Cochlear Implantation in Cochlear Otosclerosis

Abstract

Individuals with severe otosclerosis considering cochlear implantation can be counseled to expect similar benefit to those without, regardless of whether prior surgery occurred on the side of implantation or of severity of otic capsule involvement. There is a significant risk of facial nerve stimulation in otosclerotics with grade 3 disease.

CT Grading of Otosclerosis

“…In the cochlear implant in otosclerosis series by Marshall et al 13 and Rotteveel et al, 12 most patients had cochlear disease, 75% and 77%, respectively. The percentage of purely fenestral disease was slightly more in the Marshall et al series (17% vs 7%).…”

“…There is no universally accepted imaging grading system for otosclerosis, though many grading systems have been proposed. The CT grading of otosclerosis published by Symons and Fanning 13 is based on anatomic localization of disease. Focal spongiotic areas, sclerotic areas, and "double ring effect" are included, but classification is based on the presence of these at a particular location around the cochlea.…”

“…Marshall et al 13 demonstrated that patients with grade 3 otosclerosis have a higher risk for facial nerve stimulation after cochlear implantation, particularly with nonmodiolar hugging electrodes. Therefore, implant surgeons should be cognizant of the type of implant used when a grade 3 petrous bone is implanted.…”

“…Symons and Fanning 13 have recently published a CT grading system for otosclerosis: grade 1, solely fenestral, either spongiotic or sclerotic lesions, evident as a thickened stapes footplate, and/or decalcified, narrowed or enlarged round or oval windows; grade 2, patchy localized cochlear disease (with or without fenestral involvement) to either the basal cochlear turn (grade 2A), or the middle/apical turns (grade 2B), or both the basal turn and the middle/apical turns (grade 2C); and grade 3, diffuse confluent cochlear involvement of the otic capsule (with or without fenestral involvement). Grade 3 is differentiated from grade 2C by the diffuse confluent involvement in grade 3 of the entire cochlea, where as grade 2C has patchy focal involvement of the entire cochlea.…”

“…13 The authors chose to evaluate this grading system because it categorizes the presence of otosclerosis on the basis of both location and appearance of disease (spongiosis and/or sclerosis). This grading system also allows for more precise localization of cochlear disease.…”