Epidemiology and mechanism of stone formation
The prevalence of sialolithiasis depends on demographic factors: the urban population faces this pathology three times more often than the rural population. No gender differences in incidence have been identified, and stone formation in children is extremely rare.
The disease is polyetiological in nature. Under physiological conditions, microsialoliths are constantly formed in the ducts and are effortlessly washed out by saliva. The main pathogenetic mechanism of large calculi formation, according to V.V. Afanasyev's theory, is based on anatomical anomalies:
- Congenital ectasia (local dilation) of the ducts.
- Specific topography of the main excretory pathway, resembling a "broken straight line" with sharp bends.
In these anatomically altered areas, against the background of hyposialia (decreased secretion), retention of saliva and microstones occurs. The process is exacerbated by disorders of phosphorus-calcium metabolism, vitamin A deficiency, chronic sialadenitis, and the introduction of bacteria, actinomycetes, or foreign bodies.
Note: The parotid gland is protected against stone formation due to the presence in its secretion of statherin, a specific protein that inhibits the crystallization of calcium phosphate.
Structure and composition of salivary stones
Salivary stones are complex organomineral aggregates. The main mass of the calculus (up to 75–90%) consists of the organic matrix. Its amino acid profile, including alanine, glutamic acid, glycine, serine, and threonine, is completely identical to the structure of dental calculus.
Morphologically, a calculus consists of two zones:
- Core: located in the center. May consist of organic masses, salivary plugs, desquamated epithelium, leukocyte accumulations, actinomycete colonies, or foreign bodies.
- Shell: has a layered (lamellar) structure and contains spherical bodies. The formation of stratification is directly associated with the biological rhythms of the body (daily, monthly, seasonal).
Clinical picture and stages of development
Clinical manifestations depend on the stage of the process, the shape of the stone, and the general condition of the patient. According to the classification of I.F. Romacheva (1973), three stages of the disease are distinguished: initial, clinically manifested, and late. At late stages, the symptoms of chronic sialadenitis dominate.
Dynamics of symptom development:
- Stage of stone formation (initial stage): Proceeds asymptomatically, salivation is preserved, inflammation is absent. The stone is often detected accidentally during radiography.
- Manifestation: Occurs upon obstruction of the duct. The main symptom is "salivary colic". This is sharp pain and swelling of the gland during meals (especially spicy, sour, or salty), caused by stretching of the cavity sections due to impaired secretion outflow. After eating, the symptoms gradually subside.
- Exacerbation: Manifests with signs of sialadenitis — an increase in body temperature to 38–39 °C, dense painful swelling, leukocytosis, and an increased ESR in the blood test.
Sometimes so-called "silent" stones are encountered. These are fixed calculi with longitudinal grooves on their surface. Saliva flows freely through them into the oral cavity, so pain syndrome does not develop. Occasionally, an atypical course is observed with paroxysmal pain unrelated to meals.
Methods of physical and instrumental examination
A key diagnostic sign in the anamnesis is enlargement of the salivary gland during meals. To verify the diagnosis, the following methods are used:
Bimanual palpation Allows detection of a calculus in the parenchyma or excretory duct.
- Submandibular gland: palpated strictly from back to front. This is critically important to prevent displacement of the stone deeper into the intraglandular section.
- Parotid duct: the anterior section is palpated from the buccal mucosa, while the premasseteric and masseteric zones are palpated through the skin.
Differential diagnosis of indurations is carried out with chronic infection, phleboliths, lymphadenitis, amyloidosis, and pleomorphic adenoma.
Duct probing Performed with flexible salivary probes of various diameters. The method allows detection of the stone, measurement of the distance from the orifice to the obstruction, and evaluation of the diameter of the orifice itself. Absolute contraindication: the period of acute sialadenitis, due to the high risk of perforation of the inflamed wall.
Radiological diagnostics Radiography is the leading imaging method. The study always begins with a plain radiograph. For the parotid gland, the image is taken exclusively in the straight projection, since in the lateral projection the superimposition of bone structures makes the study uninformative. In complex cases, sialography (including digital), echosialography, and computed sialotomography are used.
Briefly: answers to topical questions
What surgical methods exist for removing calculi from the salivary glands?
Surgical methods for removing calculi depend on their localization and include intraoral accesses andextirpation of the salivary gland.
The following interventions are used:
- Afanasyev–Starodubtsev method — intraoral access for the anterior and middle sections of the parotid duct, including a linear or tongue-shaped incision with the creation of a flap outlining the duct orifice.
- Removal of a calculus from the distal sections of the parotid duct — dissection of the duct via intraoral access and removal of the stone with a curette spoon.
- Extirpation of the salivary gland — removal of the salivary gland, indicated for frequent recurrences of the disease and the impossibility of surgical removal of the salivary stone.
Alternative methods include extracorporeal lithotripsy — fragmentation of the stone with shock waves. It is used in the presence of good secretion outflow from the gland or the possibility of its creation surgically.
For the differential diagnosis of indurations during palpation, use the phrase "Crafty Chronic Flora Easily Attacks Ducts" (Calculus, Chronic infection, Phleboliths, Lymphadenitis, Amyloidosis, Pleomorphic adenoma).
Class and exam questions
Why is the parotid salivary gland rarely affected by stones?
The parotid gland secretion contains the statherin protein, which acts as a potent inhibitor of calcium phosphate precipitation from saliva.
What is the essence of the "salivary colic" symptom?
This is acute pain and swelling of the gland during meals (especially secretion stimulants — sour and salty). It occurs due to stretching of the gland capsule when the excretory duct is blocked by a stone.
Why should the movements during palpation of the submandibular gland be directed from back to front?
This direction is necessary so as not to push the calculus found in the duct deeper into the intraglandular section, which would significantly complicate its removal.
What else to study on this topic
- Quantitative saliva analysis (sialometry) and its diagnostic value.
- Technique for performing digital sialography.
- Cytological examination of salivary gland secretion smears.
- Pathomorphological changes in the gland in the late stage of sialolithiasis.
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