction by stone | Episodic meal-related swelling and pain (waxing/waning) |
| Complete chronic obstruction | Persistent swelling → eventual gland atrophy → firm, asymptomatic mass |
| Stagnant saliva behind stone | Bacterial colonization → acute sialadenitis (fever, purulent discharge) |
| Abscess formation in gland | Fluctuant mass, marked toxicity, airway compromise risk |
| Chronic inflammation/fibrosis | Ductal stricture, ductal ectasia, gland destruction |
| Gravity-dependent anatomy of Wharton's duct | Submandibular stones are 4× more common than parotid |
| High Ca²⁺ + mucin in submandibular saliva | Stones are larger and more radiopaque in submandibular gland |
High Yield Summary
-
Definition: Sialolithiasis = calcified stones in salivary glands/ducts; most common cause of obstructive salivary gland disease.
-
80% submandibular gland, 20% parotid [1]. Sublingual/minor glands rare.
-
Only 1 stone in 75% of cases [1].
-
Why submandibular? Long duct, flow against gravity, alkaline saliva, high mucin and Ca²⁺ content.
-
90% of submandibular stones are radiopaque; 90% of parotid stones are radiolucent [1].
-
Composition: Calcium phosphate and hydroxyapatite in an organic matrix.
-
Presentation: recurrent swelling and pain, worse with eating ("salivary colic") [1].
-
30% of submandibular sialolithiasis presents with painless swelling [2].
-
Complications: sialadenitis, ductal ectasia, and stricture [1].
-
Examination: Bimanual palpation of floor of mouth (submandibular) or buccal mucosa (parotid). Look for palpable stone, express saliva/pus from duct orifice.
-
Chronic sialadenitis is most commonly caused by stones → destruction of gland tissue after acute infection + blockage of saliva drainage [1].
-
Risk factors: Dehydration, anticholinergics, diuretics, hypercalcaemia, gout, smoking, chronic periodontal disease.
Active Recall - Sialolithiasis (Definition to Clinical Features)
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf (p26, p45, p52, p56, p57) [2] Senior notes: felixlai.md (sections 325–330) [3] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p27, p28) [4] Senior notes: maxim.md (section 644 — Randall's plaque concept in urolithiasis, applied by analogy)
Differential Diagnosis of Sialolithiasis
When a patient presents with a swelling or pain in the region of a salivary gland — particularly episodic, meal-related swelling — sialolithiasis is at the top of the list, but it is by no means the only possibility. The differential diagnosis can be broadly organised into categories based on the clinical question you are really asking yourself: "Is this an obstructive problem, an infectious problem, an autoimmune problem, or a neoplastic problem?"
The lecture slides explicitly prompt you to consider: Is it really a parotid swelling? and Is it really a submandibular gland swelling? — because several non-salivary conditions can mimic salivary gland pathology [1].
Differential Diagnoses — Detailed Discussion
1. Obstructive Causes
The cardinal features — recurrent swelling, pain worse with eating [1], colicky postprandial glandular swelling and pain [3] — are essentially pathognomonic. The key pathophysiological link is that eating triggers parasympathetic-mediated salivary secretion, which cannot flow past the obstructing stone, so the gland distends and hurts. When eating stops, secretion rate drops and symptoms gradually resolve [2].
Why this matters as a DDx anchor: If the swelling is episodic, clearly meal-related, and unilateral, sialolithiasis is the most likely diagnosis until proven otherwise.
- A stricture (fibrotic narrowing) of the salivary duct can mimic sialolithiasis exactly — episodic, meal-related swelling and pain — because the mechanism is the same: outflow obstruction.
- Strictures often form as a complication of prior sialolithiasis or chronic sialadenitis [1] (inflammation → fibrosis → narrowing).
- Differentiation requires imaging (sialography or sialoendoscopy) — a stricture will show ductal narrowing without a calcified stone.
- Complications of sialolithiasis include: sialadenitis, ductal ectasia, and stricture [1].
- Inspissated (thickened) mucus can transiently obstruct the duct, mimicking sialolithiasis.
- More common in dehydrated patients or those on anticholinergics.
- Tends to resolve spontaneously with hydration and gland massage; no stone seen on imaging.
A ranula is a bluish cystic swelling in the floor of the mouth ("belly of a frog") — it is a mucus retention cyst arising from a blocked sublingual gland [5]. It presents as a translucent, fluctuant mass in the floor of the mouth. It can be confused with a submandibular duct stone if it is large, but it is cystic (not hard), and there is no meal-related pain pattern. Definitive treatment is excision of the pseudocyst together with resection of the sublingual gland [5].
Why it enters the DDx: Both ranula and a submandibular stone can cause floor-of-mouth swelling. The distinguishing feature is that a ranula is soft, bluish, and cystic, while a stone is hard and palpable within the duct.
2. Infectious Causes
- Acute suppurative sialadenitis in the absence of sialolithiasis is a distinct entity that typically affects older adults, malnourished or post-operative patients [2].
- Commonly caused by Staphylococcus aureus [1][2], but S. viridans, S. pneumoniae, H. influenzae, and Bacteroides species have also been isolated [2].
- Characterized by sudden onset of a very firm and tender swelling of the involved gland [2].
- Fever and chills are present with fairly marked systemic toxicity [2].
- Purulent discharge can be expressed from the affected duct orifice — this is essentially diagnostic [2][3].
- The lecture slides specifically teach: Acute parotitis occurs in dehydrated, infirmed elderly; presents with tender swelling, pus from duct opening; S. aureus is the organism; treatment is rehydration and IV antibiotics [1].
Why this is a DDx: Both sialolithiasis and acute bacterial sialadenitis cause a painful, swollen salivary gland. The key distinction: sialolithiasis has episodic, meal-related symptoms; acute bacterial sialadenitis has constant, progressive pain with systemic toxicity and pus from the duct. Of course, they often coexist — sialolithiasis is the most common cause of sialadenitis (obstruction → stasis → infection).
- Low-grade chronic infection that eventually leads to destruction of the salivary gland [2].
- Occurs in patients with decreased salivary secretion and increased mucus content in the saliva [2].
- Predisposing factors include stones, strictures, and trauma [2].
- Chronic sialadenitis is most commonly caused by stones [1] — so sialolithiasis and chronic sialadenitis are deeply intertwined.
- The lecture slides describe: Chronic sialadenitis: destruction of gland tissue after acute infection, blockage of saliva drainage [1].
- Presentation: mild pain, worsens after meal; recurrent parotid or submandibular swelling after meal [1].
Why it is a separate DDx: Chronic sialadenitis can exist without a demonstrable stone — the original stone may have passed, leaving behind a damaged, strictured duct and chronically inflamed gland. Or the cause may be autoimmune (see Sjögren's below).
- Commonest viral cause is mumps [1][2] — the classic childhood parotitis, though it can affect adults.
- Other viruses: Coxsackievirus, CMV, Influenza [1], as well as parainfluenza, HSV, EBV, and HIV [2].
- Mumps: acute pain and swelling of one or both parotid glands, associated with a non-specific prodrome of low-grade fever, malaise, headache, myalgia, and anorexia [2].
- Diagnosis by clinical features and serology [1].
Why this is a DDx: Viral parotitis causes bilateral parotid swelling, which can superficially look like bilateral sialolithiasis. However, viral parotitis has a systemic prodrome, is usually bilateral, and does not have meal-related episodic worsening. There is no palpable stone and no pus from the duct (it is non-suppurative).
Suppurative vs Non-Suppurative
A quick bedside test: milk the gland and look at the duct orifice. If pus comes out → bacterial (suppurative) sialadenitis. If clear saliva or nothing comes out → viral sialadenitis, stone, or autoimmune. This is the single most useful clinical manoeuvre for triaging the differential.
3. Autoimmune / Systemic Causes
- Chronic inflammatory disorder characterised primarily by diminished lacrimal and salivary gland secretions resulting in symptoms of dry eyes and mouth (sicca complex) [2].
- Presents with gradual swelling of parotid or submandibular glands, typically bilaterally [2].
- Autoimmune sialadenitis causes parenchymal destruction and dilation of intraglandular ducts [2].
- The lecture slides reinforce that chronic sialadenitis can be caused by autoimmune disease (Sjögren syndrome) [1].
- Key clinical features: dry eyes (keratoconjunctivitis sicca), dry mouth (xerostomia), positive anti-Ro/SSA and anti-La/SSB antibodies, lymphocytic infiltration on minor salivary gland biopsy.
