Objectives/Hypothesis Three surgical approaches: cochleostomy (C), round window (RW), and extended round window (ERW); and two electrodes types: lateral wall (LW) and perimodiolar (PM), account for the vast majority of cochlear implantations. The goal of this study was to analyze the relationship between surgical approach and electrode type with final intracochlear position of the electrode array and subsequent hearing outcomes. Study Design Comparative longitudinal study. Methods One hundred postlingually implanted adult patients were enrolled in the study. From the postoperative scan, intracochlear electrode location was determined and using rigid registration, transformed back to the preoperative computed tomography which had intracochlear anatomy (scala tympani and scala vestibuli) specified using a statistical shape model based on 10 microCT scans of human cadaveric cochleae. Likelihood ratio chi-square statistics were used to evaluate for differences in electrode placement with respect to surgical approach (C, RW, ERW) and type of electrode (LW, PM). Results Electrode placement completely within the scala tympani (ST) was more common for LW than were PM designs (89% vs. 58%; P < 0.001). RW and ERW approaches were associated with lower rates of electrode placement outside the ST than was the cochleostomy approach (9%, 16%, and 63%, respectively; P < 0.001). This pattern held true regardless of whether the implant was LW or PM. When examining electrode placement and hearing outcome, those with electrode residing completely within the ST had better consonant-nucleus-consonant word scores than did patients with any number of electrodes located outside the ST (P = 0.045). Conclusion These data suggest that RW and ERW approaches and LW electrodes are associated with an increased likelihood of successful ST placement. Furthermore, electrode position entirely within the ST confers superior audiological outcomes. Level Of Evidence 2b.

In agreement with previously reported data, subjects with bilateral cochlear implants localized sounds in the horizontal plane remarkably well when using both of their devices, but they generally could not localize sounds when either device was deactivated. They could localize the speech signal with slightly, but significantly better accuracy than the noise, possibly due to spectral differences in the signals, to the availability of envelope ITD cues with the speech but not the noise signal, or to more central factors related to the social salience of speech signals. For most subjects the remarkable ability to localize sounds has stabilized by 5 mo after activation. However, for some subjects who perform poorly initially, there can be substantial improvement past 5 mo. Results from Experiment 2 suggest that ILD cues underlie localization ability for noise signals, and that ITD cues do not contribute.

Objectives-1) Investigate the impact of electrode type and surgical approach on scalar electrode location in a large patient cohort; and 2) examine the relation between electrode location and postoperative audiologic performance. Setting-Tertiary academic hospital. Patients-220 post-lingually deafened adults undergoing cochlear implant (CI).Main Outcome Measures-Primary outcome measures of interest were scalar electrode location and postoperative audiologic performance.Results-In 68% of implants, electrodes were observed to be located solely in the scala tympani (ST). Multivariate analysis demonstrated perimodiolar(PM) and Mid-scala(MS) electrodes were p<0.001) times more likely to have at least one electrode in the scala vestibuli (SV) compared to lateral wall(LW) electrodes, respectively. Compared to cochleostomy(C), round window(RW) and extended round window(ERW) approaches demonstrated 70% reduction in SV insertion (OR 0.28,95%CI:0.1-0.8, p=0.01; ERW (OR O.28,95%CI:0.1-0.7, p=0.005). Examining postoperative audiometric performance, CNC score increased 0.6% with every 10° increase in angular insertion depth beyond the group minimum of 208° (Coefficient 0.0006,95%CI:0.0001-0.001, p=0.03). SV insertion was associated with a 12% decrease in CNC score (Coefficient -0.12,95%CI:-0.22--0.02, p=0.02). CNC score decreased 0.3% for every 1 year increase in age (Coefficient -0.003,95%CI:-0.006--0.0006), p=0.02). HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusions-Electrode design and surgical approach were predictors of scalar electrode location. Specifically, LW electrodes showed higher rates of ST insertion compared to PM or MS. RW and ERW approaches showed higher rates of ST insertion when compared to C. In regards to performance, ST insertion, younger age, and greater angular insertion depth were predictors of improved CNC scores.

