Human Otopathology of Cochlear Implant Drill-out Procedures

2019 ◽  
Vol 161 (4) ◽  
pp. 658-665
Author(s):  
Danielle R. Trakimas ◽  
Reuven Ishai ◽  
Elliott D. Kozin ◽  
Joseph B. Nadol ◽  
Aaron K. Remenschneider
Keyword(s):  
Spiral Ganglion ◽  
Electrode Array ◽  
High Sensitivity ◽  
Spiral Ganglion Neuron ◽  
Electrode Arrays ◽  
3 Dimensional ◽  
Basal Turn ◽  
Neuronal Populations ◽  
Neuron Populations ◽  
Labyrinthitis Ossificans

Objective Human otopathology following drill-out procedures for cochlear implantation (CI) in cases with labyrinthitis ossificans (LO) has not been previously described. This study uses the high sensitivity of histopathology to (1) evaluate surgical drill-out technique with associated intracochlear findings and (2) quantify spiral ganglion neuron populations in a series of patients with LO who underwent CI. Study Design Retrospective otopathology study. Setting Otopathology laboratory. Subjects and Methods Temporal bone (TB) specimens from cases with evidence of preoperative intracochlear fibroossification that required a drill-out procedure for CI electrode array insertion were included. All cases were histopathologically evaluated and 3-dimensional reconstructions of the cochleae were performed to interpret drilling paths and electrode trajectories. Results Five TB specimens were identified, of which 4 underwent drill-out of the basal turn of the cochlea and 1 underwent a radical cochlear drill-out. In multiple TBs, drilling was imprecise with resultant damage to essential structures. Two TBs showed injury to the modiolus, which was associated with substantially decreased or even absent neuronal populations within these areas. In addition, 2 cases with inadequate drill-out or extensive LO of the basal turn resulted in extracochlear placement of electrode arrays into the vestibule due to persistent obstruction within the basal turn. Conclusion Otopathology highlights the challenges of drill-out procedures in cases of LO. Imprecise drilling paths, due to distortion of normal cochlear anatomy, risk injury to the modiolus and adjacent neurons as well as extracochlear placement of electrode arrays, both of which may contribute to poorer hearing outcomes.

Otopathologic Analysis of Patterns of Postmeningitis Labyrinthitis Ossificans

2020 ◽  
pp. 019459982093474
Author(s):  
Danielle R. Trakimas ◽  
Renata M. Knoll ◽  
Melissa Castillo-Bustamante ◽  
Elliott D. Kozin ◽  
Aaron K. Remenschneider
Keyword(s):  
Temporal Bone ◽  
Retrospective Review ◽  
Cochlear Implantation ◽  
Spiral Ganglion ◽  
Continuous Extension ◽  
Tissue Formation ◽  
Basal Turn ◽  
Labyrinthitis Ossificans ◽  
Electrode Insertion ◽  
Ganglion Neurons

Objective Labyrinthitis ossificans (LO) may occur following meningitis and, in cases where cochlear implantation is indicated, complicate electrode insertion. LO is critical to identify for successful cochlear implantation, and histopathology is more sensitive than imaging for identification of LO. Herein we utilize otopathologic techniques to study the timing and location of intracochlear tissue formation following meningitic labyrinthitis (ML). Study Design Retrospective review. Setting Academic institution. Methods Temporal bone specimens with a history of bacterial ML were histologically evaluated. The location and extent of intracochlear tissue formation within the scala tympani (ST) and scala vestibuli (SV) were graded, and spiral ganglion neurons were counted. Results Fifty-one temporal bones were identified: 32 with no intracochlear tissue formation, 9 with fibrosis alone, and 10 with LO. Fibrosis was identified as early as 1.5 weeks after ML, while ossification was found only in specimens that survived multiple years after ML. All LO cases showed ossification of the ST at the round window membrane (RWM) with continuous extension throughout the basal turn. Extent of SV ossification correlated with that in the ST but showed frequent isolated distal involvement of the cochlea. Spiral ganglion neuron counts were lower than those in age-matched controls. Conclusion In this human temporal bone study, we found that postmeningitic LO results in ossification at the RWM with continuous extension into the ST of the basal turn and variable involvement of the SV. Identification of a patent basal turn beyond RWM ossification of the ST should permit full electrode insertion. Level of Evidence Retrospective review.

