Feasibility of hearing preservation for residual hearing with longer cochlear implant electrodes

Abstract

Background: Hearing preservation is thought to be achievable following atraumatic surgery with thin cochlear implant electrodes; therefore, the surgical approach and implant electrode design are crucial considerations. Objective: To assess the feasibility of hearing preservation with long electrodes for patients meeting the criteria for conventional cochlear implantation. Methods: One hundred and two patients (132 ears) who underwent cochlear implant surgery were analyzed. Inclusion criteria included measurable residual hearing in the low frequency before implantation and not meeting the criteria for electric acoustic stimulation (EAS). Results: Of the 18 patients with residual hearing in the low frequency enrolled, 17 subjects (94.4%) retained low frequency hearing. A younger age at surgery tended to contribute to better hearing preservation than that observed in older patients. There was no clear trend regarding the influence of insertion depth angle of the electrode on hearing preservation. Conclusion: It is possible to achieve hearing preservation in the lower frequency by the use of longer electrodes. This study underscores the importance of atraumatic surgery, even for patients with only limited residual hearing, and longer electrodes should be adopted for EAS. ARTICLE HISTORY

Genetic testing has the potential to impact hearing preservation following cochlear implantation

“…This phenomenon was observed in another study using shorter electrode arrays (20 mm) [14], so that irrespective of the length of inserted electrode arrays, the intrinsic structural vulnerability of the basal- apical turn may potentially explain this. Additionally, the HP outcomes were independent of the electrode length (24 mm vs. 28 mm vs. 31.5 mm), which was consistent with the findings that there were no differences in HP score among the insertion depth angles in our and other previous reports [7,8]. Conversely, Suhling et al reported that 20-or 24-mm electrodes resulted in better HP than did those 28 mm in length [15].…”

“…As described in our previous report [7], we demonstrated that a younger age at the time of implantation led to statistically better HP, indicating that the implant age is one of the key predictors influencing residual hearing in CI surgery (Table 3). On the other hand, we did not find that HP was associated with pre-operative LFA or CDL, which contradicts some previous studies that suggest there is a positive impact on post-operative hearing [8].…”

“…Despite advances in less-invasive surgical techniques and electrode design, residual hearing still deteriorates in a certain number of patients after CI. Various groups have attempted to identify the factors that impact HP, with insertion depth angle, implant age, degree of residual hearing and cochlear duct length (CDL) being identified as potentially important factors [6][7][8][9]. While these reports are noteworthy, the factors predictive of preserving residual hearing remain a controversial topic.…”

Dose-Dependent Transient Decrease of Impedances by Deep Intracochlear Injection of Triamcinolone With a Cochlear Catheter Prior to Cochlear Implantation–1 Year Data

“…The role of material and surface properties on foreign body reactions and impedances is not fully understood and needs further investigation. However, hearing preservation in the lower frequencies is achieved even by the use of longer electrodes from the same manufacturer that has been used in the present study (26). Therefore, it seems unlikely that the electrode array has elicited a strong foreign body reaction.…”

Cochlear Implantation From the Perspective of Genetic Background

“…Regular CI has been applied for patients with insufficient amplification by hearing aids (Miyagawa et al, ) and, for the patients with residual hearing, EAS devices are a good therapeutic option (Usami et al, ; Moteki et al, , ). A significant portion of EAS patients possess CDH23 mutations (Moteki et al, , ; Yoshimura et al, submitted). Therefore, it is extremely important to perform atraumatic CI surgery to preserve residual hearing for this particular category of patients.…”