Why this is a DDx: Sjögren's causes bilateral, chronic, gradually progressive salivary gland swelling — quite different from the episodic, unilateral, meal-related pattern of sialolithiasis. However, reduced salivary flow in Sjögren's can predispose to stone formation, so both conditions can coexist.
- Extrapulmonary sarcoidosis affecting salivary glands [2].
- Characterised by bilateral painless parotid enlargement due to granulomatous infiltration [2].
- Heerfordt syndrome (uveoparotid fever) is a classic presentation: parotid enlargement + uveitis + facial nerve palsy + fever.
- Other features of sarcoidosis (bilateral hilar lymphadenopathy, erythema nodosum, elevated ACE) help clinch the diagnosis.
Why this is a DDx: Bilateral, painless parotid enlargement can initially raise the question of stones or tumour. The key differentiators are bilaterality, painlessness, and systemic features of sarcoidosis.
4. Neoplastic Causes
- Pleomorphic adenoma: slow-growing, painless mass; parotid — 90% in superficial lobe, most in tail of gland; minor salivary gland — lateral palate, submucosal mass; malignant degeneration 10–15% risk in 10 years [1].
- Warthin tumour (papillary cystadenoma lymphomatosum): second most common benign parotid tumour; strongly associated with smoking; can be bilateral.
Why this is a DDx: A chronic, slowly enlarging, painless parotid or submandibular mass could be either a tumour or a chronically obstructed, atrophied gland from sialolithiasis. Recall from the previous section: chronic complete obstruction causes the gland to become firm and asymptomatic — mimicking a focal mass [2]. Imaging (USG, CT) and FNA are required to differentiate.
- Mucoepidermoid carcinoma (most common malignant salivary tumour), adenoid cystic carcinoma, acinic cell carcinoma, carcinoma ex pleomorphic adenoma.
- Key red flags for malignancy: rapid growth, pain, fixation to skin/deeper structures, facial weakness (especially parotid malignancy involving CN VII) [2], cervical lymphadenopathy, mucosal ulceration, pain and paraesthesia [2].
- Rule of thumb: The smaller the salivary gland, the higher the probability that a neoplasm arising in it is malignant [2]. (e.g., a tumour in a minor salivary gland on the palate has a > 50% chance of being malignant; a parotid tumour has ~20% malignancy rate.)
5. Non-Salivary Mimics ("Is it really a salivary gland swelling?")
The lecture slides make a point of emphasising these mimics [1]:
| Mimic | Distinguishing Features |
|---|---|
| Masseter hypertrophy | Bilateral, firm, non-tender enlargement over the angle of mandible; becomes more prominent with jaw clenching (ask patient to clench teeth); no meal-related symptoms [1] |
| Neck lymph nodes | Multiple, may be tender if reactive; mobile or fixed depending on cause; not related to eating; check for sources of infection or malignancy in the drainage area [1] |
| Lipoma, vascular malformations | Lipoma: soft, mobile, non-tender, no change with meals. Vascular malformation: compressible, may change size with Valsalva [1] |
| Mimic | Distinguishing Features |
|---|---|
| Enlarged submandibular lymph node | Firm or rubbery, may be multiple, not meal-related; look for oral cavity pathology, dental infection, or head and neck malignancy draining to level I nodes [1] |
| Oral cavity mass with direct extension to submandibular space | Requires intraoral examination — a floor-of-mouth carcinoma or other oral cavity mass may extend through the mylohyoid into the submandibular space and feel like a gland mass from outside [1] |
Exam Must-Know — Always Consider Non-Salivary Mimics
Before diagnosing a salivary gland condition, always confirm that the swelling truly arises from the salivary gland. Masseter hypertrophy, cervical lymphadenopathy, lipoma, vascular malformations, and oral cavity masses extending into the submandibular space are all common mimics highlighted in the lecture slides [1]. Always perform an intraoral examination.
6. Other Causes of Bilateral Parotid Swelling (Sialadenosis and Drug-Induced)
- Non-inflammatory, non-neoplastic hypertrophy of the salivary gland [2].
- Usually bilateral and painless [2].
- Associated conditions: Anorexia/Bulimia nervosa (self-induced vomiting causes reflex parotid hypertrophy), alcoholic cirrhosis, diabetes mellitus [2].
- Mechanism: autonomic neuropathy of the myoepithelial cells → acinar cell enlargement → gland hypertrophy without inflammation.
- Phenytoin and other drugs can cause bilateral parotid swelling [2].
- Mechanism is thought to involve altered autonomic innervation or direct acinar cell effects.
| Condition | Laterality | Meal-Related? | Pain? | Pus from Duct? | Key Distinguishing Feature |
|---|---|---|---|---|---|
| Sialolithiasis | Usually unilateral | Yes | Yes (colicky) | Only if secondary sialadenitis | Palpable stone; radiopaque on X-ray (submandibular) |
| Acute bacterial sialadenitis | Usually unilateral | No | Yes (constant, severe) | Yes | Systemic toxicity, S. aureus, dehydrated/elderly patient |
| Chronic sialadenitis | Usually unilateral | Mild worsening | Mild | No (unless acute flare) | History of recurrent infections; stone may have passed |
| Viral sialadenitis (Mumps) | Often bilateral | No | Yes | No | Prodrome, bilateral, serology |
| Sjögren syndrome | Bilateral | No | No (or mild) | No | Dry eyes + dry mouth; anti-Ro/SSA, anti-La/SSB |
| Sarcoidosis | Bilateral | No | No | No | Bilateral painless parotid enlargement; systemic features |
| Pleomorphic adenoma | Unilateral | No | No | No | Slow-growing, painless mass; FNA diagnostic |
| Malignant tumour | Unilateral | No | Possible | No | Rapid growth, facial nerve palsy, fixation |
| Sialadenosis | Bilateral | No | No | No | Non-inflammatory; bulimia, alcoholism, DM |
| Ranula | Unilateral (floor of mouth) | No | No | No | Bluish cystic swelling in floor of mouth |
| Masseter hypertrophy | Bilateral | No | No | N/A | Prominent with jaw clenching; not a gland at all |
These are mentioned in the lecture slides under chronic sialadenitis investigations [1]:
- Clinical examination (bimanual palpation, express saliva from duct) [1]
- USG / sialogram — rule out stones or other masses [1]
- Rule out Sjögren syndrome (serology: anti-Ro/SSA, anti-La/SSB; Schirmer's test; minor salivary gland biopsy) [1]
The imaging modalities will be discussed in detail in the Diagnosis section, but the key principle is:
Ultrasound is the first-line imaging for any salivary gland swelling — it differentiates stones from tumours from lymph nodes, is non-invasive, and detects > 90% of stones ≥ 2 mm [2].
High Yield Summary
-
The DDx of sialolithiasis broadly includes: obstructive (stone, stricture, mucous plug, ranula), infectious (acute/chronic bacterial sialadenitis, viral sialadenitis), autoimmune (Sjögren syndrome), granulomatous (sarcoidosis), neoplastic (benign — pleomorphic adenoma, Warthin tumour; malignant — mucoepidermoid CA), sialadenosis (non-inflammatory hypertrophy), and non-salivary mimics (masseter hypertrophy, lymphadenopathy, lipoma, oral cavity mass).
-
The single most useful bedside manoeuvre: milk the gland and inspect the duct orifice — pus = bacterial sialadenitis; stone visible = sialolithiasis; nothing = obstruction/atrophy/tumour.
-
Always confirm the swelling is truly salivary gland — lecture slides emphasise mimics: masseter hypertrophy, neck lymph nodes, lipoma, vascular malformations, oral cavity mass extending to submandibular space [1].
-
Episodic, meal-related, unilateral = obstructive (sialolithiasis until proven otherwise). Bilateral, painless, chronic = autoimmune (Sjögren) or sialadenosis. Acute, tender, purulent, systemic toxicity = acute bacterial sialadenitis.
-
Chronic sialadenitis investigations: clinical, USG/sialogram to rule out stones/masses, rule out Sjögren syndrome [1].
-
Pleomorphic adenoma has 10–15% malignant degeneration risk in 10 years — any long-standing salivary lump should be investigated [1].
Active Recall - Differential Diagnosis of Sialolithiasis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf (p38, p50, p51, p52, p53, p54, p56, p61) [2] Senior notes: felixlai.md (sections 321, 325–330, 336) [3] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p27, p28) [5] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p26)
Diagnostic Criteria, Diagnostic Algorithm and Investigations for Sialolithiasis
Sialolithiasis does not have a formal set of "diagnostic criteria" in the way that, say, rheumatic fever (Jones criteria) or SLE (ACR/EULAR criteria) does. Instead, the diagnosis is made by the combination of compatible clinical features + confirmatory imaging. In practical terms, you need two things:
- A clinical picture consistent with salivary duct obstruction: episodic, meal-related, unilateral gland swelling ± pain (or chronic firm gland) — i.e., the history and examination point to an obstructive salivary problem.
