A case of temporomandibular joint herniation

Abstract

Temporomandibular joint herniation (TJH) is a rare condition in which the contents of the temporomandibular joint herniate into the external auditory canal (EAC). The foramen of Huschke (FH), also known as the foramen tympanicum, is an anatomical defect in the anteroinferior aspect of the EAC bone, and persisting FH is thought to be one of the causes of TJH. We report a case of spontaneous TJH along with a review of the literature.A 42-year-old man with aural fullness visited our department for the examination of the temporomandibular joint and a potentially neoplastic lesion in March 2020. Computed tomography performed previously showed a soft tissue density with a bone defect in the anterior wall of the left EAC. Otoscopic examination revealed a dome-shaped raised mass in the anterosuperior wall of the left side of the EAC. The mass protruded when the mouth was closed and disappeared when the mouth was opened. The patient was diagnosed with left TJH based on the clinical and imaging findings. Due to the lack of clinical symptoms, we decided not to perform aggressive surgical treatment for TJH, but to follow up carefully with regular imaging examinations. Fifteen months have passed since the first visit, and the symptoms have not worsened. This case report shows that TJH presents with characteristic clinical and imaging findings. Therefore, understanding the pathophysiology of this disease is essential for oral and maxillofacial surgeons who deal with temporomandibular joint diseases on a daily basis.