Prevalence and severity of external auditory exostoses in breath-hold divers

To explore the prevalence and severity of external auditory exostoses in a population of experienced breath-hold divers, and to compare these to the same parameters within surfing and self-contained underwater breathing apparatus diving populations.

A stepwise, multiple regression analysis of cross-sectional data examining the relative contributions of sea surface temperature, latitude of exposure and years of exposure to the prevalence and severity of stenosis due to external auditory exostoses. A chi-square analysis of the prevalence and severity of external auditory exostosis stenosis in the breath-hold divers was compared with previously published data for surfers and self-contained underwater breathing apparatus divers.

Seventy-six male and thirty-five female breath-hold divers attending an international 'freedive' competition completed a questionnaire describing aquatic sports habits, geography of participation and symptomatology. Those completing the questionnaire (111/154 attendees) were examined otoscopically for evidence of external auditory exostoses. Images were digitally recorded, scored and graded.

Exostoses were evident in 87.7 per cent of the 204 ears scored and graded for severity of stenosis due to external auditory exostoses. The prevalence of exostoses was no different from that found in previous studies of surfers and self-contained underwater breathing apparatus divers (p = 0.101). However, the pattern of affliction was more similar to that found in surfers. The severity of exostoses was significantly less than that found in surfing populations (p < or = 0.001 to 0.007), but greater than that found in self-contained underwater breathing apparatus diving populations (p < or = 0.001). Sea surface temperature at the location of open-water exposure was the most significant predictor of the prevalence and severity of external auditory exostoses in breath-hold divers (p = 0.019).

The prevalence and severity patterns of stenosis due to external auditory exostoses in breath-hold divers are more similar to previously published results for surfing populations than to previously published results for self-contained underwater breathing apparatus diving populations. In breath-hold divers, sea surface temperature is the strongest predictor of severity of stenosis due to external auditory exostoses.