Influence of cochlear parameters on the current practice in cochlear implantation

Objective Growing interest in measuring the cochlear duct length (CDL) has emerged, since it can influence the selection of cochlear implant electrodes. Currently the measurements are performed with ionized radiation imaging. Only a few studies have explored CDL measurements in magnetic resonance imaging (MRI). Therefore, the presented study aims to fill this gap by estimating CDL in MRI and comparing it with multislice computed tomography (CT). Study Design Retrospective data analyses of 42 cochleae. Setting Tertiary care medical center. Methods Diameter (A value) and width (B value) of the cochlea were measured in HOROS software. The CDL and the 2-turn length were determined by the elliptic circular approximation (ECA). In addition, the CDL, the 2-turn length, and the angular length were determined via HOROS software by the multiplanar reconstruction (MPR) method. Results CDL values were significantly shorter in MRI by MPR ( d = 1.38 mm, P < .001) but not by ECA. Similar 2-turn length measurements were significantly lower in MRI by MPR ( d = 1.67 mm) and ECA ( d = 1.19 mm, both P < .001). In contrast, angular length was significantly higher in MRI ( d = 26.79°, P < .001). When the values were set in relation to the frequencies of the cochlea, no clinically relevant differences were estimated (58 Hz at 28-mm CDL). Conclusion In the presented study, CDL was investigated in CT and MRI by using different approaches. Since no clinically relevant differences were found, diagnostics with radiation may be omitted prior to cochlear implantation; thus, a concept of radiation-free cochlear implantation could be established.

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“…There were 14 of 42 inacceptable clinical errors in MRI measurements, exceeding the set value of 650°(Figure 5B). 21…”

Section: Measurements Of the Almentioning

confidence: 99%

Cochlear Duct Length Measurements in Computed Tomography and Magnetic Resonance Imaging Using Newly Developed Techniques

Taeger¹,

Müller-Graff²,

Ilgen³

et al. 2021

OTO Open

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“…Another important challenge was to understand whether and how the location of the electrical channels along the CI array and their corresponding frequency were related to the reduction of tinnitus. Several concerns affect the knowledge of the exact tonotopic position of the channels inside the cochlea, including the different electrodes used, their different insertion depths, and the variable tonotopic organization in damaged cochleae (Rak et al, 2020;Niu et al, 2021). Consequently, it is very difficult to determine exactly the regions stimulated by the channels, except in patients with asymmetric hearing thresholds.…”

Section: Discussionmentioning

confidence: 99%

The Effectiveness of Targeted Electrical Stimulation via Cochlear Implant on Tinnitus-Perceived Loudness

et al. 2022

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IntroductionThe cause of tinnitus improvement in cochlear implant (CI) users is not understood. On the basis that a spatially limited dysfunction in the auditory pathway could cause tinnitus, we used single-channel stimulation to evaluate any variation of tinnitus-perceived loudness and identify the cochlear regions involved.Materials and MethodsIt was an observational prospective case-crossover study. After the first mapping, 21 adults with unilateral CI and chronic tinnitus expressed their tinnitus loudness based on the Visual Analog Scale (VAS) score (0–10) at baseline (L0), during a 10 s single-channel stimulation with C-level of electric current (L1) and 30 min after CI activation (L2). Tinnitus reduction [RT = (L0 – L1) × 100/L0] > 50% was considered significant. VAS outcomes were compared between baseline (L0) and (each) single-channel stimulation (L1) to find the channel with the greatest RT (suppressive channel-SC), whose frequency range revealed the cochlear region involved. Seven patients with asymmetric hearing loss underwent the pitch-matching test to identify the actual frequency evoked by the SC. We compared selective (L1) and non-selective (L2) intracochlear stimulation using paired t-test. Preoperative Tinnitus Handicap Inventory (THI) score was compared with those at 1, 6, and 12 months with paired t-tests to evaluate long-term tinnitus perception.ResultsWe observed a significant reduction of tinnitus loudness during the experimental procedure [L0 (6.4 ± 2.4) vs. L1 (1.7 ± 2.7), p = 0.003]. A total of 15/21 patients (71.4%) had a significant (RT > 50%) and selective improvement, reporting a mean L1 of 0.4 ± 2.0 (p = 0.0001). In 10/15 (66.6%) patients, the SC was in the apical turn, within 1,000 Hz; in 5/15 patients (33.4%) within 4,000 Hz. The cochlear region 125–313 Hz was the most affected by tinnitus improvement (p = 0.0074). Targeted stimulation was more effective than non-selective stimulation [L1 vs. L2 (4.3 ± 2.5), p = 0.0022]. In 3/7 patients, the perceived pitch did not fall within the SC frequency ranges. All patients with selective attenuation described tinnitus as monotone. Patients with non-selective attenuation had polyphonic tinnitus and better THI results after 1 year.ConclusionTargeted intracochlear electrical stimulation improved chronic tinnitus perception, especially in monotone tinnitus, and the apical region was mainly involved. Our results provide new insights into the pathophysiological mechanisms of tinnitus and targets for innovative therapeutic strategies.

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“…In the era of personalized medicine, attempts have been made to associate CI performance with the etiology of hearing loss [ 6 - 8 ] and to establish surgical techniques that can maximize performance according to individual cochlear dimensions [ 9 , 10 ]. In this review, we discuss the implications of a personalized diagnosis (both genetic and nongenetic) and how it relates to the performance of CI and decision-making in patients with prelingual and postlingual hearing loss ( Table 1 ) [ 6 - 8 , 11 - 49 ].…”

Section: Introductionmentioning

confidence: 99%

Precision Medicine Approach to Cochlear Implantation

Kim

Choi

2022

Clin Exp Otorhinolaryngol

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In the early days of cochlear implantation (CI) surgery when the types of electrodes were limited and the etiology of sensorineural hearing loss (SNHL) was not well understood, the one-size-fits-all approach to CI held true like all other fields. However, in the era of personalized medicine, there have been attempts to associate CI performance with etiology of SNHL and to establish customized surgical techniques that can maximize performance according to individual cochlear dimensions. Personalized genomic-driven assessment of CI candidates and better understanding of genotype-phenotype correlations could provide clinically applicable diagnostic and prognostic information about questions such as who, how, and when to implant. Rigorous and strategic imaging assessments also provide a better insight into anatomic etiology of SNHL and cochlear dimensions, leading to individualized surgical techniques to augment CI outcome. Further, precision medicine approach to CI is not necessarily limited to preoperative planning but can be extended to either intraoperative electrode positioning or even decision of a timing of initial switch-on. In this review, we will discuss the implications of personalized diagnosis (both genetic and nongenetic) on planning and performance of CI in prelingual and postlingual SNHL.

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Influence of cochlear parameters on the current practice in cochlear implantation

Cited by 8 publications

References 29 publications

Cochlear Duct Length Measurements in Computed Tomography and Magnetic Resonance Imaging Using Newly Developed Techniques

Cochlear Duct Length Measurements in Computed Tomography and Magnetic Resonance Imaging Using Newly Developed Techniques

The Effectiveness of Targeted Electrical Stimulation via Cochlear Implant on Tinnitus-Perceived Loudness

Precision Medicine Approach to Cochlear Implantation

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