Anatomic relationship of nasolacrimal duct and major lateral wall landmarks: cadaveric study with surgical implications.

Background: Detailed knowledge of the surgical anatomic landmarks of the lateral nasal wall is important for safe and successful endoscopic sinonasal surgery. We sought to determine the relationship of major landmarks to the nasolacrimal duct (NLD).

Methods: Twenty mid-sagittal head sections of 10 fresh frozen cadavers were studied after removal of the nasal septum. The insertion of the alar cartilage into the maxilla was taken as a fixed point and all measurements were performed in a defined axial plane at the level of the maxillary sinus natural ostium. Two surgeons independently recorded each measurement 3 times with an average of the readings used for statistical analysis.

Results: The overall agreement index was excellent (r = 0.84) between the observers. At the level of maxillary ostium, the mean distance from the alar rim to the NLD was 43.05 ± 4.76 mm on the right and 41.25 ± 4.56 mm on the left. The most anterior projection of the middle turbinate head was noted to be anterior to the NLD in 70% of specimens. In positional relationship, the maxillary line was posterior to the NLD in 55%, whereas the bulla ethmoidalis and the free edge of uncinate process were uniformly posterior to the NLD in all the specimens.

Conclusion: This study provides useful anatomic and positional relationships between the NLD and major lateral wall landmarks. Although the maxillary line and the head of the middle turbinate are often considered useful guides to the position of the ipsilateral NLD, their spatial relationship to the NLD is not consistent. These landmarks, therefore, cannot be solely relied upon during surgery to avoid injury to the NLD.