Samar Fakhri, MD
One of the most exciting aspects of attending scientific meetings is to explore new products and technologies presented during the program sessions or showcased by the exhibitors. At the recent Combined Otolaryngology Society Meetings (COSM) in Las Vegas, three-dimensional endoscopic technology generated interest among the audience and stood out among a medley of innovations that combine biochemical, physical and information sciences. Meant to enhance surgical performance and overcome limitations of current technology, this is the long-awaited answer to the lack of depth perception of conventional two-dimensional endoscopy.
There were two presentations on the utility of 3-dimensional stereoscopic vision during endoscopic sinonasal surgery. The first study compared outcomes of traditional 2-dimensional endoscopic pituitary surgery in 36 patients to a 3-dimensional endoscopic system in 27 patients.1 There was no difference between the 2 groups in blood loss, operative time, rate of CSF leak, and postoperative endocrine complications.
In the second study, a high-definition 2-D endoscopic system was used on 7 patients undergoing sinonasal and skull base surgery.2 The 3-D endoscopic system was then incorporated at key portions of the procedure. The authors reported that 3-D endoscopy enhanced depth perception and endoscopic orientation, and resulted in additional intervention including tumor resection or removal of remnant partitions in 43% of patients. There were no complications but there was inability to visualize a type III frontal cell and loss of orientation due to over-magnification during an ASB reconstruction.
We are witnessing an explosive growth in the surgical applications of information science. In the field of Rhinology, the introduction of the telescope to the modern practice of surgery is a perfect example of how the information age has enabled an unequivocal paradigm shift in the surgical management of sinonasal disease. Advances in imaging protocols, surgical navigation, computer-aided surgery, virtual endoscopy and robotics are reshaping the face of modern day surgery and forcing surgeons to engage in constant re-evaluation of the way they practice surgery. More importantly, technological advances have enhanced the quality of care delivered to individual patients.
One of the biggest challenges during endoscopic sinus surgery is to generate movements in a three-dimensional space based on feedback provided by 2-dimensional display monitors. Relying on monocular cues, even when using high-definition video endoscopy, may limit the ability of the surgeon to perform accurate and efficient maneuvers to reach surgical targets. Tracking the movement of an experienced endoscopic surgeon during conventional 2-D laparoscopy reveals an interesting pattern. Initially, the surgeon aligns the horizontal and vertical axes bringing the instrument in front of the target but then moving it slowly deeper until contact is made with the target. This obviously results in a “z lag” or slower depth positioning. Although the limitations of working under 2-D visual conditions may be minimized with practice, studies have shown that even experienced endoscopists underperform in 2-D endoscopic conditions compared with direct vision. In one study, experienced laparoscopic surgeons made 47% more movements, took 56% longer and overshot the target 35% deeper than with direct vision.3 Of course novice endoscopists fared much worse. In the same study introducing a 3-D endoscopic system halved the endoscopic “handicap” of surgeons in all objective parameters measured.
At movie theatres, the advantages of 3-D are evident in movies like Avatar. The experience of watching James Cameron’s latest blockbuster in 3-D is so spectacular, it’s a wonder we still bother watching conventional 2-D movies. I made a similar conclusion last year after performing a cadaveric sinonasal and skull base dissection using 3-D endoscopy. The rationale for using 3-D technology that provides the surgeon with a spatial map of the surgical field that approximates direct vision seems intuitive. For my skull base neurosurgery colleague, the 3-D experience is welcomed as a game-changer that will facilitate the adoption of endoscopic techniques by neurosurgeons. From my perspective, I can attest that it provides enhanced depth perception and a unique surgical experience. It is unclear, however, whether this novel technology will result into superior surgical performance in sinonasal surgery when compared with the high-definition 2-D endoscopy that I already use.
Adoption of a new technology requires careful assessment of its merits, limitations and cost. The initial limitations of 3-D telescope characteristics have been overcome, with smaller (4.0mm) diameter and angled scopes now available. As a surgeon, I am likely to adopt technologies that decrease operative risk and improve patient outcomes. While it seems instinctive that enhanced visual information should lead to more efficient and safer procedures, it is indeed difficult to correlate improvements in surgical performance with better patient outcomes. The two studies presented at COSM arrived at different conclusions regarding the impact of 3-D endoscopy on patient care. Specifically, the first study did not show any difference in patient outcomes and operative risk between 2-D and 3-D endoscopic pituitary surgery. Studies from other surgical disciplines show a similar split on the effectiveness of this technology and the benefits it provides to patients.
Considering this environment of health care reform and cost containment, it is likely that hospitals will evaluate novel and expensive technology based on a stringent evidence-based acquisition process. This technology remains prohibitively expensive and needs to prove itself before it hits the big time.