Comparative Study of Cochlear Damage With Three Perimodiolar Electrode Designs (original) (raw)
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Acta Oto-Laryngologica, 2006
Conclusions. Except for basal cochlear traumatization, all specimens implanted into scala tympani showed atraumatic insertion properties and good perimodiolar electrode positioning. Cochleostomy preparation and placement can have a significant impact on levels of basal cochlear trauma. Objective. In the past, perimodiolar cochlear implant electrodes increased the risk for intracochlear traumatization when compared to free-fitting arrays. Recently, however, clinical evidence for atraumatic perimodiolar implantations with preservation of residual hearing has been described. The aim of this paper was to histologically evaluate a perimodiolar cochlear implant array for its insertion properties in cadaver human temporal bones. Surgical and electrode factors, as well as preparation artifacts influencing intracochlear trauma, were considered in the evaluation. Materials and methods. Sixteen human temporal bones were harvested up to 24 hours post mortem and implanted immediately with the Nucleus 24 Contour Advance cochlear implant electrode array. Implantations were either performed using a regular caudal approach cochleostomy or through the round window membrane. After implantation, all bones underwent special histological processing, which allowed sectioning of undecalcified bone. Insertion properties were evaluated according to a grading system. Results. Fourteen specimens were implanted into scala tympani and only two exhibited basal trauma attributable to electrode insertion characteristics. Two bones were implanted into scala vestibuli after causing trauma in the region of the cochleostomy. Insertion depths ranged from 1808 to 4008. All bones showed good perimodiolar electrode positioning. Basal trauma due to surgical issues and histological artifacts was present in 10 of 16 bones.
BioMed Research International, 2015
Hypothesis. This study aimed to evaluate whether there is a difference in the degree of intracochlear trauma when the cochlear implant electrode arrays is inserted through different quadrants of the round window membrane.Background. The benefits of residual hearing preservation in cochlear implant recipients have promoted the development of atraumatic surgeries. Minimal trauma during electrode insertion is crucial for residual hearing preservation.Methods. In total, 25 fresh human temporal bones were subjected to mastoidectomy and posterior tympanotomy. The cochlear implant electrode array was inserted through the anterosuperior quadrant of the round window membrane in 50% of the bones and through the anteroinferior quadrant in the remaining 50%. The temporal bones were dehydrated, embedded in epoxy, serially polished, stained, viewed through a stereomicroscope, and photographed with the electrode arraysin situ. The resulting images were analyzed for signs of intracochlear trauma.Re...
Comparison of Electrode Position In the Human Cochlea Using Various Perimodiolar Electrode Arrays
Otology & …, 2000
Objective: This study was conducted to evaluate the insertion properties and intracochlear trajectories of three perimodiolar electrode array designs and to compare these designs with the standard CochlearlMelbourne array. Background: Advantages to be expected of a perimodiolar electrode array inclu<;le both a reduction in stimulus thresholds and an increase in dynamic range, resulting in a more localized stimulation pattern of the spiral ganglion cells, reduced power consumption, and, therefore, longer speech processor battery life. Methods: The test arrays were implanted into human temporal bones. Image analysis was performed on a radiograph taken after the insertion. The cochleas were then histologically processed with the electrode array in situ, and the resulting sections were subsequently assessed for position of the electrode array as well as insertion-related intracochlear damage. Intracochlear multichannel cochlear implants have successfully provided auditory information for profoundly deaf patients by electrically stimulating discrete populations of auditory nerve fibers via a scala tympani electrode array. The straight, yet flexible, tapered Melbourne/Cochlear electrode array can be safely implanted into the human cochlea. However, histologic and radiologic examination of implanted temporal bones showed that the electrode array is usually positioned along the outer wall of the scala tympani (1-5). The array is, therefore, some distance from the spiral ganglion cells in the Rosenthal canal and their peripheral processes. However,
Otology & Neurotology, 2011
