Submandibular Sialolithiasis

The treatment of salivary calculi of the submandibular gland is a function of the location and size of the sialolith (Figure 5.10). For example, sialo-liths present within the duct may often be retrieved with a transoral sialolithotomy procedure and sialodochoplasty. In general terms, if the stone can be palpated transorally, it can probably be removed transorally. A review of 172 patients who underwent intraoral sialolithotomy of a submandibular stone assessed results as to complete removal, partial removal, and failure (Park, Sohn, and Kim 2006). The effect of location, size, presence of infection, and palpability of the calculi on the results was assessed. Univariate analysis showed that palpability and the presence of infection were statistically significant factors affecting transoral sialolithotomy. Palpability was the only significant factor after multivariate analysis. This study provides scientific evidence supporting intraoral removal of extraglandular submandibular gland stones regardless of location, size, presence of infection, or recurrence of calculi as long as the calculi are palpable. This procedure involves excising Wharton's duct overlying the stone, thereby permitting its retrieval (Figure 5.11). Reconstruction of the duct in the form of a sialodochoplasty permits shortening of the duct and enlargement of salivary outflow, thereby preventing recurrence and allowing for healing of the gland (Rontal and Rontal 1987). A properly performed sialodocho-plasty ensures effective flow of saliva from the gland in hopes of maintaining the health of the salivary gland. This procedure involves suturing the edges of the duct's mucosa to the surrounding oral mucosa (Figure 5.11). The number of sutures placed is arbitrary; however, a sufficient number of sutures is required so as to stabilize the reconstructed duct to the floor of the mouth. Proper postoperative hydration of the patient with free flowing saliva maintains patency of the sialodocho-plasty, thereby enhancing the potential for reversal or stabilization of the underlying sialadenitis. Chronic submandibular obstructive sialolithiasis clearly leads to chronic sialadenitis with presumed parenchymal destruction. After removal of the sialolith, however, the apparent resiliency of the submandibular gland usually results in no adverse symptoms (Baurmash 2004). As such, the ability to effectively retrieve a sialolith usually refutes the need to also remove the affected salivary gland.

Submandibular sialolithiasis

Location

Intraglandular duct Hilum

Extraglandular duct

Size

Consider lithotripsy

Resolved?

Monitor

Submandibular gland excision

Lithotripsy

Resolved?

Transoral sialolithotomy with sialodochoplasty Consider sialoendoscopy with sialolithotomy, possible papillotomy

Resolved?

Yes i I

Monitor

Monitor

Consider sialoendoscopy with sialolithotomy possible papillotomy

Submandibular gland excision

Resolved

Monitor

Submandibular gland excision

Figure 5.10. Algorithm for submandibular sialolithiasis.

Sialoliths located within the submandibular gland or its hilum are most commonly managed with submandibular gland excision (Figure 5.12). This controversial statement is made based on the relative difficulty to retrieve stones from this anatomic region of the gland, rather than based on the assumption that proximal stones cause permanent structural damage to the gland that results in the need for removal of the gland. To this end, a study examined a series of 55 consecutive patients who underwent transoral removal of stones from the hilum of the submandibular gland (McGurk, Makdissi, and Brown 2004). Stones were able to be retrieved in 54 patients (98%), but four glands

(8%) required subsequent removal due to recurrent obstruction. The authors emphasized that it was necessary for the stone to be palpable and no limitation of oral opening should exist in order for patients to undergo their technique. They reported an acceptable incidence of complications associated with their technique, although they lamented that it remained to be seen if the asymptomatic nature of their patients would be maintained over time.

Shock wave lithotripsy has been reported as a primary form of treatment for submandibular salivary gland stones. Salivary stone lithotripsy requires a gland to be functional by virtue of production of

Figure 5.11a. A sialolith is noted at the opening of the right Wharton's duct. Since this stone was able to be palpated on oral examination, it was removed transorally without necessitating the removal of the right submandibular gland. Reprinted from: Berry, RL. Sialadenitis and sialolithiasis. Diagnosis and management. In: The Comprehensive Management of Salivary Gland Pathology, Carlson ER (ed), Oral and Maxillofacial Surgery Clinics of North America, WB Saunders, Philadelphia, 407-503.

Salivary Gland Stone Uss

Figures 5.11b, 5.11c, and 5.11d. The main stone was removed (b), after which time exploration of the proximal duct revealed two additional stones that were also removed (c). A sialodochoplasty was performed to widen and shorten the right Wharton's duct (d). A sialodochoplasty performed near the papilla of Wharton's duct is termed a "papillotomy." Reprinted from: Berry, RL. Sialadenitis and sialolithiasis. Diagnosis and management. In: The Comprehensive Management of Salivary Gland Pathology, Carlson ER (ed), Oral and Maxillofacial Surgery Clinics of North America, WB Saunders, Philadelphia, 407-503.

