INDICATION
Sialendoscopy is a minimally invasive technique where semirigid endoscopy is used to evaluate the salivary gland ducts. Development of this technology was made possible via miniaturization of instruments and enhanced resolution of imaging. , Sialendoscopy has emerged as a diagnostic and therapeutic tool to effectively evaluate salivary gland pathology. It is used in the diagnosis of obstructive salivary gland disorders. It allows for clear visualization of ductal anatomy to identify the underlying cause of gland inflammation, recognizing symptomatology due to salivary stasis and subsequent infection. Sialendoscopy is used to evaluate ductal strictures, intraductal masses (including sialoliths, mucous plugs, ductal polyps, foreign bodies), and salivary swelling of unclear origin with the capability of localizing the area of concern.
Sialendoscopy can also be used therapeutically. Most commonly, sialendoscopy is used to identify and remove mobile submandibular and parotid sialoliths. Marchal and Dulguerov classically described submandibular stones less than 4 mm in diameter and parotid stones less than 3 mm in diameter as amenable to endoscopic sialolithotomy with a wire basket retrieval device. However, it has been our experience that mobile fusiform stones with their long axis oriented in the direction of the duct may exceed the sizes classically described. Small stones in the parotid duct or distal submandibular duct and hilum may benefit from a purely endoscopic approach. Larger stones in the parotid or submandibular ductal system can be treated by either a combined approach (endoscopic localization and/or visualization with an open sialolithotomy technique) or, in certain cases, an open technique.
Ductal strictures secondary to ductal calculi or other inflammatory/autoimmune etiologies, might be both diagnosed and treated with sialendoscopy. This technology is also useful in the treatment of radioiodine-induced sialadenitis with its associated xerostomia. In many cases sialendoscopy serves a therapeutic role by allowing for simple hydrodilation of a stricture and stenoses. The irrigation of the salivary duct in simple diagnostic sialendoscopy removes mucous plugs, which may reduce inflammation and scarring. In patients with Sjögren syndrome sialendoscopy is associated with reductions in xerostomia and an increase in saliva production regardless of the irrigation fluid used.
Acute sialadenitis is one of the only relative contraindications to sialendoscopy and sialodochoplasty. The inflammation associated with acute sialadenitis increases the risk of ductal injury and perforation during stone removal and sialendoscopy. Mucopurulent saliva may prevent adequate visualization during sialendoscopy. Patients with acute sialadenitis should be managed with optimal medical management and surgical therapy performed electively.
Imaging of the affected gland is recommended before sialendoscopy as this may help identify areas of obstruction. Preferred imaging options include noncontrast computed tomography with thin slices or ultrasound. As ultrasound is operator dependent, a surgeon-performed ultrasound by an experienced provider is especially helpful in expediting diagnosis at presentation. Ultrasound is an active imaging modality that may be combined with exam maneuvers such as sonopalpation and citric acid administration to enhance identification of stones and salivary ducts. These imaging modalities allow for measurement of stone size, shape, and location to aid in surgical planning and counselling. Improper patient selection may increase the risk of stone impaction when endoscopic sialolithotomy is attempted. This may be avoided by ensuring that the stone is freely mobile and the duct between the papilla and stone is sufficiently dilated without stenotic segments that can precipitate stone impaction and basket entrapment.
Careful patient selection is essential for any office-based procedure. Obtaining a detailed past surgical history including dental procedures is helpful in assessing tolerance of awake salivary gland procedures. The senior author believes it is actually easier to perform sialendoscopy with the patient awake, as they are able to hold their mouth open and lift the tongue up to expose the floor of the mouth. The papilla is also easier to identify, which is often the rate-limiting step to successful sialendoscopy.
As with any office procedure, the risks and benefits of the procedure require full discussion. Sialendoscopy can be performed in the office for almost any pathology that can be treated in the operating room. If there is a need for significant dilation, the case may be better performed in the operating room. Additionally, if there is a plan to perform a combined approach (especially for stones in the parotid gland), then the operating room is more appropriate. However, for most strictures, mobile stones, and diagnostic procedures, the office setting is preferable.
TECHNIQUE
Equipment, Preparation, and Anesthesia
A Mayo stand is prepared with the equipment listed ( Table 6.1 , Fig. 6.1 ). The 1.1-mm or 1.3-mm all-in-one sialendoscope is connected to the light source, camera, and 0.9% NaCl saline irrigation ( Fig. 6.2 ). The patient is seated comfortably in a Fowler semisupine or upright position with the surgeon usually in a standing position. The patient is covered with a dental bib. Sialendoscopy is begun by injecting the mucosa surrounding the affected papilla with local anesthetic (1% lidocaine with 1:100,000 epinephrine).
