Surfer\'s ear: Acquired bony exostoses of the external auditory canal

Clinical History

A 30-year-old male surfer presented with bilateral severe conductive hearing loss.
Otoscopy revealed severe stenosis of the external auditory canals bilaterally.

Imaging Findings

CT of the skull base, with bony window axial and coronal reconstructions revealed severe stenosis of the bony portion of the external auditory canals bilaterally.
Narrowing was circumferential due to the development of bony exostoses.
The cartilageneous portion of the external auditory canal was patent and normal in appearance bilaterally.
The middle and inner ear cavities and the mastoid air cells were also normal bilaterally.

This is the CT appearance of acquired bony exostoses of the external auditory canal. The normal ear canal is 5-8 mm in diameter. As the narrowing of the canal from exostosis progresses, this diameter reduces substantially, to the point of occlusion if the exostosis remains untreated.

Discussion

External auditory canal stenosis resulting from the development of bony exostoses is a well reported phenomenon in individuals who are frequently exposed to cold water, such as surfers. In fact, the occurrence of this condition is so prevalent amongst this group, that it has become known colloquially as "Surfer's ear". The condition has also been reported in kayakers, divers and swimmers. The increased popularity of these activities is resulting in increased prevalence of this condition.

Several studies have observed a higher frequency of this condition amongst cold water surfers compared with warm water surfers. The severity of external auditory canal exostoses increases as the frequency and number of years of surfing increases.

Exostoses are visualised as broad based elevated lesions that protrude into the external auditory canal. These are usually detected just lateral to the isthmus and the most commonly recorded location is the anterosuperior portion of the external auditory canal. They are commonly bilaterally symmetrical. Interestingly however, King et al detected asymmetrical severity of disease affecting the right ear twice as often as the left in their cohort of surfers and they hyopthesised that greater progression of exostoses occurs in the ear with more exposure to the predominant wind.

External auditory canal exostoses continue to grow, commonly painlessly, eventually resulting in severe stenosis of the canal with resulting conductive hearing loss, impaction of cerumen and subsequent recurrent infections.
Surgical treatment (canalplasty) is generally reserved for severe symptomatic cases.

Differential Diagnosis List

Final Diagnosis

Surfer's ear: Acquired bony exostoses of the external auditory canal.

URL:	https://www.eurorad.org/case/8880
DOI:	10.1594/EURORAD/CASE.8880
ISSN:	1563-4086