Literature review

In 1965, Mandel and Baurmash studied 14 different radio-opaque contrast solutions, including Sinografin and Ethiodol, for use in sialography. Viscosity, opacity, granuloma formation, irritant effects on mucous membranes, and duration of opacity were analyzed.

Yamamoto and colleagues in 1984 reported on salivary stone chemical and structural composition with scanning electron microscopy and radiograph diffraction analyses of 18 submandibular stones. Lamellar patterned cross-sections revealed numerous shapes of mineral deposits within the lamella and led to possible explanations of sialolith formation. The main stone components were noted to be apatite and whitlock; calcium and phosphorous were the main constituent elements present, with magnesium and sulfur also occurring frequently.

Riesco and colleagues in 1989 reported on the electron microscopic structure of a minor salivary gland stone. It appeared to be only a crystal without bacterial content, undergoing early external coating toward becoming a stone.

Galili and Marmary in 1986 described the beneficial clinical effects on juvenile recurrent parotitis after sialography. They used Pantopaque and felt that the clinical improvements were caused by the dilation and flushing effects and because of the antiseptic properties of iodine. For salivary stones, Marmary in 1986 proposed electrohydraulic Dornier shock waves as a noninvasive technique based on his in vitro experiences.

Brouns reported in 1989 on his in vitro experience with the destructive effects of an electrohydraulic extracorporeal renal lithotriptor on a salivary stone and a molar tooth and the possible patient safety issues involved with using a renal lithotriptor.

In 1989, Iro and colleagues reported the first successful clinical case of shock wave extracorporeal lithotripsy; they proposed piezoelectric shock waves as a safer source. They cautioned against electrohydraulic Dornier shock waves due to tissue damage based on several animal studies. In 1990, Iro’s group reported on clinical experiences with extracorporeal piezoelectric shock wave treatment of stones in 14 patients. A 50% success rate at 3 months without complications was reported.

Briffa and Callum in 1989 described use of an interventional radiology embolectomy catheter for removal of a submandibular duct stone.

Sterenborg and colleagues in 1990 described in vitro laser lithotripsy comparing the pulse dye laser (Candela LFDL/3, Candela Corp, Wayland, Massachusetts, USA) and the Ho-YSGG laser (Laser 1-2-3, Schwartz Electro-optics, Orlando, Florida). The lasers were deemed inefficient at power levels safe for tissues. Eleven stones were analyzed and mainly composed of hydroxyapatite mixed with other minerals.

Grundlach and colleagues reported a 12-patient and in vitro experience using endoscopic intracorporeal lithotripsy in 1990. Eighteen stones were analyzed for stone photo-reflective and absorptive characteristics to help ascertain which laser might be most useful; maximal absorption was at 300 to 400 nm, while maximum reflection was at 500 to 600 nm. The XeCI excimer laser system (308 to 351nm) was judged most efficacious for stone fragmentation, with the CO ₂ and ND:YAG laser less applicable. Currently used urologic and salivary holmium lasers operate at 2100 nm.

In 1990 and 1993, Konigsberger and colleagues published a case report and series, respectively, using intracorporeal endoscopic-guided laser lithotripsy and intracorporeal electrohydraulic shock wave lithotripsy. The excimer laser was successful in the clinical case report; in the series, 19 of 23 patients had complete stone fragmentation. The shock wave probe tip was placed 1.0 mm in front of the stone, and had a pulse energy of 150 mJ at 10 Hz. Two patients had mucoproteid stones deemed too soft for lithotripsy, and six patients were excluded because of ductal stenosis barring endoscopic passage.

In 1990 and 1991, Katz wrote about flexible endoscopy of the salivary ducts. He used a 0.8 mm miniendoscope that was passively flexible, starting in 1988. Stone pathology was visualized, as well as intraductal anatomy such as the first genu of Stensens duct as it crossed the anterior border of the masseter muscle, a valve at the parotid hilum, and the genu of Wharton’s duct at the mylohyoid.

Kater and colleagues described their experiences using a shock wave device in 1990 with a 3-year update in 1993.

