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

Objective: 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. Methods: 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. Results: 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. Conclusion: 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. Dentomaxillofacial Radiology (2012) 41, 294-297. doi: 10.1259/dmfr/62359484