![]() Osteoma is a true benign neoplasm of the bone of the EAC, usually unilateral and pedunculated. Other structures at risk are the tympanic membrane and ossicular chain medially, the temporomandibular joint anteriorly, and the third segment of the facial nerve posteroinferiorly. In some cases, surgery is technically difficult and special care is taken to preserve the skin of the EAC. In such cases, and in cases in which a hearing aid is to be fitted, surgical removal of exostoses is indicated. Large lesions, however, can occlude the EAC and lead to conductive hearing loss or retention of wax and debris with subsequent otitis externa. When exostoses are small, they are asymptomatic. It is postulated that the periosteum stimulates an osteogenic reaction with each exposure to cold water, causing this stratification. Histologically, they are formed from parallel layers of newly formed bone. This explains the high incidence of exostoses among divers and cold-water bathers. ![]() The condition is caused by periostitis secondary to exposure to cold water. They vary in shape, being either round, ovoid, or oblong. They are usually multiple, bilateral, and are commonly sessile. Further radiological examinations (CT and MRI scans) are indicated in the suspect of a tumor.Įxostosis are defined as new bony growths in the osseous portion of the external auditory canal (EAC). For example, in case of exostosis and osteomas occluding the EAC a canalplasty is indicated, as well as a surgical treatment is the mainstay for most of the benign and malign tumors involving the EAC. ![]() Analysis of patient clinical history and symptoms are also of utmost importance to decide the proper therapeutic management, which is different depending on the pathology. Otoscopy is fundamental for the recognition of each clinical condition. The narrowest part of the external auditory canal is called the isthmus and lies at the junction of the cartilaginous and bony portions of the canal 5.Pathologies affecting the external auditory canal (EAC) are a wide spectrum of diseases that include: bony neoformations of the EAC (exostosis and osteomas), inflammatory diseases (external otitis, otomycosis, and inflammatory stenosis of the EAC), cholesteatoma of the EAC, benign tumors of the ear and skull base extending to the EAC (carcinoid tumor, meningiomas, facial nerve tumors, etc.), temporal bone fractures, and carcinoma of the EAC. A normal variant defect in the anteroinferior aspect of the osseous part of the canal that connects with the temporomandibular joint is known as the foramen tympanicum (foramen of Huschke). The skin of this inner part is directly applied to periosteum, with no subcutaneous tissue present. The roof and upper part of the posterior wall arise from the squamous part of the temporal bone 4. The anterior wall, floor, and lower part of the posterior wall arise from the tympanic part of the temporal bone 3,4. The medial two-thirds is surrounded by bone. Defects in the cartilaginous part of the canal, which allow transmission of infection and malignancy, are known as fissures of Santorini. The lateral one-third is bounded by a fibrocartilaginous tube continuous with the auricle 3. ![]() The external auditory canal is typically 2.5 cm in length and is S-shaped. As the term external auditory meatus is variably used to refer to the canal itself or the porus acusticus externus (the round lateral opening), it may be better to use the term external auditory canal rather than meatus to avoid potential confusion. ![]()
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