Commonly known as 'surfer's ear', exostosis is the abnormal growth of bone in the ear canal.
Exostoses themselves are not dangerous. However, they can lead to water and other debris being trapped in the ear canal, leading to infection and, in severe cases, the closure (occlusion) of the ear canal, causing hearing loss.
Exostosis is most commonly caused by repeated exposure to cold water and wind. Therefore surfers, sailors and those who spend repeated time outdoors in cold wind and water, are more likely to be affected. Cooling of the ear canal stimulates bony growths, which can narrow and block the ear canal.
Initial diagnosis is by visual inspection (otoscopy) of the ear canal by an audiology professional or ear specialist. An audiology professional will perform a test called tympanometry, which can identify issues with the eardrum and determine if the exostoses are completely blocking the ear. A hearing test will also determine whether the hearing has been affected by the exostoses.
The use of ear plugs while swimming in cold water or protecting the ears while out in cold wind can help prevent exostoses developing. Unless they are creating concerns, such as trapped debris or water, or closing the canal to sound, they are often left to be and simply monitored. However, surgery for reduction or removal can be considered amid discussion with your medical practitioner or following referral to an ear, nose and throat specialist.