Assessment of the anterior superior alveolar nerve and its impact on surgery of the lateral nasal wall.

Background: The anterior superior alveolar nerve (ASAN) plays a major role in innervation of the lateral nasal wall. Its damage during nasal surgery can cause dental paraesthesia and numbness around the upper lip.

Methodology: Retrospective evaluation of the computed tomographic (CT) scans of 50 consecutive patients analysing 100 sides. We measured the mean distance from the shoulder of the inferior turbinate to the descending portion of the anterior superior alveolar nerve, to the anterior superior alveolar canal and the anterior-posterior distance between the 'shoulder' of the inferior turbinate and the pyriform aperture.

Results: The mean distance from the shoulder of the inferior turbinate to the descending portion of the anterior superior alveolar nerve was 6.4 ± 2.33 mm, with no difference between sides The mean relative height of the shoulder in relation to the anterior superior alveolar nerve canal was 4.78 ± 2.31mm with no significant difference between the two sides. The anterior-posterior distance between the 'shoulder' of inferior turbinate and the pyriform aperture was 6.96± 2.28mm, with no significant difference between the two sides.

Conclusions: We found the anterior superior alveolar nerve to be a constant landmark in the lateral nasal wall. Therefore, the course of the ASAN should be assessed on a CT scan when a surgical approach through the pyriform aperture or anterior medial wall of the maxillary sinus is planned.