Current Distributions Produced Inside and Outside the Cochlea from a Scala Tympani Electrode Array

1987 ◽  
Vol BME-34 (11) ◽  
pp. 883-890 ◽  
Author(s):  
Tohru Ifukube ◽  
Robert L. White
Keyword(s):  
Electrode Array ◽  
Scala Tympani ◽  
Current Distributions

Electrical Cochlear Stimulation in the Deaf Cat: Comparisons Between Psychophysical and Central Auditory Neuronal Thresholds

2000 ◽  
Vol 83 (4) ◽  
pp. 2145-2162 ◽  
Author(s):  
Ralph E. Beitel ◽  
Russell L. Snyder ◽  
Christoph E. Schreiner ◽  
Marcia W. Raggio ◽  
Patricia A. Leake
Keyword(s):  
Electrical Stimulation ◽  
Auditory System ◽  
Pulse Rate ◽  
Auditory Nerve ◽  
Round Window ◽  
Electrode Array ◽  
Scala Tympani ◽  
Behavioral Thresholds ◽  
Current Pulses ◽  
Stimulation Of

Cochlear prostheses for electrical stimulation of the auditory nerve (“electrical hearing”) can provide auditory capacity for profoundly deaf adults and children, including in many cases a restored ability to perceive speech without visual cues. A fundamental challenge in auditory neuroscience is to understand the neural and perceptual mechanisms that make rehabilitation of hearing possible in these deaf humans. We have developed a feline behavioral model that allows us to study behavioral and physiological variables in the same deaf animals. Cats deafened by injection of ototoxic antibiotics were implanted with either a monopolar round window electrode or a multichannel scala tympani electrode array. To evaluate the effects of perceptually significant electrical stimulation of the auditory nerve on the central auditory system, an animal was trained to avoid a mild electrocutaneous shock when biphasic current pulses (0.2 ms/phase) were delivered to its implanted cochlea. Psychophysical detection thresholds and electrical auditory brain stem response (EABR) thresholds were estimated in each cat. At the conclusion of behavioral testing, acute physiological experiments were conducted, and threshold responses were recorded for single neurons and multineuronal clusters in the central nucleus of the inferior colliculus (ICC) and the primary auditory cortex (A1). Behavioral and neurophysiological thresholds were evaluated with reference to cochlear histopathology in the same deaf cats. The results of the present study include: 1) in the cats implanted with a scala tympani electrode array, the lowest ICC and A1 neural thresholds were virtually identical to the behavioral thresholds for intracochlear bipolar stimulation; 2) behavioral thresholds were lower than ICC and A1 neural thresholds in each of the cats implanted with a monopolar round window electrode; 3) EABR thresholds were higher than behavioral thresholds in all of the cats (mean difference = 6.5 dB); and 4) the cumulative number of action potentials for a sample of ICC neurons increased monotonically as a function of the amplitude and the number of stimulating biphasic pulses. This physiological result suggests that the output from the ICC may be integrated spatially across neurons and temporally integrated across pulses when the auditory nerve array is stimulated with a train of biphasic current pulses. Because behavioral thresholds were lower and reaction times were faster at a pulse rate of 30 pps compared with a pulse rate of 2 pps, spatial-temporal integration in the central auditory system was presumably reflected in psychophysical performance.

scholarly journals A Surgical Navigation System for Guiding Exact Cochleostomy Using Auditory Feedback: A Clinical Feasibility Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Byunghyun Cho ◽  
Nozomu Matsumoto ◽  
Shizuo Komune ◽  
Makoto Hashizume
Keyword(s):  
Feasibility Study ◽  
Navigation System ◽  
Auditory Feedback ◽  
Surgical Navigation ◽  
Complex Structure ◽  
Electrode Array ◽  
Scala Tympani ◽  
Correct Placement ◽  
Surgical Navigation System ◽  
The Common

