Effectiveness of Phantom Stimulation in Shifting the Pitch Percept in Cochlear Implant Users.

Objectives: Phantom electrode stimulation was developed for cochlear implant (CI) systems to provide a lower pitch percept by stimulating more apical regions of the cochlea, without inserting the electrode array deeper into the cochlea. Phantom stimulation involves simultaneously stimulating a primary and a compensating electrode with opposite polarity, thereby shifting the electrical field toward the apex and eliciting a lower pitch percept. The current study compared the effect sizes (in shifts of place of excitation) of multiple phantom configurations by matching the perceived pitch with phantom stimulation to that perceived with monopolar stimulation.

Evidence-Based Inclusion Criteria for Cochlear Implantation in Patients With Postlingual Deafness.

Objectives: This study determined the relationship between preoperative phoneme and word scores and the gain in speech perception after cochlear implantation in a large cohort of patients. The authors aimed to define evidence-based selection criteria for cochlear implantations in adults with postlingual deafness.

Design: This retrospective study included 364 adults with postlingual deafness who received a cochlear implant between 2000 and 2013 at the Leiden University Medical Center.

Diversity in cochlear morphology and its influence on cochlear implant electrode position.

Objectives: To define a minimal set of descriptive parameters for cochlear morphology and study its influence on the cochlear implant electrode position in relation to surgical insertion distance.

Design: Cochlear morphology and electrode position were analyzed using multiplanar reconstructions of the pre- and postoperative CT scans in a population of 336 patients (including 26 bilaterally implanted ones) with a CII HiFocus1 or HiRes90K HiFocus1J implant. Variations in cochlear diameter and cochlear canal size were analyzed.

Threshold levels of dual electrode stimulation in cochlear implants.

Simultaneous stimulation on two contacts (current steering) creates intermediate pitches between the physical contacts in cochlear implants. All recent studies on current steering have focused on Most Comfortable Loudness levels and not at low stimulation levels. This study investigates the efficacy of dual electrode stimulation at lower levels, thereby focusing on the requirements to correct for threshold variations.

Restoring speech perception with cochlear implants by spanning defective electrode contacts.

Conclusion: Even with six defective contacts, spanning can largely restore speech perception with the HiRes 120 speech processing strategy to the level supported by an intact electrode array. Moreover, the sound quality is not degraded.

Objectives: Previous studies have demonstrated reduced speech perception scores (SPS) with defective contacts in HiRes 120.

Spread of excitation and channel interaction in single- and dual-electrode cochlear implant stimulation.

Objectives: To determine how simultaneous dual-electrode stimulation (DES) can be optimized for the individual patient to deliver better sound quality and speech recognition. DES was compared with single-electrode stimulation (SES) with respect to the site of stimulation (X) in the cochlea, the spread of excitation (SOE), and channel interaction. Second, it was investigated whether the number of intermediate pitches created with DES can be predicted from SOE, channel interaction measures, current distribution in the cochlea, or distance of the electrode to the medial wall.

Influence of widening electrode separation on current steering performance.

Objectives: Current steering between adjacent electrodes makes it possible to create more spectral channels than the number of electrodes in an electrode array. With current steering on nonadjacent electrodes, called "spanning," it could be possible to bridge a defective electrode contact or potentially reduce the number of electrode contacts for the same level of access to the auditory nerve. This study investigates the effectiveness of spanning in terms of the number of intermediate pitches, loudness effects, and linearity of the current weighting coefficient (α) with respect to the perceived pitch.

Simultaneous and non-simultaneous dual electrode stimulation in cochlear implants: evidence for two neural response modalities.

Conclusion: There are two modalities of dual electrode stimulation: a shifting, continuous excitation, which is the desired effect, and a split excitation with considerable variation in loudness. The first one most likely occurs in the basal turn, with adjacent contacts, stimulated simultaneously rather than sequentially.

Objectives: This study examines the effects on place pitch and loudness of simultaneous current steering and sequential stimulation.