CT analysis of the prelacrimal recess: an access route to the maxillary sinus.

PURPOSE: Accessing the anterolateral maxillary sinus is challenging. The endoscopic pre-lacrimal recess approach (PLRA) involves removing the medial wall of the pre-lacrimal recess (PLR) between the piriform aperture (PA) and the nasolacrimal duct (NLD) while preserving the inferior turbinate and NLD. We studied the radiologic dimensions of the medial wall of the PLR to assess the feasibility of this approach across different maxillary sinus pathologies. METHODS: A retrospective analysis of 104 triplanar CT scans (208 sides) was conducted in patients with maxillary sinus pathologies. Anteroposterior distances from the piriform aperture (PA) to the NLD were measured at three axial levels (inferior, middle, superior). Vertical height from the nasal floor to the orbital floor was recorded. Data were compared between sides using paired t-tests, and between sexes using patient-level averaged values to account for within-patient clustering; level differences were assessed with repeated-measures ANOVA and post-hoc Bonferroni-corrected paired testing. RESULTS: Mean anteroposterior distances were: inferior, 6.8/6.9 mm (right/left); middle, 5.7/5.8 mm; superior, 4.7/4.7 mm. Mean vertical height was 25.1/25.0 mm. All level-to-level differences were significant (p < 0.0001). Males showed a trend toward greater dimensions at all levels, though this did not reach statistical significance after accounting for within-patient clustering (p = 0.08-0.09); vertical height remained significantly greater in males (p < 0.0001). Bilateral symmetry was observed for most measurements. CONCLUSION: The PLR medial wall shows significant interindividual variation, with the widest anteroposterior corridor consistently located inferiorly and a vertical height reliably exceeding 20 mm. Individualized preoperative CT assessment is essential when planning the PLRA.