David W. Kennedy, MD, is Vice Dean for Professional Services and Senior Vice President of the University of Pennsylvania Health System and is Professor of Otorhinolaryngology at University of Pennsylvania School of Medicine in Philadelphia.
Endoscopic sinus surgery was introduced into the United States more than 20 years ago; over that time period it has undergone significant changes, in terms of both surgical technique and our understanding of the disorder of chronic rhinosinusitis. However, the concept of using a transnasal approach is far from novel. The ancient Egyptians used the transnasal route to remove brain tissue prior to mummification. The approach was used surgically but then fell into disrepute with the era of prefrontal lobotomy.
Endoscopic sinus surgery itself has become more meticulous, with greater attention to both mucosal preservation and the complete removal of bony partitions within the area of disease. Technological advances have markedly improved our endoscopic capabilities, and further developments on the horizon promise to further expand the surgical potential. To date the surgical techniques originally introduced for inflammatory disease have been extended to skull base and pituitary tumors, orbital lesions and skull base defects, and our ability to tackle lesions within the frontal sinus has been significantly expanded. At the same time, rhinology itself has become an identified subspecialty, with approximately 20 institutions now offering advanced fellowship training in the field of rhinology and sinus disorders.
What We Know Now
Although we still have a long way to go, we have learned significantly more about some of the etiologic factors involved in chronic rhinosinusitis, and we know that this disease has a markedly greater impact on quality of life than was previously appreciated by most otolaryngologists, let alone by physicians in other specialties.
Twenty years ago we thought that anatomic factors were a major factor in the pathogenesis of this disease and that providing ventilation alone was sufficient to resolve the majority of cases. Today we better understand the complexity of the disorder of chronic rhinosinusitis and the interplay of complex environmental, general, and local host factors in its genesis. We understand that chronic disease is not primarily a bacterial infection, but is an inflammatory disorder that may be exacerbated by bacteria or fungi. We also believe that the bacteria may, at least in some situations, exist in a biofilm, relatively resistant to both antibiotics and our own host responses. The associated inflammation is also able to spread through the underlying bone, and the bone inflammation itself may be a significant factor in this disease process.
We now know that it is unwise to open up virgin mucosa to the same environmental factors that caused the inflammation to develop in the first place, unless those environmental factors have been removed or their effects medically controlled. Additionally, we have demonstrated conclusively that improvement in symptoms does not correlate with resolution of disease and that the latter typically requires prolonged medical therapy and careful endoscopic follow up. Indeed, it appears that in many cases surgery alone does not create a long-term resolution, and prolonged medical therapy is typically required for control of this chronic disorder.
Whereas, 20 years ago, the surgery itself was limited, quick, and frequently involved some stripping of mucosa from the ethmoid sinuses, it is now a much more meticulous procedure, with the surgeon taking care to preserve the mucoperiosteum and to avoid exposed bone. At the same time, significantly greater attention is given to completely removing the bony partitions in the areas of disease, because we now believe that this inflamed bone may lead to persistent inflammation and scarring. This surgical evolution has been aided by the development of through-cutting forceps and the microdebrider. As microdebrider technology has improved, so has the potential to remove disease rapidly with excellent mucoperiosteal preservation. However, with the use of powered instrumentation, there has also some suggestion that the degree of severity of complications may have again risen, because of the potential for microdebriders to rapidly remove either orbital contents or brain should the surgeon stray out of the normal surgical field.
A number of other technological advancements have had a significant impact on our ability to improve endoscopic sinus surgery. The ability of the Endoscrub™ to maintain clear visualization in the presence of bleeding, improved charge-coupled device (CCD) camera technology, and the development of suction irrigation drills have all enhanced our ability to completely remove disease and to extend the surgery beyond just the treatment of rhinosinusitis and beyond the boundaries of the nose. Although there is very limited evidence to suggest that the use of computer-assisted surgical navigation reduces complications, it clearly improves the surgeon’s ability to perform a complete surgical procedure and is a superb teaching tool. However, perhaps most important, scrolling through the images in a triplanar display preoperatively enables the surgeon to gain 3-D conceptualization of the anatomy, which is difficult to achieve with static images, even when they are available for review in all three planes. A significant limitation of computer-assisted surgical navigation, however, is its reliance on the preoperative scans. An exciting new development in this field is the introduction of portable low-radiation-dosage intraoperative CT with the ability to update the information in the image-guidance computer with real-time intraoperative images. Our preliminary work with such intraoperative CT scans suggests that they will be of significant benefit in ensuring the completeness of surgery.
Surgical precision continues to improve. With dramatic improvements in anesthetic safety, surgical time is no longer as critical an issue as it was previously, enabling the prudent surgeon to further reduce mucosal trauma, while at the same time performing a more complete procedure. The recent introduction of high-pressure dilation balloons (balloon sinuplasty) may further reduce mucosal trauma in highly selected cases. However, the positioning of this device as an alternative to surgery in many of the patients currently undergoing surgery would appear to be an unfortunate deception imparted on the patient population that we are trying to serve.
What the Future Holds
The demonstrated ability of rhinologists to close skull base defects and cerebrospinal fluid leaks with greater success rate than by craniotomy has already significantly extended the potential for endoscopic transnasal approaches. Benign, and even selected malignant, skull base tumors can now be approached by skilled endoscopic surgeons with major reductions in patient morbidity and improved surgical visualization. Yet we may have barely begun to scratch the surface of what is possible through an endoscopic approach. Although currently still too large for transnasal use, the surgical robot has demonstrated excellent utility for transoral surgery and carries the potential to dramatically enlarge the type of surgery that can be performed at the skull base and intracranially via the intranasal route. When small enough to be utilized intranasally, this device caries the potential to allow intracranial manipulation without tremor and with a level of dexterity not available even to the most skilled skull base surgeons. Additionally, it caries the potential to use vascular clipping or bipolar cauterization of intracranial blood vessels which cannot be reached with currently available technology significantly expanding the intracranial horizons for this type of surgery, while at the same time also reducing postoperative complications by allowing direct suture closure of dural patches.
The past 20 years have been an exciting period for rhinology, and evidence would suggest that the rapid advancements which have occurred to date will continue in the years ahead. The primary advances in terms of chronic rhinosinusitis will likely occur in the realm of further improvements in the understanding of the inflammatory pathways and their pharmacological control. However, surgery will likely continue to play a significant role for a minority of patients whose quality of life is impacted by this disorder. Since current estimates place the number of affected individuals at approximately 32 million people in the United States, it is likely that there will still be a sizeable population requiring surgical intervention, even as our medical therapies continue to improve. The sinus surgery is likely to be considerably more meticulous and less traumatic than it frequently is today. Additionally, the potential for advancements in skull base surgery remains large.
The concept of using a transnasal approach is far from novel, dating back to ancient Egypt. However, under endoscopic visualization the transnasal route has now again proven viable for the meticulous removal of skull base lesions, and it appears likely that in the future it will be extended to other lesions currently still treated by open craniotomy, with the potential for significant further reductions in patient morbidity.
©2007 The Triological Society