For benign maxillary sinus lesions, many experts in China currently use the combined nasal endoscopic surgery via the traditional Caldwell-Luc pathway to treat maxillary sinus lesions. In June 2007, Bing Zhou et al. reported a new endoscopic nasal lateral wall dissection (ENLWD) into the maxillary sinus with preservation of the nasolacrimal duct and inferior turbinate. method. From January 2008 to January 2010, our department applied this method to treat 15 cases involving benign lesions of maxillary sinus with complete follow-up data, and achieved good results, which are reported below. I. Data and methods 1. General data 15 patients, including 9 males and 6 females, aged 19-72 years, average 41 years, with a disease duration of 3 months to 30 years. Among them, 6 cases were diagnosed histopathologically as maxillary sinus involute papilloma, 4 cases of mycobacterial septal sinusitis, 3 cases of nasopharyngeal fibrovascular tumor, 1 case of hemorrhagic necrotic polyp, and 1 case of maxillary sinus cyst. The patients underwent CT and or MRI examinations, and all were examined pathologically to exclude malignant tumors. (1) Inverted papilloma: 6 cases in this group, 4 males and 2 females, aged 34-81 years old, average 54 years old, complained of nasal congestion, blood in the mucus, and new gray-white papillary organisms in the nasal cavity were seen on nasal endoscopy. Coronal and horizontal CT scans of the sinuses showed that the affected septal sinus and maxillary sinus were filled with high-density shadows with uneven density and osteophytes in the sinus wall, and 3 cases showed partial destruction of the bone in the medial wall of the maxillary sinus by resorption. According to the krouse stage, there were 3 cases of stage 2, 2 cases of stage 3, and 1 case of stage 4 (involving the medial wall of the inferior temporal fossa) (2) Mycobacterium globulus type maxillary sinus septal sinusitis: 4 cases in this group, 2 males and 2 females, age 41-67 years old, average 48 years old, complained of blood in the snot, nasal congestion, nasal odor, nasal endoscopy can be seen in the nasal cavity brown clay-like mass-like material and lychee meatus-like material coexist, coronal and horizontal position of the sinus CT showed heterogeneous or homogeneous clouding of the maxillary sinus septum, calcified shadow in 3 cases, and partial resorption and destruction of the bone in the medial wall of the maxillary sinus in 2 cases. (3) Nasopharyngeal fibrovascular tumor: 3 cases in this group, all male, aged 15-22 years old, average 19 years old, complained of progressive nasal congestion and rhinorrhea, red mass in the nasal cavity or nasopharynx was seen under nasal endoscopy, soft and easy to bleed when touched, imaging examination found that the tumor originated from the posterior lateral wall of the nasopharynx and extended to the pterygopalatine fossa, and the bone of the posterior wall of the ipsilateral maxillary sinus was destroyed. (4) Hemorrhagic necrotic polyp, 1 case, male, 45 years old, admitted with blood in aspirated snot, sinus CT showed soft tissue shadow of maxillary sinus and bone of the medial wall of maxillary sinus was partially destroyed by resorption. (5) One case of maxillary sinus cyst, male, 15 years old, complained of deformation of the cheek bulge for 1 year, all sinus CT showed soft tissue shadow of maxillary sinus, and the bone of the medial wall of the anterior wall of maxillary sinus was partially resorbed. The puncture had coffee-colored cystic fluid. 2. Surgical method All 15 patients were operated with general anesthesia tracheal intubation and controlled blood pressure lowering assisted by anesthesiologists during the operation. Specific operation: under 0° nasal endoscopy, first along the lateral wall of the nasal cavity above the anterior edge of the inferior turbinate (2.0 mm from the posterior edge of the nasal foramen), make an arcuate incision from above to the base of the nose, peel off from under the periosteum to the most anterior part of the lateral nasal wall attachment of the inferior turbinate bone, and cut off the root of the inferior turbinate attachment. Next, the mucosa above the root of the inferior turbinate is detached posteriorly to near the natural opening of the maxillary sinus, and then the mucosa below the root of the inferior turbinate is detached posteriorly to around the opening of the nasolacrimal duct. If necessary, a portion of the frontal process of the maxilla was abraded with