# Sialolithiasis: Interventional and Surgical Management

## Introduction

Sialolithiasis, the formation of calcified stones within the salivary gland ductal system, is the most common cause of obstructive salivary gland disease, accounting for approximately 50% of all major salivary gland pathology. The submandibular gland is affected in 80 to 90% of cases. Management has evolved significantly with the advent of minimally invasive techniques, particularly sialendoscopy, which has reduced the need for gland excision.

## Pathophysiology

Salivary stones form through precipitation of calcium salts (primarily calcium phosphate and calcium carbonate) around an organic nidus. Contributing factors include salivary stasis, ductal inflammation, altered saliva composition, and dehydration. The submandibular gland predominance (80-90%) is due to Wharton's duct being longer and wider with an antigravity course, submandibular saliva being more alkaline and viscous (higher mucin content), and higher calcium and phosphate concentrations in submandibular saliva. Parotid stones account for 5 to 10%, and sublingual stones are rare. Multiple stones are present in 25% of cases, and bilateral sialolithiasis occurs in approximately 3% of patients.

## Clinical Presentation

The hallmark is mealtime syndrome, consisting of acute swelling and pain of the affected gland during eating caused by obstruction of salivary flow against the stone. Swelling typically resolves within 1 to 2 hours as saliva slowly passes around the obstruction. Acute sialadenitis may develop as a secondary bacterial infection with erythema, purulent discharge from the duct orifice, fever, and trismus. Chronic obstructive sialadenitis produces recurrent episodes of swelling and progressive gland damage. A palpable stone may be felt in the floor of mouth (submandibular duct) or buccal mucosa (parotid duct).

## Diagnosis

### Clinical Examination

Bimanual palpation of the floor of mouth along Wharton's duct is performed. The duct orifice is expressed to assess salivary flow (reduced, purulent, or absent). The gland is palpated for tenderness, induration, and enlargement.

### Imaging

An occlusal radiograph identifies radiopaque submandibular duct stones, which are radiopaque in 80% of cases. Panoramic radiographs may show stones superimposed on the mandible. CBCT provides superior spatial resolution, identifying stone size, number, and precise location. Ultrasound is the first-line imaging modality, identifying stones greater than 2 mm, ductal dilation, and glandular changes, though it is operator-dependent. CT without contrast is highly sensitive for calcified stones and useful for deep or intraglandular stones. MR sialography provides non-invasive ductal imaging without contrast and identifies strictures and non-radiopaque stones. Conventional sialography involves contrast injection into the duct to identify filling defects, strictures, and ductal anatomy but is contraindicated in acute infection.

![Imaging comparison showing sialolith identification on occlusal radiograph, ultrasound, and CBCT](images/sialolithiasis-imaging.jpg)

## Management Algorithm

### Conservative Management

Conservative management is indicated for small stones (less than 5 mm) without acute infection and includes hydration, sialagogues (lemon drops, vitamin C), warm compresses, and gland massage. Antibiotics for acute sialadenitis include amoxicillin-clavulanate or clindamycin, with culture if purulent discharge is available. Spontaneous passage occurs in approximately 20 to 30% of small stones.

### Transoral Stone Removal

Transoral removal is indicated for palpable stones in the anterior or middle third of Wharton's duct. Under topical or local anesthesia, the duct mucosa is incised directly over the stone and the stone is extracted with a hemostat or curette. The duct is marsupialized to prevent stricture. The success rate is 85 to 95% for anterior duct stones. The lingual nerve must be identified and protected for posterior duct stones.

### Sialendoscopy

Sialendoscopy is a minimally invasive endoscopic technique introduced in the 1990s that uses semi-rigid endoscopes (0.8-1.6 mm diameter) inserted into the ductal orifice. Diagnostically, it visualizes stones, strictures, polyps, mucus plugs, and ductal anatomy. Interventionally, it enables wire basket extraction, intracorporeal lithotripsy (laser, pneumatic), balloon dilation of strictures, and steroid irrigation. It is indicated for stones up to 7 to 8 mm, multiple stones, strictures, and recurrent sialadenitis without a visible stone. The success rate is 80 to 95% for stone removal with gland preservation in 85 to 90%. Its advantages include gland preservation, minimal morbidity, and outpatient performance. Limitations include the need for specialized equipment and training, and large stones (greater than 8 mm) may require a combined approach.

### Combined Approach (Sialendoscopy-Assisted Surgery)

For large stones or those in the hilum or parenchyma not removable by sialendoscopy alone, the endoscope-guided transoral removal technique uses the sialendoscope to transilluminate the stone location, guiding a targeted incision and stone retrieval through the floor of mouth. The success rate is 90 to 95% with gland preservation.

