Sialolithiasis: retrospective analysis of the effect of an escalating treatment algorithm on patient-perceived health-related quality of life

The most common cause of obstructive sialadenitis of the major salivary glands is sialolithiasis [1]. This disease is characterized by formation of calcified stones (sialoliths) within the gland’s ductal system that hinder saliva outflow into the oral cavity. Etiologically, changes in ion composition, quantity and flow rate as well as pH changes of the saliva, nicotine abuse and dehydration are currently being discussed [2, 3]. The incidence of sialolithiasis within the general population is estimated to be between 28 and 59 cases per million and year [2]. The mean age for onset of symptoms due to sialolithiasis is approximately 45 years [4]. Of all major salivary glands the submandibular gland (SMG) is specifically prone to sialolith formation due to its seromucous saliva content as well as a long and curved duct (Wharton’s duct) both of which facilitate calcification [5]. The parotid gland (PG) is the second most affected gland followed by the sublingual gland (SLG) which rarely is affected [6]. The average time between the occurrence of symptoms like recurrent colicky pain and swelling of the affected gland and final diagnosis is 2.4 years [7]. Without removal of the obstructive sialolith complications like abscesses, fistulas and phlegmonous inflammations have been reported [8]. Cervical sonography is the gold-standard modality for diagnosis of sialolithiasis due to its ubiquitous availability, low cost and non-invasiveness [9]. The specificity and sensitivity of sonography in sialolith detection is reported to be 94 and 86%, respectively [10]. In the 1990s the procedure of diagnostic sialendoscopy was introduced as a method to directly visualize sialoliths by insertion of a semi-rigid endoscope with a diameter of no more than 1.7 mm into the gland’s excretory duct [11]. Additionally, sialography, computer tomography (CT), cone-beam computer tomography (CBCT) as well as magnetic resonance sialography (MRS) can be conducted to diagnose sialolithiasis [12]. The line of therapy follows an escalating treatment algorithm depending on the type of affected gland as well as the position and number of sialoliths [13, 14]. Due to the deep position within the ductal system sialolith formation in the hilus and the parenchyma is most difficult to treat [4]. Whereas sialadenectomy was often conducted in these cases the innovative guidance of the developed treatment algorithm nowadays allows gland preservation in > 90% of cases leading to lower postoperative complication rates such as wound infection and injuries to the lingual and facial nerve [4, 15]. According to the treatment algorithm initial prescription of antibiotics in combination with analgesics, sialogogues and massage of the affected gland should be attempted to enable spontaneous sialolith discharge [12, 13]. Sialoliths of the SMG and PG with a diameter of no more than 3 mm can usually be removed with sialendoscopy with success rates of > 90% [10, 16]. Larger sialoliths within the distal third of Wharton’s duct can be removed by papillotomy, whereas sialoliths within the middle third are commonly extracted by sialendoscopy [17]. Sialoliths within the parenchyma of SMG and PG that cannot be removed by interventional sialendoscopy (ISE) or extracorporeal shockwave lithotripsy (ESWT) alone may be removed by an intraoral (SMG) or extraoral (PG) endoscopy-assisted sialolithotomy (IEAS) with success rates of > 90% [18, 19]. As a last resort in rare cases with inaccessible symptomatic sialoliths sialadenectomy has to be performed.

The aim of the present study was to retrospectively analyze and evaluate the therapeutic success rates of an escalating treatment algorithm in sialolithiasis. The novelty in this study is the special emphasis on the patient perceived physical and psychological strain throughout therapy.

In the last 15 years a paradigm shift in sialolithiasis treatment became obvious which favors gland preservation in most cases to avoid facial nerve lesions [21, 22]. Depending on the type of affected gland therapy follows a minimally-invasive treatment algorithm [20]. Studies reported improved health-related quality of life (HRQoL) of sialendoscopy despite higher costs [23]. In the present study we found a male:female ratio of 1:1 which is in line with the findings by Zenk et al. (1999) [7]. At initial symptomatic manifestation of sialolithiasis we found women to have a mean age of 44.86 years and men of 45.48 years. These data are comparable with other studies [4, 7]. In this study the SMG was affected in 58.6% of cases. In a study by Andretta et al. (2005) the SMG was affected in 92% of cases which significantly differs from our finding [24]. One reason for such discrepancy could be the smaller patient collective of our study with only 87 patients. On average patients with sialolithiasis of the SMG were 41.67 years old, whereas patients with obstructed PG were 48.91 years old. These findings are in accordance with data shown by other studies [7]. Pain and swelling were the most common symptoms of sialolithiasis in the present and comparable studies [25]. In the present study no patient presented with asymptomatic sialolithiasis. Other studies report significantly higher numbers [7]. This can be explained as only symptomatic patients were comprised in this study. Asymptomatic sialolithiasis usually does not require treatment. 86.2% of patients could be cured in the present study. Other studies report success rates of 75.5, 80.5 and 88.9% [1, 4, 26]. To patients, loss of pain and swelling of the affected gland was most relevant, whereas asymptomatic residual sialoliths posed only minor concerns. This partially explains the difference between patient perception of the term cured (94.3% of cases) and the surgeons perception (86.2%). These results can be explained by the good overall patient-perceived tolerability of sialendoscopy, especially, also shown by other studies [27]. In the present study parotidectomy could be omitted in 100% of patients and submandibulectomy was only necessary in one patient. These results may be due to the small number of patients included in the study but also point to the possibility that the treatment algorithm works better for parotid stones. Recurrence of sialolithiasis was more common for the PG than the SMG. Although the present study did not comprise patients who suffered from chronic sclerosing salivary gland inflammation caused by sialolithiasis we suggest the same treatment algorithm for this disease as it was shown by Marchal et al. (2001) that histological restoration of the gland’s sclerotic parenchyma to a physiological appearance can be achieved in some cases [28]. In cases of persisting symptomatic sclerotic sialadenitis gland resection may be a final option. On average, success rates of the step-by-step approach in sialolithiasis are reported with 84.23% in the current literature which is comparable to our finding with 86.2% [18, 19, 29, 30]. Sialolith removal from the PG was more tolerable to patients than from the SMG. The different therapeutic modalities like papillotomy, interventional sialendoscopy, ESWT and intraoral sialolithotomy were regarded as more tolerable than the symptoms of sialolithiasis themselves by patients. Contemporary studies describe holmium laser-assisted lithotripsy as an additional promising therapy for sialolithiasis [31]. Best outcomes using this technique were reported for midsize sialoliths with a diameter between 4 and 8 mm [32]. Generally, increased risks of damage to the excretory duct were not found to be higher using intraductal laser therapy compared to other treatment modalities [33]. It would be interesting to include laser lithotripsy to the presented treatment algorithm for future trials. However, currently a holmium laser is not available at our clinic. The treatment algorithm could significantly ease symptoms. This could also be shown by other studies [23, 34‐37]. 94.3% of patients would want to receive the same therapy again in case of recurrent sialolithiasis which supports improved HRQoL.

Treatment of sialolithiasis using a minimally-invasive treatment algorithm is a promising, well-established method to omit gland resection. The present study shows that patient-perceived improvement of HRQoL due to ease of symptoms has even higher success rates than stone removal alone.