In 1992, Buckenham and colleagues reported on strictures treated with balloon dilation by interventional radiology.

Katz in 1993 reported on use of the Dormia basket and dye laser lithotripsy on yellow-colored stones.

Nahlieli and colleagues reported multiple times on endoscopic experiences starting in 1994. The evolution of endoscopic intervention starting with a 2.7 mm rigid arthroscope is chronicled. Initially, stones were removed by suction vacuum. Larger stones were crushed with a forceps before vacuum extraction. The CO ₂ laser was used to incise the submandibular duct for anterior stones. Unusual etiologies for stones were noted, such as hair and plant fiber niduses. In 1997, Nahlieli and colleagues provided a treatment algorithm, wherein stones were removed endoscopically by forceps, suction, or basket. Larger stones were crushed with a forceps or laser fragmented (Calcutrip, K. Storz, Tuttlingen, Germany). Sialadenectomy was reserved for large stones or those proximal to a stenosis. Intraparenchymal stones, severe duct angles, and strictures also caused endoscopic failures. Bupivacaine 0.5% totaling 2 mL intraductally allowed 30- to 60-minute operative durations. Postoperative antibiotics were used for 7 days. In 1999, Nahlieli and colleagues forwarded two endoscope designs: a 1.1 mm diameter diagnostic type and a 2.3 mm treatment type. Acute sialadenitis and stones larger than 10 mm were contraindications. The overall success rate was 82%. A 2 mm wide polyethylene tubing stent was placed for 2 weeks. Specific recommendations for treatment of strictures and duct kinks were given in 2001.

In 1994, Arzoz and colleagues reported on a lithiasis case using a #7fr urethroscope (K. Storz) with a 1 mm working channel and using an Alexandrite laser at 60 mJ and 2000 pulses to fragment the stone. In 1996, Arzoz and colleagues described a 19-patient series with sialolithiasis. A Pneumoblastic energy source was deemed most effective compared with laser or electromagnetic Dornier sources. Two patients were treated using a renal lithotriptor. Duct dilation problems were noted to be obstacles to endoscopic progress. Stones were analyzed and noted to be composed of calcium carbonate and octacalcium.

Iro and colleagues in 1995 described use of the Rhodamine 6-G Flashlamp pumped dye laser (Technomed International, France) for lithiasis. An energy of 120 mJ with 1500 pulses delivered was used; the unit featured an automatic feedback cut-out to prevent duct injury by laser mistargeting. In vitro success of 75% translated to 65% total or partial fragmentation in vivo. The authors cautioned against using electrohydraulic and eximer laser lithotripsy because of duct damage. Their in vitro studies showed poor stone fragmentation with the Nd:YAG and Alexandrite (Lithognost, Telemit Co, Munich, Germany) lasers.

Ottaviani and colleagues in 1996 reported on using the Minilith SL-1 lithotriptor (K. Storz). Fifty-two patients with prior salivary duct dissection or obstacles to endoscopic access were treated. Acute sialadenitis patients first were treated using antibiotics until quiescent. Overall, 46% were free of stones; 31% had sand of less than 2.0 mm, and 23% had fragments larger than 2.0 mm after treatment. Seven percent needed sialadenectomy because of stones larger than 2.0 mm.

Harrison and colleagues in 1997 reported on the etiologies and mechanisms of submandibular sialolithiasis formation and the histopathology, having also published on ultrastructure of microliths in 1993 with Triantalyllou.

Zenk and colleagues in 1998 reported on duct diameters. The mean diameters of normal ducts were 0.5 to 1.4 mm for Stensen ducts and 0.5 to 1.5 mm for Wharton’s ducts. The minimum width of the ducts was at the ostium. The upper limit for instrument design was recommended to be 1.2 mm.

In 2001, Marchal and colleagues found that among 48 consecutive submandibular adenectomy patients with proven stones, 10 had normal histology; 18 had intermediate alterations, and 20 glands had extensive atrophy and fibrous. The implications were that most glands are near normal except for the ductal calculus, and therefore, gland-preserving techniques should be attempted when removing the stones. Also in 2001, Marchal and colleagues expanded on Nahlieli’s findings of foreign bodies as a nidus for stone formation.

