Electrophysiological Detection of Scalar-Changing Perimodiolar Cochlear Electrode Arrays: A Six-Month Follow-Up Study

2015 ◽  
Vol 20 (6) ◽  
pp. 400-405 ◽  
Author(s):  
Philipp Mittmann ◽  
Ingo Todt ◽  
Thomas Wesarg ◽  
Susan Arndt ◽  
Arneborg Ernst ◽  
...  
Keyword(s):  
Electrode Array ◽  
Neural Response ◽  
Scala Tympani ◽  
Electrode Arrays ◽  
Follow Up Study ◽  
Neural Response Telemetry ◽  
Threshold Ratio ◽  
Intracochlear Electrode Array ◽  
Array Position

The position of the cochlear electrode array within the scala tympani is essential for optimal hearing benefit. An intraoperative neural response telemetry ratio (NRT ratio; a threshold ratio of pairs of apical and basal electrodes) has been established, which can provide information about the intracochlear electrode array position. Out of a previous collective of 85 patients, the 6-month follow-up electrophysiological NRT data of 37 patients have been included in this study. Comparing the intraoperatively estimated NRT ratio with the 6-month follow-up NRT ratio, it remained unchanged intraindividually in 92% of cases. Within this group the NRT ratio and the intracochlear position of the electrode array matched in all cases. There were two newly occurring mismatches and one new match was observed. After a period of 6 months the NRT ratio remained unchanged in most cases and showed a good correlation with the intracochlear position of the electrode array.

Radiological and NRT-Ratio–Based Estimation of Slim Straight Cochlear Implant Electrode Positions

2016 ◽  
Vol 126 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Philipp Mittmann ◽  
Ingo Todt ◽  
Arneborg Ernst ◽  
Grit Rademacher ◽  
Sven Mutze ◽  
...  
Keyword(s):  
Electrode Array ◽  
Controlled Study ◽  
Data Sets ◽  
Scala Tympani ◽  
Tertiary Referral ◽  
Flat Panel ◽  
Tomography System ◽  
Neural Response Telemetry ◽  
Intracochlear Electrode Array ◽  
Array Position

Objectives: An intraoperative neural response telemetry-ratio (NRT-ratio) was established, which can provide information about the intraoperative intracochlear electrode array position for perimodiolar electrodes. Methods: In a retrospective controlled study in 2 tertiary referral centers, the electrophysiological data sets of 50 patients with measured intraoperative auto-NRTs and postoperative radiological examinations were evaluated. All patients were implanted with Nucleus slim straight electrodes. The NRT-ratio was calculated by dividing the average auto-NRT data from electrodes 16 to 18 with the average from electrodes 5 to 7. Using a flat panel tomography system or a computed tomography, the position of the electrode array was certified radiological. Results: Radiologically, 2 out of 50 patients were identified with an electrode translocated from the scala tympani into the scala vestibuli. The radiologically estimated electrodes indicating a scalar change showed a regular NRT-ratio but nonspecific NRT-level changes at the localization of translocation.

Electrophysiological detection of scalar changing perimodiolar cochlear electrode arrays: a long term follow-up study

2016 ◽  
Vol 273 (12) ◽  
pp. 4251-4256 ◽  
Author(s):  
Philipp Mittmann ◽  
I. Todt ◽  
A. Ernst ◽  
G. Rademacher ◽  
S. Mutze ◽  
...  
Keyword(s):  
Electrode Arrays ◽  
Follow Up Study ◽  
Long Term Follow Up

Scala Tympani Cochleostomy Survey: A Follow-up Study

2013 ◽  
Vol 149 (2_suppl) ◽  
pp. P237-P237
Author(s):  
Claire E. Iseli ◽  
Oliver F. Adunka ◽  
Craig A. Buchman
Keyword(s):  
Scala Tympani ◽  
Follow Up Study

