Cochlea and Cochlear Implantation Essay

Submitted By kelmjos
Words: 1403
Pages: 6

Hinrich Staecker, Sandra Prentiss
Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, MS 3010, 3901
Rainbow Blvd, Kansas City, KS 66160, U.S.A.
Corresponding author: Hinrich Staecker, Department of Otolaryngology Head and Neck Surgery,
University of Kansas School of Medicine, MS 3010, 3901 Rainbow Blvd, Kansas City, KS 66160, U.S.A., e-mail:
Background: Hearing preservation cochlear implantation has become commonplace, giving patients who are poor hearing aid candidates but who have significant residual hearing an opportunity to take part in the hearing world. Hearing preservation cochlear implantation has been extended into pediatric populations, but little attention has been paid to geriatric implantation.
Material and Methods: Cochlear implant candidates with residual low frequency hearing implanted between 2009 and 2011 were studied. Pure tone average was evaluated pre- and post-operatively and plotted against patient age.
Results: There was a statistically significant relationship between loss of hearing (PTA before and after implantation) and age.
Conclusions: Hearing preservation cochlear implantation is feasible in the elderly but there is a slightly larger change in hearing. We review factors that may affect hearing preservation outcomes in the elderly.
Keywords: cochlear implantation • hearing preservation • aging • presbycusis

Recognition that preservation of residual low frequency hearing improves cochlear implant (CI) function has been widely described (Gstoettner et al., 2004; Kiefer et al., 2004; Dorman and Gifford, 2010). Among patients, the elderly represent a population where down-sloping hearing losses with poor speech discrimination are common, and hence they are a group from which potential hearing preservation CI patients may be recruited. A key question is whether the elderly have the same outcomes in terms of hearing preservation as younger patients. To examine this we looked at changes in hearing after implantation as a function of age; we then examined the correlation between age and change in pure tone average. We also looked at cochlear implant outcomes as a function of age for hearing preservation patients. We discuss some of the potential causes of observed differences between the patient populations.

Subjects and outcomes measures
Informed consent was obtained prior to testing, and the protocol was approved by the University of Kansas Medical Center human subjects board. A total of 18 patients with residual hearing between 125 and 500 Hz (5 males and 13 females) were implanted between 2009 and 2011.
Ages ranged from 26 to 84 with a mean age of 63.2 years.
All candidates fell within Food and Drug Administration (FDA) or Medicare guidelines for implantation. Prior to implantation, all patients underwent blood testing
© Journal of Hearing Science® · 2012 Vol. 2 · No. 4

to screen for autoimmune inner ear disease and had an
MRI scan to rule out the presence of retrocochlear disease.

Surgical approach
The extended round window approach was used in all cases. After performance of a mastoidectomy and facial recess (posterior tympanotomy) approach to the middle ear, all bone dust was irrigated out of the wound. Hemostasis was obtained and 0.5 ml of Decadron (10 mg/ml) was applied to the round window niche. The bony overhang of the round window niche was then carefully removed with a 1 mm diamond burr and the round window clearly visualised by testing the round window reflex. The wound was once again irrigated and Healon was used to cover the round window (RW). The RW was then opened with a small pick and the implant electrode carefully inserted. All patients were implanted with a Med-El medium (M) electrode array. Pure tone thresholds were obtained before surgery and 2 weeks post-operatively using insert earphones. The change in pure tone