Sialolithotomy of the submandibular duct using sialendoscopy

Chronic obstructive salivary gland disease can be caused by salivary stones, mucus plugs, duct stenosis, foreign bodies, or anatomical variation in the ductal system of salivary glands, and it can lead to the retention of saliva in the duct, discomfort, or infection, if not treated properly [1, 2].

In particular, sialolithiasis (also termed salivary calculi or salivary stones) is a condition in which a calcified mass forms within a salivary gland, usually in the duct of the submandibular gland (also termed ‘Wharton’s duct’), due to anatomical and physiological factors. It can cause swelling and pain in the affected salivary gland and worsens when salivary flow is stimulated. If it does not get removed spontaneously, the condition is usually managed by removing the stone surgically [2–4].

Previously, radiosialography, ultrasound, and magnetic resonance sialography have been used for the diagnosis of these salivary gland diseases. Radiosialography is the commonly used imaging technique for the study of salivary gland diseases, especially in the case of calculi [4, 5]; however, it is contraindicated in acute infection or in case of sensitivity to contrast medium. Ultrasonography is a first-level, noninvasive, and inexpensive imaging technique for the study of salivary gland disease without contrast medium. However, the sensitivity and specificity of the results vary widely because less mineralised or early-stage stones may not be detected, and they depend on the experience and expertise of the examiner. Other diagnostic methods that also aid in visualising salivary gland diseases indirectly, such as computed tomography (CT), magnetic resonance imaging (MRI), MR sialography, or scintigraphy, are expensive and need additional procedural steps with no specific advantage [4, 6–8].

At present, with the development of sialendoscopy, a noninvasive approach has emerged, and it has been effectively used to establish the diagnosis and treatment plan for the diseases of salivary duct system and glands. Sialendoscopy allows direct access into the duct, dilatation and irrigation of the duct system, and confirmation of its patency with a minimally invasive approach that widens or bypasses the stenosis [1, 4].

In this study report, we discuss the cases of two patients who underwent sialolithotomy with a sialendoscope at Korea University Anam Hospital. Additionally, we will discuss the differences from conventional techniques.

The symptoms of obstructive salivary gland diseases include recurrent, painful swelling of the major salivary glands, and these symptoms can lead to a marked reduction in the patient’s quality of life [3, 9]. Previously, radiosialography, sonography, and MR sialography were used to diagnose salivary gland diseases. Radiosialography is the primary method of examination of salivary ducts, which can be used to diagnose gland lesions by acquiring images after injecting contrast media into the duct. However, it is contraindicated when there is an adverse reaction to the contrast media or an acute infection. Sonography is noninvasive and useful for the diagnosis of salivary gland calculi, but this technique depends on the experience and technique of the surgeon and is difficult to use for diagnosing disorders in the duct. MR sialography is another noninvasive method that can overcome the existing limitation by showing the entire salivary duct system, but it can cause distortion artifacts due to intraoral restorations. However, as the introduction of salivary endoscopy enabled direct visualisation of the duct system, these diagnostic limitations were overcome. Moreover, it is less invasive than conventional surgical methods for patients with stenosis or stones in the duct system or sialadenitis, which can reduce the discomfort of patients and alleviate symptoms [1, 4, 6, 10].

A few research groups have also investigated patient satisfaction after sialendoscopy-guided treatment for obstructive salivary gland diseases. Kroll et al., using the Short Form 36 (SF-36) questionnaire, found a high level of patient satisfaction [9, 11]. Aubin-Pouliot et al., using a questionnaire designed to obtain a chronic obstructive sialadenitis score showed similar results. The results showed that symptoms decreased significantly after sialendoscopy-assisted salivary duct surgery in submandibular glands more than in parotid glands [9, 12].

Recent studies have shown that microsialoliths play a major role in the pathogenesis of chronic sialadenitis. They can accumulate in normal salivary glands and lead to obstructive atrophy. This atrophy enables colonisation and proliferation of microbes, causing inflammation in the periphery duct system, followed by more severe atrophy and progressive infection, leading to chronic sialadenitis [3]. According to Quinn et al., intraductal instillation of penicillin allows antibiotics to reach the remaining microbes in the parenchyma, thus helping to relieve symptoms, but equally good results can be obtained with saline irrigation itself, which may be considered a more important factor [3, 13].

Radioactive iodine (RAI) therapy is another cause of salivary gland disease. According to Kim et al., chronic sialadenitis is the most common complication of RAI for the removal of remnant tissue after thyroidectomy. The prevalence of chronic RAI sialadenitis is 11–65% after RAI therapy. RAI-induced salivary gland damage results in obstructive sialadenitis, presenting recurrent swelling with or without pain at mealtime. In the chronic state, it further causes hypo-salivation and leads to other complications, such as speech and swallowing difficulties, taste alterations, oral candidiasis, and dental caries. Currently, RAI-induced chronic sialadenitis is treated conservatively by ensuring good oral hygiene and frequent hydration, using salivary substitutes and salivary stimulatory treatments, such as gland massage [14, 15]..

According to Kim’s study, sialendoscopy showing sialocentesis effect (intraductal irrigation with sterilized normal saline) could improve obstructive symptoms 3 months after sialendoscopic mechanical dilation; however, sialendoscopic treatment for chronic RAI sialadenitis was found to have some limitations in its ability to relieve xerostomia and improve weakened salivary gland functions [15].

This study was conducted to report the use of a sialendoscope in removing salivary stone. Recently, the development of salivary endoscopy has overcome the limitations of conventional methods and has become applicable in the diagnosis and treatment of salivary stones. Further, the patients’ discomfort is less compared with the conventional procedures. In this case, the patient had complete relief from foreign body sensation after surgery and showed slight relief from dryness. There were no significant complications after the operation and no significant side effects during the follow-up period.

We reported two cases of noninvasive sialolithotomy with sialendoscopy instead of the conventional methods. If a sialendoscope is applied in the appropriate case not only in sialolithiasis but also in duct stenosis and sialadenitis, the patient will be less likely to experience discomfort and complications and can expect good treatment outcomes. For determining the long-term effects, further study is needed with a larger number of patients and longer follow-up. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.