- Demonstration of a calculus on imaging (or directly visualised on examination / at sialoendoscopy).
Sometimes the diagnosis is made purely clinically — if you can palpate a rock-hard stone in the duct or see it at the duct orifice, that is diagnostic without any imaging at all [2]. But in most cases, imaging confirmation is sought.
When is the Diagnosis 'Confirmed'?
The diagnosis of sialolithiasis is confirmed when a stone is directly visualised (at the duct orifice, on sialoendoscopy) or demonstrated on imaging (USG, X-ray, CT). A classic history of meal-related colicky gland swelling is highly suggestive but not confirmatory — you could have a ductal stricture or mucous plug producing identical symptoms.
The approach to diagnosing sialolithiasis follows a logical sequence: History → Examination → First-line imaging → Second-line imaging (if needed) → Interventional diagnostic/therapeutic procedure. Here is the full algorithm:
Investigation Modalities — Detailed Discussion
1. Clinical Examination (The "Zero-Cost Investigation")
Clinical examination is not just a prelude to imaging — it can be diagnostic on its own.
Intraoral inspection is explicitly taught on the lecture slides [1] and should assess:
- Parotid duct opening (Stensen's duct orifice — opposite upper 2nd molar on buccal mucosa) [1]
- Submandibular duct opening (Wharton's duct orifice — sublingual caruncle on floor of mouth) [1]
- Floor of mouth swelling (may indicate a large Wharton's duct stone or ranula) [1]
- Tumour in floor of mouth / oral cavity (to exclude non-salivary causes) [1]
- Pus in the salivary duct openings — if present, indicates secondary sialadenitis [1][3]
Why inspect the duct orifice? Small stones may be visible at the duct orifice, sometimes moving in and out of view with compression of the gland [2]. A stone at the orifice can be directly removed then and there.
Palpation of the glands and ducts is the next critical step [1]:
- Confirm the lesion is not arising from the skin (i.e., pinch the overlying skin — if the lump moves independently of skin, it is deeper) [1]
- Palpate the ducts for stones [1]
- Express pus from the duct by milking the gland [1]
The lecture slides honestly state: "Cannot really differentiate between submandibular lymph nodes or gland/submandibular tumour" and "Also difficult to ascertain mass is a parotid tumour" by palpation alone [1] — which is why imaging is almost always needed.
Specific technique (detailed from senior notes [2]):
| Duct | Technique | Key Findings |
|---|---|---|
| Wharton's duct (submandibular) | Palpate the floor of mouth in a posterior-to-anterior direction; have the patient close their mouth slightly to relax the floor-of-mouth musculature [2] | Stone felt as rock-hard, small, smooth or irregular structure in the duct |
| Stensen's duct (parotid) | Palpate the buccal mucosa around the orifice; then palpate externally from the earlobe forward along the jaw-line with one hand outside, one inside the mouth [2] | Stone felt along the duct course; may be harder to palpate than submandibular stones |
Expected normal findings: The gland should feel spongy and elastic. Clear saliva should flow from the duct when the gland is compressed [2]. Absence of saliva flow, turbid/purulent discharge, or a palpable hard structure are all abnormal.
Exam Tip — The Bimanual Exam
In an OSCE station, always demonstrate bimanual palpation of the floor of the mouth for submandibular pathology. One finger intraorally, one hand extraorally. Tell the examiner: "I am checking for palpable stones in Wharton's duct and will attempt to express saliva from the orifice to assess for pus or obstruction."
Ultrasound is the first-line investigation for any salivary gland swelling [1].
Why USG first?
- Non-invasive, no radiation, widely available, inexpensive, real-time
- Can be performed at the bedside or in clinic
- Excellent for superficial structures like salivary glands
What USG can do (from lecture slides [1] and senior notes [2]):
| Capability | Explanation |
|---|---|
| Confirm origin of mass | Determine whether a palpable lump truly arises from the salivary gland or from adjacent structures (lymph node, masseter, etc.) [1] |
| Detect stones | > 90% of stones ≥ 2 mm in diameter can be detected [2]. Stones appear as hyperechoic foci with posterior acoustic shadowing — the same principle as detecting gallstones on abdominal USG |
| Detect dilated ducts | Proximal ductal dilatation behind an obstructing stone is a key indirect sign [1] |
| Enlarged neck lymph nodes | Assess for cervical lymphadenopathy [1] |
| Differentiate stones from masses and lymph nodes | Stones are hyperechoic with shadowing; tumours are hypoechoic solid masses; lymph nodes have a characteristic oval shape with echogenic hilum [2] |
| Detect radiolucent stones | Unlike plain X-ray, USG is not dependent on calcium content — it detects both radiopaque and radiolucent stones [2] |
| Detect stones superimposed on bone | Radiopaque stones overlying the mandible can be invisible on X-ray but detectable on USG [2] |
| Assess periglandular structures | Better than sialography for this purpose, and less invasive [2] |
Limitations of USG:
- Operator-dependent
- Cannot visualise the deep portion of the parotid gland well (acoustic shadow from mandible)
- May miss very small stones ( < 2 mm) or stones deep within the gland parenchyma
- Cannot assess the full length of the duct in detail (cf. sialoendoscopy)
Typical USG findings in sialolithiasis:
- Hyperechoic focus within the duct or gland with posterior acoustic shadowing
- Dilated duct proximal to the stone
- Enlarged, oedematous gland if secondary sialadenitis is present (diffusely hypoechoic, increased vascularity on Doppler)
Plain X-ray can detect radiopaque stones — but its utility depends entirely on which gland is affected [1][2]:
| Gland | Radiopacity | X-Ray Usefulness |
|---|---|---|
| Submandibular | 90% radiopaque [1] | Good — most stones will be visible |
| Parotid | 90% radiolucent [1] | Poor — most stones will NOT be visible |
Views used:
- Occlusal view (lower): for submandibular duct stones — the X-ray film is placed in the patient's mouth on the floor of mouth, and the beam is directed from below the chin. This gives an excellent view of the floor of mouth and Wharton's duct.
- Lateral oblique / PA mandible: for proximal submandibular or parotid stones.
- AP/lateral cheek: for parotid duct stones.
Limitations (from lecture slides [1]):
- Still can miss small stones [1] — small calculi may be below the resolution of plain radiography
- Radiolucent stones (90% of parotid stones) will be invisible
- Stones superimposed on bone (e.g., overlying the mandible) may be obscured — USG is better for these [2]
Why X-ray is still sometimes used: It is cheap, quick, readily available, and if you see a calcified stone in the floor of mouth on an occlusal film in a patient with classic symptoms, that is essentially diagnostic. But it should not be relied upon as the sole investigation, especially for parotid stones.
High Yield Radiopacity Factoid
90% of submandibular stones are radiopaque; 90% of parotid stones are radiolucent [1]. This is one of the most frequently tested facts about sialolithiasis. The reason: submandibular stones are heavily calcified (calcium phosphate / hydroxyapatite predominate), while parotid stones have more organic matrix and less mineral content.
CT scan is the imaging modality of choice for evaluation of salivary stones [2].
Why CT is superior:
- Most stones contain enough Ca²⁺ to be visible on non-contrast imaging [2] — even stones that are "radiolucent" on plain X-ray (because the calcium content, while not enough to show on a plain film, is enough for the far greater contrast resolution of CT)
- Provides detailed anatomical information: exact stone location (intraductal vs intraglandular), size, number, relationship to surrounding structures
- Can identify complications: abscess formation, ductal dilatation, gland enlargement
- Can assess for differential diagnoses (tumour, lymphadenopathy)
Protocol: Non-contrast CT of the neck/face is usually sufficient. Contrast is added if sialadenitis/abscess is suspected (to delineate abscess walls and assess enhancement patterns).
Typical CT findings:
- Hyperdense calcified focus within the duct or gland on non-contrast CT
- Dilated duct proximal to the stone
- Gland enlargement and stranding of surrounding fat if sialadenitis is present
- Rim-enhancing collection if abscess has formed (on contrast-enhanced CT)
When to use CT over USG:
- USG inconclusive or technically limited
- Need to localise the stone precisely for surgical planning (transoral vs sialoendoscopy vs gland excision)
- Suspected complications (abscess, deep space infection)
- Parotid stones (deep gland involvement poorly seen on USG)
Sialography is a classical investigation that involves cannulation of the duct and injection of radiopaque contrast (dye), followed by plain films [2].
