There are a substantial number of people with sinus inflammatory disease—sinusitis—that could benefit from sinus surgery. Patients with sinusitis can be grouped according to the severity of their sinusitis into those with mild and those with severe anatomic evidence of sinusitis. The latter category includes those patients with significant anatomic anomalies, patients previously operated on who have substantial postoperative defects in the diseased areas, and those with significant paranasal sinus polyps. The remaining group with mild anatomic evidence of inflammation, which makes up the largest portion of those suffering from sinusitis, may nonetheless have significant and persistent symptoms despite undergoing medical therapies. Many patients are understandably resistant to traditional surgery, such as functional endoscopic sinus surgery (FESS), in particular if their symptoms are mild. Thus, that is the target group for non-invasive treatments. The goal is a procedure that is reliable, long lasting, pain free, safe, has no tissue removal, and allows an immediate return to full activities.
Development of non-invasive procedures requires an understanding of the anatomical features of the sinuses and the nasal cavity as well as an appreciation of the mucus drainage pathways. Clinically, there are five major groups of sinuses in a human patient: frontal, anterior ethmoid, posterior ethmoid, maxillary, and sphenoid. The ethmoid is divided into anterior and posterior portions to account for the clinical observation that sinus cells anterior to the basal lamella (the lateral attachment of the middle turbinate) have a separate mucus drainage pathway from those posterior to the basal lamella. The maxillary, anterior ethmoid and frontal sinuses often are affected by inflammatory disease in unison. That tendency is believed by some to be due to a shared common drainage location; in any case, current dogma holds that inflammation in the anterior ethmoid is an indication of inflammation in the maxillary and frontal sinuses. For the maxillary sinus, the drainage site is the ethmoid infundibulum, the very narrow space between the uncinate process medially and the orbit laterally. For drainage of the anterior ethmoid sinuses, there are multiple sites, usually including the ethmoid infundibulum for a small portion, and relying on the hiatus semilunaris superior for most of the cells. That anatomic observation is not universally known to routine practitioners of the current art. For the frontal sinus, the ostium usually just posteromedial to the superior end of the uncinate (or just external to the ethmoid infundibulum proper), but sometimes is lateral to the uncinate, and therefore within the infundibulum. That slight anatomic separation coheres with the clinical observation that the maxillary and anterior ethmoid are very frequently inflamed in unison, with the frontal sinus also inflamed somewhat less often.
The posterior ethmoid and sphenoid sinuses are believed to have individual drainage sites posterior to the basal lamella. For the sphenoid, it is indisputable—the ostium can be easily seen at the sphenoid rostrum in nearly every patient if proper exposure can be obtained. For the posterior ethmoid, the putative drainage sites are not so explicit. There is some sharing of inflammatory disease by the sphenoid and posterior ethmoid sinuses. Analogous to the maxillary/anterior ethmoid/frontal system, it is believed that there is a shared pathway for the posterior ethmoid and sphenoid sinuses in the sphenoethmoid recess, the space just anterior to the sphenoid rostrum (where, as noted above, the sphenoid ostium is found) and extending laterally. (Stammberger, H. Functional Endoscopic Sinus Surgery. Mosby (St. Louis) 1991. See pp. 49-67.)
The vast majority of the patient group with mild anatomic sinusitis, regardless of symptom severity, has maxillary or anterior ethmoid inflammation, which also is referred to as limited maxillary and anterior ethmoid disease. If a minimally invasive treatment is to be effective for a majority of patients, it must be effective for patients with maxillary or anterior ethmoid inflammation.
The Maxillary Sinus
The maxillary sinus is a large air space, filling essentially the entire cheekbone in the typical patient. From the transnasal aspect, that air space lies just lateral to the entire lower half of the lateral wall of the nose. From the oral/sublabial aspect, it lies just superior to the tooth roots from the canine to the last molar and extends to the orbit. The maxillary sinus is relatively large and most of it is relatively far from the eye, which is the most important structure in that area. Traditional access to the maxillary sinus involved either forcing a trocar through the low lateral nasal wall or sublabially through the anterior wall of the sinus just lateral to the canine root or both, followed by the enlargement of the resulting hole via removal of bone to drain the sinus and remove any diseased tissue. Those approaches were developed to best avoid damaging the eye, yielding a suitable surgical margin of error for that purpose. At the end of the procedure, one sought to preserve the intranasal hole in the belief that the sinus would continue to drain through it for the rest of the patient's life, an assumption later realized to be incorrect.
