Minimal surgery for parotid stones: a 7-year endoscopic experience

Abstract

The results of endoscope-assisted parotid surgery are presented as a minimally invasive alternative to parotidectomy for large parotid stones. From 1999 to 2007, 70 patients with parotid sialoliths were treated by minimally invasive surgical techniques in three specialist centres. At surgery a combination of sialoendoscopic and ultrasound examination was used to locate the stone within the duct. The calculus was released by incising the duct through a pre-auricular approach (40 patients) or by direct transcutaneous incision over the stone (27 patients). Four patients were treated using other minimally invasive procedures. Local anesthesia was used in 22 patients and general anesthesia in 48. The average follow-up was 25.5 months with two patients lost to review. In 3 patients treatment had long-term complications (persistent stone fragment; obstructive symptoms due to a fibrous stricture; a visible scar on the cheek). In one patient, endoscopy was abandoned due to stricture. 85 stones were retrieved successfully from 69 patients. The average size of the stones was 7.2 mm. There were no cases of facial nerve weakness or salivary fistula. The data suggest that endoscopic-assisted surgery is a viable alternate to adenectomy for the treatment of large or recalcitrant parotid stones.

Endoscopy has gained popularity and is a minimally invasive addition to modern surgical techniques. Owing to developments in optical technology, micro-endoscopes are available commercially that allow inspection and micro-instrumentation of the salivary ductal system. Sialendoscopes have been used to retrieve small (<5 mm) mobile stones from the submandibular or parotid glands using micro-forceps or baskets. If cases are selected appropriately, >75% of stones are retrieved successfully. Larger (>8 mm) or fixed parotid stones are mainly treated by extracorporeal lithotripsy supplemented with endoscopic removal of residual fragments as required. Lithotripsy eliminates approximately 60% of these stones, with some debris remaining in 30% of cases, although without obstructive symptoms. 10% of stones are symptomatic and require futher treatment. In countries where lithotripsy is available, this 10% are managed using an endoscopic-assisted surgical approach. In the USA, where extracorporeal lithotripsy does not have FDA approval, this approach has wider application.

Baurmarsh et al described a transcutaneous extra-oral sialolithectomy approach to the parotid stone whereby the calculus was localized using plain radiographs and high resolution ultrasound. The stone was removed through a horizontal skin incision made directly over the calculus. This technique was restricted to relatively large stones in the superficial part of the duct, in the region of the anterior border of the masseter muscle. The present article builds on this experience and describes techniques that offer wider application. The results from three centres specializing in minimally invasive salivary gland surgery are presented. The main advantage of a minimally invasive approach is that it avoids the need for superficial parotidectomy, with its attendant complications.

Patients & Methods

Endoscopically assisted open surgery was performed on 69 of 70 patients (35 female: 34 male; aged 12–82 years). One patient was excluded from analysis because of a stricture that could not be passed with the endoscope, so the procedure was terminated before surgery took place. In all patients, a prior attempt to remove the parotid obstruction by lithotripsy, basket or endoscopic retrieval had failed. The calculi lay in the middle (19%), proximal (65%) or hilar (16%) portion of the duct. The patients were assessed preoperatively by using plain radiographs, sialography, ultrasound or magnetic resonance imaging (MRI) scans. The investigations of choice were ultrasound and sialography. Patients with stones impacted in the proximal third of the duct or hilum (N = 47) had the procedure performed under general anaesthesia through a standard preauricular incision. Large superficial stones in the mid portion of the duct were approached under local anaesthesia (N = 22) using a vertical transcutaneous incision directly over the stone.

Immediately before surgery the stone position was identified endoscopically, ultra-sonographically or by a combination of the two, and its exact position marked on the cheek ( Fig. 1 ).

Fig. 1
Transillumination by the endoscope through the cheek. The endoscope lies in the parotid duct. The exact stone position can be seen and marked on the skin.

The appropriate skin flap (preauricular or transcutaneous) was elevated to expose the tissues approximately 1–2 cm around the stone. The endoscope was then re-inserted and the light at the tip of the scope used to guide the surgeon to the stone ( Fig. 2 ). Once the calculus is identified, it is removed through a longitudinal incision made in the duct wall directly over the calculus. The buccal branch of the facial nerve lies close to the duct and is usually easily identified if strict haemostasis is maintained (20/26 nerves identified in Guy’s Hospital without consequence). Once the stone is removed, the endoscope is advanced into the gland to exclude additional stones. A stent, such as the parotid duct drain (Sialotechnology, Inc., Ashkelon, Israel) can be placed to help maintain patency and is suture-secured to the buccal mucosa. The stent is left in position for approximately 2–3 weeks. The duct can be closed with 5-0 Vicryl™ (Ethicon Corporation) sutures, though some ductal re-anastomosis closures require microvascular technique and 9-0 Ethibond™ (Ethicon Corporation, Somerville, New Jersey, USA). It is advisable to apply a pressure dressing for 48 h and give a short course of perioperative antibiotics.

Fig. 2
Exposure of the parotid duct using an endoscope to facilitate duct identification. The stone will be found at the lighted tip of the endoscope, and palpation of the duct will confirm the position.

Results

From November 1999 to December 2007, 70 patients were treated with the endoscopically assisted open technique in the Salivary Units at Guy’s Dental Hospital, London, UK, the Barzilai Medical Centre, Ashkelon, Israel, and at the Indiana University Medical Center, Indianapolis, USA ( Table 1 ). Information was available for 67 of 69 (97%) patients with a median follow up of 25 months (range 2–81 months). 85 stones were retrieved successfully from 69 patients. The stone clearance rate was 66 of 67 (99%). In two cases, mucus but no stones were found. The average size of the stones was 7.2 mm (range 3–15 mm).

Table 1
Combined patient data from Guy’s Hospital–Kings College London, Barzilai Medical Center, Askhelon, Israel, and Indiana University Medical Center, Indianapolis, Indiana, USA.
No. Cases (Operated/Follow-up) Mean Follow-up (Months) Mean Age Sex (M/F) Anaesth. (LA/GA) Incision (cheek/pre-auricular) Mean stone diameter (mm) Assistance
3 Centres 69/67 25.5 54/53 34/35 22/47 25/41 7.2
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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Minimal surgery for parotid stones: a 7-year endoscopic experience
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