an electric drill to facilitate exposure of the medial wall of the maxillary sinus. The lateral wall of the maxillary sinus is removed from the root of the lateral nasal wall of the inferior turbinate, alternately using an electric drill and biting forceps from anterior to posterior. The lesions in the sinus cavity, including the soft tissues at the natural sinus opening and the diseased tissues of the maxillary sinus apex and the external superior portion, are removed under direct 0° nasal endoscopic view. Anterior or anterior-inferior maxillary sinus wall lesions can be removed with the aid of an angled speculum. In the case of invasive papilloma or nasopharyngeal fibrovascular tumor involving the pterygopalatine fossa, the posterior wall of the maxillary sinus should be occluded and the pterygopalatine and infratemporal fossae should be opened to reveal the tumor. In the case of nasopharyngeal fibrovascular tumor, the middle turbinate should be removed, the root of the tumor should be identified, the mucosa and periosteum should be dissected around the tumor, and the tumor should be removed after complete freeing of the root. If necessary, the anterior wall of the pterygoid sinus is opened. The surgical cavity is flushed with saline, the membranous nasolacrimal duct-inferior turbinate mucosal flap is reset, and the mucosal incision is fixed with counter sutures. Finally, the mucosa of the lateral wall of the inferior nasal tract was incised to make a window in the maxillary sinus of the inferior nasal tract for postoperative observation and drainage, and then the diffuse lesion tissue of the nasal cavity was removed under 0° nasal endoscopy, the other sinuses involved were opened and the lesion was completely removed, the lesion tissue at the natural opening of the maxillary sinus was removed, and the natural opening of the maxillary sinus was enlarged. Nasal tamponade. Postoperatively, antibiotics and hemostatic agents were used appropriately, and all gauze was removed after 48-72h. At daily dressing changes, 1% ephedrine cotton tablets were used to astringentize the nasal cavity and clean up blood crusts and secretions. All medication changes were performed under nasal endoscopy before discharge and the maxillary sinus opening was observed. After discharge, regular nasal endoscopy was performed once a month, and outpatient follow-up was performed for more than six months. II. Results Among the cases in this group, three cases of nasopharyngeal fibrovascular tumor had an average operation time of 3.5 h and an average bleeding volume of 850 ml. The other cases had an average operation time of (1.5±0.2) h and an average bleeding volume of (150±20) ml. All 15 patients were followed up for 6 to 24 months. Postoperatively, the patients had good inferior turbinate morphology. No recurrence was observed by CT scan and nasal endoscopy during the patients’ follow-up period. None of the 15 patients had any postoperative complications such as cheek numbness, tearing, intraorbital hemorrhage, visual impairment or cerebrospinal fluid nasal leakage. III. Discussion The theoretical basis of the classical Caldwell-Luc procedure is the complete removal of diseased mucosa from the maxillary sinus cavity and the simultaneous establishment of maxillary sinus drainage through the inferior nasal tract to treat maxillary sinus lesions. Since the Caldwell-Luc procedure is prone to numbness and sensory abnormalities in the infraorbital nerve distribution, pj.wormald chose to improve the classic Caldwell-Luc procedure by calling it the “endoscopic middle nasal canal window”. The transapical fossa approach facilitates observation of the walls of the maxillary sinus and facilitates intra-sinus surgery, while protecting the normal anatomy and physiological function of the maxillary sinus and its adjacent structures due to the small incision and selective removal of the lesion. However, there is still a risk of damage to the infraorbital and superior alveolar nerve branches when entering the anterior wall of the maxillary sinus, which is only slightly reduced compared to the classical procedure. Endoscopic endonasal septal sinus excision (or opening) with middle or inferior nasal tract maxillary sinus opening or acinar fossa opening combined with nasal endoscopic middle nasal tract opening has gradually replaced the Caldwell-Luc procedure as the mainstay of treatment of benign maxillary sinus lesions. The middlemeatus antrostomy (MMA) or combined