Auditory Exostoses
From bonepath
Auditory exostoses are bony growths that occur in the external auditory meatus (Hutchinson et al. 1997). Some researchers include osteomas under the umbrella of exostoses, while others differentiate them. Velasco-Vazquez et al. (2000) group osteomas and exostoses to be any bony anomaly on the wall or floor of the tympanic region. Hutchinson et al. (1997) differentiate the two based on location and number. Osteomas are growths located on the tympanosquamous or tympanomastoid sutures and appear singly; exostoses are growths in the external auditory meatus and typically appear in numbers greater than one.
There is a correlation between the presence of auditory exostoses and the amount of time spent in cold-water, leading researchers to suggest that prolonged cold-water swimming causes auditory exostoses to form (Velasco-Vazquez et al. 2000). However, Hutchinson et al. (1997) suggest that exotoses may be due to changing the pH of the ear canal or to otitis externa (an infection that causes inflamed skin).
In living individuals, auditory exostoses makes it difficult to drain water from the ear and can cause earache, tinnitus, hearing loss, and make the ear itch (Nakanishi, Tono, and Kawano 2011). A recent study of warm- and cold-water Japanese surfers found some form of exostoses in both groups, slightly more exostoses in cold-water surfers, and more cases of no exostoses in warm-water surfers (Nakanishi, Tono, and Kawano 2011). This suggests that exostoses may form from increased exposure to water, but may intensify in cold-water environments.
[edit] Examples from Ford Collection
[edit] References
Hutchinson DL, et al. 1997. A Reevaluation of the Cold Water Etiology of External Auditory Exostoses. American Journal of Physical Anthropology 103:417-422.
Nakanishi H, Tono T, and Kawano H. 2011. Incidence of External Auditory Canal Exostoses in Competitive Surfers in Japan. Otolaryngology -- Head and Neck Surgery [Internet]. Available from: http://oto.sagepub.com/content/early/2011/03/14/0194599811402041.abstract
Velasco-Vazquez J, et al. 2000. Auricular exostoses in the prehistoric population of Gran Canaria. Am. J. Phys. Anthropol 112:49-55.
