Foramen tympanicum or foramen of Huschke: anatomical cone beam CT study

Abstract

The foramen of Huschke (foramen tympanicum) represents a developmental defect in the antero-inferior aspect of the bony external auditory meatus. The foramen is located at the antero-inferior aspect of the external auditory canal, posteromedial to the temporomandibular joint. The aim of this study is to define the prevalence and location of the foramen of Huschke. We retrospectively examined 207 cone beam CT (CBCT) studies (414 ears). We used flat panel detector (FPD)-based CBCT (New Tom FP; Quantitative Radiology, Verona, Italy) for imaging in our department. We noted the location of the foramen tympanicum and calculated its prevalence as a percentage. We found a foramen tympanicum in 37 (17.9%) of 207 patients. This was unilateral in 24 patients (11.6%) and bilateral in 13 patients (6.3%). Mean axial diameter was 5 mm and mean sagittal diameter was 2 mm. The foramen tympanicum is an uncommon disorder and is well demonstrated on CBCT. This is the first study to detect the foramen tympanicum using FPD-based CBCT.