Graeme Clark Collection

Permanent URI for this collection

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

Filters

1997 - 1999 3
Reset filters

Settings
Statistics
Citations
Author: COHEN, LAWRENCE × Author: PYMAN, BRIAN × End date: 1999 × Start date: 1991 × Subject: cochlear implants ×

Search Results

Now showing 1 - 3 of 3
  • Item
    Thumbnail Image
    Insertion study using new peri-modiolar electrode array designs [Abstract]
    Treaba, Claudiu ; Clark, Graeme M. ; Cowan, Robert S. ; Tykocinski, Michael J. ; Cohen, Lawrence T. ; Saunders, Elaine ; Pyman, Brian C. ; Briggs, Robert S. ; Dahm, Markus C. ( 1999)
    Intracochlear multi-channel cochlear implants have been shown to successfully provide auditory information for profoundly deaf patients by electrically stimulating discrete populations of auditory nerve fibers via a scala tympani (ST) electrode array. Histological and radiological examination of implanted human temporal bones showed that the current straight Nucleus® array is usually positioned against the outer wall of the ST. An electrode array close to the modiolus could be expected to reduce stimulation thresholds and result in a more localized neural excitation pattern.
  • Item
    Thumbnail Image
    Benefits of pre-curved electrode arrays for the Nucleus multichannel cochlear implant [Abstract]
    Pyman, B. ; Clark, Graeme M. ; Saunders, Elaine ; Cohen, Lawrence T. ; Cowan, Robert S. C. ; Treaba, C. ; Dahm, M. ; Tykocinski, M. ( 1998)
    The purpose of the study was to evaluate whether placement of an electrode closer to the modiolus would provide a more efficient interface with the auditory nerve. A pre-curved, banded 22-electrode array has been developed. Following comprehensive safety studies, the array was inserted in three adult patients. Detailed x-ray analyses have been conducted to specify the positions of the electrode bands. Psychophysical studies have been conducted, within each subject, using electrodes which lie at differing distances from the modiolus. These studies have shown that as the distance from the modiolus decreased, electrode threshold currents decreased and dynamic ranges increased. Thresholds were lower than in a comparison group of standard array users. Forward masking studies showed current spread to be more focused at the electrodes lying closer to the modiolus. Electrode discrimination was also better at electrodes closer to the modiolus. JND for loudness, expressed as a function of dynamic range also decreased in this condition. Thus, a preliminary profile of the parameters of interest, for an improved implant design, suggest that an array which lies closer to the modiolus can result in lower current requirements and a more localised pattern of neural excitation.
  • Item
    Thumbnail Image
    Peri-modiolar electrode arrays: a comparison of electrode position n the human temporal bone
    Shepherd, R. K. ; Treaba, C. G. ; Cohen, L. ; Pyman, B. ; Huigen, J. ; Xu, J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    This paper describes a radiologic evaluation of three types of peri-modiolar arrays, comparing their trajectory within the scala tympani with a standard Mini-22 electrode. All peri-modiolar arrays were found to lie closer to the modiolus for much of their insertion length compared with the standard array. While one design showed evidence for the potential of increased insertion trauma, two designs produced satisfactory results. Although further electrode development, temporal bone and histopathologic studies arE required, it would appear that the benefits of peri-modiolar electrode arrays will be realised clinically.