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Syndromes and Diseases

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Vertigo, oscillopsia induced by loud noise, changes in middle ear or ICP, positive Hennebert sign, and Tullio phenomenon. Dehiscence of bone overlying superior SCC can lead to vestibular as well as auditory sx. Vestibular abnormalities include vertigo and oscillopsia (apparent motion of objects that are known to be stationary) induced by loud noises and or by manuvers that can change middle ear or ICP. Eye movements in the plane of superior canal in response to loud noises in affect ear (Tullio). Insufflation of air into the EAC or pressure on the tragus can, in some pts, result in similar abnoramlities (Hennebert sign).

The auditory abnormalities include autophony, hypersensitivity for bone conducted sounds, and pulsatile tinnitus. Pts may complain of seemingly bizzare sx as hearing their eye movements in the affected ear. May experience uncomfortable sensation of fullness or pressure in ear brought about by activities that lead to vibration or motion in long bones like running. Weber tuning fork often localizes to affected ear. Audiogram will frequently show an air bone gap in the low frequencies, and bone conduction thresholds may be better than 0 dB. Findings on audiometry can resemble otosclerosis. Some pts may have undergone stapedectomy, which does not lead to closure of air bone gap.

Acoustic reflex testing can be beneficial in distinguishing an air bone gap due to superior canal dehiscence from one due to otosclerosis. Acoustic reflexes absent = otosclerosis vs. present= SCD.

Workup with HIGH RESOLUTION CT. Conventional CT has high false positive rate. Sx due to "mobile third window" into the inner ear. VEMP testing shows lowered threshold for eliciting a VEMP response in ear affected by this disorder. VEMP response can also have a larger than normal amplitude in SCD.

Surgery via middle cranial fossa approach. Better outcomes with both plugging and resurfacing together.