Transoral Robotic Surgery for Submandibular Sialolithiasis

Transoral robotic surgery (TORS) was invented at the University of Pennsylvania and subsequently Food and Drug Administration (FDA) approved in 2009. Transoral surgery of the submandibular gland for tumors and inflammatory disease has not been popular because access to the hilum is difficult. TORS has been utilized in the author’s institution to allow better visualization for transoral submandibular gland excision, primarily for neoplasms. This remains a challenging operation. Sialendoscopy has been combined with transoral access to the posterior oral cavity to allow management of hilar stones.

Walvekar first reported using TORS for a submandibular megalith, and Razavi et al. have provided a series of patients using TORS in combined approaches for hilar stones.

TORS is now utilized for hilar stones in two different ways. The author has termed these approaches “TORS-sialo” and “Sialo-TORS-sialo”. In the former, TORS is done immediately and then followed by sialendoscopy for stones that are easily palpated, usually larger, most commonly single stones and is the more commonly performed operation. The Sialo-TORS-sialo approach is utilized for situations when evaluation of the duct and stone prior to doing the combined approach is needed.

TORS-Sialo

Nasal intubation with general anesthesia and muscle relaxant is used. The robot is draped and the monopolar cautery arm is placed on the ipsilateral side. A Maryland dissector is placed on the contralateral side. The 0° camera is used. A Jennings mouth gag is placed with the handle on the contralateral side. Two side arms for self-retaining retractors are used and a sweetheart is placed on the contralateral side to retract the tongue away. A cheek retractor is placed on the ipsilateral side. These two retractors reduce head movement. An alternative is to attach one of the side arms directly to the Jennings mouth gag and retract the tongue with sutures. The retraction of the tongue is dynamic and is facilitated by the bedside assistant. An incision is made in the floor of mouth and, if needed for exposure, the inferior aspect of the tonsillar pillar. This is a paralingual approach and occasionally a lower parapharyngeal space approach is helpful for challenging stones. The monopolar cautery is set at 10 Watts (W). The cutting pedal is used to make the incision, preserving adequate mucosa laterally to allow closure. Small vessels can be cauterized either using monopolar on low setting or by the assistant with bipolar. The lingual nerve is identified as is the posterior aspect of the sublingual gland. Usually the mylohyoid can be seen after careful blunt dissection. The triangle formed by the posterior border of the sublingual gland, the lingual nerve, and the mylohyoid/mandible is then inspected. The lingual nerve usually must be gently retracted medially but in rare cases, when the stone is very large and bulging medially, the duct can be opened medial to the lingual nerve and the nerve remains lateral to the dissection of the duct. Occasionally, when there has been severe sialadenitis, the nerve will be very adherent to the duct in the exact area where the duct needs to be incised. The nerve may require additional mobilization and only performed if absolutely necessary. The assistant will use two suctions: one will retract the sublingual gland anteriorly and one will retract the mylohyoid laterally. The surgeon will carefully place the Maryland dissector just lateral to the lingual nerve and the spatula tip cautery can bluntly dissect until the duct is outlined. Once the position of the stone is identified, a second assistant provides upward pressure from the neck to facilitate incision in the duct. The incision in the duct can be carried out with monopolar cautery, again emphasizing the need to use a very low wattage (10 W). The incision is extended as needed to allow removal of the stone without fragmenting the stone and avoiding dissection except on the superficial aspect of the duct. In some cases, the stone may be quite adherent to the duct wall. In such cases, the bedside assistant may utilize a cottle elevator to gently dissect the stone out of the duct. In this situation, the robotic arms now serve as a retractor. The approach is modular, in that sometimes the surgeon at the console is removing the stone and sometimes the assistant is doing so and the console surgeon is assisting. Once the stone is removed, the duct is explored through the wound to look for any fragments and irrigation is performed. Then, a conventional sialendoscopy procedure is performed ideally via the normal papilla. Generally, a 1.3 mm all-in-one sialendoscope is then used to inspect the duct and if any additional fragments of stone are seen, these are removed by irrigation or by basket retrieval (Video 21.1 ). Caution is advised in basket retrieval as it is possible for the basket to catch on the edge of the previously opened duct, which could result in avulsion of the duct when retrieving the basket with the stone. For this reason, if the patient is felt to have small stones in addition to a larger hilar stone, Sialo-TORS-sialo is preferred to get these stones out prior to performing the hilar duct incision (Video 21.2 ).