The Role of Hearing Preservation on Electrical
Thresholds and Speech Performances
in Cochlear Implantation
Alessandra D’Elia, Roberto Bartoli, Francesca Giagnotti, and Nicola Quaranta
Otolaryngology Department, Section of Otologic and Neurotologic Surgery, University of Bari, Bari, Italy
Objective: The purpose of this study was to verify if the pre-
servation of residual hearing after cochlear implantation in
classic adult cochlear implant candidates implanted with a
perimodiolar electrode correlates with the electric thresholds
and with speech perception measures.
Study Design: Retrospective study.
Setting: Cochlear Implant Center at a tertiary referral University
Hospital.
Patients: Forty-one patients with cochlear implant were involved
in our study. They were subdivided into 2 groups according to the
average preoperative hearing loss at the frequencies of 125 and
250 Hz (low-frequency pure tone average [LFPTA]). Group A
included 21 patients with a mean LFPTA of 90 dB HL or lower;
group B included 20 patients with a mean LFPTA of greater than
90 dB HL. They underwent 12 months’ follow-up after cochlear
implantation, including standard audiologic investigation, speech
discrimination tests, and electrical measurements.
Results: No significant differences were found in speech per-
ception tests among groups. In group A, hearing was preserved
in 8 (group A1) and was lost in 13 patients (group A2); the
postoperative LFPTA was significantly better ( p G 0.0001) in
A1. Group A1 patients present significantly higher C values
( p G 0.0001) than the other 2 groups, and the dynamic range
was therefore significantly wider ( p G 0.001).
Conclusion: Preservation of residual hearing should be at-
tempted in all cases. In fact, although effects on the speech
perception are not evident with the standard evaluation, lar-
ger electrical dynamic range can be achieved and may repre-
sent a sign of cochlear ‘‘well-being,’’ potentially allowing a
more complex electric stimulation of the nerve. Key Words:
Electrical thresholdsVHearing preservationVLow-frequency
residual hearingVSpeech performances.
Otol Neurotol 33:343Y347, 2012.
Candidacy criteria for cochlear implantation have evolved
from including only patients with profound hearing loss
to incorporating patients with more residual hearing. The
rationale for including these patients stands on the better
auditory perception with a cochlear implant (CI) com-
pared with hearing aids (1).
Since the description of a ‘‘soft’’ surgical technique
aimed at the preservation of residual hearing (2), there
has been a growing interest among audiologist in the
outcomes for people with cochlear implants in terms of
postoperative residual hearing and its influence on speech
discrimination results (3,4).
The preservation of residual hearing is, in fact, becoming
a high priority for the CI surgeon because recent studies
have confirmed that it can be achieved, minimizing surgi-
cal trauma, in 50% of cases (3). In addition, the possibil-
ity to maintain preoperative hearing has allowed a new
treatment, namely, electric-acoustic stimulation (EAS) for
patients with severe-to-profound high-frequency hearing
loss but considerable remaining low-frequency hearing (5).
EAS combines the electrical stimulation of the cochlear
basal end with the acoustic stimulation of the low fre-
quencies; EAS has been shown to confer advantages,
such as better speech understanding, especially in the
presence of background noise (3,6,7), and better music
appreciation (8,9).
However, EAS is indicated only in a restricted num-
ber of patients, whereas the majority of CI candidates still
present with a severe-to-profound HL and a poor low-
frequency hearing. The question whether it is useful to
preserve hearing residuals and, therefore, to use ‘‘soft’’
surgical techniques also in traditional CI candidates has
been recently addressed by Balkany et al. (10). Although,
in case of profound hearing loss, low-frequency hearing
Address correspondence and reprint requests to Nicola Quaranta,
M.D., Clinica Otorinolaringoiatrica ‘‘G. Lugli’’, Microchirurgia Otolo-
gica e Otoneurologica, Policlinico di Bari, P.zza G. Cesare 11, 70124
Bari, Italy; E-mail: nicola.quaranta@orl.uniba.it
The authors disclose no conflicts of interest.
Otology & Neurotology
33:343Y347 Ó 2012, Otology & Neurotology, Inc.
343
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