Figure 5.12a. The clinical appearance of a man with pain Figure 5.12c. A standard transcutaneous approach was and left submandibular swelling. followed to submandibular gland excision.

Figure 5.12b. His panoramic radiographic shows a sialo-lith in the left submandibular gland.

Figure 5.12d. A subfascial dissection of the gland was performed. Inferior retraction on the gland allowed for preservation of the marginal mandibular branch of the facial nerve.

Figure 5.12e. Superior and anterior retraction of the gland allowed for identification of the sialolith that was located at the hilum of the gland.
Figures 5.12f and 5.12g. The excised gland (f) was bisected (g) and demonstrated significant scar tissue formation.

saliva in order for the stone fragments to be eliminated from the duct. Some authors have implemented a sour gum test prior to performing extracorporeal lithotripsy (Williams 1999). This test involves the patient chewing sour gum while the clinician looks for swelling of the gland. The development of swelling indicates that the gland is functional such that extracorporeal lithotripsy may be attempted. In the absence of swelling, extracorporeal lithotripsy is contraindicated, and the gland is planned for removal. Two techniques of salivary lithotripsy have been developed, including extra-corporeal sonographically controlled lithotripsy and intracorporeal endoscopically guided litho-tripsy (Escudier 1998). Extracorporeal shockwave lithotripsy was first used to treat renal stones in the early 1980s. The shockwaves can be generated by electromagnetic, piezoelectric, and electrohydrau-lic mechanisms and the resultant waves are brought to a focus through acoustic lenses. They then pass through a water-filled cushion to the stone, where stress and cavitation act to fracture the stone. At the sialolith-water interface a compressive wave is propagated through the stone, thereby subjecting it to stress. Cavitation occurs when reflected energy at the sialolith-water interface results in a rebounding tensile or expansion wave that induces bubbles. When these bubbles collapse a jet of water is projected through the bubble onto the stone's surface. This force is sufficient to pit the stone and break it. Extracorporeal lithotripsy for submandibular gland stones is somewhat less successful than that of parotid stones (Williams 1999). Ottaviani and his group evaluated the results of 52 patients treated with electromagnetic extracorporeal lithotripsy for calculi of the submandibular gland (n = 36 patients) and parotid gland (n = 16 patients). Complete disintegration was achieved in 46.1% of patients, including 15 with submandibular sialolithiasis and 9 with parotid sialolithiasis. Elimination of the stones was confirmed by sonogram. Residual con-crements were detected by ultrasound in 30.8% of patients, including 9 with submandibular stones and 7 with parotid stones. Four patients with re -sidual submandibular stones required surgical retrieval. The authors concluded by indicating that if hilar and intraglandular duct stones are smaller than 7 mm in size, they may be successfully treated with lithotripsy (Williams 1999). The surgeon should proceed with submandibular gland excision if this trial of lithotripsy is not successful, or if stones larger than 7 mm are identified.

Intracorporeal lithotripsy techniques are now used in which a miniature endoscope is utilized to manipulate the stone under direct vision. In this technique, shockwaves are applied directly to the surface of the stone under endoscopic guidance. The shockwave may be derived from an electro-hydraulic source, a pneumoballistic source, or from a laser. Pneumoballistic energy has been shown to produce calculus fragmentation with greater efficiency than lasertripsy (Arzoz et al. 1996). The disadvantage of these techniques is that the size of the endoscope and probe requires that the duct be incised so as to facilitate entry.

Finally, interventional sialoendoscopy has been developed that may permit the use of a fine a b

Figures 5.13a and 5.13b. Interventional sialoendoscopic instrumentation for retrieval of salivary calculus, including the operating sheaths (a) that accept the miniature endoscope (Karl Storz Endoscopy-America, Inc., Culver City, California) in the telescope channel (b).

sialoendoscope to retrieve salivary stones (Nakayama, Yuasa, and Beppu et al. 2003) (Figure 5.13). The size of some sialoliths, however, is such that an incision of the papilla may be necessary for their delivery. Interventional sialoendoscopy may be used with lithotripsy to fragment large c e

Figures 5.13c, 5.13d, and 5.13e. The grasping forceps (c), are placed within the working channel of the operating sheaths (d), and are able to retrieve stones that may be identified on diagnostic sialoendoscopy (e). Figure 5.13e courtesy of Dr. Maria Troulis, Boston, Massachusetts.

c d a b e stones so as to achieve a completely non-invasive therapeutic sialoendoscopy.

McGurk, Escudier, and Brown (2004) assessed the efficacy of extracorporeal shock wave litho-tripsy, basket retrieval as part of interventional sialoendoscopy, and intraoral surgical removal of salivary calculi. Three hundred twenty three patients with submandibular calculi were managed. Extracorporeal shockwave lithotripsy was successful in 43 of 131 (32.8%) patients, basket retrieval was successful in 80 of 109 (73.4%) patients, and surgical removal was successful in 137 of 143 (95.8%) patients with submandibular stones.

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