inferiormeatusantrstomyIMA and apical fossa opening combined with nasal endoscopic middle nasal opening have become the routine maxillary sinus surgery. However, due to the characteristics of the maxillary sinus anatomy and the primary maxillary sinus lesion, there are still areas in the maxillary sinus that cannot be visualized and treated. In particular, the inner wall of the maxillary sinus, the anterior wall, the odontoid crypt and the anterior lacrimal crypt. In general, for benign lesions of the nasal sinuses, patients are more receptive to minimally invasive surgical approaches …… Clinically, for benign maxillary sinus lesions that involve the anterior wall, or the anterior-inferior wall, or for nasopharyngeal fibrovascular tumors with involuted papillomas involving the pterygopalatine and infratemporal fossae, we try to use the ENLWD approach to maxillary sinus surgery The treatment was performed. From our clinical results, the efficacy is definite, and the recurrence rate is low at short-term (six-month) postoperative follow-up. This procedure also has the advantage of wide field of view, which can fully reveal the entire maxillary sinus cavity, including the anterior lacrimal fossa and odontoid fossa, facilitating the observation and treatment of intra-sinus lesions without dead ends; by applying endoscopic transnasal operation, the inferior turbinate and nasolacrimal duct can be preserved, preserving the morphological structure and function of the nasal cavity and lacrimal duct, with minimal risk of damage to the inferior orbital nerve and superior alveolar nerve branches; compared with the open surgery category of The Caldwell-Luc procedure, mid-facial lift, lateral nasal dissection, and external or transnasal maxillary partial excision highlight its minimally invasive advantages over other methods that fall into the open surgical category. The key steps of this procedure are the exposure of the nasolacrimal duct and the treatment of the inferior turbinate to obtain space for maxillary sinus access. The nasolacrimal duct-inferior turbinate flap is moved inward to create a wide enough field of view that the lesion can be easily removed, usually with a 0° scope. With the aid of a 70° endoscope and conventional instruments, all parts of the maxillary sinus can be visualized and treated, especially the anterior lacrimal fossa and the odontoid fossa. However, the surgical approach requires a high level of anatomical knowledge and nasal endoscopic technique. The nasolacrimal duct runs longitudinally through the bony and membranous parts and involves complex structures such as the lacrimal bone, the sieve cardboard, the frontal process of the maxilla, the orbital floor, and the inferior turbinate. The superior port is located at the lower edge of the nasal mound, while the inferior port is located at the top of the anterior curvature of the inferior nasal canal and its lateral wall, the site is hidden, and the adjacent structures with the nasal cavity and sinuses are highly variable, making it a vulnerable site for nasal endoscopic surgery. Clinicians need to have solid anatomical knowledge and skilled endoscopic operation to accurately judge and locate the subtle anatomical structures during surgery in order to thoroughly clean the lesion, while avoiding damage to the adjacent critical anatomical structures as much as possible. In this group, there were no surgical complications such as nasolacrimal duct injury, orbital wall injury and facial numbness. ENLWD provides a new access and method for complete excision of maxillary sinus lesions, it preserves and protects the structure and function of the inferior turbinate and nasolacrimal duct, and it is a minimally invasive approach with obvious advantages for the simultaneous management of nasopharyngeal fibrovascular tumors and involuted papillomas involving the pterygopalatine and infratemporal fossae. In clinical practice, we only apply it to refractory inflammatory maxillary sinus lesions and benign tumors originating from the maxillary sinus that are difficult to remove through the conventional transnasal maxillary sinus (combined) opening, while the suitability of malignant tumors of the maxillary sinus for this procedure needs further clinical exploration. The number of cases completed after we performed this procedure is limited, but from the present summary, the clinical efficacy is satisfactory if the surgical indications are reasonably selected, and it has some clinical value.