Variational Anatomy of the Human Cochlea

Erixon, Elsa; Högstorp, Herman; Wadin, K.; Rask‐Andersen, Helge

doi:10.1097/mao.0b013e31818a08e8

Cited by 252 publications

(113 citation statements)

References 23 publications

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“…13 We elected to examine cochlea volume, as it represents the entire three-dimensional space in which CI electrodes reside. While we suspected that smaller cochlear volumes would predispose to interscalar translocation and thus higher rates of SV insertion, no relation between cochlear volume and scalar electrode location was evident.…”

Section: Discussionmentioning

confidence: 99%

Electrode Location and Angular Insertion Depth Are Predictors of Audiologic Outcomes in Cochlear Implantation

O’Connell

Çakır

Hunter³

et al. 2016

Otology &Amp; Neurotology

209

267

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Objectives-1) Investigate the impact of electrode type and surgical approach on scalar electrode location in a large patient cohort; and 2) examine the relation between electrode location and postoperative audiologic performance. Setting-Tertiary academic hospital. Patients-220 post-lingually deafened adults undergoing cochlear implant (CI).Main Outcome Measures-Primary outcome measures of interest were scalar electrode location and postoperative audiologic performance.Results-In 68% of implants, electrodes were observed to be located solely in the scala tympani (ST). Multivariate analysis demonstrated perimodiolar(PM) and Mid-scala(MS) electrodes were p<0.001) times more likely to have at least one electrode in the scala vestibuli (SV) compared to lateral wall(LW) electrodes, respectively. Compared to cochleostomy(C), round window(RW) and extended round window(ERW) approaches demonstrated 70% reduction in SV insertion (OR 0.28,95%CI:0.1-0.8, p=0.01; ERW (OR O.28,95%CI:0.1-0.7, p=0.005). Examining postoperative audiometric performance, CNC score increased 0.6% with every 10° increase in angular insertion depth beyond the group minimum of 208° (Coefficient 0.0006,95%CI:0.0001-0.001, p=0.03). SV insertion was associated with a 12% decrease in CNC score (Coefficient -0.12,95%CI:-0.22--0.02, p=0.02). CNC score decreased 0.3% for every 1 year increase in age (Coefficient -0.003,95%CI:-0.006--0.0006), p=0.02). HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusions-Electrode design and surgical approach were predictors of scalar electrode location. Specifically, LW electrodes showed higher rates of ST insertion compared to PM or MS. RW and ERW approaches showed higher rates of ST insertion when compared to C. In regards to performance, ST insertion, younger age, and greater angular insertion depth were predictors of improved CNC scores.

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Section: Discussionmentioning

confidence: 99%

Electrode Location and Angular Insertion Depth Are Predictors of Audiologic Outcomes in Cochlear Implantation

O’Connell

Çakır

Hunter³

et al. 2016

Otology &Amp; Neurotology

209

267

View full text Add to dashboard Cite

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“…However, it should be noted that there is likely to be great deal of variation in the insertion angles of the arrays used in this study as there is a great deal of variation in cochlear anatomy (e.g. Erixon et al, 2009). The users evaluated in Schatzer et al (2014) were implanted by the same surgeon at the same hospital as the subjects in this study.…”

Section: Discussionmentioning

confidence: 99%

Qualities of Single Electrode Stimulation as a Function of Rate and Place of Stimulation with a Cochlear Implant

