Imaging of electrode position in relation to electrode functioning after cochlear implantation

Wermeskerken, Gijs K. A. van; Olphen, Adriaan F. van; Graamans, K.

doi:10.1007/s00405-009-0939-2

Cited by 48 publications

(25 citation statements)

References 16 publications

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“…To explain the less efficient basal stimulation, other researchers have noted the difference in impedance caused by the larger volume of fluid near the basal electrodes [van Wermeskerken et al, 2009] or by the basal current path through the round window [Micco and Richter, 2006;van der Beek et al, 2005]. Furthermore, cochlear damage at the time of implantation and the resulting formation of new tissue and bone might negatively affect the neuron-electrode interface.…”

Section: Introductionmentioning

confidence: 99%

“…Using CT scanning, the intracochlear position of individual contacts can be visualized, and the electrode-modiolus distance and the insertion depth of each electrode can be measured [Ruivo et al, 2009;van der Beek et al, 2005;van Wermeskerken et al, 2009;Verbist et al, 2008Verbist et al, , 2010a. The positions of cochlear implant electrode contacts can be visualized rather accurately.…”

Section: Introductionmentioning

confidence: 99%

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Intracochlear Position of Cochlear Implants Determined Using CT Scanning versus Fitting Levels: Higher Threshold Levels at Basal Turn

Beek

Briaire²,

Marel³

et al. 2016

Audiol Neurotol

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Objectives: In this study, the effects of the intracochlear position of cochlear implants on the clinical fitting levels were analyzed. Design: A total of 130 adult subjects who used a CII/HiRes 90K cochlear implant with a HiFocus 1/1J electrode were included in the study. The insertion angle and the distance to the modiolus of each electrode contact were determined using high-resolution CT scanning. The threshold levels (T-levels) and maximum comfort levels (M-levels) at 1 year of follow-up were determined. The degree of speech perception of the subjects was evaluated during routine clinical follow-up. Results: The depths of insertion of all the electrode contacts were determined. The distance to the modiolus was significantly smaller at the basal and apical cochlear parts compared with that at the middle of the cochlea (p < 0.05). The T-levels increased toward the basal end of the cochlea (3.4 dB). Additionally, the M-levels, which were fitted in our clinic using a standard profile, also increased toward the basal end, although with a lower amplitude (1.3 dB). Accordingly, the dynamic range decreased toward the basal end (2.1 dB). No correlation was found between the distance to the modiolus and the T-level or the M-level. Furthermore, the correlation between the insertion depth and stimulation levels was not affected by the duration of deafness, age at implantation or the time since implantation. Additionally, the T-levels showed a significant correlation with the speech perception scores (p < 0.05). Conclusions: The stimulation levels of the cochlear implants were affected by the intracochlear position of the electrode contacts, which were determined using postoperative CT scanning. Interestingly, these levels depended on the insertion depth, whereas the distance to the modiolus did not affect the stimulation levels. The T-levels increased toward the basal end of the cochlea. The level profiles were independent of the overall stimulation levels and were not affected by the biographical data of the patients, such as the duration of deafness, age at implantation or time since implantation. Further research is required to elucidate how fitting using level profiles with an increase toward the basal end of the cochlea benefits speech perception. Future investigations may elucidate an explanation for the effects of the intracochlear electrode position on the stimulation levels and might facilitate future improvements in electrode design.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intracochlear Position of Cochlear Implants Determined Using CT Scanning versus Fitting Levels: Higher Threshold Levels at Basal Turn

Beek

Briaire²,

Marel³

et al. 2016

Audiol Neurotol

View full text Add to dashboard Cite

show abstract

“…Close proximity to the modiolus has been shown to lower M levels or C levels (depending on the brand) and electrically evoked compound action potential thresholds, which facilitate more focused stimulation and optimization of pulse width [Dorman et al, 2007;Filipo et al, 2008;van der Beek et al, 2005;van Wermeskerken et al, 2009]. According to Briggs et al [2001], proximity to the modiolus can be achieved without intracochlear damage, provided a free-fitting electrode array of appropriate size and shape is used and inserted in the scala tympani.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Cochlear Implant Electrode Position on Performance

Marel¹,

Briaire²,

Verbist

et al. 2015

Audiol Neurotol

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Objectives: To study the relation between variables related to cochlear implant electrode position and speech perception performance scores in a large patient population. Design: The study sample consisted of 203 patients implanted with a CII or HiRes90K implant with a HiFocus 1 or 1J electrode of Advanced Bionics. Phoneme and word score averages for the 1- and 2-year follow-up were calculated for 41 prelingually deaf and 162 postlingually deaf patients. Analyses to reveal correlations between these performance outcomes and 6 position-related variables (angle of most basal electrode contact, surgical insertion angle, surgical insertion, wrapping factor, angular insertion depth, linear insertion depth) were executed. The scalar location, as an indication for the presence of intracochlear trauma, and modiolus proximity beyond the basal turn were not evaluated in this study. In addition, different patient-specific variables (age at implantation, age at onset of hearing loss, duration of deafness, preoperative phoneme and word scores) were tested for correlation with performance. Results: The performance scores of prelingual patients were correlated with age at onset of hearing loss, duration of deafness and preoperative scores. For the postlingual patients, performance showed correlations with all 5 patient-specific variables. None of the 6 position-related variables influenced speech perception in cochlear implant patients. Conclusions: Although several patient-specific variables showed correlations with speech perception outcomes, not one of the studied angular and linear position-related variables turned out to have a demonstrable influence on performance.

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“…EI measurements may have future implications for atraumatic electrode insertion and preservation of residual hearing. Intraoperative testing provides a baseline for device function over time [12,13,14]. The study showed that intraoperatively, ECAP cannot be recorded in all electrodes for the three types of implants in 7.7% patients with Freedom-cochlear, 8.9% with Sonata-Medel and 7.7% patients with Harmony-AB while absent in basal electrodes in 2.6%, 2.9% and 3.8% for the three implants respectively (Tables 2 and 3).…”

Section: Discussionmentioning

confidence: 96%