Localization of Foramen Ovale According to Bone Landmarks of the Splanchnocranium : A Help for Transforaminal Surgical Approach to Trigeminal Neuralgia

Trigeminal neuralgia is a painful condition, usually treated through surgical procedures focusing on the foramen ovale (FO). A detailed localization of FO relative to reference landmarks is therefore crucial to avoid possible complications.The present study aims at assessing the position of FO according to the surrounding bone structures: 100 CT-scans of patients, equally divided between sexes, aged between 18 and 86 years were examined. From each subject, the 3D models of FO and the maxillary bones, the zygomatic bones and the zygomatic process of the temporal bones were segmented through ITK-SNAP software. The distance between the center of the FO and subnasale, zygion, and the upper edge of the zygomatic bone at the origin of the frontal process were measured on 3D models. On CT-scans three cranial measurements were taken as well (distance between anterior and posterior nasal spine, upper facial height and bizygomatic breadth).Statistically significant differences in the three distances according to side and sex were assessed through two-way ANCOVA test, using the three cranial measurements (ANS-PNS, NP, ZZ) as covariates (P < 0.05).Distances between the centre of FO and subnasale, zygion and the upper edge of the zygomatic bone were on average 82.3 ± 3.4 mm, 41.9 ± 2.6 mm and 48.8 ± 3.5 mm in males, 77.3 ± 3.9 mm, 38.2 ± 2.5 mm and 45.5 ± 3.1 mm in females, with a significant difference according to sex (P < 0.05).Results provide innovative data for the localization of FO and will be useful for the management of transforaminal procedures in case of trigeminal neuralgia.