scholarly journals Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons

2021 ◽  
Author(s):  
Kristy Truong ◽  
Braden Leigh ◽  
Joseph T. Vecchi ◽  
Reid Bartholomew ◽  
Linjing Xu ◽  
...  
Keyword(s):  
Cochlear Implants ◽  
Microcontact Printing ◽  
Spiral Ganglion ◽  
Neurite Growth ◽  
Spiral Ganglion Neuron ◽  
Electrode Arrays ◽  
Prosthetic Devices ◽  
Neural Prosthetic ◽  
Flat Surfaces ◽  
Ganglion Neurons

AbstractFunctional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90° angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.

scholarly journals Intraoperative use of cone-beam computed tomography in a cadaveric ossified cochlea model

2009 ◽  
Vol 140 (5) ◽  
pp. 697-702 ◽  
Author(s):  
Emma Barker ◽  
Keith Trimble ◽  
Harley Chan ◽  
James Ramsden ◽  
Sajendra Nithiananthan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Temporal Bone ◽  
Cone Beam Computed Tomography ◽  
Intraoperative Imaging ◽  
Electrode Array ◽  
Cone Beam ◽  
Electrode Placement ◽  
Electrode Arrays ◽  
Labyrinthitis Ossificans ◽  
Conventional Ct

Objectives: To describe a cadaveric temporal bone model of labyrinthitis ossificans and investigate the utility of intraoperative cone-beam computed tomography (CBCT) in the facilitating cochlear implantation. Design: Cadaveric temporal bone study. Methods: Five cadaveric heads had cement introduced into the 10 cochleas. CBCT and a conventional CT scan were compared to assess the extent of cochlear obliteration. The cement was drilled-out (under CBCT guidance, if required) and cochlear implant electrode arrays (from 3 different manufacturers) inserted. Results: CBCT images demonstrated temporal bone anatomy and the extent of cochlear obliteration as clearly as conventional CT in all cases. Intraoperative CBCT guided drilling and facilitated electrode placement in two of five heads (3 of 10 ears). Streak-artifact from the electrodes of two devices partially obscured image clarity. Conclusions: The obliterated cochlear model reproduced a disease-ossified cochlear both radiographically and surgically. CBCT is useful for intraoperative imaging to facilitate electrode array placement in the obliterated or congenitally abnormal cochlea.

scholarly journals Spiral Ganglion Neuron Explant Culture and Electrophysiology on Multi Electrode Arrays

10.3791/54538 ◽  
2016 ◽  
Author(s):  
Stefan Hahnewald ◽  
Marta Roccio ◽  
Anne Tscherter ◽  
Jürg Streit ◽  
Ranjeeta Ambett ◽  
...  
Keyword(s):  
Spiral Ganglion ◽  
Explant Culture ◽  
Ganglion Neuron ◽  
Spiral Ganglion Neuron ◽  
Electrode Arrays

scholarly journals The Pull-Back Technique for the 532 Slim Modiolar Electrode

2019 ◽  
Vol 2019 ◽  
pp. 1-5 ◽  
Author(s):  
C. Riemann ◽  
H. Sudhoff ◽  
I. Todt
Keyword(s):  
Temporal Bone ◽  
Round Window ◽  
Spiral Ganglion ◽  
Electrode Array ◽  
Electrode Arrays ◽  
Current Spread ◽  
Temporal Bones ◽  
Hearing Outcomes ◽  
White Marker

Introduction. The distance between the modiolus and the electrode array is one factor that has become the focus of many discussions and studies. Positioning the electrode array closer to the spiral ganglion with the goal of reducing the current spread has been shown to improve hearing outcomes. The perimodiolar electrode arrays can be complemented with a surgical manoeuvre called the pull-back technique. This study focuses its attention on the recently developed 532 slim modiolar electrode. Objective. To investigate the intracochlear movements and pull-back technique for the 532 slim modiolar electrode. Material and Methods. A decapping procedure of the cochlea was performed on 5 temporal bones. The electrode array was inserted, and the intracochlear movements were microscopically examined and digitally captured. Three situations were analysed: the initial insertion, the overinsertion, and the pull-back position. The position of the three white markers of the electrode array in relation to the round window (RW) was evaluated while performing these three actions. Results. The initial insertion achieved an acceptable perimodiolar position of the electrode array, but a gap was still observed between the mid-portion of the array and the modiolus (the first white marker was seen in the RW). When we inserted the electrode more deeply, the mid-portion of the array was pushed away from the modiolus (the second and third white markers were seen in the RW). After applying the pull-back technique, the gap observed during the initial insertion disappeared, resulting in an optimal perimodiolar position (the first white marker was once again visible in the RW). Conclusion. This temporal bone study demonstrated that when applying the pull-back technique for the 532 slim modiolar electrode, a closer proximity to the modiolus was achieved when the first white marker of the electrode array was visible in the round window.