TABLE 6.1
Sialendoscopy Equipment
Telescope
Irrigation
Anesthetic
Surgical instruments
Disposables
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Sialendoscopy instruments and setup for procedure in the clinic. A stand is set up with 1.1 mm all-in-one sialendoscope connected to camera, light source, and saline irrigation. Stand contains syringe with 1% lidocaine with 1:100,000 epinephrine, guide wire, salivary access dilator, needle driver, lacrimal probes, conical dilator, scissors, scalpel, hemostat, forceps.
Saline irrigation. IV pole with 0.9% NaCl saline and tubing with stopcock or 3-way valve. 10 mL syringe attached to 3-way valve.
Cannulation and Dilation
The papilla is then identified by grasping nearby mucosa with forceps and gently retracting anteriorly to help straighten the duct. Ductal patency is confirmed by passing a 0.015-inch-diameter × 50-cm-long fixed core guidewire into the papilla ( Fig. 6.3 ). The salivary access dilator is then wet and threaded onto the guidewire ( Fig. 6.4 ). Successive dilations can be made with progressively larger access dilators. At this point the surgeon may instill viscous lidocaine through the salivary access dilator using a syringe attached to the incorporated Luer-Lok connection. Viscous lidocaine provides additional anesthetic effect, but the increased viscosity of this instillate provides a stenting effect, which can be useful if the affected duct demonstrates a propensity to collapse. This may also facilitate insertion of the sialendoscope during subsequent steps. Instillation of any fluid into the duct is often associated with a sense of fullness and swelling of the affected gland in the awake patient. The patient should be counseled that this is an expected sensation with sialendoscopy.
(A) Papilla identified with attempted cannulation with a guidewire. (B) If unable to visualize ductal orifice, mucosal dissection can be used to identify the duct (C) guidewire inserted into the main duct.
Salivary access dilator is threaded onto the guidewire.
While lacrimal probes and a conical dilator may be used for the initial cannulation and dilation, it is the senior author’s preference to perform the initial cannulation with a guidewire as this allows for the subsequent steps of dilation and possible instillation using a Seldinger technique. This facilitates an efficient technique and reduces the risk of repeat trauma associated with repeated cannulation of the duct.
Diagnostic Sialendoscopy
Before inserting the sialendoscope, the saline-filled intravenous (IV) tubing should be flushed until saline drains from the working end of the sialendoscope to ensure no air bubbles are present. Now that the papilla and anterior duct have been dilated, the sialendoscope may be inserted into the affected papilla and the ductal lumen visualized ( Fig. 6.5 ). While advancing the scope, an assistant may apply gentle positive pressure on the saline-filled syringe and IV tubing attached to the sialendoscope’s irrigation port. This helps to stent the duct open while the scope is advanced within the salivary tree. This is instilled very slowly, usually at a rate less than 0.5 mL/min. The scope is advanced until the secondary and tertiary ducts are visualized, or the pathology of interest is visualized including mucus plugging, stricture, or sialolith. During diagnostic sialendoscopy any stenosis, dilation, or sialolithiasis should be noted. , If a stone is present, it should be noted whether the stone is free-floating in the duct or fixed. The size of the stone should be estimated. The location of the stone should be noted in the floor of mouth or buccal mucosa via transillumination or palpation with a gloved finger. These factors are essential in the clinical decision-making to best approach stone removal. Approaches include endoscopic sialolithotomy, a transoral approach with ductal cut-down, or a hybrid approach. The character of any stenotic segments should be noted including diaphragmatic stenosis, isolated main ductal stenosis, multiple or diffuse main ductal stenosis, or ductal stenosis involving both the main duct and intraglandular ducts. , Dilation may also be characterized similarly using Marchal et al.’s classifications, which includes isolated dilated segments, multiple dilated segments, or diffuse dilation of the entire salivary tree. If mucus plugging is encountered, gentle small-volume pulsation of the irrigation syringe may help to clear any mucous from the duct.
Sialendoscope inserted into the papilla and advanced into the anterior duct.
Endoscopic Dilation
If short stenotic segments are encountered dilation may be performed to alleviate associated obstruction. Dilation may be performed using numerous adjuncts including a balloon, bougie, or rigid dilator, but dilation with saline hydrodilation and the endoscope itself are the simplest and most efficient techniques for short-segment stenosis. Hydrodilation by instillation of saline at stenotic segments may allow for sufficient dilation while avoiding the use of more aggressive instrumentation, which risks further ductal trauma. Sialendoscopy also allows for the use of a balloon dilator in the main duct. The choice of technique is based on the pattern of stenosis and location within the salivary tree.
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