Impact of Frequency Mismatch and Modiolar Proximity on Speech Perception in Single-Sided Deafness Cochlear Implant Patients
Authors List
Ramos P., Collins A., Briggs R., O’Leary S., Webb H., Gerard JM.,
Department of Otolaryngology of the University of Melbourne & Royal Victorian Eye and Ear Hospital, Melbourne, Australia
Introduction
Single-sided deafness (SSD) presents a unique auditory challenge. Cochlear implants (CIs) offer a solution by providing auditory stimulation to the deaf ear. Most patients are fitted with default frequency allocation maps, leading to frequency shifts between the natural frequency of neurons stimulated by the implant electrodes. Understanding the relationship between the place of stimulation and the corresponding perceived pitch is crucial for optimizing CI fitting, especially in SSD. This study hypothesized that frequency mismatch (FM), evaluated using the Stakhovskaya formula, adversely affects speech perception (SP) outcomes at 3- and 12-months post-operation in CI recipients with SSD.
Aims
This study evaluated FM and its impact on SP at 3- and 12-months post-operation in CI recipients with SSD. Additionally, it assessed the influence of electrode proximity to the modiolus on SP outcomes.
Methods
Forty-two SSD patients underwent CI surgery between 2014 and 2023, with at least 12 months of follow-up. Statistical analyses utilized SPSS.
Results
Significant correlations were found between FM and SP at 3 months (p=0.004). Additionally, correlations were observed at 12 months (p= 0.034). Analysis by electrode placement showed stronger correlations in the basal (E1-E7) and midline (E8-E15) groups (p= 0.024 and p=0.023, respectively) compared to the apical (E16-E22) group (p=0.170) at 3 months. Proximity to the modiolus in basal electrodes correlated negatively with SP at 3 months (p= <0.010).
Conclusions
Lower FM correlated with improved SP at 3 months, suggesting deeper electrode insertions may initially enhance speech perception. Proximity of basal electrodes to the modiolus significantly influenced SP outcomes. These findings underscore the importance of precise electrode positioning and frequency allocation in optimizing CI outcomes for SSD patients.
References
Stakhovskaya O, Sridhar D, Bonham BH, Leake PA. Frequency map for the human cochlear spiral ganglion: implications for cochlear implants. J Assoc Res Otolaryngol. 2007 Jun;8(2): 220-33.doi: 10.1007/s10162-007-0076-9
Ramos P., Collins A., Briggs R., O’Leary S., Webb H., Gerard JM.,
Department of Otolaryngology of the University of Melbourne & Royal Victorian Eye and Ear Hospital, Melbourne, Australia
Introduction
Single-sided deafness (SSD) presents a unique auditory challenge. Cochlear implants (CIs) offer a solution by providing auditory stimulation to the deaf ear. Most patients are fitted with default frequency allocation maps, leading to frequency shifts between the natural frequency of neurons stimulated by the implant electrodes. Understanding the relationship between the place of stimulation and the corresponding perceived pitch is crucial for optimizing CI fitting, especially in SSD. This study hypothesized that frequency mismatch (FM), evaluated using the Stakhovskaya formula, adversely affects speech perception (SP) outcomes at 3- and 12-months post-operation in CI recipients with SSD.
Aims
This study evaluated FM and its impact on SP at 3- and 12-months post-operation in CI recipients with SSD. Additionally, it assessed the influence of electrode proximity to the modiolus on SP outcomes.
Methods
Forty-two SSD patients underwent CI surgery between 2014 and 2023, with at least 12 months of follow-up. Statistical analyses utilized SPSS.
Results
Significant correlations were found between FM and SP at 3 months (p=0.004). Additionally, correlations were observed at 12 months (p= 0.034). Analysis by electrode placement showed stronger correlations in the basal (E1-E7) and midline (E8-E15) groups (p= 0.024 and p=0.023, respectively) compared to the apical (E16-E22) group (p=0.170) at 3 months. Proximity to the modiolus in basal electrodes correlated negatively with SP at 3 months (p= <0.010).
Conclusions
Lower FM correlated with improved SP at 3 months, suggesting deeper electrode insertions may initially enhance speech perception. Proximity of basal electrodes to the modiolus significantly influenced SP outcomes. These findings underscore the importance of precise electrode positioning and frequency allocation in optimizing CI outcomes for SSD patients.
References
Stakhovskaya O, Sridhar D, Bonham BH, Leake PA. Frequency map for the human cochlear spiral ganglion: implications for cochlear implants. J Assoc Res Otolaryngol. 2007 Jun;8(2): 220-33.doi: 10.1007/s10162-007-0076-9