scholarly journals The Development of CMOS Amperometric Sensing Chip with a Novel 3-Dimensional TiN Nano-Electrode Array

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 994 ◽  
Author(s):  
Chun-Lung Lien ◽  
Chiun-Jye Yuan
Keyword(s):  
Electric Field ◽  
Three Dimensional ◽  
Electrode Array ◽  
High Sensitivity ◽  
Complementary Metal Oxide Semiconductor ◽  
Electrochemical Sensing ◽  
Oxide Semiconductor ◽  
High Catalytic Activity ◽  
Detection Range ◽  
3 Dimensional

An electrochemical sensing chip with an 8 × 8 array of titanium nitride three-dimensional nano-electrodes (TiN 3D-NEA) was designed and fabricated via a standard integrated complementary metal oxide semiconductor process. Each nano-electrode in 3D-NEA exhibited a pole-like structure with a radius of 100 nm and a height of 35 nm. The numeric simulation showed that the nano-electrode with a radius of around 100 nm exhibited a more uniformly distributed electric field and a much higher electric field magnitude compared to that of the microelectrode. Cyclic voltammetry study with Ru(NH3)63+ also revealed that the TiN 3D-NEA exhibited a much higher current density than that obtained from the microelectrode by two orders of magnitude. Further studies showed that the electrocatalytical reduction of hydrogen peroxide (H2O2) could occur on a TiN 3D-NEA-based sensing chip with a high sensitivity of 667.2 mA⋅mM−1⋅cm−2. The linear detection range for H2O2 was between 0.1 μM and 5 mM with a lowest detection limit of 0.1 μM. These results indicated that the fabricated TiN 3D-NEA exhibited high catalytic activity and sensitivity to H2O2 and could be a promising sensor for H2O2 measurement.

scholarly journals Comparison of Place-versus-Pitch Mismatch between a Perimodiolar and Lateral Wall Cochlear Implant Electrode Array in Patients with Single-Sided Deafness and a Cochlear Implant

2019 ◽  
Vol 24 (1) ◽  
pp. 38-48 ◽  
Author(s):  
Jeroen P.M. Peters ◽  
Edwin Bennink ◽  
Gijsbert A. van Zanten
Keyword(s):  
Cochlear Implant ◽  
Spiral Ganglion ◽  
Electrode Array ◽  
Lateral Wall ◽  
Electrode Arrays ◽  
High Resolution Computed Tomography ◽  
Significant Difference ◽  
Electrode Contact ◽  
The Difference ◽  
Single Sided Deafness

Background: In electric-acoustic pitch matching experiments in patients with single-sided deafness and a cochlear implant, the observed “mismatch” between perceived pitch and predicted pitch, based on the amended Greenwood frequency map, ranges from –1 to –2 octaves. It is unknown if and how this mismatch differs for perimodiolar versus lateral wall electrode arrays. Objectives: We aimed to investigate if the type of electrode array design is of influence on the electric-acoustic pitch match. Method: Fourteen patients (n = 8 with CI422 + lateral wall electrode array, n = 6 with CI512 + perimodiolar electrode array; Cochlear Ltd.) compared the pitch of acoustic stimuli to the pitch of electric stimuli at two test sessions (average interval 4.3 months). We plotted these “pitch matches” per electrode contact against insertion angle, calculated from high-resolution computed tomography scans. The difference between these pitch matches and two references (the spiral ganglion map and the default frequency allocation by Cochlear Ltd.) was defined as “mismatch.” Results: We found average mismatches of –2.2 octaves for the CI422 group and –1.3 octaves for the CI512 group. For any given electrode contact, the mismatch was smaller for the CI512 electrode array than for the CI422 electrode array. For all electrode contacts together, there was a significant difference between the mismatches of the two groups (p < 0.05). Results remained stable over time, with no significant difference between the two test sessions considering all electrode contacts. Neither group showed a significant correlation between the mismatch and phoneme recognition scores. Conclusion: The pitch mismatch was smaller for the perimodiolar electrode array than for the lateral wall electrode array.