Guerrissi and Taborda in 2001 reported on the first endoscopic intraoral resection of the submandibular gland on two patients. Both patients had sialolithiasis as the underlying problem. The main technical difficulty was with “the vascular pole…posterior third of gland” and the narrow confines between jaw and tongue.

Terris and colleagues used a laparoscopic endoscope to achieve total excision of the submandibular gland in a porcine model in 2001 and on a cadaver lower neck entry in 2004. The cadaver procedure duration ranged from 50 to 150 minutes depending on experience. Balloon dissection was used to allow for a field of view through three incisions in the lower neck to accommodate the endoscope and two instruments.

In 2002, Drage and colleagues investigated if the submandibular duct genu was related to sialolithiasis or adenitis. No correlation was found from 102 sialograms; there was a wide variation in the angle in unaffected normals ranging from 24° to 178°, with a mean of 103°, 108° in those with duct calculi, and 91° in those with adenitis.

Lewkowicz and colleagues in 2002 reported on experiences with parotid gland and duct traumatic injuries. They formulated a decision tree. Primary closure was indicated if no leakage was seen coming from the traumatic gland and facial wound after retrograde infusion of saline into the duct. End-to-end anastomosis with an intraductal stent for 14 days was recommended if leakage occurred and both duct ends were found. If leakage occurred and only the proximal end was found, or if the laceration was extensive, then end-to-end anastomosis was recommended with an intraductal stent for 14 days; if only the proximal end was found, or if the laceration was extensive, then clamping of the remaining proximal portion was indicated with suturing. Traumatic sialocele treatment also was discussed. Although not mentioned, facial nerve considerations would need simultaneous attention.

The combined approach was reported in 2002 on 12 patients by Nahlieli and colleagues. Some parotid stones may present as impossible to treat endoscopically; yet they can be seen intraductally with the endoscope. The endoscope was used intraductally as a skin transilluminator to locate the stone and was combined with a 1 cm vertical cheek skin incision over the stone. After stone removal by incising the duct, endoscopy was performed to explore the remaining duct for secondary stones. The duct was closed with 4-0 Vicryl and allowed to heal over a stent (1.7 mm polyethylene tube) for 2 weeks. Perioperative antibiotics were given, and a 48-hour compression bandage was placed over the site.

In 2002, Morimoto and colleagues reported on their new magnetic resonance imaging (MRI) protocol allowing for virtual endoscopy of the salivary duct, modeled on similar virtual endoscopy protocols for the bronchial tree, colon, vascular structures, and urinary tract. An update was offered in 2004. Su and colleagues in 2006 compared their virtual endoscopy protocol with actual endoscopy and found clear, detailed views.

In 2003, Marchal and Dulguerov forwarded their treatment algorithm. They combined submandibular and parotid gland endoscopic treatments into one decision tree. If a small stone (less than 4 mm/submandibular and 3.0 mm/parotid) was found, then wire basket extraction was recommended. If the stones were greater than 4.0 mm and 3.0 mm for the submandibular and parotid glands, respectively, then either extracorporeal shock wave lithotripsy or laser intracorporeal lithotripsy (2100 nm holmium laser) would be followed by wire basket extraction. Stenoses were corrected with metallic dilators or soft balloon catheters.

In 2004, Zenk and colleagues reported a 10-year experience with extracorporeal shock wave lithotripsy for submandibular stones. Over 10 years, 191 patients were treated with the Piezolith 2500 (R. Wolf Company, Knittlingen, Germany). Stones were treated at 80 Megapascals, 3000 shock waves, and monitored by a B-mode 7.5 MHz ultrasound scanner. The shock wave treatment was followed by massage, duct bougienage, and Dormia basket extraction. Results showed that of the originally treated group, 71% had some residual asymptomatic stone material in the ducts, of which half had long-term symptoms requiring further therapy such as transoral removal of stones or adenectomy. There was an upper size limit of 12 mm for shock wave treatment. The sole prognostic criterion for certain shock wave success was being free of stones after treatment.

