Minimally invasive skull base surgery has advanced substantially with the advent of endoscopic technology, novel instrumentation, and intraoperative image-guidance capabilities. Robotic technology has been accepted into the surgeon’s armamentarium, with its implementation into abdominal, thoracic, and head and neck surgery. However, the application of surgical robotics to the skull base has yet to be achieved. This article highlights current preclinical research and applications of robotic surgery to the skull base.
Key points
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Although still in the developmental stages, robotic applications to skull base surgery are forthcoming.
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Transantral robotic surgery provides stereoscopic endoscopic access to the anterior skull base and pituitary fossa, and allows 2-handed endoscopic manipulation and reconstruction.
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Traditional suture and reconstructive techniques can be implemented in this confined surgical site with the use of robotic technology.
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Future development and refinement of endonasal robotic instrumentation is critical before applying these techniques in the clinical setting.
Introduction
In the past several years, transnasal endoscopic approaches have been increasingly used for surgical access and treatment of neoplastic and benign lesions of the anterior and central skull base. Endoscopic surgery is used with increasing frequency for surgical resection of tumors of the sinonasal tract, such as inverted papilloma, angiofibroma, osteoma, and other benign fibro-osseous lesions, and in selected patients with malignant sinonasal tumors. Endoscopic approaches are also becoming popular for transsphenoidal access to the sella turcica, and are considered by many centers to be the preferred surgical approach for treatment of pituitary adenomas. More recently, there has been an emerging trend to expand the use of transnasal endoscopic approaches in the surgical treatment of suprasellar, petroclival, infratemporal, and other intracranial skull base tumors.
The increasing popularity of these endoscopic skull base approaches may be attributed to a larger trend toward more minimally invasive techniques across all surgical disciplines. The main advantage of transnasal endoscopic skull base approaches is providing more direct access to the anterior and central skull base while avoiding craniofacial incisions and extensive bone removal, which are commonly used in open surgical approaches. Also, the wider angle of vision and angled lenses increase the range of the endoscopic visual surgical field compared with the line-of-sight visual field gained by surgical loupes or microscopes.
One major disadvantage of transnasal endoscopic approaches is the inability to provide watertight dural closure and reconstruction, which limits its safety and widespread adoption in surgery for intradural skull base tumors. Current techniques of endoscopic skull base reconstruction, such as tissue grafts, mucosal flaps, and tissue sealants, provide adequate reconstruction of limited skull base defects, such as a posttraumatic cerebrospinal fluid leak. However, for larger dural defects, these endoscopic techniques have higher cerebrospinal fluid leak rates compared with traditional reconstructive techniques used in open surgery, such as the vascularized pericranial flap.
Although the application of robotic technology to surgery has rapidly expanded over the last 5 years, little-studied but fertile area for application of surgical robotics in the head and neck is minimally invasive skull base surgery. The advantages that these novel systems offer include the ability to perform bimanual surgery in confined cavities with instrumentation that exceeds the capabilities of the human hand, and providing the surgeon with a three-dimensional (3D) view of the surgical field. Significant advances in surgical robotics have been made, although a role for robot-based applications in skull base surgery has not been completely defined.
Introduction
In the past several years, transnasal endoscopic approaches have been increasingly used for surgical access and treatment of neoplastic and benign lesions of the anterior and central skull base. Endoscopic surgery is used with increasing frequency for surgical resection of tumors of the sinonasal tract, such as inverted papilloma, angiofibroma, osteoma, and other benign fibro-osseous lesions, and in selected patients with malignant sinonasal tumors. Endoscopic approaches are also becoming popular for transsphenoidal access to the sella turcica, and are considered by many centers to be the preferred surgical approach for treatment of pituitary adenomas. More recently, there has been an emerging trend to expand the use of transnasal endoscopic approaches in the surgical treatment of suprasellar, petroclival, infratemporal, and other intracranial skull base tumors.
