Surfer's ear (exostoses of the external auditory canal)

• exostoses of the external auditory canal (external auditory exostoses (EAEs))
  • are generally a benign condition
  • more commonly occurs in people who avidly engage in aquatic activities - this increased incidence in people who engage in aquatic activities has led to this condition also being known as “surfer’s ear”
  • often an incidental finding in asymptomatic patients
    • often multiple and bilateral in their presentation - appear as broadly based lesions that protrude into the external auditory canal
      • histologically EAEs are dense, concentric layers of subperiosteal bone originating from near the tympanic ring
      • EAEs are a distinct clinical entity from temporal bone osteomata (1)
        • temporal bone osteomata are generally seen as single, unilateral, and pedunculated growths originating from suture lines more laterally in the osseous canal
    • EAEs are relatively common - are seen in about 6% of patients treated at ENT departments (1)
    • although generally an asymptomatic condition, some cases EAEs can result in significant obstruction of the external auditory canal
      • significant obstruction of the external auditory canal may contribute to development of conditions such as chronic cerumen impaction, recurrent otitis externa, and conductive hearing loss
  • aetiology
    • cause of EAEs has never been conclusively established - however there is a significant body of evidence to suggest that these lesions arise as a result of repeated exposure to cold water
      • when comparing coastal populations - EAEs are more commonly found in civilizations located near colder waters
      • a biologic basis for believing cold water to be a more potent stimulator of exostosis development than warm water has yet to be firmly established
  • a study of 202 surfers revealed that (1):
    • professional surfers (odds ratio 3.8) and those subjects who surfed predominantly in colder waters (odds ratio 5.8) were found to be at a significantly increased risk for the development of EAEs. The number of years surfed was also found to be significant, increasing one's risk for developing an exostosis by 12% per year and for developing more severe lesions by 10% per year
    • the study authors concluded that EAEs are more prevalent in cold water surfers, and additional years surfing increase one's risk not only for developing an EAE but also for developing more severe lesions
  • a study of 21 Oregon surfers revealed (2):
    • degree of canal obstruction caused by exostoses increased with increasing number of years surfing and with increasing number of sessions surfing per year
    • most patients with exostoses had minimal complaints and had not required surgical resection

Reference:

1. Kroon DF et al. Surfer's ear: external auditory exostoses are more prevalent in cold water surfers.Otolaryngol Head Neck Surg. 2002 May;126(5):499-504
2. Deleviannis FW et al. Exostoses of the external auditory canal in Oregon surfers.Am J Otolaryngol. 1996 Sep-Oct;17(5):303-7.