A seminal development in sinus surgery was Messerklinger's work in the 1960's (and applied clinically in the 1980's) on the physiology of sinus clearance of mucus, and its rather rigid connection to sinus microanatomy. (Messerklinger, W., multiple references quoted in Stammberger, ibid., pp. 27-28.) Among other observations, Messerklinger's work involved placing traceable, visible granules into the maxillary sinuses. Using a high resolution endoscope, he observed that the granules would migrate along the lining in a very specific path, exiting the maxillary sinus through an ostium near the anterior superior extreme of the sinus, lateral to the uncinate process, and following an explicit and narrow stream just above the inferior attachment of the uncinate to the lateral wall, before exiting that narrow space posteriorly. Of crucial interest, that pathway was preserved independent of any other, even larger, holes that might exist, naturally or surgically, in the medial wall of the sinus. In effect, the cilia always push sinus mucus in the direction of the so-called natural ostium, whether or not other ostia exist or are created. That observation suggested that the previously-held belief in the benefit of surgically-created sinus ostia was misplaced. The new paradigm was to become surgical enlargement of the natural ostium explicitly, finally gaining wide adoption in the early 1990's with utilization of functional endoscopic sinus surgery (FESS), particularly among new trainees and professors. That strategy subsequently has been validated clinically. Placement of ostia elsewhere was too often found to be useless or injurious and, crucially, those problems could be reliably corrected only by addressing the natural ostium in an appropriate way. That principle continues to be important, beneficially if honored, detrimentally if neglected.
In state-of-the-art endoscopic maxillary sinus surgery today, the uncinate process first is removed from its posterior margin back to its anterior maxillary attachment, revealing the (often small) natural ostium just posterior to the anterior maxillary attachment. The natural ostium is assessed. If deemed too small to effectively permit long-term drainage from the sinus (an arbitrary decision), it is enlarged posteriorly. In approximately one-third of patients, there is a naturally occurring accessory ostium posterior to the natural ostium. In those patients, the surgeon enlarges the natural ostium to broadly connect with and encompass the accessory ostium to avoid having mucus recirculate; i.e., to prevent mucus that is exiting the sinus via the augmented natural ostium from reentering via the accessory ostium. It is not clear how often that pathway is utilized for recirculation, if ever. A problem results, however, if a surgeon creates a new ostium posterior to the natural ostium, which often does cause recirculation, or if a surgeon enlarges an accessory ostium thinking it to be the natural one, which will not achieve the objective and might, as discussed above, cause recirculation. If those errors occur, they usually can be corrected by finding the natural ostium and connecting it with the accessory ostium to create a single large ostium.
The minimally invasive balloon sinuplasty surgical method for application to the maxillary sinus, as exemplified by the transnasal approach of U.S. Pat. No. 7,500,971, which is incorporated herein by reference in its entirety, involves placing a curved, tubular guide into the posterior slit-like opening of the infundibulum, between the posterior margin of the uncinate medially and the orbital wall laterally. A guide wire is then fed through the lumen of the tube and into the infundibulum. The wire is gently manipulated until it, by trial and error, drops into the ostium. The tip can be verified to be in the sinus by X-ray fluoroscopy or more commonly by light from the wire tip seen to transilluminate the cheek. See, e.g., U.S. Pat. No. 7,559,925. Both X-ray fluoroscopy and transillumination are cumbersome to a degree, fluoroscopy especially so as it requires large machines that are not normally present at sinus surgery and get in the way of easy, interruption-free operating. The wire transillumination method is more convenient, but requires the surgeon to juggle instruments in his/her hands and creates tangles on an operative field already wound with a variety of suction hoses and cords. Fluoroscopy and transillumination can assist the surgeon in determining if the instrument is in the sinus, but do not indicate whether the instrument is in the natural ostium. Thus, they are not substitutes for direct visualization. The balloon catheter is passed through the lumen of the tubular guide over the wire until it is believed to be spanning the ostium at which point it is expanded, putatively stretching the ostium and spreading the space between the orbit and uncinate by stretching the uncinate medially. As noted above, that action may instead result in dilation of an accessory ostium.
Another minimally invasive sinuplasty method, as exemplified by the canine fossa approach of U.S. Pat. No. 7,520,876, which is incorporated herein by reference in its entirety, utilizes the older sublabial approach to the maxillary sinus (described above), which requires puncturing the bone of the alveolus just above the tooth roots in the canine fossa region. The anterior wall of the maxillary sinus is punctured a bit lateral to the canine root. A miniature endoscope is passed coaxially through a tubular guide and advanced into the sinus and the natural ostium is directly visualized from this lateral aspect. The balloon catheter is passed into the ostium by manipulation of the guide according to what is visualized with the endoscope and the balloon is expanded.
