Surgical anatomy of the lacrimal fossa - A prospective computed tomodensitometry scan analysis

Purpose: To establish the accurate surgical anatomy of endonasal dacryocystorhinostomy (DCR) based on the radiological analysis of underlying bony structures. Design: Prospective noncomparative observational case series study. Participants: Fifty-nine patients with complete nasolacrimal stenosis underwent a computed tomodensitometry (CT) scan before endonasal DCR. Methods: High-resolution CT scanning with contrast injection of the lacrimal sac was performed. Image reconstruction was performed to obtain continuous 1.0-mm axial and coronal sections for review. Main Outcome Measures: Relationship of the lacrimal fossa (LF) to the operculum of the middle turbinate (OMT), the uncinate process (UP), and the frontal recess (FR); symmetry of the right and left anatomies; location of the OMT; position of the most anterior insertion of the UP with respect to 2 main references (the posterior lacrimal crest and the junction between the maxillary and lacrimal bones) on axial sections at 3 different levels (upper, intermediate, and lower of the LF); height of the LF; and distance of the OMT from the lower limit of the LF. Results: The OMT, the UP, and the FIR were adjacent to the LF in 41 (53.2%), 73 (94.8%), and 23 cases (29.9%), respectively. There was a right-left symmetry in 10 of 18 patients (55%). The OMT was always anterior to the junction between the maxillary bone and the lacrimal bone. The UP was more frequently posterior (32.5%) or adjacent (45.5%) to the LF at the lower level, adjacent to the maxillary bone (55.8%) at the intermediate level, and adjacent to the middle turbinate (61%) at the upper level. The height of the LF was 12.06 +/- 1.93 mm. The OMT was located 5.96 +/- 2.05 mm upward from the lower limit of the LF. Conclusion: The almost constant overlapping of the UP onto the LF at the level of the common canaliculus indicates that the most effective approach for successful DCR osteotomy is via a submucosal cleavage and resection of the anterior part of the UP. The management of these landmark structures should be an integral part of the endonasal DCR method.