Katz reported in 2004 on 1773 cases of sialendoscopy and extracorporeal lithotripsy. Overall, 96% of patients had elimination of stones endoscopically. In 63% of lithotriptor cases, the stones were completely destroyed, with 35% resulting in fragmentation with spontaneous or endoscopically assisted expulsion. One case required parotidectomy because of a basket wire snare that became lodged in the duct around a large stone fragment. Ultimately, 4% of endoscopic cases and 2% of lithotriptor cases required gland removal.

In 2004, McGurk and colleagues reported conservative open surgical procedures of the parotid and submandibular glands. For the parotid gland, a combination endoscopic intraductal and open surgical approach was used. The intraductally situated endoscope transilluminated the cheek soft tissues at the stone site, while a preauricular incision parotid flap allowed access to the parenchyma overlying the stone. Incising directly through the Superficial Musculoaponeurotic System (SMAS) and gland overlaying the stone down to the duct, the stone could be removed. The duct with a stent in place and gland were oversewn. A pressure dressing was applied for 48 hours, and perioperative antibiotics were used. The authors also discussed selected parotid tumor removal by capsule dissection. The submandibular gland stones were removed through the floor of the mouth, in a transoral approach similar to that reported by Van den Akker and colleagues, who also evaluated postoperative function in 1983.

Makdissi and colleagues in 2004 evaluated submandibular gland function after intraoral calculus removal in 43 patients. Technetium pertechnetate 0.5 milliseverts was given preoperatively, and the abnormal gland was compared with its paired normal gland; 3 months postoperatively, scintigraphic examination also was performed. Stones were removed in 97% of cases. In 52% of stone removal cases, gland function was improved; 14% remained unchanged, and 34% deteriorated. Gland recovery was related inversely to size of the stone. Recently, Su reported on 15 patients with technetium scintigraphy before and after stone removal by endoscopy. Compared with the preoperative status, after stone removal treatment, both the 13 submandibular and 4 affected parotid glands showed no statistically significant side-to-side difference. Nishi, in 1987, and Yoshimura in 1989 also evaluated submandibular salivary gland function after sialolithectomy. Also in 2004, Jongerius and colleagues studied salivary flow rates. They found that salivary flow rates varied considerably between individuals, but were relatively constant within a given individual.

Nahlieli and colleagues in 2004 reviewed management of chronic recurrent parotitis. Although complete adenectomy was the only cure for persistent-symptom patients, some patients had treatable findings. Of endoscopic interest were sausage-like ducts amenable to balloon dilation, strictures helped by expansion with the miniforceps, and mucous plugs removed by flushing. The balloon technique was either through the endoscope working lumen or next to the endoscope. Among the etiologies reviewed, nanobacteria were cited from another journal, although there has been no further substantiation of these. Chronic enlargement of the salivary glands also was noted to be caused by Mikulicz disease, Sjögren syndrome, recurrent childhood parotitis, and lymphoepithelial lesion of Godwin.

Nahlieli and colleagues in 2004 also reviewed their treatment modality for juvenile recurrent parotitis and again in 2009 by Sracham with a total of 70 children. Endoscopic findings included white appearance of the ducts without typical blood vessels. Strictures and kinks were seen in the most severe cases. Treatment consisted of preoperative sialography (Ultravist, Schering, Berlin) followed by sialendoscopy with vigorous 60 mL saline lavages. Any strictures were treated with a balloon or microdrill (0.3 mm). Finishing the case, hydrocortisone 100 mg was injected through the endoscope. Postoperative antibiotics were used. Only five patients (7.1%) needed a repeat endoscopy; nine (12.9%) had another mild episode after treatment. Also reporting on juvenile recurrent parotitis were Quenin and colleagues in 2008 with a similar protocol to Nahlieli and with 10 patients. One patient (10%) needed a repeat sialendoscopy; two patients (20%) had a contralateral episode.

Qi and colleagues in 2005 microscopically analyzed sialendoscopic irrigation fluid in obstructed parotid glands. Fiber-like substances, which were connected to the duct wall and floating and blocking the lumen were seen to be composed of desquamative epithelial and inflammatory cells.

