Temporomandibular joint herniation into the external auditory canal.

OBJECTIVES/HYPOTHESIS: Herniation of the temporomandibular joint (TMJ) into the external auditory canal (EAC) is a very rare condition, and it mostly occurs in patients with bony wall defects in the anterior EAC. The purpose of this study was to evaluate the clinical and radiological findings and the treatment results of TMJ herniation into the EAC by reviewing a large sample of temporal bone computed tomography (CT) scans.

STUDY DESIGN: A retrospective study.

METHODS: We reviewed 985 adult temporal bone CT scans and evaluated the presence of defects, the size and location of defects, and TMJ herniation. We enrolled 23 cases with anterior EAC wall defects.

RESULTS: Twenty-three (2.3%) patients from the 985 temporal bone CT cases revealed an anterior wall defect involving the EAC. We identified the causes for the defects, such as canal cholesteatoma and trauma, in eight of the 23 cases. We observed 15 (1.5%) patients with patent foramen of Huschke. The mean defect size was 3.06 × 2.69 mm. Among the patients with these lesions, six had a TMJ herniation into the EAC. Four of the six cases were surgically reconstructed using a titanium mesh via a preauricular approach, whereas the remaining two cases were managed with endaural removal and skin graft.

CONCLUSIONS: TMJ herniation into the EAC is very rare and may not occur even if an anterior wall defect of the EAC is present. Lesions can be successfully managed with surgical reconstruction of the TMJ via a preauricular approach, whereas small lesions can be managed using an endaural approach.