et al. 2016

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Objectives Although it has been previously shown that changes in temporal coding produce changes in pitch in all cochlear regions, research has suggested that temporal coding might be best encoded in relatively apical locations. We hypothesized that although temporal coding may provide useable information at any cochlear location, low rates of stimulation might provide better sound quality in apical regions that are more likely to encode temporal information in the normal ear. In the present study, sound qualities of single electrode pulse trains were scaled to provide insight into the combined effects of cochlear location and stimulation rate on sound quality. Design Ten long term users of MED-EL cochlear implants with 31 mm electrode arrays (Standard or FLEXSOFT) were asked to scale the sound quality of single electrode pulse trains in terms of how “Clean”, “Noisy”, “High”, and “Annoying” they sounded. Pulse trains were presented on most electrodes between 1 and 12 representing the entire range of the long electrode array at stimulation rates of 100, 150, 200, 400, or 1500 pulses per second. Results While high rates of stimulation are scaled as having a “Clean” sound quality across the entire array, only the most apical electrodes (typically 1 through 3) were considered “Clean” at low rates. Low rates on electrodes 6 through 12 were not rated as “Clean” while the low rate quality of electrodes 4 and 5 were typically in between. Scaling of “Noisy” responses provided an approximately inverse pattern as “Clean” responses. “High” responses show the trade-off between rate and place of stimulation on pitch. Because “High” responses did not correlate with “Clean” responses, subjects were not rating sound quality based on pitch. Conclusions If explicit temporal coding is to be provided in a cochlear implant, it is likely to sound better when provided apically. Additionally, the finding that low rates sound clean only at apical places of stimulation is consistent with previous findings that a change in rate of stimulation corresponds to an equivalent change in perceived pitch at apical locations. Collectively, the data strongly suggests that temporal coding with a cochlear implant is optimally provided by electrodes placed well into the second cochlear turn.

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“…Studies have shown that conventional length electrodes often acquire a lateral wall orientation in the distal basal turn of the cochlea and beyond (1). When moving from the basal cochlea to the apex, the turning radius of the cochlea shortens, and the cross-sectional area of the scala tympani lessens (23); the combination of these 2 factors results in increased outer wall impingement and may cause fracturing of the interscalar partition and excursion of the electrode into the scala media or scala vestibuli far from the intended site of stimulation (4,9,22). Studies using computed tomography of implanted patients have shown that those with electrode positions within the scala vestibuli have diminished speech performance scores (11,21,24).…”

Section: Discussionmentioning

confidence: 99%

Implications of Minimizing Trauma During Conventional Cochlear Implantation

Carlson

Driscoll²,

Gifford³

et al. 2011

Otology &Amp; Neurotology

216

176

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Objective To describe the relationship between implantation-associated trauma and postoperative speech perception scores among adult and pediatric patients undergoing cochlear implantation using conventional length electrodes and minimally traumatic surgical techniques. Study Design Retrospective chart review (2002–2010). Setting Tertiary academic referral center. Patients All subjects with significant preoperative low-frequency hearing (≤70 dB HL at 250 Hz) who underwent cochlear implantation with a newer generation implant electrode (Nucleus Contour Advance, Advanced Bionics HR90K [1J and Helix], and Med El Sonata standard H array) were reviewed. Intervention(s) Preimplant and postimplant audiometric thresholds and speech recognition scores were recorded using the electronic medical record. Main Outcome Measure(s) Postimplantation pure tone threshold shifts were used as a surrogate measure for extent of intracochlear injury and correlated with postoperative speech perception scores. Results Between 2002 and 2010, 703 cochlear implant (CI) operations were performed. Data from 126 implants were included in the analysis. The mean preoperative low-frequency pure-tone average was 55.4 dB HL. Hearing preservation was observed in 55% of patients. Patients with hearing preservation were found to have significantly higher postoperative speech perception performance in the cochlear implantation-only condition than those who lost all residual hearing. Conclusion Conservation of acoustic hearing after conventional length cochlear implantation is unpredictable but remains a realistic goal. The combination of improved technology and refined surgical technique may allow for conservation of some residual hearing in more than 50% of patients. Germane to the conventional length CI recipient with substantial hearing loss, minimizing trauma allows for improved speech perception in the electric condition. These findings support the use of minimally traumatic techniques in all CI recipients, even those destined for electric-only stimulation.

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Variational Anatomy of the Human Cochlea

Cited by 252 publications

References 23 publications

Electrode Location and Angular Insertion Depth Are Predictors of Audiologic Outcomes in Cochlear Implantation

Electrode Location and Angular Insertion Depth Are Predictors of Audiologic Outcomes in Cochlear Implantation

Qualities of Single Electrode Stimulation as a Function of Rate and Place of Stimulation with a Cochlear Implant

Implications of Minimizing Trauma During Conventional Cochlear Implantation

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