The current indications for robotic-assisted surgery for tonsillar cancer are tumors amenable to total resection with negative margins. The patients who are the best candidates typically have early-stage (T1 to T2) tumors and have the potential to avoid chemoradiation therapy. Those who have advanced-stage (T3 or T4) tumors will generally require chemoradiation therapy and may not always benefit as greatly from surgery. However, in the case of low-volume T3 disease, undergoing robotic surgery may still allow the patient to receive adjuvant radiation alone, without chemotherapy [9, 13, 14]. Therefore, advanced-stage disease is not a contraindication for TORS and is performed routinely at many institutions. Finally, robotic-assisted surgery may also be indicated in certain circumstances of salvage surgery for early T-stage tumors [15].

Contraindications of TORS for tonsillar cancer are separated into two major categories: tumor-related factors and patient-related factors. Factors that make the tumor unresectable include carotid artery involvement, fixation to the prevertebral fascia, and unresectable neck lymphadenopathy. T4a lesions with mandible invasion, hard palate invasion, >50% tongue base involvement, and >50% posterior pharyngeal wall involvement are also contraindicated [9, 13, 16]. Patient-related factors include anatomical issues such as trismus and kyphosis, retropharyngeal location of the internal carotid artery, and medical comorbidities precluding general anesthesia or inhibiting wound healing by secondary intention [9, 13, 16].

When using the da Vinci robotic system, the setup for robotic-assisted radical tonsillectomy is similar to that in other transoral robotic head and neck surgery cases. The robot base is on the patient’s left and the scrub nurse on the patient’s right. A bedside assistant is seated at the head of the patient. Intubation can be achieved either transnasally or transorally using a RAE endotracheal tube. Exposure to the oropharynx is typically achieved using either a Crowe-Davis or Dingman mouth gag. The tongue blade accompanies the mouth gag to push the tongue inferiorly. Three robotic arms are inserted transorally [9] with the endoscope in the center and a spatula tip monopolar cautery and a Maryland dissector on the ipsilateral and contralateral arms, respectively, 30–45° from the center (Fig. 7.2). A 0 degree endoscope is typically utilized at the start of the case, but may be changed to a 30° scope later to better visualize the base of tongue. A retraction suture can be placed through the midline of the tongue for additional retraction. The bedside assistant should have suction in the oral cavity to remove smoke from the surgeon’s view and an instrument for cheek retraction if necessary [9, 17–19].

When using the Flex robotic system, the robot is mounted to the surgical table rails and arranged to approach the oral cavity from the caudal direction (Fig. 7.3). The robot is then driven via the physician controller to enter the oral cavity and travel midline until the tonsillar region is reached (robot docking). Once the flexible robot had been docked in the desired position, the surgeon inserts flexible endoscopic instruments into the external accessory channels to perform the procedure. A 3.5 mm grasper is used for tissue retraction and manipulation, and a 3.5 mm cauterizing instrument and a laser guide are used for cutting. Flexible instrumentation can be inserted by the surgeon from the direction opposite the flexible robot, in this case from the cephalic direction [20].

Once adequate visualization of the tonsillar fossa is established using either robotic system, a dissector or other grasper is used to provide medial retraction of the tonsil. Monopolar cautery is used to make a mucosal incision in the anterior tonsillar pillar and soft palate (Figs. 7.4 and 7.5). The plane of dissection is developed deep to the superior constrictor muscle, leaving pharyngeal fat laterally. The spatula tip cautery or other instrument can be used for blunt dissection in this plane (Figs. 7.6 and 7.7). Pulsations from the carotid artery area easily visualized with the three-dimensional magnified view deep to the parapharyngeal fat. Dissection is carried to the styloglossus with the pterygoid muscles laterally.

Superiorly, the soft palate incision is carried down through both the palatoglossus and palatopharyngeus muscles to the prevertebral fascia. Here, again, the spatula cautery can be used to bluntly dissect the superior constrictor muscle off of the prevertebral fascia. Inferiorly, the use of the robot gives the surgeon complete visualization of the tongue base, allowing a cuff of tongue base muscle to be included as the inferior margin of the resection (Fig. 7.8). The styloglossus and stylopharyngeus muscles are encountered and carefully dissected circumferentially and typically transected [9, 17]. Branches of the external carotid, including lingual artery, are encountered 5–8 mm deep to the styloglossus muscle and should be carefully avoided or ligated with surgical clips.

The glossopharyngeal nerve can also be identified at the junction of the posterior tonsillar pillar and base of tongue. While distal branches and even the main trunk may require transection from an oncologic standpoint, the magnification and enhanced visualization of the robotic system can also give the surgeon the ability to trace the nerve and leave it intact [18].

Finally, the constrictor muscle is transected at the medial deep limit of the dissection and the posterior mucosal cut is completed, freeing up the specimen [9] (Figs. 7.9 and 7.10). Any bleeding which is encountered can be controlled with either monopolar cautery or vascular clips [17]. The bedside assistant may also be able to use bipolar forceps for hemostasis, or apply pressure to compress the lingual artery at the level of the hyoid to improve visualization [9].

The wound may be left open to heal by secondary intention or a skin graft can be placed to cover raw muscle edges. More extensive reconstruction is often unnecessary following TORS, as the intact buccopharyngeal fascia avoids exposure of any major vessels. If neck dissection is performed in a staged fashion, then fistulous connection to the neck is also avoided, precluding the need for local and/or free flap reconstruction [16].

Reported complication rates following da Vinci TORS for tonsillar cancer are as high as 19% [9]. Bleeding is one of the most serious and potentially life-threatening acute complications. The incidence of bleeding following all transoral robotic surgery has been reported as 9.8%. The tonsil bed was found to be the second most common site of bleeding, following the base of tongue. T2 and T3 tumors trended toward higher bleeding rates than T1 tumors. Bleeding can be controlled by a variety of methods including silver nitrate cauterization, monopolar or bipolar cauterization, embolization, and transcervical arterial ligation. If the neck dissection is staged prior to resection of the primary tumor, the facial and lingual arteries can be ligated at their origin from the external carotid artery. Additionally, if performed concurrently with the primary tumor resection, the neck dissection should include ligation of the external carotid arterial branches, particularly the facial, lingual, and ascending pharyngeal branches. This theoretically can minimize post-TORS catastrophic bleeds. Airway protection is critical in post-TORS oropharyngeal hemorrhage and can prevent a catastrophic outcome [21].