What it shows:
- The entire ductal anatomy in exquisite detail
- Stones appear as filling defects within the contrast-opacified duct
- Can identify strictures, sialectasis (ductal dilatation), and cystic degeneration of the duct and gland [2] — i.e., it is excellent for diagnosing non-stone causes of obstruction
Strengths (from lecture slides [1]):
- Useful for chronic sialolithiasis [1]
- May flush out stones or debris (therapeutic) — the act of injecting contrast under pressure can dislodge small stones [1]
Limitations and caveats:
- Superseded by USG / sialoendoscopy [1] — modern practice favours non-invasive imaging first
- Cannulation of the duct may be difficult [1] — especially if the orifice is oedematous or stenosed
- Contraindicated in patients with acute sialadenitis (risk of worsening infection/spreading bacteria) or contrast allergy [2]
- Largely supplanted by high-resolution CT scan and ultrasound [2]
When is sialography still used?
- When you suspect a ductal stricture or sialectasis rather than a stone (these are better characterised by sialography than by CT/USG)
- As a therapeutic manoeuvre — the hydraulic pressure of contrast injection may dislodge small stones
- In centres without access to sialoendoscopy
Sialoendoscopy (sialon = saliva, endo = within, scopy = looking) involves inserting a miniature endoscope directly into the salivary duct to visualise the lumen.
What it offers:
- Direct visualisation of the ductal anatomy, stones, strictures, mucous plugs
- Can find stones that have gone undetected by other imaging techniques [2]
- Simultaneously therapeutic: small stones can be retrieved with baskets or graspers; strictures can be dilated; the duct can be irrigated
- Can be performed after transoral calculus removal to check for residual stone fragments [2]
- Recent advance highlighted in lecture slides as the modern approach [3]
When to use sialoendoscopy:
- When USG/CT confirms a stone but its location makes transoral removal difficult (proximal duct, intraglandular)
- When imaging is inconclusive but clinical suspicion remains high
- When there is concern for stricture or other ductal pathology alongside or instead of a stone
- For combined diagnostic + therapeutic intent (increasingly the standard approach)
Standard MRI will NOT visualise stones [2] — this is because calcified structures have very low signal on all MRI sequences (they contain very few mobile protons). So MRI appears as a signal void, which is easily missed.
However, MRI has specific roles:
- MR sialography (heavily T2-weighted sequences) can show the ductal system non-invasively (saliva is bright on T2), revealing ductal dilatation, strictures, and filling defects (stones appear as signal voids within bright saliva)
- Tumour assessment: if the differential is between a stone and a salivary gland tumour, MRI provides excellent soft tissue contrast for tumour characterisation
- No radiation: useful in young patients or pregnant patients
Bottom line: MRI is not used to diagnose stones per se, but MR sialography can show ductal anatomy non-invasively, and MRI is the modality of choice when tumour is in the differential.
Blood tests do not diagnose sialolithiasis directly, but they are important for:
| Test | Purpose |
|---|---|
| FBC (Full blood count) | Leucocytosis suggests secondary infection (sialadenitis/abscess) |
| CRP / ESR | Elevated in sialadenitis; helps monitor treatment response |
| Serum calcium | To exclude hypercalcaemia as a predisposing cause (e.g., hyperparathyroidism) |
| Serum uric acid | To exclude gout/hyperuricaemia as a predisposing factor |
| Anti-Ro/SSA, Anti-La/SSB | Rule out Sjögren syndrome [1] — as emphasised on the lecture slides for chronic sialadenitis workup |
| Serum amylase | May be elevated in acute sialadenitis (salivary amylase, not pancreatic) |
| Blood culture | If septic from complicated sialadenitis/abscess |
| Investigation | Role | Key Findings in Sialolithiasis | Limitations |
|---|---|---|---|
| Clinical exam | Bedside; can be diagnostic | Palpable stone, visible stone at orifice, pus from duct | Cannot detect deep/small stones; cannot differentiate gland from LN |
| Ultrasound (first-line) [1] | First-line imaging | Hyperechoic focus + posterior shadowing; dilated duct | Operator-dependent; poor for deep parotid; misses < 2 mm stones |
| Plain X-ray [1] | Quick, cheap | Radiopaque calculus (90% submandibular) | Misses small stones; useless for radiolucent parotid stones (90%); bone overlap |
| CT scan (non-contrast) [2] | Imaging modality of choice for stones | Hyperdense calcified focus; precise localisation | Radiation; cost; does not show ductal anatomy as well as sialography |
| Sialogram [1] | Chronic / complex cases | Filling defect in duct; stricture; sialectasis | Superseded by USG / sialoendoscopy; difficult cannulation; contraindicated in acute sialadenitis |
| Sialoendoscopy [2][3] | Diagnostic + therapeutic | Direct stone visualisation; stricture; mucous plug | Requires specialised equipment and expertise; cannot access very proximal ducts or intraglandular stones |
| MRI [2] | Tumour assessment; MR sialography | Will not visualise stones directly; ductal anatomy on MR sialography | Not for stone detection; expensive; long scan time |
| Bloods | Supporting | Leucocytosis, ↑CRP (sialadenitis); ↑Ca²⁺ (hyperPTH); anti-Ro/La (Sjögren) | Not diagnostic for the stone itself |
The lecture slides provide a specific investigation list for chronic sialadenitis [1]:
- Clinical examination
- USG / sialogram — to rule out stones / other masses [1]
- Rule out Sjögren syndrome (serology: anti-Ro/SSA, anti-La/SSB; Schirmer test for dry eyes; minor salivary gland biopsy of lower lip for lymphocytic infiltration) [1]
This is because chronic sialadenitis is most commonly caused by stones, but Sjögren syndrome is an important alternative aetiology that must be excluded — the management is completely different (immunosuppression vs stone removal).
Investigation Hierarchy — How to Remember
Think of it as a "bedside → non-invasive imaging → invasive imaging → intervention" ladder:
- Bedside: History + bimanual palpation + express saliva from duct
- First-line imaging: USG (non-invasive, no radiation, detects > 90% of stones ≥ 2 mm)
- Second-line imaging: CT (imaging modality of choice — best for stone localisation and surgical planning) or Plain X-ray (quick screen for radiopaque stones)
- Third-line / specialised: Sialography (for ductal anatomy, strictures — largely superseded) or Sialoendoscopy (diagnostic + therapeutic — the modern approach)
- Supporting: Bloods (FBC, CRP, Ca²⁺, uric acid, Sjögren serology)
High Yield Summary
-
No formal diagnostic criteria — diagnosis = compatible clinical picture + demonstration of stone (palpable, visible, or on imaging).
-
Ultrasound is the first-line investigation [1] — detects > 90% of stones ≥ 2 mm; confirms gland origin; differentiates stone from tumour from lymph node; detects dilated ducts.
-
CT scan is the imaging modality of choice for definitive stone evaluation [2] — most stones visible on non-contrast CT regardless of radiopacity on X-ray.
-
Plain X-ray: useful for submandibular stones (90% radiopaque), poor for parotid stones (90% radiolucent); still can miss small stones [1].
-
Sialography: useful for chronic sialolithiasis; superseded by USG / sialoendoscopy; cannulation may be difficult; may flush out stones or debris (therapeutic); contraindicated in acute sialadenitis [1][2].
-
MRI will NOT visualise stones [2] — used for tumour assessment or MR sialography for ductal anatomy.
-
Sialoendoscopy is both diagnostic and therapeutic — the modern approach for stones beyond reach of transoral excision [2][3].
-
For chronic sialadenitis workup: Clinical + USG/sialogram to rule out stones/masses + rule out Sjögren syndrome [1].
-
Clinical exam: bimanual palpation for stone; milk gland to express saliva/pus from duct orifice. A palpable stone is diagnostic.
Active Recall - Diagnosis and Investigations of Sialolithiasis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf (p40, p41, p43, p44, p45, p54, p56) [2] Senior notes: felixlai.md (sections 325–330) [3] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p27, p28)
Management of Sialolithiasis
The management of sialolithiasis follows a simple, logical escalation ladder. Think of it from the patient's perspective: every salivary gland you can save is a gland that continues to produce saliva for the rest of their life. Modern management therefore follows a gland-preserving philosophy — you start with the least invasive option and escalate only if needed. Gland excision is the last resort.
The key decision points are:
- Is there active infection (sialadenitis)? → Treat the infection first before any stone removal.
