CC-BY-NC 3.0 SIALOLITHIASIS: TRADITIONAL & SIALENDOSCOPIC TECHNIQUES Robert Witt & Oskar Edkins Sialoliths vary in size, shape, texture, and The anterior FOM has a covering of delicate consistency; they may be solitary or multi- oral mucosa through which the thin-walled ple. Obstructive sialadenitis with or without sublingual/ranine veins are visible (Figures sialolithiasis represents the main inflamma- 1 & 2). The veins are visible on the ventral tory disorder of the major salivary glands. surface of the tongue, and accompany the Approximately 80% of sialolithiasis in- hypoglossal nerve (Figure 2). volves the submandibular glands, 20% oc- curs in the parotid gland, and less than 1% is found in the sublingual gland. Patients typically present with painful swelling of the gland at meal times when obstruction caused by the calculus becomes most acute. When conservative management with sial- ogogues, massage, heat, fluids and antibiot- ics fails, then sialolithiasis needs to be surgi- cally treated by transoral, sialendoscopic Figure 2: Ranine veins and sialendoscopy assisted techniques; or as a last resort, excision of the affected gland The paired sublingual salivary glands are (sialadenectomy). located beneath the mucosa of the anterior FOM, anterior to the submandibular ducts Surgical anatomy and above the mylohyoid and geniohyoid muscles (Figures 3 & 4). The glands drain The paired submandibular ducts (Whar- via 8-20 excretory ducts of Rivinus into the ton’s ducts) are immediately deep to the submandibular duct and also directly into mucosa of the anterior and lateral floor of the mouth on an elevated crest of mucous mouth (FOM) and open into the oral cavity membrane called the plica fimbriata which to either side of the frenulum (Figure 1). is formed by the gland and is located to ei- The frenulum is a mucosal fold that extends ther side of the frenulum of the tongue). along the midline between the openings of the submandibular ducts. In the anterior floor of mouth the lingual nerve is located posterior to the duct; it crosses deep to the submandibular duct in the lateral floor of mouth (Figures 3, 4, 5). Ranine veins Frenulum Puncta of submandib- ular ducts Submandibular duct Figure 1: Anterior FOM www.openbooks.uct.ac.za/ENTatlas 7-1 Robert Witt & Oskar Edkins Lingual nerve intraoral examination. The salivary ductal Intraoral SMG orifice may be red and oedematous. One Floor of mouth should massage the gland to milk and in- Ducts of Rivinus spect the saliva; frank infection may be rep- Sublingual gland resented by plaques or whitish secretions Mylohyoid emanating from the duct. Manual palpation Submental artery of the parotid gland allows a surgeon to de- Cervical SMG termine the consistency of the gland. Figure 3: Sagittal view floor of mouth Lingual nerve Sublingual gland Parotid duct Submandibular duct Opening parotid duct Wharton’s duct Submandibular gland Mylohyoid muscle Geniohyoid muscle Figure 4: Superior, intraoral view of submandibular gland, duct, lingual nerve and mylohyoid and gen- iohyoid muscles Figure 6: Stensen’s duct crosses and hooks around the anterior aspect of the masseter, and pierces the bucci- nator muscle to enter the mouth (Gray’s anatomy) Lingual nerve Bimanual palpation (finger inside and out- Submandibular duct side the mouth) is particularly important Sublingual gland when examining the submandibular gland Submandibular gland and its duct. Mylohyoid muscle Figure 5: Intraoral view of left sublingual gland with Salivary Imaging ducts of Rivinus, submandibular gland and duct, lin- gual nerve and mylohyoid muscles Imaging modalities for inflammatory con- ditions of glands are plain X-rays (Figures The parotid (Stensen’s) duct exits the ante- 7a, b), sialography (Figure 8), ultrasound rior edge of the parotid gland, and crosses (Figure 9), and computed tomography (Fig- the surface and hooks around the anterior ure 10). aspect of the masseter, traverses the buccal fat pad, and pierces the buccinator muscle Plain X-rays have less value with parotid nd to enter the mouth opposite the 2 upper stones because of the higher percentage (60- molar (Figure 6). 