Objectives: To describe objective tinnitus complicated with transient low-tone hearing loss coinciding with mouth opening, which was related to the connection between the mandibular fossa and middle ear space.
Patients: A 41-year-old man presented with tinnitus, ear fullness, and hearing loss in the left ear on mouth opening.
Main Outcome Measures: Clinical case records, audiological data, and radiological analyses including computed tomography (CT) and magnetic resonance imaging.
Results: Hearing thresholds on the ipsilateral side, which were evaluated with mouth opening, showed elevations of approximately 20 dB in the frequencies below 1000 Hz. Again, peak pressure on the tympanogram deviated negatively to -220 mmH2O under mouth opening without changing peak amplitude. These results showed that the tensor tympani would not have contributed to movement of the ear drum in the present case. High-resolution CT with multi-planar reconstruction showed a connection between the mandibular fossa and middle ear space, as revealed by a gas collection around the joint capsule evaluated in 2 phases (with and without mouth closing). Ear symptoms resolved after myringotomy.
Conclusions: Although an influence of temporomandibular disorder (TMD) on tinnitus perception has been debated, whether this association is causal or fortuitous has remained contentious. The present case showed a unique feature of tinnitus attributed to a connection between the mandibular fossa and middle ear space. This connection might be related to the petrotympanic fissure (with or without variant course), which is a narrow slit allowing the TMJ and middle ear space to communicate. Radiological analysis including high-resolution CT with multi-planar reconstruction referring to the petrotympanic fissure would be helpful to clarify the pathogenesis of patients suffering from otological symptoms related to TMD.