Abstract
Semicircular canal dehiscence is an important entity often presenting with symptoms of noise or pressure induced vertigo, autophony, aural fullness and conductive hearing loss. Due to its varied presentation and mimic of other otologic conditions its consideration is of increased importance. Within we report a case of right sided posterior semicircular canal dehiscence secondary to an enlarged and high jugular bulb. The results of this observation indicate a need for patients with auditory symptoms and high riding jugular bulbs to be evaluated for possible posterior semicircular canal dehiscence.
1
Observation
An otherwise healthy 27 year old male presented with a history of right aural fullness worse with exercise, autophony and intermittent vertigo with noise. Physical examination suggested a dehiscent right semicircular canal. Audiogram was normal. High-resolution CT images (0.63 mm thick reformatted in Pöschl, and Stenver planes) demonstrated an enlarged and high right sided jugular bulb measuring 2.2 cm in diameter. Size and height of jugular bulb created secondary focal dehiscence of the right posterior semicircular canal ( Fig. 1 ).
2
Discussion
Semicircular canal dehiscence may occur in the superior, lateral or posterior canal. Symptomatically, patients experience vertigo and oscillopsia after exposure to noise or changes in pressure . Additionally, hearing loss with a conductive component or autophony may be present making its differentiation from other otologic problems such as otosclerosis or patulous eustachian tube important. Continued debate exists as to the etiology of superior canal dehiscence . In contrast lateral canal dehiscence is thought to occur secondary to cholesteatoma or otitis media and posterior canal dehiscence has been linked to jugular bulb abnormalities eroding adjacent bone . All three canals can become dehiscent after iatrogenic injury. Epidemiologically, posterior canal dehiscence secondary to a jugular bulb abnormality is a rare event with an approximate rate of 0.0006% . Radiographic rates may over estimate rates of posterior canal dehiscence as residual bone is often seen on histologic studies that may be too thin to be detected with current imaging practices. Clinically it is important for patients with auditory symptoms and a high riding jugular bulb to be evaluated for possible dehiscence.
Acknowledgements
None.
Yale IRB Approval 1503015533 John F. Kveton.
1 Contributed to design, manuscript preparation and editing.
2 Tel.: + 1 203 785 2181; fax: + 1 203 785 3970.
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