In cochlear implantation (CI), the insertion of the electrode array into the appropriate compartment of the cochlea, the scala tympani, is important for an optimal hearing outcome. The current surgical technique for CI depends primarily on the surgeon’s skills and experience level to achieve the correct placement of the electrode array, and the surgeon needs to confirm that the exact placement is achieved prior to completing the procedure. Thus, a surgical navigation system can help the surgeon to access the scala tympani without injuring important organs in the complex structure of the temporal bone. However, the use of a surgical microscope has restricted the effectiveness of the surgical navigation because it has been difficult to deliver the navigational information to the surgeon from outside of the surgeon’s visual attention. We herein present a clinical feasibility study of an auditory feedback function developed as a computer-surgeon interface that can guide the surgeon to the preset cochleostomy location. As a result, the surgeon could confirm that the drilling point was correct, while keeping his or her eyes focused on the microscope. The proposed interface reduced the common frustration that surgeons experience when using surgical navigation during otologic surgeries.

scholarly journals Tubular manipulators: a new concept for intracochlear positioning of an auditory prosthesis

2015 ◽  
Vol 1 (1) ◽  
pp. 515-518 ◽  
Author(s):  
Thomas S. Rau ◽  
Josephine Granna ◽  
Thomas Lenarz ◽  
Omid Majdani ◽  
Jessica Burgner-Kahrs
Keyword(s):  
Inner Ear ◽  
Preliminary Investigation ◽  
Electrode Array ◽  
Maximum Error ◽  
Patient Specific ◽  
Final Position ◽  
Auditory Prosthesis ◽  
Scala Tympani ◽  
Potential Applicability ◽  
Torsion Stiffness

AbstractThe aim of this study was to investigate the applicability of tubular manipulators as an actuator mechanism for intracochlear positioning of the electrode array (EA) of a cochlear implant (CI). This is motivated by the vision of an atraumatic insertion of the EA into the inner ear (cochlea) without any damage to the intracochlear structures in combination with a well-defined final position. To realize this, an actuator mechanism is required which allows consideration of the patient-specific anatomy. We propose a tubular manipulator for this task. It consists of three concentric tubes: A straight outer tube serves as a guiding sleeve to enter the inner ear (cochlea) and two additional telescoping, superelastic, helically precurved tubes. By selecting helical tube parameters of both tubes prior insertion, a patient-specific curling behaviour of the tubular manipulator can be achieved. For preliminary investigation, segmentation and skeletonization of 5 human scala tympani were performed to determine their centrelines. These centrelines were considered as individual ideal insertion paths. An optimization algorithm was developed to identify suitable tube set parameters (curvature, diameter, length, torsion, stiffness) as well as configuration parameters (translation and rotation of the 2 inner tubes). Different error values describing the deviation of the shape of the tubes with respect to the insertion path were used to quantify the optimization results. In all cases tube set parameters for a final position within the cochlea were found, while keeping the maximum error below 1mm. These preliminary results are promising in terms of the potential applicability of tubular manipulators for positioning auditory prosthesis inside the scala tympani of the inner ear.

Evaluation of the HiFocus® electrode array with positioner in human temporal bones

2003 ◽  
Vol 117 (7) ◽  
pp. 527-531 ◽  
Author(s):  
Antje Aschendorff ◽  
Thomas Klenzner ◽  
Bernhard Richter ◽  
Ralf Kubalek ◽  
Heiner Nagursky ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Electrode Array ◽  
Scala Tympani ◽  
X Ray ◽  
Temporal Bones ◽  
Scala Vestibuli

The aim of the study presented was to assess the insertion mode and possible intracochlear trauma after implantation of the HiFocus® electrode with positioner in human temporal bones. The study was performed in five freshly frozen temporal bones. The position of electrodes was evaluated using conventional X-ray analysis, rotational tomography and histomorphological analysis. Insertion of the HiFocus® electrode with positioner resulted in considerable trauma to fine cochlear structures including fracture of the osseous spiral lamina, dislocation of the electrode array from the scala tympani into the scala vestibuli and fracture of the modiolus close to the cochleostomy. The implication of the results regarding clinical outcome will be discussed.

