[Progressive sensorineural hearing loss in cochlear otosclerosis].
Otosclerosis is a bone dysplasia limited to the otic capsule causing abnormal resorption and redeposition of bone. The existence of the entity "pure labyrinthine otosclerosis" or "cochlear otosclerosis" is not accepted by all authors; however, there is clinical and histologic evidence to support the existence of a progressive sensorineural hearing loss due to otospongiotic-otosclerotic lesions of the labyrinthine capsule, although diagnosis of this condition may be difficult. The involvement of the inner ear is described as degenerative changes in the spiral ligament, stria vascularis, organ of Corti, and cochlear neurons. The most frequent audiometric configuration is a "bite-type" curve, but flat or rising shapes can also be observed; speech discrimination appears unusually good for a pure sensorineural hearing loss and recruitment is frequently absent. A cochlear otosclerosis should be suspected when there is a family history of otosclerosis, the onset of the hearing loss occurs from the third to fifth decade, and worsening of the hearing loss is observed during periods of intense hormonal and endocrine activity, a positive Schwartze sign is present and bilateral sensorineural loss is associated with signs of unilateral stapedial ankylosis. A definitive diagnosis of cochlear otosclerosis can be made only with computed tomography, which allows a quantitative assessment of the involvement of the labyrinthine capsule by spongiotic or sclerotic areas. The factors to be considered are: otosclerotic foci 1 mm or more in diameter and a density different from that of the normal otic capsule, partially or completely erased contour of the capsule, double ring effect, bony neoformation in the labyrinthine spaces, and increased thickness of the cochlear capsule. The medical management of cochlear otosclerosis is based on sodium fluoride, in association with calcium and vitamin D; some authors have also proposed diphosphonates as inhibitor agents of bone resorption. Surgery may be useful only in those patients presenting a hearing loss so severe that the bone threshold cannot be evaluated and a gap between air and bone conduction cannot be excluded; in these cases stapes operations can improve hearing to a level that may be useful in hearing aid application.
Sellari-Franceschini
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S
Dipartimento di Neuroscienze, Università degli Studi di Pisa.
Ravecca
F
F
De Vito
A
A
Berrettini
S
S
D003051:Cochlea / Q000473:pathology*; D018450:Disease Progression; D006319:Hearing Loss, Sensorineural / Q000209:etiology*; D006801:Humans; D010040:Otosclerosis / Q000150:complications* / Q000473:pathology