Zenk and colleagues in 2005 reviewed their series of intraoral submandibular stone extractions. In the 683 patients, no distinct area for stone location was noted. The stone was approached by incising from the punctum in a posterior direction. The lingual nerve was identified, and the incision continued until the stone was found. When the stone was located further into the parenchyma of the gland, a submandibulotomy external incision approach was used to assist removal. There were 98.3% symptom-free patients, although 6.9% had stone rests; 1.7% required adenectomy for symptom relief.

Capaccio and colleagues in 2005 reported on 11 patients using conservative transoral stone removal for submandibular glands. The stones, ranging from 8 to 25 mm, were removed successfully. Closure of the hilum area was by a net of fibrillar surgicel (Tabotamp, Johnson & Johnson, Skipton, United Kingdom) to achieve hemostasis and antimicrobial properties and avoid risk of stricture and stenosis.

Chossegros and colleagues in 2006 described entering a tight duct by first placing a guidewire, followed by threading the endoscope over the guidewire and into the duct, as a variation of standard interventional radiology procedure described as a novel technique in 1953 by Seldinger.

In 2006 and earlier, Fritsch reported on his experiences with the endoscopic open approach as an extension of McGurk’s work but without access to extracorporeal lithotripsy. Further developments included Segmental gland resection of the irreversibly diseased gland drainage basin proximal to the stone; leaving postresection normally draining gland tissue for cosmesis; retrograde saline duct irrigations to locate any cross-cut duct openings in the parenchyma, allowing for oversewing to prevent sialocele; use of the NIMS facial nerve monitor; Staged techniques; and microvascular technique for duct or vein anastomoses. These were later partially reported on by Marchal.

Geisthoff and colleagues in 2006 reported on their using ultrasonographic visualization of the duct in sialolithiasis cases. Sialendoscopic instrumentation with the 0.8 mm endoscopic microforceps may not be effective for stone fragmentation because of the fragile nature of the forceps. In their new technique, using an ear surgery alligator forceps, the relatively robust nature of the forceps was able to efficiently crush the stones and also retrieve the fragments all under real-time ultrasonographic observation without any need of an endoscope.

The issue of I-131 parotiditis continues to be a problem for patients. In 2007, Kim and colleagues outlined their treatment for I-131 sialadenitis in 21 patients and reviewed the pertinent literature. The parotid gland was involved 90% of the time. Symptoms began about 5 months after administration of I-131 and appeared to be dose-related. For 70% of cases, conservative therapy using a regime of aggressive massage, sialogogues, steroids, antibiotics, nonsteroidal anti-inflammatory drugs, vitamin B12, zinc, and pilocarpine was successful. For the remainder, a 50% success rate was achieved by sialendoscopy. The major problem encountered was stenosis, and it was treated by dilation with various diameter endoscopes or with balloons. Unsuccessful cases ended in resection of the involved gland. Another protocol, forwarded by Silberstein in 2008, is conservative but is started before the I-131 administration. Despite the article title, pilocarpine resulted in no additional protection compared with his routine and effective regime incorporating dexamethasone, dolsetron, 2400 mL nondairy fluids, and sialogogues starting before I-131. There were 60 patients in his study with reference to 109 prior cases using the same treatment. His overall strategy was to quickly remove any I-131 accumulated in the gland by expectoration so that it did not linger. The regime continued for both daytime and nights. Remarkable results were achieved in this series, with sialadenitis present in only 3% to 7% of patients. Lastly, amifostine has been used successfully, although unremitting nausea in people is a frequent reason for noncompliance. There is also concern regarding suppression of radiation effects in the target tissue.

In 2007, Nakayama and colleagues described their experiences with an intracorporeal electrohydraulic lithotripsy system through an endoscope (Salivascope T PD-ZS-2002, 1.35 mm O.D. Polydiagnost, Pfaffenhofen, Germany). Acrinol (ethacrine lactate) was instilled into the duct as an antimicrobial at the end of the procedure, with no dosage given. Previously, Iro in 1989 and Konigsberger in 1993 had experiences with electrohydraulic extracorporeal and intracorporeal lithotripsy, respectively.

