Foramen tympanicum: tomographic study of a large cohort of Europeans.

Purpose: The foramen tympanicum (FT) is an anatomical variation of the tympanic part of the temporal bone located in the anteroinferior part of the external auditory pore (EAP) and posteromedial to the temporomandibular joint (TMJ). The FT is most often asymptomatic, but it can be symptomatic in rare cases. The prevalence of FT varies widely in the literature. The aim of our study was to determine the radiological prevalence in a European population.

Methods: We retrospectively analyzed the presence of FT in all patients who underwent brain or rock scans from January 2021 to July 2022 in University Hospital. Demographic characteristics such as age and gender were collected. Morphometric measurements on the FT were also carried out manually: axial, sagittal and area calculation. Binomial test, Pearson's Chi2 test or Student's T test were carried out according to the type of analysis.

Results: A total of 2040 patients were included. 145 patients with FT were identified, giving a prevalence of 7.11%. FT were unilateral in 39% and bilateral in 61% of cases (p = 0.008). Women were statistically more likely to have one (p = 0.00002). Higher age was correlated with an increase in the prevalence of FT (p = 0.03). The morphometric measurements did not reveal any differences depending on the side.

Conclusion: This study is the largest series of Computed Tomography (CT) scans on the prevalence of foramen tympanicum. Although rare, every surgeon must keep in mind this anatomical entity to limit the risk during a surgical procedure.