Temporomandibular disorder (TMD) encompasses pain and/or dysfunction of the temporomandibular joint (TMJ) and associated structures, representing the most common nondental pain in the maxillofacial region. Its prevalence is 8% to 15% in women and 3% to 10% in men, increasing with age. Internal derangement of the TMJ is defined as an abnormal positional relationship between the articular disc and the mandibular condyle, glenoid fossa, or articular eminence. Posterior disc displacement is rare, accounting for 0.7% to 2.2% of cases, with about 16% showing central perforation. These cases often occur in degenerative joints and are more frequent in women. 1
TMD can cause pain, trismus, or clicking, while otologic symptoms—tinnitus, vertigo, ear fullness, or hearing loss—are uncommon but clinically important due to the TMJ—ear anatomical proximity. 2 , 3 Dynamic hearing loss, characterized by fluctuations in auditory function with jaw movement, has not been reported.
Case Presentation
We report a 68‐year‐old woman with a two‐month history of left‐sided hearing impairment and aural fullness, triggered by a TMJ dislocation during yawning and relieved by mouth opening. She denied pain, trismus, or clicking during mastication.
Otoscopy revealed a bulging mass on the anterior wall of the left external auditory canal (EAC) that obstructed the canal when the mouth was closed (Figure 1A) and resolved with mouth opening (Figure 1B). Audiometry showed a 20‐dB air‐bone gap that normalized with mouth opening. Temporal bone CT revealed a calcified mass posterior to the left mandibular condyle causing EAC stenosis (Figure 2A). TMJ MRI confirmed a centrally perforated disc with a posteriorly displaced calcified fragment (Figure 2B).
Figure 1.
Dynamic otoscopic views of the left external auditory canal. (A) Complete obstruction of the canal when the mouth is closed. (B) Resolution of the obstruction with mouth opening.
Figure 2.
Imaging findings of the left TMJ. (A) CT showing a calcified mass (red arrow) posterior to condyle causing EAC stenosis (green arrow). (B) MRI showing a perforated disc (white arrow) and posteriorly displaced calcified fragment (red arrow). CT, computed tomography; MRI, Magnetic resonance imaging; TMJ, temporomandibular joint.
The patient underwent endoscopic partial removal of the calcified disc via an external auditory approach and canaloplasty. Histopathology confirmed a calcified disc. Postoperative follow‐up showed complete resolution of her symptoms.
This report was approved and exempted by the Institutional Review Board of Cathay General Hospital (CGH‐IRB No.: CGH‐P114006). Written informed consent was obtained for publication of anonymized data and media materials.
Discussion
Otologic symptoms associated with TMJ internal derangement are thought to result from both anatomical proximity and shared neural pathways between the TMJ and auditory structures. Proposed mechanisms of hearing loss in TMD include dysfunction of the tensor tympani muscle secondary to masticatory muscle spasm, altered tympanic membrane tension, or direct mechanical compression of the EAC by displaced TMJ components. In rare instances, conductive hearing loss may arise from spontaneous TMJ herniation through a foramen tympanicum (Huschke foramen), but no previous literature has described dynamic hearing loss caused by posterior disc displacement. 2 , 3
Treatment of TMJ internal derangement is generally conservative—physical therapy, occlusal splints, pharmacologic intervention, or minimally invasive procedures such as arthrocentesis or arthroscopy. Surgical intervention is reserved for refractory cases with severe disc pathology, perforation, or advanced degenerative changes. 4 , 5 In our patient, a minimally invasive endoscopic approach via the EAC allowed direct visualization and partial discectomy of the calcified posteriorly displaced disc, confirming its role in EAC obstruction and dynamic hearing change. This case highlights an extremely rare manifestation of posterior TMJ disc displacement presenting as dynamic hearing loss, emphasizing the importance of considering TMJ pathology in patients with position‐dependent conductive hearing impairment.
Author Contributions
Hao‐Yun Chang, primary manuscript drafting, patient care, and review literature; Su‐Yi Hsu, primary manuscript drafting, patient care, review literature, and finalization.
Disclosures
Competing interests
None.
Funding source
None.
Supporting information
Video 1. Dynamic Otoscopic ExaminationVideo demonstrates complete EAC obstruction by TMJ disc with mouth closed and resolution upon opening.
Endoscopic video.
References
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Associated Data
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Supplementary Materials
Video 1. Dynamic Otoscopic ExaminationVideo demonstrates complete EAC obstruction by TMJ disc with mouth closed and resolution upon opening.
Endoscopic video.