Transoral robotic surgery (TORS) has become increasingly used to manage laryngeal and pharyngeal cancers, although the published experience in the larynx is small. Although there is burgeoning use of TORS for primary pharyngeal cancer, its application in the larynx is currently more limited. Successful TORS of the larynx has been predominantly as supraglottic laryngectomy, although there is some experience in total laryngectomy and cordectomy. Limitations of TORS of the larynx are primarily those of access and instrumentation, with respect to both the surgical robot and the retractors used to access the larynx transorally.
Key points
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Appropriate patient selection, from both a tumor and anatomic standpoint, is the most important consideration in transoral robotic laryngeal surgery.
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The patient must understand the possible complications and limitations of the surgery, and the surgery must be part of a comprehensive plan to manage the cancer.
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The goal should be negative margin surgery and treatment consolidation, attempting unimodal therapy whenever possible.
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En bloc resection, when appropriate, is often possible with this technique.
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It is clearly preferable to perform this surgery before radiation therapy, as radiation complicates the healing and functional outcomes.
Introduction
The current techniques of transoral robotic partial and total laryngectomy represent waypoints along a continuum in the development of minimally invasive surgery for laryngeal cancer. The acceptance of transoral robotic surgery (TORS) as a whole, and for the larynx in particular, has been rapid and is based on few clinical data. The oncologic basis of this approach comes from the results of transoral laser microsurgical (TLM) resection of larynx cancer, which has an established record of success. TORS is a natural extension of the TLM technique. Some argue that TLM is superior, as there are a wider variety of endoscopes and instruments used during the resection, whereas others believe the 3-dimensional high-definition visualization provided by the surgical robot, among other factors, makes TORS a more preferable modality. Increasing experience with TORS techniques have led to decreased complication rates and decreased hospitalization. In addition, TORS management of oropharynx and supraglottic cancers has been shown to result in better short-term and long-term swallowing function in comparison with chemoradiotherapy. This article focuses primarily on TORS supraglottic partial laryngectomy, with some discussion of TORS total laryngectomy and cordectomy. Other laryngeal TORS techniques have been reported, including benign lesion excision and supracricoid partial laryngectomy, but are not discussed here.
Introduction
The current techniques of transoral robotic partial and total laryngectomy represent waypoints along a continuum in the development of minimally invasive surgery for laryngeal cancer. The acceptance of transoral robotic surgery (TORS) as a whole, and for the larynx in particular, has been rapid and is based on few clinical data. The oncologic basis of this approach comes from the results of transoral laser microsurgical (TLM) resection of larynx cancer, which has an established record of success. TORS is a natural extension of the TLM technique. Some argue that TLM is superior, as there are a wider variety of endoscopes and instruments used during the resection, whereas others believe the 3-dimensional high-definition visualization provided by the surgical robot, among other factors, makes TORS a more preferable modality. Increasing experience with TORS techniques have led to decreased complication rates and decreased hospitalization. In addition, TORS management of oropharynx and supraglottic cancers has been shown to result in better short-term and long-term swallowing function in comparison with chemoradiotherapy. This article focuses primarily on TORS supraglottic partial laryngectomy, with some discussion of TORS total laryngectomy and cordectomy. Other laryngeal TORS techniques have been reported, including benign lesion excision and supracricoid partial laryngectomy, but are not discussed here.
Treatment goals
As with any oncologic surgery, the main goal of treatment is to cure the patient of cancer. A secondary, although equally important, goal in patients with larynx cancer is maximization of their function and quality of life. Successful achievement of cure and preservation of function is aided by TORS partial laryngectomy. Negative margin transoral supraglottic laryngectomy, with selective neck dissection, provides cure rates equivalent to those of chemoradiotherapy, and has the potential to avoid the use of adjuvant radiation, which can result in superior swallowing and speech function while maintaining excellent cure rates.
The overall goals remain the same for primary TORS laryngeal surgery or salvage surgery: tumor eradication with maintenance of the laryngeal functions of speech, swallowing, and breathing. The outcomes and complications are different in the 2 scenarios, with poor wound healing and loss of function being more significant in the salvage setting. Significant dysphagia is more common in the salvage group because of delayed healing and, although rarely required in a primary setting, tracheotomy may be required during the perioperative and healing phase in salvage surgery. Previously irradiated laryngeal tissues have a higher propensity for edema of the residual tissue, which will nearly always resolve over time. In either primary or salvage TORS for laryngeal cancer, swallowing and airway function are excellent in most patients.
