Published Oct 1, 2026
Updated Oct 1, 2026
The nasopharynx and retropharyngeal space represent a natural, although technically demanding, extension of transoral robotic surgery (TORS). Unlike the oropharynx, these are deep anatomical regions in which conventional transoral instrumentation is constrained by the geometry of the oral cavity, the palate and the pharyngeal walls. The potential attraction of robotic surgery is therefore not simply increased dexterity. It is the possibility of bringing a stable three-dimensional view and articulated instruments into a deep surgical field that is difficult to reach through conventional transoral approaches.
The concept was explored experimentally very early in the development of TORS. O’Malley and Weinstein investigated robotic access to the midline skull base in cadaveric models in 2007, demonstrating that the transoral route could be extended considerably beyond the oropharynx. Shortly afterwards, Ozer and Waltonen reported the first clinical application of transoral robotic nasopharyngectomy. The subsequent development has been relatively focused: nasopharyngectomy, particularly for recurrent nasopharyngeal carcinoma, has become the principal clinical application, while retropharyngeal surgery has remained a smaller but increasingly interesting field.
Anatomy and surgical corridors
The nasopharynx is located above the soft palate and behind the nasal cavities. From the mouth, the surgeon approaches it from an inferior direction, while the surgical target extends superiorly and laterally.
The first robotic experiments therefore concentrated on determining whether the nasopharyngeal mucosa could be adequately exposed and dissected through the mouth.
Ozer and Waltonen demonstrated the feasibility of transoral robotic nasopharyngectomy in 2008. Wei and Ho subsequently reported its application to recurrent nasopharyngeal carcinoma, establishing the clinical rationale that has driven most of the subsequent experience. The attraction in recurrent disease is particularly clear. Salvage surgery after radiotherapy can be technically demanding, and achieving adequate exposure while minimizing additional morbidity is an important consideration. A transoral robotic approach can potentially provide direct access to the posterior nasopharynx without a conventional external approach.
Several approaches have been investigated to overcome the limitations of the transoral route. The original technique uses a mouth gag to expose the oropharynx, with the patient-side cart positioned towards the head. A 30° robotic endoscope is particularly useful because it allows the surgeon to look superiorly into the nasopharynx.
The soft palate can be divided when additional exposure is required. Alternatively, it can be retracted inferiorly, sometimes using transnasal suction catheters passed through the nostrils and brought out through the mouth (a surgical maneuver familiar for any otolaryngologist).
Once the nasopharynx is exposed, the relevant anatomy includes the posterior edges of the choanae, the vomer, the posterior nasopharyngeal wall, the Eustachian tube openings, the fossae of Rosenmüller, and the transition between the nasopharynx and oropharynx (Passavant ridge).
The robotic instruments provide traction and countertraction while the mucosa is progressively elevated and divided. The resection can be performed as a complete mucosectomy or in separate right and left components. An alternative is a T-shaped mucosal incision, with the horizontal component along the upper edge of the choanae and the vertical component in the midline of the posterior nasopharyngeal wall. This allows each half of the nasopharynx to be dissected separately.
Tsang and colleagues described a lateral palatal flap approach. Cadaveric studies subsequently investigated several corridors, including transoral, transnasal and transpalatal approaches. These studies demonstrated that different corridors provide different views and working angles, and that the most appropriate route depends on the precise location of the target.
It is also possible tu use combined approaches. Dallan and colleagues demonstrated a combined transoral-transnasal robotic approach in a cadaveric study. The transnasal route (endoscopic) can provide a superior view of the nasopharynx, while the transoral route (robotic) provides space for articulated robotic instruments. Tsang and colleagues subsequently reported combined transnasal endoscopic and transoral robotic resection in patients with recurrent nasopharyngeal carcinoma.
Retropharyngeal space
The retropharyngeal space is a logical continuation of this concept. It is a deep compartment immediately posterior to the pharyngeal constrictor muscles and anterior to the prevertebral fascia. Its anatomy makes external access unnecessarily disruptive for some selected lesions, while conventional transoral instruments have limited reach and maneuverability.
TORS provides an alternative: the surgeon can enter through the pharyngeal wall and dissect within the retropharyngeal space using articulated instruments under magnified visualization. The best established application has been retropharyngeal lymph-node dissection.
Givi and colleagues demonstrated the feasibility of transoral robotic retropharyngeal node dissection in patients with head and neck cancer. Subsequent series have explored the technique particularly in patients with oropharyngeal squamous cell carcinoma. However, this remains a highly specialized procedure, with relatively small published series and substantial selection of patients.
Clinical experience in nasopharyngeal carcinoma
The largest clinical experience with robotic nasopharyngectomy comes from recurrent nasopharyngeal carcinoma. Tsang and colleagues reported their early experience in 2015. Their series demonstrated that robotic-assisted nasopharyngectomy could achieve complete resection in most selected patients, establishing the procedure as a potential salvage option. The subsequent long-term series published in 2022 included 31 patients undergoing robotic-assisted nasopharyngectomy. Twenty-five patients had rT1 disease and six had tumour invading the sphenoid floor (rT3). At a median follow-up of 38 months, the reported five-year local control was 85.1%, overall survival 55.7% and disease-free survival 69.1%.
At the same time, the evidence needs to be interpreted appropriately. The literature consists mainly of anatomical studies, technical reports and relatively small retrospective clinical series from highly experienced centres. There are no randomized comparisons demonstrating that robotic nasopharyngectomy is superior to established endoscopic or open salvage approaches. The current role is therefore best understood as a specialized surgical option for carefully selected patients, rather than a replacement for other approaches.
Where are the limitations?
The technology remains far from perfect for this anatomy. The main limitations are not necessarily related to the precision of the robotic instruments themselves. They are related to the access geometry. The conventional multi-arm systems require the camera and instruments to enter through the oral cavity. The nasopharynx is located at the end of a relatively narrow and curved corridor, and the soft palate can become a significant obstacle. The surgeon must also work around the Eustachian tube openings, Rosenmüller’s fossae and the lateral pharyngeal wall while maintaining an adequate surgical plane.
For retropharyngeal surgery, the principal concern is different: the surgeon is operating close to major neurovascular structures, and the surgical field can be narrow and deep.
The absence of haptic feedback is another limitation. The surgeon relies predominantly on visual information when manipulating tissues and identifying tissue planes.
These limitations help explain why the clinical adoption of robotic surgery in these regions has remained relatively restricted despite the technology being available for almost two decades.
The next generation
The future of robotic access to the nasopharynx and retropharyngeal space is likely to depend more on miniaturization and flexibility than simply on increasing the dexterity of existing systems. The development of single-port platforms is particularly relevant. Flexible robotic instruments could be even more important.
The nasopharynx is not a simple straight cavity. Its lateral recesses and superior extension require the instruments to work around corners. A future system combining a flexible camera with flexible, independently articulating instruments could therefore provide an entirely different type of access.
Finally, haptic or force feedback (now already available for da Vinci 5) could potentially provide information that is currently obtained almost exclusively through vision.
These developments could make robotic surgery considerably more useful in deep soft-tissue anatomy even without fundamentally changing the instruments themselves.
References
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