Robotic Exoscopic Resection of Pituitary Tumors

Background Surgical strategies to approach anterior skull base and pituitary pathology through transnasal corridors was originally made possible in a safe and efficacious manner due to the magnification and illumination afforded by the operating microscope. Technical advancements in optics, illumination, and miniaturization led to the mainstream use of endoscopes for the transnasal corridor. Advances continue to be made leading to experimentation with 3D endoscopes that are now used at a few select centers. Further developments in surgical visualization have led to the use of exoscopes in lieu of the operating microscope for cranial surgery but have not been adopted in anterior skull base surgery through a transnasal corridor. We describe our initial experience in using an exoscope, mounted to a robotic arm to assist in the resection of pituitary tumors through a transnasal corridor.

Methods We utilized an exoscope mounted to a robotic arm, with the assistance of an endoscope, to remove two pituitary tumors through a transnasal approach. The first patient was a 54-year-old man presenting with bitemporal hemianopsia and a 3-cm sellar mass with suprasellar extension (Fig. 1). The second is a 63-year-old woman with an incidental 2-cm sellar mass found during an evaluation for headache that was seen to be rapidly enlarging on surveillance imaging (Fig. 2). Patients underwent operative management in a joint fashion with a neurosurgeon and otorhinolaryngologist. A binostril technique was used with a nasal speculum through which the exoscope was focused and an endoscope through the other (Fig. 3). The initial cases were used with endoscopic assistance as this work represents a pilot project to evaluate the feasibility. The exoscope was mounted to a robotic are that was coregistered to neural navigation so that as a navigational pointer was placed at the area of interest, the robotic arm would match the focal point and trajectory of the pointer (Fig. 4). This allowed for smooth and accurate positioning of the optics. Resection proceeding through a transsphenoidal route followed by local skull base reconstruction with the mucosa bone fragments that were removed from the sphenoid sinus during the approach.

Results There were no intraoperative or postoperative complications in association with this procedure. Gross total resection was obtained in both cases as seen during the surgical procedure and on postoperative imaging. No cerebrospinal fluid leak was encountered in either procedure. Similar to the endoscope, the exoscope provides a two-dimensional view (Fig. 5). The quality of the optics and illumination with the endoscope still made for a very intuitive experience and we did not note any added difficulty with visualization. The surgical instruments were used mainly through the corridor maintained by the speculum, which minimized the trauma that may be seen while passing instruments during an endoscopic procedure. Additionally, this avoided the “sword fighting” commonly experienced as collisions occur between instruments and the endoscope competing for the same space.

Conclusion Exoscopic robotic-assisted endoscopic resection of pituitary tumors is a viable adjunct to current endoscopic techniques that provides excellent illumination and visualization.

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