Sialolithiasis

Section: Head and neck Curriculum: Curriculum, page 42

Definition

• Stones within the salivary glands and or ducts

Epidemiology

• M>F
• Age 30-60
• Majority unilateral (R=L) and single

Pathogenesis

• 1. Salivary stasis
  • Reduced flow of saliva promotes precipitation of organic and inorganic materials
  • Causes:
    • Dehydration
    • Anticholinergic medications
    • Poor oral intake
    • Duct obstruction (e.g. duct stricture or external compression)
    • Gland inflammation
• 2. Nidus formation
  • A core or nidus forms from:
    • Desquamated epithelial cells
    • Mucus
    • Bacterial debris
    • Local injury
    • Inflammation
  • This acts as a scaffold for mineral deposition
• 3. Mineral precipitation
  • Saliva is supersaturated
    • Calcium and phosphate
    • Hydroxyapatite + Mg, K and ammonia
  • With stasis and pH changes, these precipitate onto the nidus
    • Alkaline pH (more common in submandibular gland) favours precipitation
• Location
  • Submandibular 80% - larger, in duct
  • Parotid 20% - smaller, multiple
  • Other few
  • Submandibular stones more common - draining against gravity through a long duct, draining mucoid saliva with high calcium level

Aetiology

• Anything that could cause above issues
  • V - Hypovolaemia
  • I- Infection/inflammation - chronic periodontal disease
  • N- Neoplasia
  • D - Drugs - anticholinergics, diuretics, smoking
  • I - Iatrogenic - prev instrumentation, floor of mouth surgery
  • C -
  • A -
  • T- Trauma
  • E- Endocrine - gout, stone producer (hx nephrolithiasis)

Risk factors

• Not well known
• They are thought to include
  • Smoking
  • Drugs - anticholinergics and diuretics
  • Inflammation - periodontal disease

Clinical

• Pain and swelling
  • Precipitated by eating or anticipation of eating
  • Intermittent vs constant
• Incidental exam or radiographs/painless swelling
• Worsening pain/fever/erythema - ?secondary infection
• Examine the ducts
  • Parotid
    • Orifice at buccal mucosa across from 2nd upper molar
    • Bimanual palpation - outside from earlobe to molar and inside
  • Submandibular
    • Orifice at base of lingual frenulum
    • Bimanual palpation
  • Pertinent Findings
    • Tenderness of gland
    • Compression of gland should cause a jet of saliva to shoot out
    • Stone or pus at orifice
      • Stones are hard and small
      • Firm and non tender - suspect cancer

Complications

• Secondary bacterial infection
  • Ductal obstruction and salivary stasis
  • Give antibiotics
  • Can progress and cause airway obstruction rarely
• Chronic sialadenitis
  • Recurrent episodes of stone obstruction
  • Saliva excretion can recover if gland is not atrophied
  • Can lead to gland atrophy and fat replacement (seen on CT)

Diagnosis

• Clinical
  • As above
• With imaging
  • Indications for imaging
    • Diagnostic uncertainty
    • Stone location
    • Tumour
    • Complication - abscess
  • Modality
    • NON CONTRAST CT with fine slice
    • MRI
    • Sialography (superceeded)
    • OPG XR
• Solid lesion more likely tumour - benign, malignant, lymphoma
• Cystic more likely benign - lymphoepithelial cyst (HIV), warthins

Investigations

• CT (non con with fine cuts) = gold standard
  • Sens 98%/Spec 88%
• USS
  • Good for >2mm stones
  • But not great for dx cancers or complications
• MRI sialography (non invasive with no intraductal dye needed)
  • Normal MRI cant see stones well
  • Better than USS and lower failure rate than conventional sialography
• Sialography (conventional)
  • Replaced by CT mainly
  • Cannulate duct and inject radiopaque dye then do plain xrays

Differential Diagnosis

• Infection/Inflammatory
  • Viral - mumps (parotid), flu, coxsackie, EBV, HIV (superinfected lymphoepithelial cysts)
  • Bacterial - acute/chronic, staph, strep pneumoniae/viridans, haemophilus, bacteroides
  • Sarcoidosis
• Neoplasia/Nutrition
  • Tumours
  • Malnutrition
• Iatrogenic
  • RTX, IV contrast
• Autoimmune
  • Sjogren’s - dry eyes dry mouth

Management

Conservative

• Hydration
• Moist heat pack
• Massage gland
• Milk the duct
• Sialogogues
  • Promote salivary flow
  • Lemon sucking candies
  • Chewing gum
• Stop anticholinergics
• Stop smoking
• Imaging (CT if suspicion of cancer or complication)

Medical

• Analgesia
  • Panadol, NSAIDs
• Antibiotics if signs of secondary infection
  • Flucloxacillin
  • If ongoing - duct culture and change to broader coverage - Augmentin

Endoscopic

• LA or GA
• Sialoendoscopy (85% success and improved with combined peroral open)
  • <3mm stones in parotid and <4mm stones in submandibular
  • Retrieve, baskets, microlaser, drills to fragment
• More successful if small stones, distal duct and submandibular

Surgical

Submandibular

• Transoral slit and marsupialization (LA)
  • Risks
    • DROP STONE DEEPER → suture first
    • HAEMATOMA
    • Ranula - formation of retention cyst on floor of mouth
    • Traumatise duct
    • Stricture
    • Recurrent infection
• Submandibular gland excision
  • Indications
    • Recurrent failure of simpler methods
    • Recurrent infection
  • Risks
    • Nerve injury - MMN, lingual and CN12

Parotid

• Transoral
  • Only if at distal Steensons duct
• Parotidectomy
  • Indications
    • Recurrent failure of simpler methods
    • Recurrent infection
  • Risks
    • Nerve injury - auriculotemporal N, facial N
    • Usual parotid risks