- Where is the stone? (Distal duct → easily accessible transoral; proximal duct → sialoendoscopy; intraglandular → may need gland excision)
- How big is the stone? (Small stones may pass spontaneously; large stones need intervention)
- Is this recurrent or are there multiple stones? → Gland excision may be the definitive answer.
Treatment Modalities — Detailed Discussion
Conservative management is the first step for small, uncomplicated stones, and is also the supportive backbone of management at every stage [1][2].
The rationale is straightforward: if you can increase salivary flow and reduce viscosity, the increased hydraulic pressure may flush the stone out through the duct orifice naturally. This works best for small, distal stones.
Conservative — small stones to pass by themselves [1].
| Measure | Mechanism | Practical Details |
|---|---|---|
| Adequate hydration [2] | Increases overall fluid status → increases salivary production → more flow through the duct → hydraulic pressure to push the stone out | Encourage oral fluid intake of ≥ 2–3 L/day; IV fluids if the patient is acutely unwell or unable to tolerate oral intake |
| Sialogogues to promote ductal secretions [2] | Sialogogues (sialon = saliva, agogos = leading/promoting) are substances that stimulate salivary flow. They work by activating the gustatory reflex arc — sour taste → afferent via CN VII/IX → salivatory nuclei → efferent parasympathetic → salivary secretion | Examples include tart hard candies such as lemon drops [2]; used throughout the day as often as tolerated [2]. Vitamin C tablets, sour sweets, or even just sucking on a lemon wedge will work |
| Massaging the gland [2] | Mechanical compression of the gland squeezes saliva (and potentially the stone) toward the duct orifice | Gentle but firm external massage over the gland, directed anteriorly toward the duct opening |
| Milking the duct [2] | Specifically applies pressure along the course of the duct (posterior → anterior for Wharton's duct) to push the stone distally | Bimanual technique: intraoral finger on the floor of mouth presses the duct while external hand supports the gland |
| Apply moist heat to involved area [2] | Warmth causes local vasodilatation → reduces oedema around the stone → widens the duct lumen slightly → facilitates stone passage; also provides symptomatic pain relief | Warm compress or warm towel applied to the affected side of the face for 15–20 min, several times daily |
When conservative management is appropriate:
- Small stones ( < 5 mm)
- Distal location (near the duct orifice)
- First episode, mild symptoms
- No signs of infection
When conservative management is NOT enough:
- Large stones (unlikely to pass spontaneously)
- Proximal or intraglandular stones
- Recurrent episodes despite conservative measures
- Secondary sialadenitis or abscess
Clinical Pearl — Sialogogues
Sialogogues are underappreciated. Even after surgical stone removal, continuing sialogogues for weeks helps keep the duct flushed, preventing recurrence. They are essentially "physiotherapy for the salivary duct."
2. Medical Treatment
NSAIDs serve a dual purpose: analgesics and decrease inflammation [2].
- Why NSAIDs? Ductal obstruction causes capsular distension (pain) and local inflammation (swelling, oedema). NSAIDs inhibit cyclooxygenase (COX) → ↓ prostaglandin synthesis → ↓ pain and ↓ inflammatory swelling. Reducing periductal oedema also helps widen the duct lumen around the stone.
- Example: Ibuprofen [2].
- Alternative: Paracetamol if NSAIDs are contraindicated (renal impairment, peptic ulcer disease, aspirin-sensitive asthma).
Antibiotics are NOT needed for uncomplicated sialolithiasis. They are indicated if superinfection is suspected from increasing pain, fever or purulent discharge from the salivary duct [2].
- Rationale: Stagnant saliva behind the stone is colonised by oral bacteria that ascend through the duct. Once infection establishes (sialadenitis), antibiotics are needed to control sepsis before any stone removal is attempted.
- Anti-staphylococcal antibiotics should be administered because S. aureus is the most common organism in acute suppurative sialadenitis [2].
- Examples: dicloxacillin and cephalexin [2] — both are anti-staphylococcal β-lactams.
- Dicloxacillin (di- = two, clox- = cloxacillin derivative): a penicillinase-resistant penicillin → effective against MSSA (methicillin-sensitive S. aureus)
- Cephalexin (1st generation cephalosporin): good gram-positive coverage including MSSA
- For penicillin-allergic patients: clindamycin (also covers anaerobes, which is useful given the polymicrobial nature of many salivary infections).
- Duration: typically 7–10 days; lack of improvement or focal worsening within the gland despite antibiotics for 7–10 days suggests possibility of abscess formation [2] — at which point incision and drainage is needed.
The lecture slides for sialadenitis treatment reinforce: hydration, sialogogues, massage, heat, antibiotics during acute attacks [1].
Treat Infection Before Stone Removal
Never attempt transoral stone removal or sialoendoscopy in the setting of acute sialadenitis — the tissues are oedematous, friable, and there is a risk of spreading infection. Control the infection first (antibiotics, hydration, sialogogues), let the acute inflammation settle, then plan definitive stone removal.
3. Surgical Treatment — Gland-Preserving Approaches
The goal of modern surgery is to remove the stone while preserving the gland. The gland is only sacrificed when gland-preserving techniques are not feasible or have failed.
Transoral removal/excision [1] is the classic approach for distal duct stones.
- Indication: Stones that are palpable within the mouth are generally amenable to this procedure [2] — i.e., distal Wharton's duct stones that can be felt on bimanual palpation of the floor of mouth, or stones visible at the duct orifice.
- Technique: Under local anaesthesia, an incision is made over the stone in the floor-of-mouth mucosa directly over the palpable calculus. The stone is delivered. The duct is then either left open (marsupialisation) or loosely re-approximated.
- Treatment in the past included marsupialisation and calculus removal [3] — marsupialisation means opening the duct over the stone site and suturing the duct edges to the oral mucosa, creating a new, wider duct opening. This prevents stricture formation at the incision site.
Complications to watch for:
- Care must be taken to avoid excess trauma to the duct and associated sublingual glands to avoid formation of ranula — a ranula is a retention cyst on the floor of mouth that can form if the sublingual gland ductules are injured [2].
- Lingual nerve injury (sensory branch of CN V3): runs in close proximity to Wharton's duct on the floor of mouth. Damage causes numbness of the ipsilateral anterior 2/3 of the tongue and loss of taste (carried by chorda tympani which runs with lingual nerve).
- Wharton's duct stricture: if the duct heals with scarring at the incision site → future obstruction.
Advantages: Simple, quick, can be done under local anaesthesia, minimal morbidity, preserves the gland.
Limitations: Only works for distal, palpable stones. Cannot reach proximal duct or intraglandular stones.
Sialoendoscopy and removal [1] represents the recent advance [3] in sialolithiasis management and has transformed the field.
- What it is: A miniature semi-rigid or flexible endoscope (0.8–1.6 mm diameter) is introduced into the duct orifice and advanced along the duct to the stone.
- Technique: Once the stone is visualised, it can be retrieved with wire baskets, grasped with micro-forceps, or fragmented with laser lithotripsy (see below) before retrieval. The duct can also be dilated and irrigated.
- Sialoendoscopy may be utilized to visualize the ductal anatomy and to remove small stones that are beyond the reach of traditional transoral surgical procedures [2].
- Can find stones that have gone undetected by other imaging techniques [2].
- Can also be performed after traditional transoral calculus removal to check for presence of residual stone fragments [2] — this is an important quality-control step.
Indications:
- Stones in the proximal duct (beyond the reach of transoral excision)
- Small-to-moderate sized intraductal stones
- Failed conservative management
- Need for combined diagnostic + therapeutic procedure
- Post-transoral removal — to check for residual fragments
Limitations:
- Cannot access very proximal hilum or intraglandular stones in some cases
- Stone too large for endoscopic retrieval (may need lithotripsy first)
- Requires specialised equipment and training
- Duct may be too stenosed or inflamed to allow scope passage
Lecture slides highlight sialoendoscopy under both sialolithiasis treatment [1] and sialadenitis treatment: remove stones — exploration of submandibular duct, sialoendoscopy [1].
Extracorporeal lithotripsy [2] — "extra" = outside, "corporeal" = body, "litho" = stone, "tripsy" = crushing.
- What it is: Focused shock waves generated outside the body are directed at the stone to fragment it into smaller pieces that can then be flushed out naturally or retrieved endoscopically.
- Indicated in patients in whom a simple transoral surgical approach is not possible or fails — typically stones located in proximal ducts or in salivary glands themselves [2].
- Effective for intraductal stones < 7 mm [2].
Advantages: Non-invasive, no incision, can reach stones in proximal ducts or within the gland parenchyma.