Difficulty in proving efficacy of a single modality is present in all studies on SNHL secondary to multiple treatment protocols, variable rates of recovery, and a high rate of spontaneous recovery. Forty percent of patients showed some improvement in SDS or PTA after treatment failure. When criteria of 20-dB PTA or 20% is considered to define improvement, the recovery rate was 27.5%. Modest improvement is seen with the current protocol of a single intratympanic steroid injection of 24 mg/mL dexamethasone in patients who failed systemic therapy. Dramatic hearing recovery in treatment failures was rarely encountered. No patient showed significant benefit from intratympanic steroids after 36 days when using this protocol for idiopathic sudden SNHL. If patients injected after 6 weeks are excluded from the study, the improvement rate increases from 26.9% to 39.3%. Earlier intratympanic injection had a significant impact on hearing recovery, although with any therapeutic intervention for sudden SNHL, early success may be attributed to natural history. If we further exclude seven patients treated with intratympanic steroids within 2 weeks of the onset of symptoms (i.e., study only those patients treated with intratympanic dexamethasone between 2 and 6 weeks after onset of symptoms), still, 26% improved by 20 dB or 20% SDS. The recovery rates after initial systemic failure are higher than would be expected in this treatment failure group given our control group (9.1%) and literature review. These findings indicate a positive effect from steroid perfusion in this patient population.

These results support a growing consensus that bilateral implantation provides functional benefits beyond those of unilateral implantation. Longitudinal data suggest that some aspects of binaural processing continue to develop up to 1 yr after implantation. The squelch effect, often reported as absent or rare in previous studies of bilateral cochlear implantation, was present for most subjects at the 1 yr measurement interval.

Over the last 20 years, cochlear implants (CIs) have become what is arguably the most successful neural prosthesis to date. Despite this success, a significant number of CI recipients experience marginal hearing restoration, and, even among the best performers, restoration to normal fidelity is rare. In this article, we present image processing techniques that can be used to detect, for the first time, the positions of implanted CI electrodes and the nerves they stimulate for individual CI users. These techniques permit development of new, customized CI stimulation strategies. We present one such strategy and show that it leads to significant hearing improvement in an experiment conducted with 11 CI recipients. These results indicate that image-guidance can be used to improve hearing outcomes for many existing CI recipients without requiring additional surgical procedures.

Cochlear implant surgery is a procedure performed to treat profound hearing loss. Clinical results suggest that implanting the electrode in the scala tympani, one of the two principal cavities inside the cochlea, may result in better hearing restoration. Segmentation of intra-cochlear cavities could thus aid the surgeon to choose the point of entry and angle of approach that maximize the likelihood of successful implant insertion, which may lead to more substantial hearing restoration. However, because the membrane that separates the intra-cochlear cavities is too thin to be seen in conventional in vivo imaging, traditional segmentation techniques are inadequate. In this work, we circumvent this problem by creating an active shape model with micro CT (μCT) scans of the cochlea acquired ex-vivo. We then use this model to segment conventional CT scans. The model is fitted to the partial information available in the conventional scans and used to estimate the position of structures not visible in these images. Quantitative evaluation of our method, made possible by the set of μCTs, results in dice similarity coefficients averaging 0.75. Mean and maximum surface errors average 0.21 and 0.80 mm.

The cochlear implant (CI) has been labeled the most successful neural prosthesis. Despite this success, a significant number of CI recipients experience poor speech understanding, and, even among the best performers, restoration to normal auditory fidelity is rare. While significant research efforts have been devoted to improving stimulation strategies, few developments have led to significant hearing improvement over the past two decades. We have recently introduced image processing techniques that open a new direction for advancement in this field by making it possible, for the first time, to determine the position of implanted CI electrodes relative to the nerves they stimulate using computed tomography images. In this article, we present results of an image-guided, patient-customized approach to stimulation that utilizes the electrode position information our image processing techniques provide. This approach allows us to identify electrodes that cause overlapping stimulation patterns and to deactivate them from a patient's map. This individualized mapping strategy yields significant improvement in speech understanding in both quiet and noise as well as improved spectral resolution in the 68 adult CI recipients studied to date. Our results indicate that image guidance can improve hearing outcomes for many existing CI recipients without requiring additional surgery or the use of ‘experimental' stimulation strategies, hardware or software. i 2014 S. Karger AG, Basel