Graeme Clark Collection

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http://hdl.handle.net/11343/375

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Author: Clark, Graeme × Author: TYKOCINSKI, MICHAEL × Author: Xu, Jin × End date: 2001 × Start date: 2000 × Type: Journal Article ×

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    The role of radiographic phase-contrast imaging in the development of intracochlear electrode arrays
    XU, JIN ; Stevenson, Andrew W. ; Gao, Dachao ; TYKOCINSKI, MICHAEL ; LAWRENCE, DAVID ; Wilkins, Stephen W. ; Clark, Graeme M. ; Saunders, Elaine ; Cowan, Robert S. ( 2001)
    Objective: This study describes the application of a new radiographic imaging modality, phase-contrast radiography, to in vitro human temporal bone imaging and investigates it use in the development of new electrode arrays for cochlear implants. Background: The development of perimodiolar electrode arrays for cochlear implants requires detailed information from postoperative radiologic assessment on the position of the array in relation to the cochlear structures. Current standard radiographic techniques provide only limited details. Materials and Methods: Nucleus standard electrode arrays and perimodiolar Contour electrode arrays were implanted into the scala tympani of 11 human temporal bones. Both conventional and phase-contrast radiographs were taken of each temporal bone for comparative purposes. Results: Phase-contrast imaging provides better visulization of anatomic details of the inner ear and of the structure of the intracochlear electrode array, and better definition of electrode location in relation to cochlear walls. Conclusion: Phase-contrast radiography offers significant improvement over conventional radiography in images of in vitro human temporal bones. It seems to be a valuable tool in the development of intracochlear electrode arrays and cochlear implant research. However, this new radiographic technique still requires certain computational and physics challenges to be addressed before its clinical use can be established.
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    Comparison of electrode position in the human cochlea using various perimodiolar electrode arrays
    TYKOCINSKI, MICHAEL ; Cohen, Lawrence T. ; Pyman, Brian C. ; Roland (Jr), Thomas ; Treaba, Claudiu ; PALAMARA, JOSEPH ; Dahm, Markus C. ; Shepherd, Robert K. ; XU, JIN ; Cowan, Robert S. ; Cohen, Noel L. ; Clark, Graeme M. ( 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 Cochlear /Melbourne array. Background: Advantages to be expected of a perimodiolar electrode array include 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. Results: All perimodiolar electrode arrays were inserted deeper and showed trajectories that were generally closer to the modiolus compared with the standard electrode array. However, although the precurved array designs did not show significant insertion trauma, the method of insertion needed improvement. After insertion of the straight electrode array with positioner, signs of severe insertion trauma in the majority o fimplanted cochleas were found. Conclusions: Although it was possible to position the electrode arrays close to the modiolus, none of the three perimodiolar designs investigated fulfilled satisfactorily all three criteria of being easy, safe, and a traumatic to implant.