Limitations:
- Less effective for large stones ( > 7 mm)
- Multiple sessions often required
- Fragments may not all be expelled — residual fragments can serve as nidi for recurrence
- Not widely available in all centres
- Contraindicated in patients with coagulopathies or acute sialadenitis
Laser lithotripsy [2] — performed inside the duct via a sialoendoscope.
- Performed via an endoscope to allow fragmentation of stones prior to endoscopic removal [2].
- A laser fibre (e.g., Holmium:YAG or Thulium laser) is passed through the working channel of the sialoendoscope and directed at the stone surface. Laser energy fragments the stone into smaller pieces which are then flushed out or retrieved with baskets.
Advantages: Allows treatment of larger stones that cannot be retrieved whole through the endoscope. Combined with sialoendoscopy, it is a single-session, gland-preserving procedure.
Limitations: Requires specialised equipment; risk of ductal injury from thermal effect; not suitable for intraglandular stones.
4. Surgical Treatment — Gland Excision (Definitive)
Excision of the gland [1] is the definitive, last-resort treatment when gland-preserving approaches are not feasible.
The lecture slides provide clear indications for gland excision [1]:
Excision of the gland:
- Proximal stone — inaccessible by scope or transoral excision
- Recurrent stones
- Multiple stones
An additional indication from the pathophysiology discussion:
- Destroyed gland from chronic sialadenitis: If the gland has already been destroyed by chronic inflammation/fibrosis (the end-stage of repeated infection/obstruction), there is no functioning gland left to save. Removing it eliminates a source of recurrent infection [1].
Treatment in the past relied heavily on submandibular gland excision [3] — this was the standard before sialoendoscopy became available. Now, gland excision is reserved for cases that fail minimally invasive approaches.
- Approach: External incision in the neck, ~2 cm below the lower border of the mandible (in a skin crease for cosmesis), following the submandibular triangle.
- Key structures at risk:
- Marginal mandibular branch of the facial nerve (CN VII): runs superficially along the lower border of the mandible — if damaged, the patient loses the ability to depress the lower lip on that side (asymmetric smile). This is the most important nerve to protect.
- Lingual nerve (CN V3): runs in intimate contact with the deep part of the submandibular gland (loops under Wharton's duct). Injury → numbness of ipsilateral anterior 2/3 of tongue + loss of taste.
- Hypoglossal nerve (CN XII): runs deep to the gland on the hyoglossus muscle. Injury → ipsilateral tongue deviation (tongue deviates toward the side of the lesion on protrusion because the contralateral genioglossus is unopposed).
- Much less commonly needed for sialolithiasis (parotid stones are rarer, and many can be managed endoscopically).
- Approach: Modified Blair incision (pre-auricular, extending behind the ear and into the neck).
- Key structure at risk: Facial nerve (CN VII) — runs through the substance of the parotid gland. The nerve must be identified and preserved. Superficial parotidectomy (removing only the superficial lobe) is the standard if the stone is in the superficial portion.
- Complications: facial nerve palsy (temporary or permanent), Frey syndrome (gustatory sweating — aberrant reinnervation of sweat glands by parasympathetic fibres intended for the parotid), salivary fistula, great auricular nerve injury (earlobe numbness).
When to Excise the Gland — Summary
Use this mnemonic: PRM-D — Proximal stone inaccessible, Recurrent stones, Multiple stones, Destroyed gland. If any of these apply, gland excision is the answer [1].
The lecture slides provide a dedicated treatment slide for sialadenitis [1]:
Sialadenitis — treatment:
- Hydration
- Sialogogues, massage, heat, antibiotics during acute attacks
- Remove stones:
- Exploration of submandibular duct
- Sialoendoscopy
- Excision of the gland
This confirms the stepwise approach: medical stabilisation → stone removal → gland excision if needed.
Abscess management: If lack of improvement or focal worsening within the gland despite antibiotics for 7–10 days suggests abscess formation [2], then:
- CT with contrast to confirm abscess
- Incision and drainage (I&D) — either percutaneous (USG-guided) or open surgical drainage
- Abscess formation can potentially compromise the airways [2] — especially submandibular abscesses, which can extend into the submandibular space (Ludwig's angina) or parapharyngeal space. This is an ENT emergency requiring urgent airway management + drainage.
After successful stone removal, counsel the patient on prevention:
| Measure | Rationale |
|---|---|
| Adequate hydration (≥ 2 L/day) | Maintains salivary flow → prevents stasis and supersaturation |
| Avoid anticholinergic medications where possible | These reduce salivary flow, predisposing to stasis |
| Regular sialogogues | Periodic use of sour candies keeps ducts flushed |
| Good oral hygiene | Reduces bacterial load → less risk of ascending infection if partial obstruction recurs |
| Treat underlying metabolic causes | Correct hypercalcaemia (e.g., treat hyperparathyroidism), gout (urate-lowering therapy) |
| Smoking cessation | Smoking reduces salivary flow and alters saliva composition |
| Step | Treatment | Indication | Key Points |
|---|---|---|---|
| 1 | Conservative | Small, distal stones; first episode | Hydration, sialogogues, massage, moist heat [1][2] |
| 2 | Medical | Pain / inflammation / superinfection | NSAIDs (ibuprofen); antibiotics (dicloxacillin/cephalexin) if sialadenitis [2] |
| 3 | Transoral removal | Palpable distal duct stone | Incision over stone in floor of mouth; risk of ranula, lingual nerve injury [2] |
| 4 | Sialoendoscopy ± lithotripsy | Proximal duct stones; failed transoral; combined diagnostic-therapeutic | Recent advance; can also check for residual fragments post-transoral [2][3] |
| 5 | ESWL | Intraductal stone < 7 mm; proximal or intraglandular; transoral not possible | Non-invasive; may need multiple sessions [2] |
| 6 | Gland excision | Proximal stone inaccessible; recurrent stones; multiple stones; destroyed gland [1] | Submandibular sialadenectomy or parotidectomy; watch for CN VII, lingual nerve, CN XII |
High Yield Summary
-
Management philosophy: Gland-preserving → escalate as needed → gland excision is last resort.
-
Conservative management: small stones to pass by themselves [1] — hydration, sialogogues (lemon drops), massage, milking the duct, moist heat [2].
-
NSAIDs for pain and inflammation; antibiotics (anti-staphylococcal: dicloxacillin/cephalexin) only if superinfection suspected [2].
-
Transoral removal for distal, palpable stones — beware ranula formation and lingual nerve injury [2].
-
Sialoendoscopy and removal — the recent advance [3]; for proximal duct stones beyond transoral reach; can also check for residual fragments after transoral removal [2].
-
ESWL effective for intraductal stones < 7 mm [2].
-
Gland excision indications: proximal stone inaccessible by scope or transoral excision, recurrent stones, multiple stones [1], destroyed gland from chronic sialadenitis.
-
Sialadenitis treatment: hydration, sialogogues, massage, heat, antibiotics during acute attacks → remove stones → excision of gland [1].
-
Abscess formation (failure to improve on antibiotics for 7–10 days) → CT → I&D; can potentially compromise airways [2].
-
Past treatment: marsupialisation and calculus removal, submandibular gland excision. Current: sialoendoscopy [3].
Active Recall - Management of Sialolithiasis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf (p45, p55, p56, p57) [2] Senior notes: felixlai.md (sections 326–330) [3] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p27, p28)
Complications of Sialolithiasis
Understanding the complications of sialolithiasis is really about understanding what happens when a duct is blocked and left unmanaged over time. Every complication flows logically from a single pathophysiological root: a stone obstructing the salivary duct. Think of it as a cascade — obstruction → stasis → infection → destruction — with each step producing its own set of clinical problems.
The lecture slides explicitly list the three key complications of sialolithiasis: sialadenitis, ductal ectasia, and stricture [1].
Complications of the Disease Itself
Complication: sialadenitis [3] — this is the most common and most clinically significant complication.
Superimposed infection leads to secondary infection as a result of ductal obstruction and stasis [2].
Pathophysiology — from first principles:
- A stone obstructs the duct → saliva stagnates behind it → the stagnant, warm, protein-rich saliva is an ideal bacterial culture medium → oral bacteria (predominantly S. aureus, S. viridans, H. influenzae, anaerobes like Bacteroides) ascend through the duct orifice retrograde → colonise the stagnant pool → multiply → acute sialadenitis.
- The gland becomes swollen, erythematous, and exquisitely tender. The patient develops fever, chills, and systemic toxicity.
- Pus is expressed from the ductal orifice when the gland is milked [3] — this is essentially pathognomonic of suppurative sialadenitis.