Both the transnasal and canine fossa approaches have disadvantages. In the transnasal approach, the advance to the infundibulum is awkward. Surgical instrumentation—including the guides, balloon catheter, endoscope and guide wire—is introduced into the nose from anterior to posterior, but the infundibulum is entered posteriorly and the wire advanced anteriorly from that point. Those two maneuvers necessitate a 180 degree turn of the guide, guide wire and balloon catheter that is difficult to execute atraumatically in the tight spaces involved.
Another substantial problem with the transnasal approach is that the method is performed blindly because the surgeon's view of the natural ostium and any intervening accessory ostia is blocked by the more medial uncinate. The instrumentation is rounded and made flexible to avoid inadvertent introduction into the eye. However, that does not prevent inadvertent introduction into and cannulation of an accessory ostium, rather than the natural ostium, caused by the surgeon's inability to see the position of the instrument. In fact, in the significant number of cases that an accessory ostium is present (estimated at about one third of all patients), the accessory ostium is encountered first by the guide wire, as it is more posteriorly placed, and is probably more likely to be dilated than the natural ostium. In such cases, the surgeon mistakenly enlarges the accessory ostium rather than the natural ostium. As discussed above, that is not helpful and often harmful. Protecting against that eventuality is difficult. It is common, therefore, for surgeons to resort to a “hybrid” invasive/non-invasive procedure in which the lower uncinate is surgically removed to visualize the natural ostium in the usual fashion. Performed appropriately by a competent surgeon, the “hybrid” approach solves the problem, but necessitates reverting to an essentially standard approach that is more than minimally invasive. Using a balloon to dilate the now visible natural ostium is of questionable benefit compared to the standard surgical approach of trimming the posterior margin of the ostium—likely a mere victory of style over substance. Surgeons that would prefer a minimally invasive method will often revert to the unsatisfactory “hybrid” procedure because of frustration with the awkward approach to the natural ostium or because of concern that they will inadvertently and unknowingly dilate the wrong (accessory) ostium.
The canine fossa approach offers the advantage that the surgeon accesses the maxillary sinus and views the ostia from inside the sinus, from which they can be seen unobstructed. If more than one ostium exists, the natural ostium will be the anterior one, so verification of the natural ostium and avoidance of the accessory ostium is possible. The route also is direct. It does not require a 180 degree turn. Proponents of the canine fossa approach of U.S. Pat. No. 7,520,876 further represent that the balloon dilation succeeds in also enlarging the ethmoid infundibulum in that it stretches the uncinate medially, and it certainly seems that it does so. They claim that balloon dilation of the ethmoid infundibulum, in addition to treating the maxillary sinus, results in treating the primary ethmoid drainage, which apparently is believed to be located in the ethmoid infundibulum. The anatomic evidence, however, is overwhelmingly against that possibility.
Nonetheless, the problems with the canine fossa approach are substantial. It requires a separate incision and access for a trocar under the lip. Thus, it is not easily and naturally combined with intranasal procedures. Moreover, it is more difficult or impossible to access the ethmoid, frontal, and sphenoid sinuses from the canine fossa access site. Access to the anterior ethmoid is possible, but cumbersome. Access to the frontal sinus is quite difficult, and access to the posterior ethmoid and sphenoid is virtually impossible. Surgeons must utilize another “hybrid” invasive/non-invasive procedure for those sinuses that require a second incision site and a cumbersome combination of nasal and oral procedures. The primary incision required by the canine fossa approach might be undesirable to patients seeking less rather than more surgery. Surgeons likewise might hesitate to embrace it.
The canine fossa procedure also utilizes a miniature endoscope. The image quality of the miniature endoscopes that are commercially available are suboptimal due to the very fine fiberoptic thread transmitting the image. The endoscope is understandably fragile with a short (25 procedures) life and therefore carries a rather high cost per use.
In sum, there is a need for a minimally invasive method to access and dilate the natural ostium of the maxillary sinus, preferably via transnasal access, without commonly resorting to traditional resection as a “hybrid” rescue during the procedure. Access to the natural ostium should be direct and not awkward so as to not frustrate the surgeon and to avoid trauma, should be verifiable, and should be easy to combine with minimally invasive approaches to the other sinuses.
