Introduction
Salivary duct stenosis is a relatively rare pathologic condition. Of the stenosis cases, 70–75% are located in the parotid duct system. Salivary duct stenosis is the second most common cause of obstruction in the parotid gland, representing 15–25% of cases and making up 50–90% of cases of unclear duct dilation or gland swelling.
Parotid stenosis can be associated with various conditions/diseases; however, chronic (recurrent) parotitis may be the only cause. Stenosis develops in up to 13% of patients after prior surgery of the gland or the duct system, and is associated with sialolithiasis in over 15% of cases, which complicates treatment. Parotid duct stenosis is classified into inflammatory, fibrous, megaduct, duct anomaly-associated stenosis, and pure fibrous fixed stenosis without duct anomaly.
Stenosis can be treated with success rates of >90% by a sialendoscopic minimally invasive and gland-preserving therapy, with good short- and long-term outcome. The success rates of the procedures are >80%, with improvement of symptoms reported in 70–90%, and gland preservation in 90–100% (see Chapter 27 ).
Not all stenosis can be treated by sialendoscopic means. High-grade stenosis with complete duct obstruction and scarring can be managed only by more invasive surgical means. High-grade stenosis can occur after surgical procedures of the cheek region, Stensen’s duct itself, or after abscess formation due to sialolithiasis or in combination with other diseases.
Almost all patients presenting with stenosis report a history of longstanding duct obstruction and excretion of murky and thick, sometimes jelly-like secretion. The gland function in many of these cases is compromised, reducing the chance of successful outcome.
Stenosis associated with duct anomalies represent another group that may require more invasive measures to achieve a successful outcome. The grade of the stenosis with duct anomalies is generally mild to moderate; however, it can also be high-grade or nearly complete. This kind of stenosis is often complicated by kinking with an associated megaduct, in particular in the distal duct region.
Diagnostic Work-Up and General Preoperative Considerations
Although interventional sialendoscopy is the first choice in the treatment of ductal stenosis, transoral duct surgery or a combination of sialendoscopy and transcutaneous approaches may be the only treatment alternatives to ablation of the function of the gland or its resection. Meticulous diagnostic work-up is needed to assess if transoral or combined surgery is possible. Diagnostic information should include the course of the duct and the exact location of the stenosis and the nature of the surrounding tissue.
The presence of a megaduct is an important precondition to successful transoral duct surgery, as it will allow marsupialization of the proximal duct to the oral mucosa more readily. If no megaduct is present, the chance for a successful outcome decreases.
Ultrasound, magnetic resonance (MR)-sialography, conventional sialography, and computed tomography (CT) or cone beam-CT with sialography are the diagnostic imaging tools that can all contribute to a more precise characterization of stenosis (see Chapter 3 ). The duct itself, the surrounding tissues, and their relationship to the duct system can be determined by CT with sialography, MR-sialography, or by ultrasound. In papillary stenosis and/or distal duct stenosis, ultrasound can used to measure the length of the stenosis, the distance from the oral mucosa to the most distal visible lumen, and the diameter of the duct lumen proximal to the stenosis, which are important criteria that help to indicate or to abandon transoral duct surgery ( Fig. 28.1 ). In papillary or prepapillary and distal duct stenosis, the distance between the oral mucosa to the most distal visible duct lumen should not exceed 15 mm, because suturing of the duct to the oral mucosa may not be possible or only possible with a higher risk of complications due to increased tension. Creation of any neo-ostium must be performed without any tension in order to avoid re-stenosis. The ductal lumen proximal to the stenosis can be measured also by ultrasound. A megaduct with a duct diameter exceeding 5 or even 10 mm represents a favorable situation, because it offers an adequate lumen to allow suturing of the pre-stenotic duct to the oral mucosa with creation of a wide neo-ostium and is one important precondition to perform successful transoral duct surgery in parotid gland duct stenosis ( Figs. 28.2 , 28.3 ). In complete stenosis, the sialendoscope cannot be inserted into the duct system primarily but it is important to perform stent implantation, indicated in virtually all cases.
Methods of Transoral Duct Surgery
Various invasive surgical procedures in the distal duct system have been described, such as papillotomy or meatotomy, sialodochoplasty with duct reinsertion, and duct ligation. High failure rates exceeding 50% with the above techniques have been described. All methods of transoral duct surgery described here are restricted to the premasseteric distal duct system.
