Fig. 16.1
Traditional surgical approach to oropharyngeal tumors (lip splitting and mandibulotomy). This technique is associated with disfigurement and with an increased risk of osteoradionecrosis and fracture at the mandibulotomy site after adjuvant radiotherapy
16.1 The Ascent of TORRS
The defects created after TORS require meticulous reconstructive techniques to preserve normal anatomy and ensure good functional outcomes. Small defects, such as those at the base of tongue, can heal by secondary intention with good functional outcomes, and hence do not require reconstruction. Those in the tonsillar area and those extending to the soft palate, however, require vascularized tissue coverage as they result in carotid sheath exposure, oro- or pharyngocutaneous fistulas, and a potential for velopharyngeal incompetence. Some of these defects can be satisfactorily reconstructed with facial artery musculomucosal (FAMM) flaps, buccal rotation flaps, and pharyngeal flaps. Bonawiz et al. reported successful reconstruction of defects of the soft palate in five patients who underwent combined robotic-assisted resection of malignant lesions with immediate FAMM flap reconstruction [8]. Also, Selber reported the use of the robot to reconstruct a defect of the soft palate, tonsillar pillar, and pharyngeal wall with a FAMM flap in one patient in his case series describing robotic reconstruction [9].
Defects resulting from larger tumor resections are more complex and often extend from the tip of the tongue all the way to the epiglottis, involving a significant pharyngeal component and a pharyngotomy. The reconstructive challenge created by these minimally invasive resections is that the cylinder of the oropharynx remains almost entirely closed, severely restricting access to oropharyngeal anatomy as plastic surgeons attempt to inset and contour vascularized tissue. The anatomic region between the uvula and the epiglottis is very difficult to approach without a mandibulotomy or a wide pharyngotomy. Preserving a competent velopharyngeal sphincter, a watertight seal between the pharynx and neck, and adequate sensations and volume in the tongue base are necessary to optimize the physiological function of the oropharynx and minimize functional deficits [10, 11]. To achieve these goals, transoral robotic reconstructive surgery (TORRS) [12], whether using free flaps, local flaps, or primary closure, seems to be a logical approach. This technique appears to be a superior option in some cases and also holds great promise in expanding the indications for minimally invasive resection procedures. Combining transoral robotic flap inset with a manual approach through the existing pharyngotomy defect is also feasible. It is worth noting that although a pharyngotomy was created, it is much smaller than the wide pharyngotomies traditionally required for accessing such tumors as access to the upper pharynx is achieved robotically rather than through the neck. The senior author has thoroughly documented the value of TORRS for challenging defects of the head and neck and has demonstrated both feasibility [13] and effectiveness [9] of this reconstructive method. More recently, Song et al. reported their experience with free flap robotic reconstruction of oropharyngeal defects after robotic extirpation and also showed the feasibility of this new reconstructive approach in insetting flaps at a deep portion of the oropharynx without the need to perform a traditional mandibulotomy [10].
In addition, by taking this approach, plastic surgeons are able to provide a reliable reconstructive support for the head and neck surgeon to robotically resect larger, deeper, and more complex tumors that would be very challenging to reconstruct through traditional methods.
16.2 Indications and Preoperative Evaluation
Clear-cut indications for the application of TORRS are still not well defined. Reports describing its use have elaborated so far on its feasibility, safety, and extent of applicability; no clear instructions incorporating patient and tumor factors have yet been put forth. Longfield et al. proposed recently an algorithm for the use of TORRS based on tumor site, tumor extent, and patient-specific factors [14]. This can be used a structural scheme to which future recommendations can be incorporated.
16.2.1 Tumor Site
Tumor site is most probably the most important factor affecting the feasibility of a transoral robotic approach for resection and reconstruction.
Oral cavity lesions are accessible manually and would not benefit from TORS. An exception however is large retromolar trigone lesions. Tumors in this area are adjacent to the base of tongue (BOT), tonsil, and mandibular ramus. A robotic approach in this setting would be a good option for both resection and reconstruction. Local flaps such as the FAMM flap, buccal fat pad flap, and buccal and pharyngeal mucosal transposition flaps can be used. Free flaps are rarely used. The area is very restricted for flap inset, and also this would entail dissecting and exposing the neck to the oropharynx. So unless there is an indication for free tissue transfer (such as prior radiation or resections), avoiding such method is advocated.
On the other hand, tumors located within the oropharynx (tonsil, BOT, soft palate) benefit significantly from transoral robotic resection and reconstruction. It is true that these tumors were resected by alternative methods for many years [15, 16]; however, limited dexterity and visualization have always been a major disadvantage. With the ascent of robotic technology, improved visualization and more precise instrumentation have allowed the resection of more complex and invasive tumors. Defects created by such large resections (where critical structures—carotid sheath or bone—are exposed) are best addressed using robotic free flap reconstruction [9, 17]. Free flap options include radial forearm and anterolateral thigh flaps, and recipient vessels include either the superior thyroid artery or the facial artery.