Clinical significance:
- Fever, chills, marked systemic toxicity [2]
- Pain, swelling and erythema of the gland [2]
- Purulent discharge from the salivary duct [2][3]
- Lack of improvement or focal worsening within the gland despite antibiotics for 7–10 days suggests possibility of abscess formation [2]
Management (as covered in the Management section):
- Hydration, sialogogues, massage, heat, antibiotics during acute attacks [1]
- Anti-staphylococcal antibiotics (dicloxacillin, cephalexin) [2]
- Once infection settles → definitive stone removal
Abscess formation is the progression of untreated or inadequately treated sialadenitis [2].
Pathophysiology:
- Acute sialadenitis → bacteria continue to proliferate → localised collection of pus forms within the gland parenchyma or periglandular tissues → a walled-off abscess develops.
- The abscess creates a fluctuant, tender mass within or adjacent to the gland. The patient appears systemically unwell with spiking fevers and rigors.
Why this is dangerous — airway compromise: Abscess formation can potentially compromise the airways [2]. This is the main reason abscess is a feared complication:
-
Submandibular abscess: The submandibular gland lies in the submandibular space (below the mylohyoid). Infection can spread to:
- Sublingual space (above the mylohyoid) → bilateral sublingual + submandibular space involvement = Ludwig's angina — a rapidly progressive, life-threatening cellulitis of the floor of mouth that causes tongue elevation, drooling, trismus, and airway obstruction.
- Parapharyngeal space → lateral pharyngeal wall swelling → airway narrowing.
-
Parotid abscess: Can spread to:
- Parapharyngeal space (the deep lobe of the parotid is separated from the parapharyngeal space by only a thin fascial layer).
- Parapharyngeal abscess → risk of septic jugular thrombophlebitis (Lemierre's syndrome) [2] — infection of the internal jugular vein with septic thrombosis, classically caused by Fusobacterium necrophorum, leading to septic emboli to the lungs and other organs. This is rare but devastating.
Clinical clue for abscess: Lack of improvement or focal worsening within the gland despite antibiotics for 7–10 days [2] — this should trigger urgent imaging (CT with contrast) to look for a rim-enhancing collection.
Management: Incision and drainage (I&D) + continued IV antibiotics + airway monitoring.
Airway Emergency
A submandibular abscess from sialolithiasis can progress to Ludwig's angina. If a patient with submandibular sialolithiasis develops bilateral floor-of-mouth swelling, difficulty swallowing, drooling, or stridor — this is an airway emergency. Secure the airway first (may need fibreoptic intubation or surgical airway), then drain the abscess.
Ductal ectasia [1] (from Greek ektasis = dilation/stretching) refers to abnormal dilation of the salivary duct proximal to the obstructing stone.
Pathophysiology:
- A stone causes chronic partial obstruction → saliva continues to be produced but cannot flow freely → pressure builds up behind the stone → the duct wall stretches and dilates over time → ectasia.
- This is analogous to hydronephrosis from a ureteric stone, or to bile duct dilatation from a common bile duct stone — the same principle of "back-pressure dilation proximal to an obstruction."
Clinical significance:
- Ectatic ducts have poor motility (the muscle wall is stretched thin) → even after stone removal, the dilated duct may not contract back to normal → continued stasis → predisposition to recurrent stone formation or chronic sialadenitis.
- On imaging (USG or sialography), ductal ectasia appears as a dilated, tortuous duct. On sialography specifically, the duct appears as a "sausage-shaped" or irregularly widened structure with contrast pooling.
Stricture [1] refers to fibrotic narrowing of the salivary duct.
Pathophysiology:
- Chronic obstruction by a stone → repeated episodes of inflammation (sialadenitis) around the stone → the duct wall becomes inflamed and oedematous → healing occurs by fibrosis → the duct narrows (stricture) → a new point of obstruction is created, independent of the stone itself.
- This is the same process that creates oesophageal strictures from chronic reflux or urethral strictures from chronic infection — inflammation → fibrosis → narrowing.
Clinical significance:
- Even after the stone is removed, the patient may continue to have obstructive symptoms (episodic meal-related swelling) because the stricture itself is now the obstruction.
- Strictures are a common cause of recurrent sialolithiasis — the narrowed segment creates turbulent flow and stasis → new stones form.
- On sialography, strictures appear as focal narrowing of the duct with proximal dilatation.
- Management: sialoendoscopic balloon dilatation of the stricture, or in severe cases, gland excision.
Chronic sialadenitis is the long-term consequence of repeated or unresolved acute sialadenitis.
Chronic sialadenitis is most commonly caused by stones [1]. The lecture slides describe the pathological process: destruction of gland tissue after acute infection and blockage of saliva drainage [1].
Pathophysiology:
- Repeated cycles of obstruction → infection → inflammation → resolution → more obstruction → more infection...
- Each cycle causes progressive parenchymal destruction: acinar cells (the saliva-producing cells) are destroyed by inflammatory infiltrate and replaced by fibrous tissue.
- Eventually, the gland is replaced by fibrotic, non-functioning tissue — it becomes firm, shrunken, and non-tender.
- Complete obstruction of salivary gland outflow will lead to persistent swelling of glands. Swelling will eventually regress as the obstruction results in the glands ceasing to produce saliva. Salivary gland will then feel to be firm and mistaken to be a focal mass [2].
Clinical significance:
- The destroyed, fibrotic gland serves no useful function but can be a source of recurrent infection if not excised.
- The firm, non-tender gland can mimic a salivary gland tumour on examination — this is a classic diagnostic pitfall [2].
- Management: excision of the gland [1] — there is nothing left to save.
A ranula is not a complication of sialolithiasis itself but a complication of its surgical treatment — specifically, transoral stone removal from Wharton's duct.
Care must be taken to avoid excess trauma to the duct and associated sublingual glands to avoid formation of ranula, which is a retention cyst on the floor of mouth [2].
Pathophysiology:
- During transoral removal of a submandibular duct stone, the sublingual gland and its delicate ductules lie in close proximity to the surgical field.
- If these ductules are inadvertently damaged, mucus (from the sublingual gland, which is predominantly mucinous) accumulates in the floor of mouth, forming a retention pseudocyst.
- A ranula is a bluish cystic swelling in the floor of the mouth ("belly of a frog") — a mucus retention cyst arising from the blocked sublingual gland [5].
Types:
- Simple (oral) ranula: confined to the floor of mouth, above the mylohyoid.
- Plunging ranula: extends through or around the mylohyoid muscle into the submandibular space or even the neck — can present as a neck mass.
Definitive treatment: excision of the pseudocyst together with resection of the sublingual gland [5]. Simple aspiration or marsupialisation alone has a high recurrence rate because the damaged sublingual gland continues to produce mucus.
When sialolithiasis of the parotid gland leads to sialadenitis or abscess, additional complications specific to the parotid region can occur [2]:
| Complication | Mechanism |
|---|---|
| Airway obstruction | Parapharyngeal extension of infection → pharyngeal wall oedema → airway narrowing |
| Facial nerve palsy | The facial nerve (CN VII) runs through the parotid gland. Inflammatory oedema or abscess within the gland can compress or injure the nerve → ipsilateral facial weakness (lower motor neuron pattern — forehead AND lower face) [2] |
| Septicaemia | Spread of infection into the bloodstream, especially in immunocompromised or debilitated patients [2] |
| Parapharyngeal abscess | Deep lobe of parotid is in direct continuity with the parapharyngeal space — infection easily tracks medially [2] |
| Septic jugular thrombophlebitis (Lemierre's syndrome) | Parapharyngeal abscess → inflammation/thrombosis of the internal jugular vein → septic emboli to lungs and elsewhere [2] |
| Osteomyelitis of adjacent facial bone | Contiguous spread of infection to the mandible or temporal bone [2] |
| Complication | Pathophysiology | Clinical Features | Management |
|---|---|---|---|
| Sialadenitis [1][3] | Stasis behind stone → bacterial colonisation → ascending infection | Fever, painful swollen gland, pus from duct | Antibiotics, hydration, sialogogues → stone removal |
| Abscess formation [2] | Progression of untreated sialadenitis → walled-off pus | Fluctuant mass, spiking fevers, failure to respond to antibiotics 7–10 days | CT → I&D + IV antibiotics; airway monitoring |
| Ductal ectasia [1] | Chronic back-pressure → duct wall stretching | Persistent stasis, recurrent stones; dilated duct on imaging | Stone removal; may need sialoendoscopic intervention |
| Ductal stricture [1] | Chronic inflammation → fibrosis → duct narrowing | Recurrent obstructive symptoms even after stone removal | Sialoendoscopic balloon dilatation; gland excision if severe |
| Chronic sialadenitis / gland destruction [1] | Repeated infection cycles → parenchymal fibrosis | Firm, non-tender gland mimicking tumour; recurrent infections | Gland excision |
| Airway compromise [2] | Submandibular abscess → Ludwig's angina; parotid abscess → parapharyngeal extension | Floor-of-mouth swelling, drooling, stridor | Emergency airway management + surgical drainage |
| Ranula (surgical complication) [2][5] | Sublingual gland ductule injury during transoral stone removal | Bluish cystic floor-of-mouth swelling | Excision of pseudocyst + sublingual gland resection |
| Facial nerve palsy (parotid) [2] | Inflammatory compression of CN VII within the parotid | Ipsilateral LMN facial weakness | Treat infection; nerve usually recovers if compression relieved |
| Septicaemia [2] | Haematogenous spread from infected gland | Systemic sepsis features | IV antibiotics, source control (drainage) |
High Yield Summary
-
Three named complications from the lecture slides: sialadenitis, ductal ectasia, and stricture [1].
