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 FR 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.