# Sialolithiasis and Obstructive Salivary Disease

## Introduction

**Sialolithiasis** (salivary gland stones) is the most common cause of obstructive salivary gland disease, accounting for approximately **50% of major salivary gland disorders**. The condition predominantly affects the submandibular gland due to its anatomic and physiologic characteristics. The advent of **sland-preserving techniques**, including sialendoscopy, has transformed management away from routine gland excision.

## Pathophysiology

Salivary calculi are composed of **calcium phosphate and hydroxyapatite** in an organic matrix. Stone formation is multifactorial: salivary stasis, altered saliva composition, ductal inflammation, and microliths acting as nidus. **Submandibular gland** is affected in **80-90% of cases** due to: Longer, wider duct with an antigravity course. More alkaline, mucin-rich saliva with higher calcium and phosphate concentrations. Dependent position of the gland. Parotid gland: 10-20% of cases; sublingual and minor glands: rare.

## Clinical Presentation

**Recurrent, meal-related swelling** of the affected gland (postprandial swelling). Pain and tenderness, exacerbated by eating (especially sour/acidic foods). **Bimanual palpation** may reveal a stone in the floor of mouth (submandibular) or buccal mucosa (parotid). Purulent discharge from the duct orifice if secondary infection (sialadenitis). Chronic obstruction may lead to gland atrophy and fibrosis.

## Diagnostic Workup

### Imaging
**Ultrasound**: first-line imaging; sensitivity 70-90% for stones >2 mm; identifies gland enlargement and ductal dilation. **CT without contrast**: excellent for calcified stones; identifies location within the duct or hilum. **Cone beam CT (CBCT)**: high resolution for stone localization. **MR sialography**: noninvasive evaluation of the ductal system; identifies strictures and non-calcified stones. **Conventional sialography**: largely replaced by noninvasive modalities; contraindicated in acute infection. **Sialendoscopy**: both diagnostic and therapeutic; direct visualization of the ductal lumen.

![Axial CT demonstrating a large calcified stone in the right Wharton duct at the hilum of the submandibular gland](/images/submandibular-sialolith-ct.jpg)

## Classification

### By Location
**Distal (anterior) duct stones**: accessible transorally. **Proximal (hilar) stones**: near the gland parenchyma; more challenging. **Intraglandular stones**: within the gland substance.

### By Size
Small (<5 mm): amenable to sialendoscopy. Medium (5-10 mm): combined approach (sialendoscopy-assisted transoral). Large (>10 mm): often require gland excision or open duct surgery.

## Management

| Approach | Indications | Success Rate | Key Details |
|----------|-------------|-------------|-------------|
| Conservative | Small stones, acute episode | Variable (spontaneous passage) | Hydration, sialagogues, massage |
| Transoral removal | Distal submandibular duct stones, palpable | >90% | Intraoral ductotomy |
| Sialendoscopy | Stones <5 mm, strictures | 80-90% | Gland-preserving, diagnostic + therapeutic |
| ESWL | Parotid stones 5-10 mm | 50-70% | Multiple sessions, combined with endoscopy |
| Gland excision | Failed minimally invasive, neoplasm | Definitive | Submandibular excision or parotidectomy |

### Conservative Management
**Hydration**, sialagogues (sour candies, lemon drops), warm compresses, gland massage. **Antibiotics** if secondary infection (amoxicillin-clavulanate or clindamycin). May be sufficient for small stones that pass spontaneously.

### Transoral Stone Removal
For **distal submandibular duct stones** that are palpable in the floor of mouth. Intraoral incision over the stone, longitudinal ductotomy, stone extraction. Marsupialization of the duct or primary closure.

### Sialendoscopy
Minimally invasive endoscopic technique using miniature scopes (0.8-1.6 mm). **Diagnostic and therapeutic**: direct visualization, stone fragmentation (laser lithotripsy), basket extraction, balloon dilation of strictures. Success rate: **80-90%** for stones <5 mm. Gland preservation rate >95%. Can be combined with transoral approach for larger or hilar stones (**combined approach**).

### Extracorporeal Shock Wave Lithotripsy (ESWL)
Fragments stones into smaller pieces that can pass spontaneously or be retrieved endoscopically. Best for parotid stones 5-10 mm, Multiple sessions often required.

### Gland Excision
Reserved for **failed conservative/minimally invasive management**, recurrent sialadenitis with gland destruction, or suspicion of neoplasm. Submandibular gland excision or parotidectomy.

![Sialendoscopic view showing a round salivary stone being captured with a wire basket for extraction](/images/sialendoscopy-stone-extraction.jpg)

## Complications of Untreated Obstruction

**Acute suppurative sialadenitis**: painful swelling, purulent discharge, fever. **Abscess formation**: may require I&D. **Chronic sialadenitis**: gland fibrosis and atrophy. **Ranula formation**: mucocele from sublingual gland obstruction or ductal injury.

![Intraoral photograph showing a palpable stone at the orifice of Wharton duct in the anterior floor of mouth](/images/wharton-duct-stone-intraoral.jpg)

## Key Clinical Pearls

**Meal-related swelling** is the hallmark symptom of salivary duct obstruction. The submandibular gland is affected in 80-90% of sialolithiasis cases due to its anatomy and saliva composition. **Sialendoscopy** has dramatically reduced the need for gland excision; it is both diagnostic and therapeutic. Always rule out a **salivary neoplasm** in patients with persistent gland swelling without clear obstruction. The **lingual nerve** courses in close proximity to Wharton duct and must be protected during transoral duct surgery.

## References

1. Marchal F, Dulguerov P. Sialolithiasis management: the state of the art. *Arch Otolaryngol Head Neck Surg*. 2003;129(9):951-956.
2. Koch M, Zenk J, Iro H. Algorithms for treatment of salivary gland obstructions. *Otolaryngol Clin North Am*. 2009;42(6):1173-1192.
3. Strychowsky JE, Sommer DD, Guber I, et al. Sialendoscopy for the management of obstructive salivary gland disease: a systematic review and meta-analysis. *Arch Otolaryngol Head Neck Surg*. 2012;138(6):541-547.
4. Walvekar RR, Carrau RL, Schaitkin B. Sialendoscopy: minimally invasive approach to the salivary ductal system. *Op Tech Otolaryngol*. 2009;20(2):131-137.