Endoscopic localization of the sphenopalatine foramen: do measurements matter?

The objective of this study was to evaluate different methods and measurements for localization of the sphenopalatine foramen (SPF) during endoscopic transnasal exposure. The study design consisted of descriptive anatomical study and the setting was in Microsurgical Cadaver Dissection Lab. Sixteen lateral nasal walls were dissected endoscopically to identify and localize the SPF. Multiple measurements were obtained from nasal sill (NS) to SPF, ethmoid crest (EC), and other related landmarks. The results showed that EC was identified in all sides with different degrees of projection. SPF extended below the inferior edge of EC, i.e., lying both in the superior and middle meatus, in 12 sides (75 %), while it was laying only in the superior meatus in 4 sides (25 %). An accessory foramen was identified in 3 sides (18.7 %), all of which were located in middle meatus. The distance from NS to SPF ranged widely from 55 to 76 mm (mean ± SD 64.4 ± 6 mm). The average angle of elevation formed between SPF to NS and nasal floor was 11.4° (range 11-12°). Although many previous studies have reported measurements to SPF, we do not believe these measurements are of practical help due to the wide range of measurements and the lack of standard reference points. The main constant landmark for SPF remains the EC. Since SPF frequently extends below EC, the mucoperiosteal flap should be extended below the inferior edge of this crest to avoid missing the middle meatal part of SPF or any accessory foramina.