Intra-oral Parotid Duct Exploration and Ductoplasty for Large Parotid Duct Stones: How We Do It

Salivary duct stones are a common occurrence, most frequently found in the submandibular gland. A smaller proportion of stones can be found in the parotid system (5%–10%).1 Saliva drains from the parotid gland via Stensen's duct, which emerges from the anterior surface of the parotid gland, superficial to the masseter muscle. At the anterior border of the masseter muscle, it pierces the buccopharyngeal fascia and continues in the submucosa to enter the oral cavity at the papilla lateral to the second upper molar. It is approximately 4-cm long, with a diameter of 2–3 mm. Sialoendoscopy has gained popularity over the past number of years to extract proximal duct stones, however, larger impacted stones may not be amendable to this approach and pose a clinical dilemma for surgeons.2 For these patients a trans-facial approach may be advocated, or even a parotidectomy can be required.2 Both of these approaches can be challenging and are significantly invasive, not least associated with cosmetically unsightly scars and also a risk of facial nerve injury.3 This article demonstrates an alternative approach of intra-oral parotid duct exploration and ductoplasty technique for large impacted parotid duct stones. This technique is particularly suitable for difficult cases following unsuccessful sialoendoscopy, and as an alternative to the trans-facial approach. A retrospective review of the senior author's approach to parotid duct stones was performed over a three-year period. The attached video demonstrates operative approach by a single surgeon at our institution. Recording was performed with a zero-degree endoscope (Karl Storz, Tuttlingen, Germany). This study has been approved by our hospital's institutional review board. After standard induction and nasal intubation, a dental bite block is placed on the contralateral side to improve access. All patients receive prophylactic broad-spectrum antibiotics and intravenous corticosteroids at induction of anesthesia. Surgical loupes with 2.5× magnification are used to aid visualization. The duct and gland are palpated to try and identify the location of the stone. Retraction of the tongue and buccal mucosa is performed using a combination of Langenbeck and malleable retractors. At the proposed incision site 2% Lidocaine with adrenaline is injected. A U-shaped incision (using a number 15 blade scalpel), with a 1-cm radius is made around the papilla. The tip of the U should be facing laterally, and it is imperative to avoid the papilla with the incision. Using a combination of blunt and sharp dissection between the soft tissue of the cheek laterally and the parotid duct medially, we dissect toward and up to the anterior aspect of the masseter muscle. A lacrimal probe placed in the duct can be helpful during dissection to delineate the duct and also to avoid damage to the buccal nerve. The duct is then opened longitudinally over the stone to prevent stenosis, with the incision large enough to safely extract the stone without trauma. Frequently, the tissue over the duct is thickened and fibrosed. The stone is then gently removed. We flush the duct with normal saline to ensure no further stone remnants remain. A sialoendosope can be inserted at this stage to reassess the ductal system. The parotid duct is reconstructed with intermittent 6-0 monofilament sutures. The mucosa surrounding the parotid duct is preserved and then sutured in its initial position with 4-0 monofilament sutures. Postoperatively the patient is instructed to massage their parotid gland (from back to front) and use saline mouthwash after meals. Sialagogues are encouraged, and we advise patients to chew sugar-free gum between meals. If there is any evidence of infection, we commence the patient on oral broad-spectrum antibiotics for 5 days. Patients typically remain in hospital overnight post-procedure. Postoperative endoscopy is not routinely carried out, as we emphasize minimal surgical intervention after stone removal. All patients are reviewed in the outpatient department 6 weeks postoperatively. Over a three-year period, five patients have undergone a parotid duct exploration and ductoplasty for impacted parotid duct stones, which were not amenable to endoscopic removal (Table I). All patients who had distal parotid duct stones were selected for this procedure. Patients who had proximal, non-impacted stones underwent endoscopic removal. Median age was 48 years (range 68 to 37) with an equal gender distribution. One patient had previously had an unsuccessful endoscopic stone removal. All patients underwent preoperative imaging, with ultrasound the most frequently utilized modality (n = 3). Median length of procedure was 32 min (range 20 to 41 min). All patients were discharged the morning after surgery. All patients experienced complete resolution of their symptoms post-procedure and reported minimal postoperative pain. Multiple methods have been employed for the removal of parotid duct stones, including but not limited to lithotripsy, sialoendoscopic retrieval, and transcutaneous approaches.2 Although duct exploration has been used for proximal stones, this study is the first to demonstrate its utility for the extraction of more distal stones.4 We typically use a sialoendoscope initially to attempt retrieval and this approach can then be utilized as a back-up if sialoendoscopic retrieval is unsuccessful. As with any surgical intervention, careful patient selection is imperative. In our experience, this approach is particularly useful for large, impacted stones greater than 3 mm in the middle third of the parotid duct. These stones can be removed via a trans-facial approach, but aside from the risk of morbidity and cosmetic change, this approach can be challenging for deep stones.3 Also branches of the facial nerve are at risk with the trans-facial approach, but with the intra-oral approach these branches are easily avoided. Dissection is performed close to the duct, up to the anterior border of the masseter which is the limit of our dissection. This minimizes the risk of injury to the buccal branch of the facial nerve. Stones greater than 3 mm are known to be challenging to remove endoscopically.5 Thus, our technique can be utilized in these cases too, regardless of location, and also as an alternative to unsuccessful sialoendoscopic removal. This approach is associated with minimal morbidity. Patients return to a normal diet postoperatively. Operative time is short compared to other approaches, and patients are generally discharged the morning after surgery. Theoretically, patients are at risk of duct stenosis, but we have not experienced this in our institution. In some institutions stents are advocated to reduce the risk of stenosis, but stenting is not routinely used in our practice, and (in our estimation) they are poorly tolerated at the duct/gland junction.4 We follow up the patients 6 weeks postoperatively. No patients in this study required further intervention post-procedure. The small patient number and lack of long-term follow-up is a limitation of this study. In summary, we have found that intra-oral parotid duct exploration and ductoplasty as described is a safe and effective treatment option for parotid duct stones. It has a high success rate for stone retrieval and resolution of symptoms, and avoids the potential adverse effects of more invasive procedures. This article and video can be used as a guide so that other institutions can add this approach to their armamentarium in the management of parotid duct stones. Open access funding provided by IReL. Video S1. Intra-oral parotid duct exploration and ductoplasty for large parotid duct stones. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.