Scala tympani cochleostomy survey: A follow-up study

2014 ◽  
Vol 124 (8) ◽  
pp. 1928-1931 ◽  
Author(s):  
Claire Iseli ◽  
Oliver F. Adunka ◽  
Craig A. Buchman
Keyword(s):  
Scala Tympani ◽  
Follow Up Study

scholarly journals Radiological evaluation of a new straight electrode array compared to its precursors

2020 ◽  
Author(s):  
Manuel Christoph Ketterer ◽  
A. Aschendorff ◽  
S. Arndt ◽  
I. Speck ◽  
A. K. Rauch ◽  
...  
Keyword(s):  
Round Window ◽  
Electrode Array ◽  
Lateral Wall ◽  
Study Groups ◽  
Cone Beam ◽  
Special Focus ◽  
Electrode Arrays ◽  
Academic Center ◽  
Cochlear Morphology ◽  
Array Position

Abstract Objective The aim of this study is to examine electrode array coverage, scalar position and dislocation rate in straight electrode arrays with special focus on a new electrode array with 26 mm in lengths. Study design Retrospective study. Setting Tertiary academic center. Patients 201 ears implanted between 2013 and 2019. Main outcome measures We conducted a comparative analysis of patients implanted with lateral wall electrode arrays of different lengths (F24 = MED-EL Flex24, F26 = MED-EL Flex26, F28 = MED-EL Flex28 and F31.5 = MED-EL FlexSoft). Cone beam computed tomography was used to determine electrode array position (scala tympani (ST) versus scala vestibuli (SV), intracochlear dislocation, position of dislocation and insertion angle). Results Study groups show no significant differences regarding cochlear size which excludes influences by cochlear morphology. As expected, the F24 showed significant shorter insertion angles compared to the longer electrode arrays. The F26 electrode array showed no signs of dislocation or SV insertion. The electrode array with the highest rate of ST dislocations was the F31.5 (26.3%). The electrode array with the highest rates of SV insertions was the F28 (5.75%). Most of the included electrode arrays dislocate between 320° and 360° (mean: 346.4°; range from 166° to 502°). Conclusion The shorter F24 and the new straight electrode array F26 show less or no signs of scalar dislocation, neither for round window nor for cochleostomy insertion than the longer F28 and the F31.5 array. As expected, the cochlear coverage is increasing with length of the electrode array itself but with growing risk for scalar dislocation and with the highest rates of dislocation for the longest electrode array F31.5. Position of intracochlear dislocation is in the apical cochlear part in the included lateral wall electrode arrays.

Intra-operative skull X-ray for misdirection of the cochlear implant array into the vestibular labyrinth

2015 ◽  
Vol 129 (9) ◽  
pp. 923-927 ◽  
Author(s):  
A M Hassan ◽  
R Patel ◽  
M Redleaf
Keyword(s):  
Computed Tomography ◽  
Cochlear Implant ◽  
Case Series ◽  
Electrode Array ◽  
Plain Film ◽  
Neural Response ◽  
Reliable Indicator ◽  
X Ray ◽  
Vestibular Labyrinth ◽  
Neural Response Telemetry

AbstractObjectives:This paper reports five cases of aberrant cochlear implant electrode array insertion into the vestibular labyrinth. A review of the literature was conducted in order to clarify reasonable preventive and detection strategies and endorse the routine use of intra-operative plain skull X-ray.Methods:The study entailed a clinical case series and literature review. The setting was a tertiary academic referral centre. The following data were evaluated: pre-operative temporal bone computed tomography, operative reports, intra-operative imaging, neural response telemetry/imaging and post-operative imaging.Results:There were no consistent pre-operative risk factors found on computed tomography scans and no reliable intra-operative signs of electrode array misdirection. All misdirections in our case series, and those in the literature, were easily detectable on intra-operative plain film X-ray.Conclusion:These reported cases demonstrate implant misdirection without the surgeon's awareness. Aberrant insertion cannot be anticipated, and neural response telemetry/imaging is not a reliable indicator of misdirection. Routine intra-operative anteroposterior plain X-ray of the head is a reliable indicator of misdirection, and is fast and relatively inexpensive.

