Incidence of bony outgrowths of the external ear canal in U.S. Navy divers.

Bony outgrowths of the temporal bone into the external ear canal are common in populations that participate in cold water activities. The incidence in professional divers is unknown. Eighty-seven U.S. Navy divers were interviewed and examined to determine the history of aquatic activity and degree of ear canal compromise. An age-matched control population of 42 non-divers without significant history of aquatic activities was also examined. The outgrowths, or exostoses, were found in 23 (26%) divers, and in no controls. Sixteen (70%) of the exostoses were minor, causing 10-20% narrowing of the auditory canal. The largest exostoses were found in divers with an extensive history of aquatic activities. The difference in total hours of aquatic activity was significant between divers and controls. The difference in total hours diving, as well as total time of all aquatic activities, was statistically significant between divers with exostoses and those divers without exostoses. The data confirm the relatively common incidence of this condition in a professional diving community.