Applications of transoral, transcervical, transnasal, and transpalatal corridors for Robotic surgery of the skull base

Abstract

Endoscopic endonasal approaches (EEAs) provide an alternative surgical corridor to treat benign and malignant lesions of the sinonasal tract and skull base. According to the extent of the lesion and the surgical team experience, an endoscopic endonasal skull base approach can provide exposure of vital neurovascular structures and enable the surgeon to resect the lesion safely and completely. Similarly, robotic-assisted surgery facilitates the performance of highly complex surgeries in areas of the upper aerodigestive tract that are relatively difficult to access or to manipulate instruments, such as the oral cavity, nasopharynx, oropharynx or hypopharynx, supraglottis, glottis, parapharyngeal space and infratemporal fossa (ITF). Operative time and time of hospitalization are superior to those associated with open approaches and are associated with less morbidity. Various feasibility studies have suggested that robotic-assisted surgery may be applied to skull base surgery with similar results.1 In general, skull base surgery is difficult and complex due to its anatomical intricacies, deep-seated nature, and the presence of adjacent vital structures. In addition, the relative rarity of indications increases the difficulty for a surgeon to become familiar with the detailed anatomy and the various pathologies affecting the region. This study was undertaken to better define and understand the potential use and limitations of current robotic approaches to the skull base. A fresh cadaveric specimen was dissected after approval by the Committee for Oversight of Research Involving the Dead (CORID) at the Robotic Skills Laboratory of The Ohio State University Medical Center. Our laboratory environment was designed to be similar to that of our operating room, using a standard operating room table and securing the specimen with a Mayfield 3-pin fixation system. A da Vinci Surgical System Model S (Intuitive Surgical; Sunnyvale, CA) was used. This robot was equipped with an 8 mm, 0°, and 30° high-definition 3D camera; plus two Endowrist robotic arms equipped with Maryland forceps, unipolar electrocautery (spatula tip) and/or dissecting scissors. A Crowe-Davis oral retractor (Storz, Heidelberg, Germany) maintained the oral aperture and retracted the tongue. A co-surgeon provided additional traction or countertraction, as well as suction of smoke and fluids within the surgical field. For a combined EEA and TORS technique, a rod lens endoscope (4-mm diameter; 18-cm length) with 0° lens, coupled to a high definition (HD) camera and monitor (Karl Storz Endoscopy Inc., Tuttlingen, Germany) provided visualization during the EEA. In addition, a “Total Performance System” drill (TPS, Stryker Co., Kalamazoo, MI) with an angled hand-piece and 3-mm to 4-mm rough diamond burrs (short and long) and endoscopic dissecting instruments (Karl Storz Endoscopy Inc., Tuttlingen, Germany) were used as needed. During the transoral approach, the 30° high-definition, 3D camera was inserted into the oral cavity to display the posterior and lateral nasopharynx. In order to avoid conflict within the operative field between the robotic arms and the camera, they were placed as parallel as possible on each side of the camera. To facilitate the transnasal-transoral approach, we performed a posterior septectomy, thus enabling the transnasal introduction of an 8-mm 0° robotic camera. This provided visualization of upper clivus and the rostral aspect of the sphenoid sinus while transoral robotic instruments were used to dissect. A transoral corridor provided access to the hard palate. For the transpalatal approach, a U-shaped mucosal incision was performed 5-mm medial to the maxillary dentition of the hard palate. This created a posteriorly based mucoperiosteal flap based on the greater palatine neurovascular pedicles. This flap was elevated following a subperiosteal plane in an anteroposterior direction that reached the posterior-most end of the hard palate. A Sonopet Ultras