scholarly journals Evaluation of the Relationship between the NRT-Ratio, Cochlear Anatomy, and Insertions Depth of Perimodiolar Cochlear Implant Electrodes

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Philipp Mittmann ◽  
Grit Rademacher ◽  
Sven Mutze ◽  
Frederike Hassepass ◽  
Arneborg Ernst ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Scala Tympani ◽  
Flat Panel ◽  
Insertion Depth ◽  
Tomography System ◽  
Neural Response Telemetry ◽  
Auditory Performance ◽  
The Relationship ◽  
Scala Vestibuli

The position of the cochlear implant electrode array within the scala tympani is essential for an optimal postoperative hearing benefit. If the electrode array changes in between the scalae intracochlearly (i.e., from scala tympani to scala vestibuli), a reduced auditory performance can be assumed. We established a neural response telemetry-ratio (NRT-ratio) which corresponds with the scalar position of the electrodes but shows within its limits a variability. The aim of this study was to determine if insertion depth angle or cochlea size influences the NRT-ratio. The intraoperative electrophysiological NRT data of 26 patients were evaluated. Using a flat panel tomography system, the position of the electrode array was evaluated radiologically. The insertion depth angle of the electrode, the cochlea size, and the NRT-ratio were calculated postoperatively. The radiological results were compared with the intraoperatively obtained electrophysiological data (NRT-ratio) and statistically evaluated. In all patients the NRT-ratio, the insertion depth angle, and the cochlea size could be determined. A significant correlation between insertional depth, cochlear size, and the NRT-ratio was not found. The NRT-ratio is a reliable electrophysiological tool to determine the scalar position of a perimodiolar electrode array. The NRT-ratio can be applied independent from insertion depth and cochlear size.

Neural Response Telemetry and Auditory/Nonauditory Sensations in 15 Recipients of Auditory Brainstem Implants

2005 ◽  
Vol 16 (04) ◽  
pp. 219-227 ◽  
Author(s):  
Steven R. Otto ◽  
Michael D. Waring ◽  
Johannes Kuchta
Keyword(s):  
Neuronal Activity ◽  
Vestibular Schwannoma ◽  
Electrode Array ◽  
Neurofibromatosis Type ◽  
Auditory Brainstem ◽  
Neural Response ◽  
Neural Response Telemetry ◽  
Auditory Brainstem Implants ◽  
Sound Processor

Auditory brainstem implants (ABIs) provide a means of restoring some hearing sensations to individuals with neurofibromatosis type 2 (NF2) who are deaf after vestibular schwannoma removal. In this study, neural response telemetry (NRT) was used to record electrically evoked neuronal activity near the ABI electrode array in 15 such subjects. Our interest was to investigate whether NRT recordings from the brainstem might be useful in implanting or programming ABIs. We therefore sought relationships between postoperative NRT recordings and the sensations reported by the subjects in response to the test stimuli. However, no clear relationships among these variables were found, and it was not possible to differentiate recordings associated with auditory versus nonauditory sensations. The findings suggest that the categorization of NRT recordings used in this study is inappropriate for assisting with placement of an ABI electrode array intra-operatively or for programming the sound processor postoperatively.

Cochlear Implantation with the CI512 and CI532 Precurved Electrode Arrays: One-Year Speech Recognition and Intraoperative Thresholds of Electrically Evoked Compound Action Potentials

2019 ◽  
Vol 24 (6) ◽  
pp. 299-308 ◽  
Author(s):  
Pernilla Videhult Pierre ◽  
Martin Eklöf ◽  
Henrik Smeds ◽  
Filip Asp
Keyword(s):  
Speech Recognition ◽  
Cochlear Implantation ◽  
Action Potentials ◽  
Electrode Array ◽  
University Hospital ◽  
Electrode Arrays ◽  
Neural Response Telemetry ◽  
Significant Difference ◽  
Compound Action Potentials ◽  
Compound Action

