HERNIATION OF TEMPOROMANDIBULAR JOINT STRUCTURES INTO THE TYMPANIC CAVITY: THE ROLE OF FORAMEN TYMPANICUM IN PATHOGENESIS AND DIAGNOSIS
DOI:
https://doi.org/10.37219/b78fzs33Keywords:
temporomandibular joint, foramen of Huschke, foramen tympanicum, herniation, computed tomography, magnetic resonance imaging, differential diagnosis.Abstract
Background: Herniation of temporomandibular joint (TMJ) structures through the tympanic foramen (foramen tympanicum, foramen of Huschke) is a rare anomaly caused by the persistence of an embryonic defect in the tympanic part of the temporal bone. This pathology establishes a communication between the TMJ and the external auditory canal (EAC) or the middle ear, frequently mimicking otolaryngological diseases.
Objective: To analyze the role of the persistent foramen tympanicum in the development of TMJ structure herniation, to determine its specific prevalence within the spectrum of temporal bone pathology, and to evaluate the capabilities of and develop an algorithm for CT/MRI diagnosis of this anomaly.
Materials and Methods: Between January 2024 and May 2026, 150 patients (80 males, 70 females) aged 25–55 years presenting with temporal bone pathology were examined at the State Institution "O. S. Kolomiychenko Institute of Otolaryngology of the National Academy of Medical Sciences of Ukraine". All patients underwent multidetector computed tomography (slice thickness 0.5–0.6 mm). When necessary, 1.5 T TMJ MRI with dynamic maneuvers (open- and closed-mouth views) was performed.
Results: Within the structure of the detected pathology, the most prevalent conditions were: chronic otitis media – 43.3% (n = 65), mastoiditis – 16.7% (n = 25), fenestral otospongiosis – 12.0% (n = 18), cholesteatoma – 10.0% (n = 15), labyrinthitis ossificans – 9.3% (n = 14), and EAC exostoses – 3.3% (n = 5). No pathological changes were found in 4.0% (n = 6) of cases. Herniation of TMJ structures through the foramen of Huschke was diagnosed in 2 female patients (1.3% of the total sample and 2.9% within the female cohort). The primary complaints included TMJ pain, masticatory tinnitus, and a foreign body sensation in the EAC. CT clearly visualized a defect in the anterior EAC wall (4.5 × 5.0 mm), while MRI confirmed the joint origin of the prolapsed retrodiscal tissues in dynamics. A step-by-step CT/MRI diagnostic workflow was developed and implemented to differentiate herniation from neoplasms and granulation tissue.
Conclusions: Herniation of TMJ structures through the foramen of Huschke is a casuistically rare pathology (1.3%) requiring multidisciplinary awareness. CT is the method of choice for the morphometry of the bony defect, whereas dynamic MRI is crucial for verifying the soft-tissue substrate. The proposed CT/MRI algorithm optimizes the diagnostic process, prevents erroneous and hazardous biopsies of prolapsed tissues, and ensures the selection of an appropriate conservative or surgical management strategy.
Keywords: temporomandibular joint, foramen of Huschke, foramen tympanicum, herniation, computed tomography, magnetic resonance imaging, differential diagnosis
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