scholarly journals Evaluating and Comparing Behavioural and Electrophysiological Estimates of Neural Health in Cochlear Implant Users

2020 ◽  
Author(s):  
Tim Brochier ◽  
François Guérit ◽  
John M. Deeks ◽  
Charlotte Garcia ◽  
Manohar Bance ◽  
...  
Keyword(s):  
Spiral Ganglion ◽  
Electrode Array ◽  
Growth Function ◽  
Spiral Ganglion Neuron ◽  
Temporal Representation ◽  
Neuron Density ◽  
The Difference ◽  
Ganglion Neurons ◽  
Test Retest Reliability ◽  
Different Characteristics

Abstract Variations in neural health along the cochlea can degrade the spectral and temporal representation of sounds conveyed by cochlear implants (CIs). We evaluated and compared one electrophysiological measure and two behavioural measures that have been proposed as estimates of neural health patterns, in order to explore the extent to which the different measures provide converging and consistent neural health estimates. All measures were obtained from the same 11 users of the Cochlear Corporation CI. The two behavioural measures were multipulse integration (MPI) and the polarity effect (PE), both measured on each of seven electrodes per subject. MPI was measured as the difference between thresholds at 80 pps and 1000 pps, and PE as the difference in thresholds between cathodic- and anodic-centred quadraphasic (QP) 80-pps pulse trains. It has been proposed that good neural health corresponds to a large MPI and to a large negative PE (lower thresholds for cathodic than anodic pulses). The electrophysiological measure was the effect of interphase gap (IPG) on the offset of the ECAP amplitude growth function (AGF), which has been correlated with spiral ganglion neuron density in guinea pigs. This ‘IPG offset’ was obtained on the same subset of electrodes used for the behavioural measures. Despite high test–retest reliability, there were no significant correlations between the neural health estimates for either within-subject comparisons across the electrode array, or between-subject comparisons of the means. A phenomenological model of a population of spiral ganglion neurons was then used to investigate physiological mechanisms that might underlie the different neural health estimates. The combined experimental and modelling results provide evidence that PE, MPI and IPG offset may reflect different characteristics of the electrode-neural interface.

scholarly journals The Importance of Intraoperative Plain Radiographs during Cochlear Implant Surgery in Patients with Normal Anatomy

2021 ◽  
Vol 11 (9) ◽  
pp. 4144
Author(s):  
Ohad Cohen ◽  
Jean-Yves Sichel ◽  
Chanan Shaul ◽  
Itay Chen ◽  
J. Thomas Roland ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Cost Effective ◽  
X Rays ◽  
Normal Anatomy ◽  
Electrode Arrays ◽  
Plain Radiographs ◽  
Hearing Function ◽  
Tertiary Center ◽  
Cochlear Implant Surgery

Although malpositioning of the cochlear implant (CI) electrode array is rare in patients with normal anatomy, when occurring it may result in reduced hearing outcome. In addition to intraoperative electrophysiologic tests, imaging is an important modality to assess correct electrode array placement. The purpose of this report was to assess the incidence and describe cases in which intraoperative plain radiographs detected a malpositioned array. Intraoperative anti-Stenver’s view plain X-rays are conducted routinely in all CI surgeries in our tertiary center before awakening the patient and breaking the sterile field. Data of patients undergoing 399 CI surgeries were retrospectively analyzed. A total of 355 had normal inner ear and temporal bone anatomy. Patients with intra or extracochlear malpositioned electrode arrays demonstrated in the intraoperative X-ray were described. There were four cases of electrode array malposition out of 355 implantations with normal anatomy (1.1%): two tip fold-overs, one extracochlear placement and one partial insertion. All electrodes were reinserted immediately; repeated radiographs were normal and the patients achieved good hearing function. Intraoperative plain anti-Stenver’s view X-rays are valuable to confirm electrode array location, allowing correction before the conclusion of surgery. These radiographs are cheaper, faster, and emit much less radiation than other imaging options, making them a viable cost-effective tool in patients with normal anatomy.

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