Nahlieli and colleagues in 2007 reported on the ductal stretching technique. The endoscope is introduced first to locate the stone, followed by a lacrimal probe. The duct is dissected and isolated; the gland and stone are pushed from below to herniate the stone forward. Incision of the duct follows with lithectomy, then reattachment of the anterior duct to the mouth floor, having excised the anterior 5 mm of duct. The stretching appears to mean straightening of the duct to allow the stone to slip past the obstacle of the lingual nerve before incision and extraction from a more anterior location.

In 2008, Walvekar and colleagues reported on their initial 56-case experience and complications. Major complications occurred in one case with avulsion of the duct, and minor complications occurred in 13 patients. The minor complications were mainly attributable to stenotic duct segments, duct bends, and a narrow papilla opening that gave rise to retained stones, duct tears, mucosal necrosis, and failure of the procedure. Salvage of the problems was by applying standard salivary surgery. An observation was that despite its apparent simplicity, sialendoscopy is technically challenging and requires sequential learning. Overall, sialendoscopy was judged to be a safe and effective diagnostic and treatment modality.

Nahlieli and colleagues in 2008 reviewed their experiences with Stensen’s duct injuries caused by facial rejuvenation cosmetic procedures. Fourteen patients were treated by sialendoscopy. Four groups of injuries with four corresponding specific treatment types were given. Type 1 was comprised of compression of the duct caused by SMAS tightening. In type 2 injuries, a laceration to the gland caused swelling that resulted in duct compression. Both types 1 and 2 were treated conservatively. Type 3 had both a compression of the duct by SMAS fascia tightening over the masseter and edema associated with gland laceration. Type 3 was treated by sialendoscopic drainage of the duct sialocele with a facial compression garment applied until facial swelling resolved. Type 4 was a complete cut of the Stensen’s duct. It was treated by sialendoscopy to find the proximal duct end through the sialocele and also the distal duct end, followed by high-pressure balloon dilation of the distal duct, an endoscopic anastomosis by a sialodrain stent inserted for 4 weeks into the entire duct to allow healing. Any sialocele was aspirated and a compression garment placed. No external ancillary incisions were used, only the stent to connect the two duct ends. In Type 4 injury repair, two of five patients had no function after 6 weeks. One of five patients for type 3 had no function; the rest had function.

Luers and colleagues in 2008 reported on a methylene blue dye swab technique of the papilla to find a nonapparent punctum. If not immediately visible, pressure on the gland could release a microdrop of saliva through the blue dye and mark the spot of the punctum.

In 2008, Fritsch reported on reported on decibel levels generated during extracorporeal shock wave lithotripsy with an 80 dB peak found. Because of the acoustic stress of shock waves administered by the thousands, hearing protection was thought advisable. Also in 2008, he reported on using a sponge and flesh-colored plastic tubing model as a reliable dry laboratory approach to teaching sialendoscopy; other wet laboratory animal and human cadaver models were deemed expensive and time-consuming to use.

Woo and colleagues in 2009 described their experiences with long-term intraoral submandibular stone removal in 14 children versus 40 adults. Although sialolithiasis is uncommon in children, a similar technique was used as in adults, with both groups having an 83% symptom-free long-term result.

Iro and colleagues in 2009 reported on a comprehensive five-group multi-institutional experience of 4691 patients regarding all diagnostic and therapeutic aspects of salivary calculi over a 14-year period. It is the most extensive clinical review to date. Submandibular stones outnumbered parotid stones by a three to one ratio. Acute sialadenitis was treated with antibiotics. Extensive algorithms were shown. Extracorporeal shock wave lithotripsy was curative in 51% of patients, partially successful in 25%, and needed repeat extracorporeal shock wave lithotripsy treatment in 23%. Further follow-up treatments included endoscopy, intraoral surgery, and gland removal. For endoscopic basket microforceps retrieval, a 92% success rate was reported. Intraoral submandibular surgery was curative in 93% of cases.