-
Sialadenitis is the most common complication — caused by ductal obstruction and stasis leading to ascending bacterial infection → fever, pus from duct [2][3].
-
Abscess formation: suspect if no improvement after 7–10 days of antibiotics; can potentially compromise the airways [2] — submandibular abscess may progress to Ludwig's angina.
-
Ductal ectasia: back-pressure dilation of the duct proximal to the stone; predisposes to recurrent stone formation.
-
Ductal stricture: chronic inflammation → fibrosis → narrowing; creates a new point of obstruction even after stone removal; common cause of recurrence.
-
Chronic sialadenitis: destruction of gland tissue after acute infection + blockage of saliva drainage [1] → firm, fibrosed gland that mimics a tumour [2].
-
Ranula: iatrogenic complication of transoral stone removal — sublingual gland ductule injury → mucus retention cyst on the floor of mouth [2][5].
-
Parotid-specific complications of sialadenitis/abscess: facial nerve palsy, parapharyngeal abscess, Lemierre's syndrome, septicaemia, osteomyelitis [2].
Active Recall - Complications of Sialolithiasis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf (p52, p55, p56, p57) [2] Senior notes: felixlai.md (sections 323, 326, 327, 330) [3] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p27, p28) [5] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf (p26)
High Yield Summary
-
Definition: Sialolithiasis = calcified stones in salivary glands/ducts; most common cause of obstructive salivary gland disease.
-
80% submandibular gland, 20% parotid [1]. Sublingual/minor glands rare.
-
Only 1 stone in 75% of cases [1].
-
Why submandibular? Long duct, flow against gravity, alkaline saliva, high mucin and Ca²⁺ content.
-
90% of submandibular stones are radiopaque; 90% of parotid stones are radiolucent [1].
-
Composition: Calcium phosphate and hydroxyapatite in an organic matrix.
-
Presentation: recurrent swelling and pain, worse with eating ("salivary colic") [1].
-
30% of submandibular sialolithiasis presents with painless swelling [2].
-
Complications: sialadenitis, ductal ectasia, and stricture [1].
-
Examination: Bimanual palpation of floor of mouth (submandibular) or buccal mucosa (parotid). Look for palpable stone, express saliva/pus from duct orifice.
-
Chronic sialadenitis is most commonly caused by stones → destruction of gland tissue after acute infection + blockage of saliva drainage [1].
-
Risk factors: Dehydration, anticholinergics, diuretics, hypercalcaemia, gout, smoking, chronic periodontal disease.
High Yield Summary
-
The DDx of sialolithiasis broadly includes: obstructive (stone, stricture, mucous plug, ranula), infectious (acute/chronic bacterial sialadenitis, viral sialadenitis), autoimmune (Sjögren syndrome), granulomatous (sarcoidosis), neoplastic (benign — pleomorphic adenoma, Warthin tumour; malignant — mucoepidermoid CA), sialadenosis (non-inflammatory hypertrophy), and non-salivary mimics (masseter hypertrophy, lymphadenopathy, lipoma, oral cavity mass).
-
The single most useful bedside manoeuvre: milk the gland and inspect the duct orifice — pus = bacterial sialadenitis; stone visible = sialolithiasis; nothing = obstruction/atrophy/tumour.
-
Always confirm the swelling is truly salivary gland — lecture slides emphasise mimics: masseter hypertrophy, neck lymph nodes, lipoma, vascular malformations, oral cavity mass extending to submandibular space [1].
-
Episodic, meal-related, unilateral = obstructive (sialolithiasis until proven otherwise). Bilateral, painless, chronic = autoimmune (Sjögren) or sialadenosis. Acute, tender, purulent, systemic toxicity = acute bacterial sialadenitis.
-
Chronic sialadenitis investigations: clinical, USG/sialogram to rule out stones/masses, rule out Sjögren syndrome [1].
-
Pleomorphic adenoma has 10–15% malignant degeneration risk in 10 years — any long-standing salivary lump should be investigated [1].
High Yield Summary
-
No formal diagnostic criteria — diagnosis = compatible clinical picture + demonstration of stone (palpable, visible, or on imaging).
-
Ultrasound is the first-line investigation [1] — detects > 90% of stones ≥ 2 mm; confirms gland origin; differentiates stone from tumour from lymph node; detects dilated ducts.
-
CT scan is the imaging modality of choice for definitive stone evaluation [2] — most stones visible on non-contrast CT regardless of radiopacity on X-ray.
-
Plain X-ray: useful for submandibular stones (90% radiopaque), poor for parotid stones (90% radiolucent); still can miss small stones [1].
-
Sialography: useful for chronic sialolithiasis; superseded by USG / sialoendoscopy; cannulation may be difficult; may flush out stones or debris (therapeutic); contraindicated in acute sialadenitis [1][2].
-
MRI will NOT visualise stones [2] — used for tumour assessment or MR sialography for ductal anatomy.
-
Sialoendoscopy is both diagnostic and therapeutic — the modern approach for stones beyond reach of transoral excision [2][3].
-
For chronic sialadenitis workup: Clinical + USG/sialogram to rule out stones/masses + rule out Sjögren syndrome [1].
-
Clinical exam: bimanual palpation for stone; milk gland to express saliva/pus from duct orifice. A palpable stone is diagnostic.
High Yield Summary
-
Management philosophy: Gland-preserving → escalate as needed → gland excision is last resort.
-
Conservative management: small stones to pass by themselves [1] — hydration, sialogogues (lemon drops), massage, milking the duct, moist heat [2].
-
NSAIDs for pain and inflammation; antibiotics (anti-staphylococcal: dicloxacillin/cephalexin) only if superinfection suspected [2].
-
Transoral removal for distal, palpable stones — beware ranula formation and lingual nerve injury [2].
-
Sialoendoscopy and removal — the recent advance [3]; for proximal duct stones beyond transoral reach; can also check for residual fragments after transoral removal [2].
-
ESWL effective for intraductal stones < 7 mm [2].
-
Gland excision indications: proximal stone inaccessible by scope or transoral excision, recurrent stones, multiple stones [1], destroyed gland from chronic sialadenitis.
-
Sialadenitis treatment: hydration, sialogogues, massage, heat, antibiotics during acute attacks → remove stones → excision of gland [1].
-
Abscess formation (failure to improve on antibiotics for 7–10 days) → CT → I&D; can potentially compromise airways [2].
-
Past treatment: marsupialisation and calculus removal, submandibular gland excision. Current: sialoendoscopy [3].
High Yield Summary
-
Three named complications from the lecture slides: sialadenitis, ductal ectasia, and stricture [1].
-
Sialadenitis is the most common complication — caused by ductal obstruction and stasis leading to ascending bacterial infection → fever, pus from duct [2][3].
-
Abscess formation: suspect if no improvement after 7–10 days of antibiotics; can potentially compromise the airways [2] — submandibular abscess may progress to Ludwig's angina.
-
Ductal ectasia: back-pressure dilation of the duct proximal to the stone; predisposes to recurrent stone formation.
-
Ductal stricture: chronic inflammation → fibrosis → narrowing; creates a new point of obstruction even after stone removal; common cause of recurrence.
-
Chronic sialadenitis: destruction of gland tissue after acute infection + blockage of saliva drainage [1] → firm, fibrosed gland that mimics a tumour [2].
-
Ranula: iatrogenic complication of transoral stone removal — sublingual gland ductule injury → mucus retention cyst on the floor of mouth [2][5].
-
Parotid-specific complications of sialadenitis/abscess: facial nerve palsy, parapharyngeal abscess, Lemierre's syndrome, septicaemia, osteomyelitis [2].