### Extracorporeal Shock Wave Lithotripsy (ESWL)

Piezoelectric or electromagnetic shock waves fragment salivary stones greater than 7 mm that are not amenable to sialendoscopy alone. Fragments are then retrieved endoscopically or passed spontaneously. Multiple sessions may be required, with a success rate of 50 to 75%. Availability is limited, and the technique is not widely adopted in the United States.

### Submandibular Gland Excision

Gland excision is reserved for failed minimally invasive approaches, intraglandular stones with chronic gland destruction, or suspected neoplasm. It is also indicated for stones greater than 10 to 15 mm with significant glandular fibrosis. It is definitive treatment with no risk of stone recurrence.

### Management Selection by Stone Characteristics

| Stone Size | Location | Recommended Approach | Success Rate | Gland Preserved |
|-----------|----------|---------------------|--------------|-----------------|
| <5 mm | Anterior duct | Conservative or transoral removal | 85-95% | Yes |
| 5-7 mm | Anterior/middle duct | Sialendoscopy (basket extraction) | 80-95% | Yes (85-90%) |
| 5-8 mm | Hilar/proximal duct | Sialendoscopy + intracorporeal lithotripsy | 80-90% | Yes |
| >7 mm | Any location | Combined sialendoscopy-assisted transoral | 90-95% | Yes |
| >7 mm | Intraglandular | ESWL + sialendoscopy | 50-75% | Yes |
| >10-15 mm | Intraglandular with fibrosis | Submandibular gland excision | Definitive | No |

![Flowchart showing the management algorithm for sialolithiasis based on stone size, location, and clinical presentation](images/sialolithiasis-management-algorithm.jpg)

## Sialendoscopy Technique

### Equipment

Equipment includes semi-rigid sialendoscopes (diagnostic 0.8-1.1 mm and interventional 1.3-1.6 mm with working channel), wire baskets, balloon catheters, laser fiber (holmium:YAG), pneumatic lithotripter, and stents for postoperative ductal patency.

### Procedure

Ductal access is achieved by dilating the duct orifice with graduated dilators (lacrimal dilators or specialized salivary dilators). The endoscope is advanced under continuous saline irrigation. The stone is identified and its size and mobility assessed. Small mobile stones are extracted with a wire basket. Larger or impacted stones undergo intracorporeal lithotripsy (laser fragmentation) followed by basket retrieval. Strictures are treated with balloon dilation and steroid irrigation (triamcinolone). A salivary stent is placed for 2 to 4 weeks to maintain ductal patency if significant dilation or stricture treatment was performed.

### Postoperative Care

Sialagogues and gland massage promote salivary flow. Antibiotics are prescribed if infection was present. The stent is removed at 2 to 4 weeks. Follow-up ultrasound at 3 to 6 months confirms resolution.

## Complications

Ductal perforation during sialendoscopy usually heals spontaneously. Ductal stricture (post-inflammatory or post-surgical) is managed with balloon dilation. Basket impaction occurs when a stone is too large for the basket and may require conversion to an open approach. Stone recurrence occurs in 10 to 20% after sialendoscopy, with higher rates when residual ductal pathology remains. Nerve injury may affect the lingual nerve during a transoral approach or the marginal mandibular nerve during submandibulectomy. Ranula formation may follow floor of mouth surgery for deep submandibular duct stones.

![Sialendoscopic images showing a salivary stone within Wharton's duct before and during wire basket extraction](images/sialendoscopy-stone-retrieval.jpg)

## Clinical Pearls

Sialendoscopy has revolutionized sialolithiasis management, allowing gland preservation in 85 to 90% of cases. The submandibular gland accounts for 80 to 90% of sialolithiasis because Wharton's duct anatomy predisposes to stone formation. Anterior duct stones are often amenable to simple transoral removal with marsupialization. A combined sialendoscopy-assisted transoral approach is the technique of choice for hilar and proximal duct stones. Submandibular gland excision is reserved for failed minimally invasive treatment, intraglandular stones with chronic gland damage, or suspected malignancy.

## References

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2. Marchal F. "A Combined Endoscopic and External Approach for Extraction of Large Stones." *Laryngoscope*. 2007;117(2):373-377.
3. Rauch S, Gorlin RJ. "Diseases of the Salivary Glands." In: Gorlin RJ, Goldman HM, eds. *Thoma's Oral Pathology*. Mosby; 1970.
4. Koch M, et al. "Sialendoscopy in Cases of Sialolithiasis of the Submandibular Gland." *Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology*. 2005;100(4):469-474.