The Anterior Ethmoid
The drainage pathways of the anterior ethmoid sinus are less explicitly defined than in the maxillary sinus. The ethmoid sinuses, anterior and posterior, are often referred to as a labyrinth. Unlike the maxillary sinus, the ethmoid is partitioned into many small contiguous cells, with the anterior cells draining anterior to the basal lamella (and containing more and smaller chambers) and the posterior cells draining posterior to the basal lamella (and containing one to three or so larger chambers). The labyrinth occupies roughly the upper half of the nose, is bounded superiorly by the rather thin skull base (and brain beyond), and laterally by the orbit. Landmarks are less explicit and more variable than those in the maxillary sinus area. Consequently, serious injuries to the eye and brain during sinus surgery can occur in approaches to the ethmoid.
Traditional invasive ethmoid surgery utilized an incision between the eye and the nose and a puncture of the medial wall of the orbit to access the ethmoid. The surgeon penetrated the ethmoid sinuses below the frontoethmoid suture line (which lies roughly at the equator of the orbit at the level of the corner of the eye) to avoid the brain while removing pieces of ethmoid bone and nasal lining. That approach was rendered obsolete for most cases in the 1990's with the maturation of endoscopic sinus surgery.
In the current standard of endoscopic surgery of the anterior ethmoid, the largest and most prominent cell of the anterior ethmoid, the ethmoid bulla, is opened and its walls and those of adjacent cells are removed until opened “enough” (an arbitrary designation). Experience has shown that the opening of the ethmoid bulla and those adjacent cells fixes mild sinusitis satisfactorily in most cases.
Minimally invasive methods for ethmoid surgery have not progressed as far as those methods for maxillary surgery. This deficiency is likely due to the significant anatomic variation of the anterior ethmoid anatomy and confusion within the field as to the location of its mucus outlets. The accepted minimally invasive paradigm would require that one identify and open those outlets, an objective only partially accomplished (usually without specific identification) in the routine art by resecting most of the septations of the anterior ethmoid, and not yet addressed in the prior balloon-dilation art.
One relatively new method in the minimally invasive realm avoids the anatomic variation problem entirely by circumventing the paradigm of dilating natural ostia. Instead, in this method, the ethmoid bulla is engaged with a trocar that is pushed through its anterior and posterior walls, into the posterior ethmoid. A reservoir is then passed into the tunnel to rest in the anterior and posterior ethmoid. The reservoir contains steroid that elutes into the sinus over days-to-weeks, decreasing inflammation.
It is reasonable to speculate that application of targeted pharmacotherapeutic agents, as in the above method, will be a helpful adjunct to the treatment of sinusitis. In the current routine sinus art, topical steroid spray is a mainstay of treatment, and topical antibiotics and antifungals are occasionally used to treat select patients. The benefits from these topical agents, however, have been limited. There is reason to suspect that the limitation is due to an inability to direct the agents to the diseased areas of intact sinuses in sufficient concentrations to be effective, rather than to some more fundamental shortcoming. In an analogous situation, acute and chronic infections and inflammation of the ear canal skin are much more rapidly and effectively treated with topical agents than with oral ones. Topical medications probably result in local pharmaceutical concentrations that are several orders of magnitude greater than those safely achievable in oral administration. Obviously, the ear canal is more easily targeted with repeated administration of concentrated therapeutic agents than the more hidden recesses of the paranasal sinuses.
The aforementioned placement of a pharmaceutical-eluting implantable device seeks to surmount that largely anatomic challenge, and has achieved some promising early results. There are certainly some drawbacks to this method, however. The placement of the device alters anterior ethmoid anatomy without explicit attention to the natural drainage pathways thereof, possibly, although not necessarily, compromising mucus clearance in the long-term. Taken together, the cost of the device and the nature of its placement do not lend themselves to repeated use in an office setting; rather, they are more suited to a single treatment or very occasional treatments in a surgical setting. As many patients have some degree of ongoing medical sinus disease, this is a significant drawback. Ideally, one would prefer that targeted pharmacotherapy be a viable alternative to oral therapy for many patients, necessitating a more convenient and inexpensive option. Lastly, the method by which the trocar is directed into the sinuses is of some concern. One would prefer, if possible, a more precise and less traumatic means of accessing the ethmoid sinuses. A reliable means to treat the maxillary sinus with targeted pharmacotherapy would also be desirable, an option lacking in the prior art. This gap in current treatment options is largely because of the presence of the uncinate, which prevents direct atraumatic access to the maxillary sinus, frustrating the guide-based system currently used.
In sum, there is a need for a minimally invasive method for accessing and treating the anterior ethmoid that augments flow through natural drainage pathways of the anterior ethmoid. There further is a need for a minimally invasive means to introduce targeted pharmacotherapeutic agents to the maxillary and anterior ethmoid sinuses (as well as others) in a more cost-effective and atraumatic manner than in the current art.