Abstract: Objective To evaluate the postoperative results of endoscopic approach for the treatment of paranasal sinus mucoceles with intraorbital extension, and to determine the indications of combined external approach. Methods Data of patients with paranasal sinus mucoceles and orbital involvement treated by endoscopic with/without combined external surgery were retrospectively collected, and the surgical approach and treatment effect were analyzed. Results A total of 36 patients (54 mucoceles) were collected in this research, including 29 frontal sinus, 21 ethmoidal sinus, 2 sphenethmoidal sinus and 1 maxillary sinus. Mucoceles caused adjacent bone wall destruction and intraorbital extension, including 6 cases involving the superior/inferior quadrant of the lateral orbit and 30 cases involving the superior/inferior quadrant of the medial orbit. Twenty-two (61.1%) patients underwent transnasal endoscopic sinus surgery, all of them were mucoceles with intraorbital extension to the superior/inferior quadrant of the medial. Fourteen (38.9%) patients underwent combined endoscopic and external surgery, including 6 cases with intraorbital extension to the superior/inferior quadrant of the lateral and 8 cases with intraorbital extension to the medial. The symptoms such as proptosis and vision loss were significantly alleviated after two kinds of operation. Cerebrospinal fluid leak occurred in 1 case after external surgery, middle turbinate adhesion occurred in 1 case after endoscopic surgery. The patients were followed up for 12-61 months. The incidence of ostium restenosis was 8.3% (3/36), all of which occurred after frontal sinus surgery. There was no recurrence of mucoceles in the endoscopic approach, and the recurrence rate of mucoceles in the treatment with combined approach was 7.1%. Conclusion Transnasal endoscopic sinus surgery is an effective method for most paranasal sinus mucoceles with orbital involvement. For laterally localized frontal mucoceles, involving the superior/inferior quadrant of the lateral orbit, or multiple adjacent frontoethmoidal mucoceles with thick bone septum, combined endoscopic and external surgery is an option.

Key words: paranasal sinus diseases, mucocele, paranasal sinus, surgical approach, transnasal endoscopy, orbitotomy