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.

scholarly journals Factors Predicting Postoperative Sentence Scores in Postlinguistically Deaf Adult Cochlear Implant Patients

1992 ◽  
Vol 101 (4) ◽  
pp. 342-348 ◽  
Author(s):  
Peter J. Blamey ◽  
Brian C. Pyman ◽  
Graeme M. Clark ◽  
Richard C. Dowell ◽  
Michael Gordon ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Electrical Stimulation ◽  
Cochlear Implant ◽  
Electrode Array ◽  
Frequency Discrimination ◽  
Gap Detection ◽  
Scala Tympani ◽  
Central Institute ◽  
Independent Variables ◽  
Profound Deafness

A sample of 64 postlinguistically profoundly to totally deaf adult cochlear implant patients were tested without lipreading by means of the Central Institute for the Deaf (CID) sentence test 3 months postoperatively. Preoperative promontory stimulation results (thresholds, gap detection, and frequency discrimination), age, duration of profound deafness, cause of deafness, lipreading ability, postoperative intracochlear thresholds and dynamic ranges for electrical stimulation, depth of insertion of the electrode array into the scala tympani, and number of electrodes in use were considered as possible factors that might be related to the postoperative sentence scores. A multiple regression analysis with stepwise inclusion of independent variables indicated that good gap detection and frequency discrimination during preoperative promontory testing, larger numbers of electrodes in use, and greater dynamic ranges for intracochlear electrical stimulation were associated with better CID scores. The CID scores tended to decrease with longer periods of profound deafness.

scholarly journals Atraumatic Insertion of a Cochlear Implant Pre-Curved Electrode Array by a Robot-Automated Alignment with the Coiling Direction of the Scala Tympani

2021 ◽  
pp. 1-8
Author(s):  
Renato Torres ◽  
Baptiste Hochet ◽  
Hannah Daoudi ◽  
Fabienne Carré ◽  
Isabelle Mosnier ◽  
...  
Keyword(s):  
Navigation System ◽  
Electrode Array ◽  
Automated System ◽  
Cone Beam ◽  
Scala Tympani ◽  
Basal Turn ◽  
Coiling Direction ◽  
Grinding Technique ◽  
Temporal Bones ◽  
Automated Alignment

<b><i>Introduction:</i></b> Electrode array translocation is an unpredictable event with all types of arrays, even using a teleoperated robot in a clinical scenario. We aimed to compare the intracochlear trauma produced by the HiFocus™ Mid-Scala (MS) electrode array (Advanced Bionics, Valencia, CA, USA) using a teleoperated robot, with an automated robot connected to a navigation system to align the pre-curved tip of the electrode array with the coiling direction of the scala tympani (ST). <b><i>Methods:</i></b> Fifteen freshly frozen temporal bones were implanted with the MS array using the RobOtol® (Collin, Bagneux, France). In the first group (<i>n</i> = 10), the robot was teleoperated to insert the electrode array into the basal turn of the ST under stereomicroscopic vision, and then the array was driven by a slow-speed hydraulic insertion technique with an estimated placement of the pre-curved electrode tip. In the second group (<i>n</i> = 5), 3 points were obtained from the preoperative cone-beam computed tomography: the 2 first defining the ST insertion axis of the basal turn and a third one at the center of the ST at 270°. They provided the information to the automated system (RobOtol® connected with a navigation system) to automatically align the electrode array with the ST insertion axis and to aim the pre-curved tip toward the subsequent coiling of the ST. After this, the electrode array was manually advanced. Finally, the cochleae were obtained and fixed in a crystal resin, and the position of each electrode was determined by a micro-grinding technique. <b><i>Results:</i></b> In all cases, the electrode array was fully inserted into the cochlea and the depth of insertion was similar using both techniques. With the teleoperated robotic technique, translocations of the array were observed in 7/10 insertions (70%), but neither trauma nor array translocation occurred with automated robotic insertion. <b><i>Conclusion:</i></b> We have successfully tested an automated insertion system (robot + navigation) that could accurately align a pre-curved electrode array to the axis of the basal turn of the ST and its subsequent coiling, which reduced intracochlear insertion trauma and translocation.

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