Objectives: This study aimed to evaluate an atraumatic prototype electrode carrier for cochlear implantation, the FLEX EAS 20 electrode. This electrode is designed to preserve hearing and to achieve a 360-degree insertion. Study Design: A cross-sectional human temporal bone study was conducted. Setting: Preliminarily, the prototype electrode was inserted in a scala tympani model to measure the insertion force. Thirteen human temporal bones were acquired postmortem and implanted with the new device using the round window approach. Three of them were implanted under radiologic control to demonstrate the insertion path. After embedding, the remaining 10 temporal bones were sectioned undecalcified and examined macroscopically and histologically. Main Outcome Measures: The insertion force was measured to determine intracochlear resistance peaks. The insertion angle was measured, and the degree of intracochlear trauma was determined. Results: The round window approach caused cochlear trauma in 1 of 10 specimens. An exact 360-degree insertion was achieved in 7 of 10 specimens (mean overall insertion angle, 360 degrees). Radiologic examination and insertion force measurements revealed the smooth and atraumatic insertion. Conclusion: The new prototype electrode carrier is suitable for clinical application. It can be handled easily and allows atraumatic 360-degree insertion of all electrode contacts. Therefore, this electrode concept allows good coverage of the cochlea for electrical and additional acoustic stimulation.
Perimodiolar electrodes—radiological and histological findings
International Congress Series, 2003
New electrode developments try to place stimulating electrodes near to the modiolus. Possible advantages are lower stimulation thresholds and a better channel separation. A position close to the modiolus can be facilitated by different means: preformed electrode shape (Contourk electrode, Cochlear, Australia), additional positioning elements like silicon in a space-filling matter (Clarion 1.2R electrode with positioner and HiFocusR electrode with positioner, Advanced Bionics, USA) and additional silicon-covered wires that allow a positioning of the electrode lead by retropositioning after insertion (perimodiolar electrode, MedEl, Austria).
Hearing research, 2016
Cochlear implant insertion should be as least traumatic as possible in order to reduce trauma to the cochlear sensory structures. The force applied to the cochlea during array insertion should be controlled to limit insertion-related damage. The relationship between insertion force and histological traumatism remains to be demonstrated. Twelve freshly frozen cadaveric temporal bones were implanted with a long straight electrodes array through an anterior extended round window insertion using a motorized insertion tool with real-time measurement of the insertion force. Anatomical parameters, measured on a pre-implantation cone beam CT scan, position of the array and force metrics were correlated with post-implantation scanning electron microscopy images and histological damage assessment. An atraumatic insertion occurred in six cochleae, a translocation in five cochleae and a basilar membrane rupture in one cochlea. The translocation always occurred in the 150- to 180-degree region. ...
Temporal Bone Results and Hearing Preservation with a New Straight Electrode
Audiology and Neurotology, 2006
Due to improved technology, cochlear implant (CI) candidacy has been widened towards patients with usable residual hearing in the low frequency range. These patients might benefit from additional acoustic amplification provided that residual hearing can be preserved with cochlear implantation. To provide a high probability of hearing preservation, a new electrode array was designed and developed at the Medizinische Hochschule Hannover. This ‘Hybrid-L’ electrode array has 22 electrodes spread over 15 mm with an overall insertion depth of 16 mm. The straight electrode with modiolus facing contacts is designed for a round window insertion. It shall provide the full range of the currently most advanced Nucleus CI system. A temporal bone study demonstrated the favorable insertion characteristics and minimized trauma to intracochlear structures. Compared to standard CI electrodes especially no basilar membrane perforation could be found. So far, 4 patients have been implanted and residual...
An improved cochlear implant electrode array for use in experimental studies
2011
Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experimental animals. We compared the insertion depth and trauma associated with the insertion of Cochlear Ltd's Hybrid-L (HL) array with a standard 8 ring array in cat cochleae. Both arrays were inserted into cadaver cochleae and an X-ray recorded their anatomical location. The implanted cochlea was serially sectioned and photographed at 300µm intervals for evidence of electrode insertion trauma.