Introduction: Precurved cochlear implant (CI) electrode arrays were developed in an attempt to improve the auditory outcome of cochlear implantation, which varies greatly. The recent CI532 (Cochlear Corp., Sydney, Australia) may offer further advantages as its electrode array is thinner than previous precurved CI electrode arrays. The aims here were to investigate 1-year postoperative speech recognition, intraoperative electrically evoked compound action potentials (ECAPs), and their possible relation in patients implanted with a CI532 or its predecessor CI512. Methods: A retrospective analysis of data from 63 patients subjected to cochlear implantation at the Karolinska University Hospital, Sweden, was performed. Speech recognition of the implanted ear was evaluated using phonemically balanced monosyllabic Swedish words at 65 dB SPL. ECAPs were evaluated using the intraoperative ECAP threshold across ≥8 electrodes generated by the automated neural response telemetry of the CI. Results: The median aided speech recognition score (SRS) 1 year after implantation was 52% (quartile 1 = 40%, quartile 3 = 60%, n = 63) and did not differ statistically significantly between patients with CI512 (n = 38) and CI532 (n = 25). The mean ECAP threshold was 188 CL (current level; SD = 15 CL, n = 54) intraoperatively and did not differ statistically significantly between patients with CI512 (n = 32) and CI532 (n = 22), but the threshold for each electrode varied more between patients with a CI512 (p < 0.0001). A higher mean ECAP threshold was associated with a worse SRS (Spearman’s ρ = –0.46, p = 0.0004, n = 54). The association remained among those with a CI512 (Spearman’s ρ = –0.62, p = 0.0001, n = 32) when stratified by CI electrode array. Conclusion: No statistically significant difference in speech recognition 1 year after cochlear implantation or in mean threshold of ECAP intraoperatively was found between patients with a CI512 and the more recent, slim CI532, but the ECAP thresholds varied more between those with a CI512. A statistically significant association between SRS and mean ECAP threshold was found, but stratified analysis suggests that the association may be true only for patients with a CI512.

A Fluid Actuator for Thin-Film Electrodes

2006 ◽  
Vol 1 (1) ◽  
pp. 70-78 ◽  
Author(s):  
Benjamin Arcand ◽  
Sudeep Shyamsunder ◽  
Craig Friedrich
Keyword(s):  
Thin Film ◽  
Electrode Array ◽  
Minimal Amount ◽  
Film Electrode ◽  
Scala Tympani ◽  
Electrode Arrays ◽  
Thin Film Electrode ◽  
Elliptical Cross ◽  
Auditory Nerves

Background. Cochlear implants have become an accepted and successful treatment for profound sensorineural deafness in both children and adults. Essential to the effective and efficient localized stimulation of the auditory nerves, is the position of the implant electrode array stimulating sites within the scala tympani (ST). However, the small size, delicate internal structures and helical shape of the cochlear chambers complicate the matter of precise positioning of the implant electrode array. The design, fabrication process, and in vitro testing of a fluid actuator to steer a thin-film electrode array is presented. The application chosen to show feasibility is for a cochlear implant, however, the actuator might be used for cortical electrode arrays, for example. Method of Approach. The actuator functions by a change of internal fluid pressure within one or more flattened and curled polymer microtubes, expanding the highly elliptical cross section of each tube thereby stiffening it and causing a change in its curling radius. The straightening from an initially helical shape allows insertion of an attached electrode array into the basal end of the in vitro cochlea and as the insertion proceeds the pressure is decreased allowing the straightened electrode array to controllably return to its initial helical shape. The allowable envelope of the scala tympani of a guinea pig was determined from published data and the actuator was designed and fabricated accordingly. Results. Multiple actuators were fabricated and tested in vitro. The insertion tests helped to confirm the viability of using this type of actuation to facilitate the insertion of an electrode array into the ST. These tests were performed in a minimal amount of time and often on the first attempt. The actuator reached the furthest extent of the in vitro cavity and achieved a position adjacent to the modiolus. Conclusions. In vitro insertion tests show that the actuator can deliver a thin-film electrode array to a depth of more than one turn into the in vitro scala tympani within a few minutes under open-loop, manual control.

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