autosomal dominant sensorineural deafness type 9
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Pathology
- sensorineural deafness
- mucopolysaccharide depositions in the channels of the cochlear nerve & vestibular nerves
- these depositions apparently cause strangulation & degeneration of dendritic fibers
Genetics
- autosomal dominant
- associated with defects in COCH
Clinical manifestations
- onset in the 4th or 5th decade of life
- initially involves the high frequencies
- deafness is progressive & usually complete by the 6th decade
- a spectrum of vestibular dysfunctions
- penetrance of vestibular symptoms is often incomplete
- some patients are minimally affected,
- others suffer from severe balance disturbances & episodes of vertigo