Endoscopic surgery on the maxillary sinus has experienced significant advances in technique and approaches since the maxillary antrostomy was introduced in the 1980s. Disease processes that previously required open surgical approaches to the maxillary sinus can now be treated endoscopically while preserving form and function of the sinus and without injuring the maxillary sinus mucosa or disrupting normal mucociliary clearance. Understanding the techniques described in this article will allow surgeons to appropriately plan treatment strategies for patients with a variety of maxillary sinus diseases from dentoalveolar origin.
A wide array of maxillary sinus diseases are from dentoalveolar origin owing to anatomic proximity.
Advancement of endoscopic instruments and intraoperative navigation systems have allowed maxillary sinus disorders to be managed through endoscopic surgical approaches without a need for open or transoral approaches.
Endoscopic techniques used in the treatment of maxillary sinus diseases from dentoalveolar origin include balloon sinuplasty, maxillary antrostomy, endoscopic maxillary mega-antrostomy, endoscopic medial maxillectomy, prelacrimal approach to the maxillary sinus, and the endoscopic Caldwell-Luc approach.
The maxillary sinus, first identified by ancient Egyptians, has been well-studied, particularly in relation to its structure, vasculature, and relationship with the dentition. , The maxillary sinus begins to form during the 10th week of embryonic development as a result of invagination of ethmoid infundibulum mucosa. The sinus continues to enlarge throughout embryonic development and continues ossification up to the 37th week of gestation. Growth progresses throughout childhood until the maxillary sinus reaches its adult size between 18 and 21 years of age.
Anatomically, the alveolar and palatine processes of the maxilla form the floor of the maxillary sinus where the roots of the posterior maxillary dentition lie in close proximity to the floor of the sinus, with the molars having a closer relationship than the premolars. As such, a wide array of maxillary sinus diseases are of dentoalveolar origin. , When medical therapy fails to control maxillary sinusitis or inflammation, or in cases of neoplasm, surgery is frequently required. The advancement of endoscopic instruments and intraoperative navigation systems has allowed endoscopic approaches using rigid nasal endoscopes to be used frequently to manage maxillary sinus diseases. In this article, we review the minimally invasive endoscopic approaches used by otolaryngologists to manage diseases of the maxillary sinus originating from dentoalveolar pathologies.
Odontogenic Maxillary Sinusitis Episode
A 49-year-old woman presented to otolaryngology clinic complaining of left maxillary sinusitis (facial pain and pressure, purulent drainage, and posterior nasal drip with a foul smell). She had received multiple courses of oral antibiotics (at least 6 months) from her local dentist, who was planning to perform a bone graft to close the bony defect between the maxillary sinus and oral cavity. She had a remote history of nasal surgery (inferior turbinate resection) about 30 years ago for her nasal congestion. On examination, purulence was noted in the left middle meatus, with culture returning as the oral anaerobic bacteria Streptococcus anginosus . This was treated with culture-directed antibiotics (clindamycin 300 mg 4 times per day) for 2 weeks and saline sinus rinse (240 mL) before a sinus computed tomography (CT) scan ( Fig. 1 A). Based on her CT findings (complete blockage of left maxillary sinus ostium and bony defect), left maxillary endoscopic sinus surgery (opening the maxillary sinus ostium) was recommended to provide an adequate sinus opening for drainage and saline rinse (for irrigation and potential topical drug delivery). The patient wished to avoid any procedure under general anesthesia; therefore, the decision was made to perform in-office balloon sinuplasty of the left maxillary sinus using local anesthesia (topical injection). Upon balloon dilation of the maxillary sinus ostium, thick purulent mucus was expressed. Postoperatively, antibiotics were prescribed in addition to saline sinus rinse. The postprocedure sinus CT ( Fig. 1 B) was obtained 6 months after the in-office procedure to confirm the resolution of left maxillary sinusitis. The postprocedure CT scan showed complete resolution of the left maxillary sinus disease and the patient was able to undergo bone grafting for closure of the bony defect. This technique is advantageous for situations where general anesthesia needs to be avoided or patient preference is to perform in the clinic under topical and local anesthesia. However, many experts agree that this technique should only be used in a select cohort of sinusitis patients based on their phenotype, anatomy, and comorbidities. ,
Scheme: Balloon sinuplasty (balloon catheter dilation of the paranasal sinuses)
Balloon catheter dilation (BCD) of the paranasal sinuses was initially introduced in 1993, and approved by the US Food and Drug Administration in 2005. BCD has the potential advantages of causing less mucosal disruption and distortion of anatomy, less need for postoperative debridement, and faster returning to regular activities because it can be performed awake in the office under local anesthesia. Several small studies have shown noninferiority of BCD when compared with traditional functional endoscopic sinus surgery. Complications have been reported from BCD, so this seemingly less invasive procedure is not without risks. Performing in-office BCD of the maxillary sinus begins with appropriate patient selection and preparation. Indications for BCD are similar to those for standard functional endoscopic sinus surgery, and patients should have a trial of medical therapy before being considered for BCD. Once the decision has been made to proceed with BCD, a thorough review of the patient’s CT scan should be performed to identify extent of disease while making note of any anatomic variants that may affect the ease with which BCD can be performed, such as deviation of the septum, concha bullosa, or silent sinus. Achieving adequate anesthesia is imperative when performing in-office BCD. Numerous local anesthetic protocols have been reported in the literature, all of which combine topical and infiltrative methods. Typically, we use a combination of 4% tetracaine with oxymetazoline on pledgets placed in the middle meatus and medial to the inferior turbinate, followed by infiltration of 1% lidocaine with 1:100,000 epinephrine along the uncinate process and the middle turbinate ( Fig. 2 A). Following adequate anesthesia, an endoscope is used to visualize the middle meatus. The middle turbinate is gently medialized and the free edge of the uncinate is palpated and gently retracted anteriorly ( Fig. 2 B). The balloon catheter device is then inserted into the infundibulum and the natural ostium is palpated ( Fig. 2 C). The wire device is introduced through the natural ostium and placement is confirmed with transillumination. The wire should easily slide into the maxillary sinus, it is important to not force the wire to avoid injury, particularly to the lamina papyracea. After confirmation of appropriate position, the balloon device can then be advanced and inflation may be initiated. Visual confirmation of dilation is evidenced by anterior and medial bulging of the uncinate process and purulent drainage from the maxillary sinus ( Fig. 2 D).