For soft palate tumors, free flaps or palatoplasties are usually performed. In select cases, similar functional outcomes may be obtained with a prosthetic obturator [18, 19].
For tumors extending to the supraglottic larynx, reconstruction is guided by the extent of hypopharyngeal involvement and whether the lesion is above or below the hyoid bone. In patients with a large oral opening, the supra- and infrahyoid areas can be directly attained, and TORS might not be required. Free tissue transfer is also not feasible in this area. In case the defect is large enough to require free flap reconstruction [20], a tracheostomy is needed and will most likely be done through the flap itself. This increases the risk of airway compromise if partial dehiscence occurs.
16.2.2 Tumor Extent
As noted previously, small tumors (i.e., T1 and T2) can be allowed to heal by secondary intention; this approach is safe and results in satisfactory functional outcomes. As for larger lesions (i.e., T3, T4) or for posterior T2 tumors, or when the carotid sheath is exposed, or a surgical fistula is created, or velopharyngeal compromise is anticipated to occur, vascularized tissue is required to reconstruct the normal anatomy and optimize functional outcomes. Some of these lesions may also undergo “hybrid” resections, i.e., combining a transoral approach with a small pharyngotomy. This is usually followed by a “hybrid” reconstruction, where TORRS is performed, and the deepest inset is completed through the neck.
16.2.3 Prior Therapy
Neck irradiation compromises both the local micro- and macrovasculature, making local flaps undesirable for reconstruction. Also, prior neck irradiation increases the odds for receiving adjuvant radiation therapy. In such cases, free tissue transfer is advocated (even when the defects are small enough not to require coverage). This type of reconstruction brings in healthy vascularized tissue ensuring a durable form of coverage and allowing for re-irradiation [10, 13].
16.2.4 Patient Factors
Patient performance status constitutes the major determinant for any type of surgery. As obesity rates are increasing [21], medical comorbidities such as diabetes and vascular diseases are becoming more common among all age groups. Such conditions compromise perfusion and wound healing and thus increase the risk of dehiscence, infections, and other wound complications. Tight glycemic control in the pre- and postoperative period is essential.
More frequent than obesity, however, head and neck cancer patients are malnourished and suffer from chronic cachexia and muscle wasting. In addition to these factors, significant smoking history and poor cardiopulmonary status may also compromise the operative course of such patients by making them susceptible to the adverse effects of long operative times and general anesthesia. It is also important to consider the other preoperative patient variables that were notoriously associated with poor postoperative performance, such as anemia [22, 23], coronary or peripheral vascular disease, dysphagia, or a history of recurrent aspirations.
16.3 Surgical Technique
16.3.1 Patient Setup
TORRS is usually combined with TORS (during which patient positioning has already been performed). Patients are usually placed in the supine position and supported with a shoulder roll to provide adequate neck extension. A doughnut gel pad is used for occipital scalp protection. Both upper and lower extremities are well padded to prevent nerve injury, especially for overweight and obese patients [24]. TED stockings and sequential compressing devices are also applied to the lower extremities in an effort to minimize deep vein thrombosis.
16.3.2 Robotic Setup
The setup for the robotic portion is similar for all TORRS cases [9]. First, an optical window is created in the mouth. When the tongue base is not involved, a Dingman retractor is placed in the mouth to create a stable interdental opening and provide lingual retraction; other retractors have also been tested for this use and were employed clinically [25]. When reconstruction of the base of tongue is however required, the tongue must remain mobile. A cheek retractor is placed to maintain a stable frame, a mouth prop is used to create a wide interdental opening, and a suture is placed at the tip of the tongue for manipulation (Fig. 16.2).
Fig. 16.2
Representative illustration of the robotic setup for oropharyngeal surgery. A Dingman oral retractor is used to keep the mouth open. Two robotic arms and an endoscope are used to operate
16.3.3 Robotic Docking
The exact location and position of the patient side cart depends on the location of the defect. Since the robotic arms function best when the working area is lined up with the base and when the arms are working back toward it, it is recommended to position the robot at 45° from the foot of the right side of the operating table for defects located in the right tonsillar area. Whereas when the defect is in the left tonsillar area, 45° from the foot of the left side is preferred. For central or posterior pharyngeal defects, either of these two positions is acceptable. In any case, the patient side cart should be against the base of the bed, in order to bring it as close as possible to the mouth. When operating on the palate, it would be more convenient to bring the robot in from the head of the bed.
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