70%) of radiolucent stones; approximately 20% of submandibular stones are not visible Clinical Evaluation with plain X-rays. Visual scanning of submandibular, Sialography provides images of the mor- preauricular, and postauricular regions is phology of the ductal system and allows di- the first step to assess for the presence of agnosis of strictures, dilatations, and filling swelling and erythema; this is followed by www.openbooks.uct.ac.za/ENTatlas 7-2 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery defects (Figure 8). Ultrasound (Figure 9) is noninvasive and has no associated discomfort. Failure to de- MR sialography is good means to measure tect a stone with ultrasound is not uncom- ductal stenosis. Although avoiding ionising mon as the distal portion of the submandib- radiation, it has less resolution than con- ular and parotid ducts can be difficult to vis- ventional sialography, thereby limiting vis- ualise using extraoral ultrasound; and ultra- ualisation of the peripheral ducts. sound may be of limited value for the deep portion of the submandibular gland. An ob- structed duct that may otherwise not be ev- ident may be better visualized after giving the patient something sour like lemon juice or sour sweets as this may cause ductal dila- tation with obstructive pathology (Figure 10). a Figure 7a: Calculi within the duct (occlusal view) Figure 9: Ultrasound: acoustic shadow cast by calcu- lus b Figure 7b: Calculi within submandibular gland Figure 10: Calculus in right mid Stensen’s duct with dilatation of duct proximal to left-sided of stone Computed tomography (CT) imaging is a Figure 8: Sialogram demonstrating stricture of sub- good imaging modality to see sialoliths (Fig- mandibular duct ures 11, 12). Another advantage is its ability to diagnose and locate intraparenchymal stones and calcification. http://openbooks.uct.ac.za/ENTatlas 25-3 Robert Witt & Oskar Edkins Limitations of ultrasound and CT include 1. Can be removed via intraoral sialoli- distinguishing non-echogenic stones from thotomy approaches, including palpa- strictures, determining the length of a ste- ble stones up to the 1st molar tooth nosis and the diameter of the duct distal to 2. Cannot be removed through intraoral an obstruction. Ultrasound is a dynamic approach and require sialadenectomy; and operator-dependent investigation and this includes stones posterior to the 1st pathology may be therefore be overlooked. molar region, or stones in the middle part of Wharton’s duct that cannot be palpated intraorally Traditional Intraoral Submandibular Si- alolithotomy (Figure 13) • Local or general anaesthesia • Administer local anaesthesia with a vas- oconstrictor in the floor of mouth at the site of the planned incision • Place two 3/0 silk sutures around the duct, posterior to the stone, to isolate Figure 11: CT scan of calculus within hilum of sub- the stone and to prevent displacing the mandibular gland stone to the proximal part of the duct or hilum of the gland (Figure 13) Figure 13: Suture placed posteriorly around subman- dibular duct which has been incised to expose the cal- culus Figure 12: CT scan shows 2 small calculi within distal segment of Stensen’s duct • Cut through mucosa directly onto the stone with a cold blade, electrosurgery, Traditional Surgical Approaches to Sub- or CO2 laser mandibular Gland Sialolithiasis • Remove the calculus • Marsupialise the opening in the duct by Prior to sialendoscopy, sialoliths in the sub- suturing the cut edges of the duct to the mandibular duct and gland were divided oral mucosa with interrupted 4/0 Vicryl into two groups: sutures (Optional) www.openbooks.uct.ac.za/ENTatlas 7-4 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery Note: Although feasible in selected cases, • Dissect bluntly and sharply around the the same sialolithotomy procedure for the duct up to the stone’s location (Figure more posterior ductal region carries a sig- 14a) nificant risk of injury to the lingual nerve • Incise the wall of the duct over the stone and the possibility of severe bleeding from (Figure 14b) the lingual vessels (Figure 2). • Remove the stone with curettes • Following sialolithotomy, massage the Traditional Surgical Approaches to Pa- gland to release saliva and plaque rotid Sialolithiasis • Suture the ductal layer to the oral mu- cosa with several 4/0 Vicryl sutures to Prior to the advent of sialendoscopy, sialo- maintain ductal patency liths in the parotid duct and gland were di- • Inserted a stent (silastic tube) to pre- vided into two groups: vent the higher incidence of ductal ste- nosis encountered with Stensen’s as 1. Can be removed via intraoral sialoli- compared to Wharton’s duct thotomy; this technique is useful only for stones located in the distal part of Parotidectomy for Sialolithiasis Stensen’s duct which is anatomically de- marcated by the curvature of the duct The difference between parotidectomy for around the masseter muscle to where sialolithiasis and a benign tumour is the the duct penetrates the buccinator mus- condition of the gland; inflammation, scar- cle (Figures 6, 12) ring and fibrosis both inside the gland and 2. Cannot be removed via intraoral ap- around Stensen’s duct make the operation proach, requiring extirpation of the pa- difficult and heighten the risk of facial nerve rotid gland injury. The 1st step therefore is to precisely locate the stone to select a