Fungal Maxillary Sinusitis Episode
A 56-year-old woman who had a history of heart transplantation and currently on immunosuppressant therapy presented to otolaryngology clinic with symptoms of recurrent acute sinusitis every 3 months (purulent drainage, facial pain and pressure, and nasal congestion). A sinus CT scan was obtained after maximal medical therapy (2 weeks of oral antibiotics, saline rinse, and topical steroid spray), which demonstrated moderate to severe mucosal thickening involving the right maxillary sinus without bony erosive or destructive changes ( Fig. 3 A). However, subtle hyperdense foci were noted within the right maxillary sinus, indicative of likely inspissated superimposed fungal colonization. Based on the CT findings and her immunocompromised status, the decision was made to perform a right endoscopic maxillary antrostomy to clean out the sinus (removing all fungal elements and creating a well-aerated cavity). The patient tolerated the procedure well under general anesthesia with the pathology returning as a fungal mycetoma (fungus ball) ( Fig. 3 B). Odontogenic factors have been reported to increase the risk of developing fungal maxillary sinusitis owing to the close relationship between the molar dentition and the maxillary sinus floor, particularly patients undergoing endodontic procedures. Tomazic and colleagues demonstrated that the risk of developing a fungal mycetoma is 2.7-fold higher in patients with odontogenic disease compared with unaffected sinuses. Odontogenic procedures are thought to induce fungal inoculation into the maxillary sinus when the sinus mucosa is penetrated during the procedure. , Additionally, materials that contain heavy metals (eg, zinc), such as root canal sealers, silver cones, or amalgam, may enter the sinus and provide favorable environment for the growth of fungal species. This patient did have a remote history of dental procedures in her right maxillary molars, although the specific procedural information was not available. Furthermore, any dental procedures that penetrate through the sinus epithelial lining can (1) cause mucociliary dysfunction, (2) deteriorate the natural drainage of sinus mucus, (3) create an anaerobic environment associated with local tissue hypoxia, and (4) allow proliferation of fungal species in the maxillary sinus. , Therefore, directed endoscopic maxillary antrostomy to enlarge the natural sinus opening (improving ventilation and aeration) and extract the fungus ball is highly effective in managing fungal sinusitis.
Scheme: endoscopic maxillary antrostomy
The endoscopic maxillary antrostomy, introduced in the United States in the 1980s, is the initial step in endoscopic sinus surgery and considered by most to be the (relatively) easiest portion of endoscopic sinus surgery. However, failure to understand the anatomy and natural drainage pathway of the maxillary sinus can lead to technical failure and the need for revision surgery. The key in endoscopic maxillary antrostomy surgery is identifying and incorporating the natural ostium of the maxillary sinus into the surgical antrostomy. Identification and complete removal of the uncinate process is the first step in identifying the natural ostium ( Fig. 4 A, B). Uncinectomy can be performed in an anterior to posterior fashion by incising the uncinate process with a sickle knife just posterior to the maxillary line, a curvilinear mucosal eminence that corresponds to the junction of the uncinate process and the maxilla. Alternatively, the uncinate process may be removed in a posterior to anterior fashion and is the authors’ preference because one is less likely to injure or penetrate the lamina papyracea, particularly with hypoplastic maxillary sinuses or cases of very narrow infundibulums. To complete this procedure, an angled ball-tipped probe is used to reflect the free edge of the uncinate process anteriorly. Cutting instruments can then be used to remove the uncinate process from posterior to its anterior attachment to the lacrimal bone. Switching to a 30°, 45°, or 70° endoscope angled laterally, one can then visualize the natural ostium of the maxillary sinus ( Fig. 4 C). Once complete uncinectomy has been performed and the natural ostium of the maxillary sinus is identified, the antrostomy can be enlarged with cutting instruments and incorporated into a posterior fontanelle if present ( Fig. 4 D). Fig. 4 demonstrate the important steps in the completion of the endoscopic maxillary antrostomy.