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Cochlear Implants
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Andrew Marshall, Stephen Broomfield
Traditionally, any residual hearing in an ear receiving a cochlear implant would be lost. With current surgical techniques (described in ‘Surgical technique’ below), it is possible to preserve hearing in some cases. This allows for combining a hearing aid with a cochlear implant in the same ear, known as electric–acoustic stimulation (EAS). Typically, this applies to the patient with a ‘ski-slope’ hearing loss, i.e. some hearing in low frequencies, dropping abruptly to a severe to profound loss in the higher frequencies such that the criteria for CI are still met. Specially designed electrode arrays are available for this situation, for example the ‘Hybrid’ electrode (Cochlear Ltd) that is shorter than other electrodes, entering only the basal turn of the cochlea and therefore covering just the higher frequencies. Many surgeons prefer, however, to use a medium or standard-length atraumatic electrode with which residual hearing can often still be preserved; but should hearing be lost, the full range of frequencies is covered by the electrode, ensuring optimal performance.
Precise evaluation of the postoperative cochlear duct length by flat-panel volume computed tomography – Application of secondary reconstructions
Published in Cochlear Implants International, 2022
Philipp Schendzielorz, Lukas Ilgen, Franz-Tassilo Müller-Graff, Laurent Noyalet, Johannes Völker, Johannes Taeger, Rudolf Hagen, Tilmann Neun, Simon Zabler, Daniel Althoff, Kristen Rak
In the preoperative diagnostics for cochlear implantation, there is an increasing interest in the exact determination of the two-turn (2TL) or cochlear duct length (CDL) in order to select the correct electrode (Alexiades et al., 2015; Koch, Elfarnawany, et al., 2017). The aim is to obtain appropriate cochlear coverage without provoking cochlear damage, especially regarding a possible application of electric-acoustic stimulation (O'Connell et al., 2017). In addition, the exact CDL is required for the prediction of a frequency map (Anandhan Dhanasingh, 2020; D. D. Greenwood, 1990). Postoperatively, the relationship between the CDL and the electrode contacts is of particular interest for continuative frequency fitting processes (Jiam et al., 2016, 2019; Landsberger et al., 2015; Schurzig, Timm, Batsoulis, John, et al., 2018; Timm et al., 2018).
Stapedius reflex evoked in free sound field in cochlear implant users compared to normal-hearing listeners
Published in International Journal of Audiology, 2021
Annett Franke-Trieger, Willy Mattheus, Josef Seebacher, Thomas Zahnert, Marcus Neudert
All participants used maps with the maximum stimulation rate. Most participants used biphasic pulses except for one bilaterally implanted subject exhibiting facial nerve co-stimulation and thus using triphasic pulses on both ears. The lowest frequency transmitted through the CI system ranged from 0.07 kHz to 0.1 kHz for all patients, except for two who had residual hearing in the low frequency region. One of these two patients uses an acoustic component for electric-acoustic stimulation with a crossover frequency of 0.375 kHz. The other one exhibits hearing threshold levels around 15 dB HL below 0.5 kHz using a map with lower frequency of 0.3 kHz. Accordingly, there is no need for using an acoustic component in this patient. The upper frequency limit was the default value of the CI system of 8.5 kHz in all subjects. The backend compression (MAPLAW) was set to the default value of 500 in all patients, with four exceptions using a MAPLAW of 300 (N = 1), 600 (N = 1) and 750 (N = 2). The number of active electrodes ranged from nine to twelve. The reduction of the number of active electrodes had different reasons: in most cases overall sound impression, co-stimulation of the facial nerve in one patient, and migration of the electrode array resulting in three electrodes located outside of the cochlea in another patient. With these adjustments of the CI system, the participants reached PTA4 (mean of hearing level at 0.5, 1, 2 and 4 kHz) values ranging from 22 to 53 dB HL, with a mean ± standard deviation of 39 ± 7 dB HL.
Initial hearing preservation outcomes of cochlear implantation with a slim perimodiolar electrode array
Published in Cochlear Implants International, 2021
Erika Woodson, Rebecca Chota Nelson, Molly Smeal, Thomas Haberkamp, Sarah Sydlowski
Cochlear implantation (CI) is a common treatment option for post-lingual adults with moderate to profound sensorineural hearing loss and poor speech understanding. Additionally, candidacy assessment has advanced to include patients with potentially serviceable acoustic hearing. Surgeons routinely attempt to preserve low frequency hearing during CI surgery to allow patients access to both electric and acoustic stimulation post-operatively. Electric-acoustic stimulation (EAS) has been shown to confer performance benefits (Büchner et al. 2009; Gifford et al. 2013; Sheffield et al. 2015). Recent studies have suggested that electrode design, as well as surgical technique, play a role in initial low frequency hearing preservation (HP) (Carlson et al. 2011; Mady et al. 2017; O'Connell et al. 2016).