A theoretical consideration of the mechanisms underlying auditory symptoms in patients with superior semicircular canal dehiscence syndrome.

BACKGROUND We were astonished after reading reports that superior semicircular canal dehiscence can cause auditory hypersensitivity such as hearing sounds of eye movements. The mechanisms underlying auditory hypersensitivity remain incompletely understood.

OBJECTIVES The aim of this hypothesis-generating, theoretical consideration was to propose a new theory regarding the mechanisms responsible for auditory symptoms in patients with superior semicircular canal dehiscence and to explore related aspects of auditory physiology.

METHOD Auditory symptoms were analyzed through 23 published reports.

RESULTS Auditory hypersensitivity occurred at a high frequency. They can be classified into two categories according to the sound source. (1) Symptoms caused by internal sources (without going through the stapes): hearing the movements of one's own eyeballs, pulsatile tinnitus and so on. (2) Symptoms caused by external sources: echoing of voices during phone calls, echoing of car horns, and so on.

CONCLUSIONS AND SIGNIFICANCE Auditory hypersensitivity can be explained by the endolymph conduction theory. The mechanism of sound perception may also be explained by this theory, in which sound waves are transmitted through the saccule, ductus reuniens, cochlear duct, tectorial membrane, stimulating hair cells.