The increasing popularity of these endoscopic skull base approaches may be attributed to a larger trend toward more minimally invasive techniques across all surgical disciplines. The main advantage of transnasal endoscopic skull base approaches is providing more direct access to the anterior and central skull base while avoiding craniofacial incisions and extensive bone removal, which are commonly used in open surgical approaches. Also, the wider angle of vision and angled lenses increase the range of the endoscopic visual surgical field compared with the line-of-sight visual field gained by surgical loupes or microscopes.
One major disadvantage of transnasal endoscopic approaches is the inability to provide watertight dural closure and reconstruction, which limits its safety and widespread adoption in surgery for intradural skull base tumors. Current techniques of endoscopic skull base reconstruction, such as tissue grafts, mucosal flaps, and tissue sealants, provide adequate reconstruction of limited skull base defects, such as a posttraumatic cerebrospinal fluid leak. However, for larger dural defects, these endoscopic techniques have higher cerebrospinal fluid leak rates compared with traditional reconstructive techniques used in open surgery, such as the vascularized pericranial flap.
Although the application of robotic technology to surgery has rapidly expanded over the last 5 years, little-studied but fertile area for application of surgical robotics in the head and neck is minimally invasive skull base surgery. The advantages that these novel systems offer include the ability to perform bimanual surgery in confined cavities with instrumentation that exceeds the capabilities of the human hand, and providing the surgeon with a three-dimensional (3D) view of the surgical field. Significant advances in surgical robotics have been made, although a role for robot-based applications in skull base surgery has not been completely defined.
Techniques
Approach to the Anterior Cranial Fossa
The feasibility of using the surgical robot to access the anterior and central skull base has been shown in a cadaver model. Caldwell-Luc incisions and wide anterior maxillary antrostomies followed by wide middle meatal antrostomies are the entry points for the surgical arms ( Fig. 1 A). Sufficient access can be obtained without compromising the infraorbital nerves (see Fig. 1 B), and a posterior septectomy provides a common bilateral surgical field. The robotic endoscope is then placed into the patient’s nare and the right and left surgical arms are introduced through the respective maxillary sinuses (see Fig. 1 C). Anterior and posterior ethmoidectomies are performed, and sphenoidotomies provide exposure to the planum sphenoidale, sella turcica, and parasellar regions ( Fig. 2 ). With current technology, this is best performed using traditional transnasal endoscopic techniques before docking the robotic patient cart. In addition, current robotic instrumentation does not include a drill, although prototypes are under preclinical investigation. Therefore, removal of the anterior skull base bone is likewise best performed without robotic assistance. Access to the anterior cranial fossa is provided by sharp dissection of the anterior skull base and incision of the dura ( Fig. 3 A, B). The dual robotic arms can be used for primary repair of the dura. This approach provides excellent access to the anterior and central skull base, including the cribriform plate, fovea ethmoidalis, medial orbits, planum sphenoidale, nasopharynx, pterygopalatine fossa, and clivus. The most significant advantage of this approach is the ability to perform 2-handed tremor-free endoscopic closure of dural defects. To date, this approach remains investigational.
Approach to the Pituitary Fossa
Although the transnasal endoscopic approach to the pituitary fossa has become a widely used technique for surgical resection, robotic surgery in this anatomic location may provide unique advantages compared with the 4-handed technique. The feasibility of a robotic approach to the pituitary fossa has been described by the authors, and remains investigational.
Similar to the approach to the anterior cranial fossa, access involves creating bilateral maxillary antrostomies and docking the robotic arms and camera, as described earlier. An anterior sphenoidotomy is then performed, and the sellar floor is removed to expose the dura of the pituitary fossa ( Fig. 4 ). The dura is opened sharply with the robotic scissors to allow for exploration of the pituitary gland ( Fig. 5 A). Blunt and sharp dissection may be then performed to excise the pituitary gland after the optic chiasm and hypothalamus are exposed (see Fig. 5 B). Dissection of the lateral wall of the sphenoid sinus may also be performed with high-speed drills and fine rongeurs to access the cavernous sinus. Using this technique, access to the central skull base, including the planum sphenoidale, the pituitary gland, cavernous carotid, mammillary bodies, and optic chiasm can be achieved.