Preoperative planning and special equipment
Preoperative planning for any tumor resection is critical. For partial, or total, laryngectomy anatomic imaging is required, with the exception of superficial T1 and select T2 glottic tumors. Standard imaging would include a contrast computed tomography (CT) scan to evaluate the thyroid and cricoid cartilages, the pre-epiglottic and paraglottic spaces, and the cervical lymph nodes. Positron emission tomography in combination with CT is increasingly used, and can help identify disease laterally in the neck in the absence of radiographically positive adenopathy on anatomic imaging. As with all patients with head and neck cancer, a frank discussion with the patient and his or her family of all available treatment modalities is crucial. Evaluation by the appropriate nonsurgical specialists with prospective presentation at a Multidisciplinary Tumor Board is also an important part of the treatment plan.
Special equipment is required for this type of surgery. In addition to the da Vinci Surgical Robot (Intuitive Surgical Systems, Sunnyvale, CA), multiple robotic instruments are important in maximizing operative success. The surgical arms should include a Maryland forceps, Schertel forceps, and Teflon-coated blade-tip electrocautery. A CO 2 fiber laser (or another type of fiber laser) is advantageous when performing TORS on the larynx. The surgical arms should be 5-mm instruments and the endoscope 12 mm if possible. If transoral suturing is planned, 8-mm needle drivers should be used in both arms, as the distal tip of the 8-mm robotic arm articulates in a much shorter radius, facilitating suturing in a confined space. The bedside assistant is responsible for the management of significant hemorrhage from vessels such as the superior laryngeal artery. A laparoscopic articulating clip applier is used for significant vessels, while the robotic cautery or a suction cautery will control the greater part of any intraoperative bleeding. The small or medium clip applier may be used, at the discretion of the surgeon. Laparoscopic peanuts and the Hurd retractor are also useful adjuvants for tissue retraction. Finally, the Feyh-Kastenbauer (FK) retractor system (Gyrus Medical Inc, Maple Grove, MN) is required to maximize exposure options during the surgery. Crowe-Davis and Dingman mouth gags may also be useful.
Special features
Patient Selection
Appropriate patient selection is critical for TORS of the larynx, accounting for features of both tumor and patient. As is the case with TLM, establishing appropriate patient expectations are paramount, as there will always be a temporary compromise of swallowing following supraglottic partial laryngectomy. Adequate pulmonary reserve is required to tolerate small amounts of temporary aspiration. In addition, poorly controlled diabetes can impair wound healing after partial laryngectomy. When TORS is used for salvage surgery, one can expect delayed healing and potentially worse functional outcomes.
Tumor stage and extent is an important consideration. Supraglottic tumors, T1 to T4a, may be considered for transoral resection. Supraglottic laryngectomy can be a technically demanding procedure, so those new to the technique should confine themselves to T1 or T2 tumors. Once a surgeon is more experienced, larger tumors can be considered. Neither pre-epiglottic space involvement nor tongue-base involvement are contraindications to TORS resection, provided the exposure is adequate. However, extension into the paraglottic area with vocal-fold immobility ( Fig. 1 ) is a contraindication to a TORS supraglottic laryngectomy if electrocautery is used for the dissection, because thermal injury near the glottis area may result in bilateral vocal-fold immobility and the need for a permanent tracheotomy. For this reason, in the author’s opinion any TORS glottic surgery should be avoided if electrocautery is used. The development of laser-carrying fibers and manipulators for the robotic arms will facilitate the development and expansion of glottic surgery with TORS. Special consideration should also be undertaken in cases of salvage partial laryngectomy. In addition to poor healing, the tissue planes relied on for margin assessment are much less obvious, and soft-tissue edema can affect the interaction of the cautery and the tissue, complicating the procedure and the outcomes.