(Extended) Papillotomy
In complete and extended papillotomy, the incision is performed through all layers of the papilla, namely oral mucosa, the whole periductal musculature, and the inner mucosal lining. Stent implantation is mandatory in this procedure and the stent should stay for at least 12 weeks to allow development of a stable scar ( Fig. 28.2 ). Due to the impaired tissue quality within the involved ductal area, characterized by scarring and/or maceration, in most cases marsupialization cannot be performed adequately. Beyond that, the advantages of a larger lumen provided by the presence of a megaduct cannot be used to create a wide neo-ostium. This procedure is associated with a higher risk of development of a re-stenosis, even with stent implantation. Cohen et al. reported recurrences after papillotomy and revision-papillotomy, with stent implantation for 2 weeks and 3 weeks, respectively. They emphasized that complete marsupialization is mandatory to achieve successful outcome. In our patients, this technique is carried out very rarely in patients presenting with a papillary stenosis in combination with sialolithiasis and stone extraction ( Fig. 28.3 ). These patients present with completely scarred papillary stenosis. If at all, this technique should be deployed only in very exceptional situations and does not represent a routine primary treatment option.
Retropapillary Ductal Incision With Creation of Ductal Neo-Ostium
In case of a short (<1 cm) papillary or prepapillary duct stenosis, papillotomy can be avoided by performing a retropapillary duct incision with subsequent marsupialization of the ductal epithelium and creation of a neo-ostium. The presence of a megaduct near the oral mucosa is an important precondition to carry out this kind of surgery. A semicircular incision is performed ~5 mm adjacent to the scarred papilla ( Fig. 28.4 ). The megaduct is prepared by careful dissection and freed from the buccal fat pad and the buccinator muscle. The opening of the duct can be made in a horizontal (alternatively also or vertical) direction, depending on the presentation. After adequate dissection of the duct, the incision is sutured to the surrounding oral mucosa with 4-0–6-0 resorbable sutures. The resulting neo-ostium is created by a “duct side wall to mucosa” – anastomosis ( Fig. 28.5 ). This technique was described for stenosis with megaduct with and without associated duct anomalies. It is used in complete fibrotic stenosis with high inflammatory activity within the gland. Complete marsupialization by suturing the oral mucosa to the ductal epithelium must be performed to avoid recurrences. Stent implantation is indicated in almost every case. This technique is also indicated with stenosis associated with megaduct and duct anomalies, but without significant inflammation. The technique is for stenosis located in the papillary, prepapillary, or most distal region. In cases of a location more proximal, with a distance to the oral mucosa/ostium exceeding 15 mm, there is an increasing risk that marsupialization with creation of a tension-free neo-ostium may not be possible.
Resection of Papilla and/or Distal Duct and Creation of Neo-Ostium by Duct Reinsertion
In cases with a short papillary, prepapillary, or distal duct stenosis (not exceeding a length of 10–15 mm) the involved segment of the parotid duct may be resected with subsequent marsupialization of the ductal epithelium with creation of a neo-ostium. The presence of a megaduct is favorable but not a mandatory precondition. If possible, a probe is inserted through the residual lumen into the proximal duct system. A circular mucosal incision is made around the (scarred) ostium. The duct must be prepared up to the part of the duct located proximal to the stenosis. The buccal fat pad must be identified. It may be an advantage to resect it to gain more space for tension-free reinsertion of the duct. To free and dissect the duct in an adequate length, the buccinator muscle must be transected in part in nearly all cases. A buccal branch of the facial nerve is commonly next to the duct. The distal part of the duct, including the stenosis, is completely resected and the uninvolved, healthy proximal duct end is marsupialized to the buccal mucosa with creation of a neo-ostium. The resulting neo-ostium is created by a “duct end to mucosa” anastomosis. The marsupialization uses 4-0–6-0 resorbable sutures ( Figs. 28.6 and 28.7 ). The technique can be applied in stenosis associated with inflammatory activity or in stenosis associated with duct anomalies, which typically do not show signs of increased inflammatory activity. The latter can be associated with high-grade stenosis, with no or nearly no visible lumen. A significant megaduct distally is almost always present, which makes for ideal candidates for performing this approach. Kandl et al. called this procedure “pull-through sialodochoplasty”. After transoral duct surgery with marsupialization, the ostium narrows. This narrowing process has to be taken into account.
