A superior semicircular canal dehiscence-induced air-bone gap in chinchilla.
An SCD is a pathologic hole (or dehiscence) in the bone separating the superior semicircular canal from the cranial cavity that has been associated with a conductive hearing loss in patients with SCD syndrome. The conductive loss is defined by an audiometrically determined air-bone gap that results from the combination of a decrease in sensitivity to air-conducted sound and an increase in sensitivity to bone-conducted sound. Our goal is to demonstrate, through physiological measurements in an animal model, that mechanically altering the superior semicircular canal (SC) by introducing a hole (dehiscence) is sufficient to cause such an air-bone gap. We surgically introduced holes into the SC of chinchilla ears and evaluated auditory sensitivity (cochlear potential) in response to both air- and bone-conducted stimuli. The introduction of the SC hole led to a low-frequency (<2000 Hz) decrease in sensitivity to air-conducted stimuli and a low-frequency (<1000 Hz) increase in sensitivity to bone-conducted stimuli resulting in an air-bone gap. This result was consistent and reversible. The air-bone gaps in the animal results are qualitatively consistent with findings in patients with SCD syndrome.
Songer
Jocelyn E
JE
Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA. jocelyns@mit.edu
Rosowski
John J
JJ
D000161:Acoustic Stimulation; D000818:Animals; D001489:Basilar Membrane / Q000503:physiopathology; D001844:Bone Conduction / Q000502:physiology*; D002682:Chinchilla / Q000502:physiology*; D003051:Cochlea / Q000503:physiopathology; D006314:Hearing Loss, Conductive / Q000503:physiopathology*; D023421:Models, Animal; D012665:Semicircular Canals / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D014722:Vestibule, Labyrinth / Q000503:physiopathology