Equipment and anatomic factors are equally important for TORS of the larynx. Current retractor systems have been, for the most part, developed for TLM and not for TORS. The instrumentation required, two 5-mm instruments and a 12-mm telescope, are much more bulky than the TLM instruments. Consequently, instrument conflicts become more significant as one proceeds into the distal pharynx or larynx, as the space becomes more constrained and the instruments begin to cone down. Therefore, maximal mouth opening is essential, precluding the surgery in cases of trismus. In addition, full dentition, particularly the presence of central incisors, can significantly impede exposure. Anterior laryngeal positioning also provides a challenge to adequate exposure, although TORS is less limited in this regard than TLM. A narrow posterior mandibular arch also negatively affects the ability to adequately expose the larynx. Adequate exposure is the most important technical feature, and a variety of retractors should be available for every case to maximize exposure. The minimum retractor complement should include a Crowe-Davis and FK retractor system. Multiple blades may be required for any given procedure, and several may need to be assessed before the optimal exposure is obtained. Exposure should be assessed carefully at the staging endoscopy. Staging endoscopy is advised for all patients with laryngeal cancer considering TORS, as a careful endoscopic evaluation of the tumor is required to determine resectability and accessibility.
Patient and Robot Positioning
As with any surgical procedure, proper positioning of patient and equipment is important.
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For TORS in general, the patient should be supine on the operating table with the head positioned 180° from anesthesia, at the foot of the bed.
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The head of the patient should be positioned as far from the base of the bed as possible, either by turning the bed so the head of the patient is at the foot of the bed or sliding the bed away from the foot support to maximize the distance between the head of the patient and the closest part of the operating room table pedestal. This location gives the maximum amount of flexibility for positioning of the robot.
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A shoulder roll is generally not necessary, as it will frequently compromise the anterior/posterior exposure.
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A suture is placed transversely through the anterior midline tongue, perpendicular to the direction of the muscle fibers, to facilitate exposure by tongue traction. Care must be taken to avoid compression of the tongue between the teeth and the retractor blade during the surgery.
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Once the retractor has been positioned and held in place with a self-retaining arm, the lips are coated with Lacrilube to minimize trauma and desiccation.
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The robot is brought in from the side of the bed, the right side at the author’s institution, at a 30° angle from the long axis of the bed.
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In general, 2 robotic arms are used and brought in from the lateral aspects of the mouth, with the camera placed centrally.
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The arms are carefully positioned to avoid conflict between each other and the cannulas guiding the arms are placed in the mouth at the fulcrum point of the arm, designated by the wide dark stripe on the cannula ( Fig. 2 ).
Fig. 2
Intraoral relationship of the FK retractor and the robotic arms. Note the wide black bands at the oral commissure denoting the rotational axis of the instrument. The endoscope is not inserted in this photo.
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The instruments are advanced into the robotic arms under visualization, and the resection begins.
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For most laryngeal TORS procedure, the 30° endoscope is used facing up.
Procedure
Supraglottic Laryngectomy
The dissection for a supraglottic laryngectomy begins superiorly, in all cases, after adequate exposure and visualization has been confirmed.
Surgical Note: The main limitations are usually in the anterior/posterior exposure of the larynx, owing to either radiation changes or anatomic features of the patient.
The following technical description is that of a complete supraglottic laryngectomy. The extent of the dissection will depend on the extent and location of the tumor. An example is presented in the accompanying video ( [CR] ), in which a complete TORS supraglottic laryngectomy is performed with the CO 2 laser.
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The dissection is initiated either at the anterior aspect of the vallecula or the lateral aspect of the pharyngoepiglottic fold ( Fig. 3 ).
Fig. 3
Lateral pharyngoepiglottic fold cut to begin a TORS supraglottic laryngectomy. The left instrument, Schertel forceps, is grasping and retracting the epiglottis while the right directs the laser.
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This dissection should be carried to the inner surface of the hyoid to facilitate complete removal of the pre-epiglottic space.
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The superior laryngeal vascular bundle is predictably encountered fairly early in the dissection of the lateral pharyngoepiglottic fold. These vessels should be taken prospectively and controlled with 5-mm vascular clips using a laparoscopic clip applier.
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If the vessel is transected before it is clipped, it should be stabilized with the robotic forceps and subsequently clipped. It should not be managed with cautery.
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The dissection proceeds anteriorly and laterally to resect the pre-epiglottic space in continuity with the tumor ( Fig. 4 ).
Fig. 4
Anterior dissection of the pre-epiglottic fat at the thyroid ala. The left thyroid ala is visible and the left robotic arm is grasping and retracting the pre-epiglottic fat.
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The aryepiglottic folds are then transected superior and lateral to the arytenoid, incising obliquely to transect the posterior vestibular fold and enter the ventricle ( Fig. 5 ).
