Conventional Cochlear Implants Research Articles

Comparison of Performance for Cochlear-Implant Listeners Using Audio Processing Strategies Based on Short-Time Fast Fourier Transform or Spectral Feature Extraction.

We compared sound quality and performance for a conventional cochlear-implant (CI) audio processing strategy based on short-time fast-Fourier transform (Crystalis) and an experimental strategy based on spectral feature extraction (SFE). In the latter, the more salient spectral features (acoustic events) were extracted and mapped into the CI stimulation electrodes. We hypothesized that (1) SFE would be superior to Crystalis because it can encode acoustic spectral features without the constraints imposed by the short-time fast-Fourier transform bin width, and (2) the potential benefit of SFE would be greater for CI users who have less neural cross-channel interactions. To examine the first hypothesis, 6 users of Oticon Medical Digisonic SP CIs were tested in a double-blind design with the SFE and Crystalis strategies on various aspects: word recognition in quiet, speech-in-noise reception threshold (SRT), consonant discrimination in quiet, listening effort, melody contour identification (MCI), and subjective sound quality. Word recognition and SRTs were measured on the first and last day of testing (4 to 5 days apart) to assess potential learning and/or acclimatization effects. Other tests were run once between the first and last testing day. Listening effort was assessed by measuring pupil dilation. MCI involved identifying a five-tone contour among five possible contours. Sound quality was assessed subjectively using the multiple stimulus with hidden reference and anchor (MUSHRA) paradigm for sentences, music, and ambient sounds. To examine the second hypothesis, cross-channel interaction was assessed behaviorally using forward masking. Word recognition was similar for the two strategies on the first day of testing and improved for both strategies on the last day of testing, with Crystalis improving significantly more. SRTs were worse with SFE than Crystalis on the first day of testing but became comparable on the last day of testing. Consonant discrimination scores were higher for Crystalis than for the SFE strategy. MCI scores and listening effort were not substantially different across strategies. Subjective sound quality scores were lower for the SFE than for the Crystalis strategy. The difference in performance with SFE and Crystalis was greater for CI users with higher channel interaction. CI-user performance was similar with the SFE and Crystalis strategies. Longer acclimatization times may be required to reveal the full potential of the SFE strategy.

Noise exposure of the inner ear during robotic drilling.

Preserving the cochlear structures and thus hearing preservation, has become a prominent topic of discussion in cochlear implant (CI) surgery. Various approaches and soft surgical techniques have been described when approaching the inner ear. Robot-assisted cochlear implant surgery (RACIS) reaches the round window in a minimally invasive manner by following a trajectory of minimal trauma. This involves the drilling of a keyhole trajectory to the round window, through the facial recess, with no need for a complete mastoidectomy. It involves less drilling, less drilling time and less structural damage. A lot of attention has been paid to the structural traumatic causes of hearing loss but acoustic trauma during the exposure of the inner ear appears to be neglected topic. The aim was to measure the noise exposure of the inner ear during the robotic drilling of the mastoid and bony overhang of the round window. The results were compared with the milling in conventional cochlear implantation surgery. RACIS on fresh frozen human cadavers. The equivalent frequency-weighted and time-averaged sound pressure level LAF in dB and the noise dose in % derived from a noise damage model, both obtained during RACIS. The robotic drilling of 6 trajectories towards the inner ear were performed, including 4 trajectories through round window access and 2 trajectories through cochleostomy. The results were compared with the data of 7 cases of conventional CI surgery that have been described in literature. The induced equivalent sound pressure level LAF was determined via an accelleration sensor at the zygomatic arch and a calibration according to bone conduction audiometry. A noise dose for the whole procedure was calculated from the equivalent sound pressure level LAF and the exposure time using a noise damage model. A noise dose of 100% is considered a critical exposure limit and values above are considered potentially harmful, with the risk of hearing impairment. The maximum LAF was 82 dB during fiducial screw placement; 87 dB during middle ear access; 95 dB for the accesses through the round window and 88 dB for the accesses through cochleostomy. The noise dose due to the HEARO®-procedure was always far below the critical value of 100%. There was no acoustic trauma of the inner ear in all cases with the noise dose being smaller than 0.1% in five out of the six cases. The maximum LAF in the seven cases of conventional CI surgery was 118 dB with a maximum cumulative noise dose of 172.6%. The critical exposure limit of 100% was exceeded in three cases of conventional CI surgery. RACIS provokes significantly less acoustic trauma than conventional mastoid surgery in our findings. There were no observable differences in noise exposure levels between a cochleostomy or a round window approach where the bony overhang needed to be drilled.

Comparison of postural control and space perception outcomes between robotic and conventional cochlear implantation in adults.

The aim of the study is to capture the difference between the groups in direct relation to the type of electrode array insertion during cochlear implantation (CI). The robotic insertion is expected to be a more gently option. As recent studies have shown, there is a difference in perception of visual vertical (SVV) and postural control related to the CI. We assume that there can be differences in postural control and space perception outcomes depending on the type of the surgical method. In total, 37 (24 females, mean age ± SD was 42.9 ± 13.0) candidates for CI underwent an assessment. In 14 cases, the insertion of the electrode array was performed by a robotic system (RobOtol, Colin, France) and 23 were performed conventionally. In all of these patients, we performed the same examination before the surgery, the first day, and 3weeks after the surgery. The protocol consists of static posturography and perception of visual vertical. The both groups, RobOtol and conventional, responded to the procedure similarly despite the dissimilar electrode insertion. There was no difference between two groups in the dynamic of perception SVV and postural parameters. Patients in both groups were statistically significantly affected by the surgical procedure, SVV deviation appeared in the opposite direction from the implanted ear: 0.90° ± 1.25; -1.67° ± 3.05 and -0.19° ± 1.78 PRE and POST surgery (p < 0.001). And this deviation was spontaneously adjusted in FOLLOW-UP after 3weeks (p < 0.01) in the both groups. We did not find a significant difference in postural parameters between the RobOtol and conventional group, even over time. Although the robotic system RobOtol allows a substantial reduction in the speed of insertion of the electrode array into the inner ear, our data did not demonstrate a postoperative effect on vestibular functions (SVV and posturography), which have the same character and dynamics as in the group with standard manual insertion. The project is registered on clinicaltrials.gov (registration number: NCT05547113).

Optical method to preserve residual hearing in patients receiving a cochlear implant

IntroductionWorldwide, thousands of patients with severe to profound hearing loss restore their hearing with cochlear implant (CI) devices. Newer developments in electrode design and manufacturing and a better understanding of cochlear mechanics allow for conserving critical structures, often translating into serviceable residual hearing and improving device performance. Monitoring insertion speed and intraluminal pressure helps mitigate some of these challenges. However, the information becomes available after irreparable damage has occurred.MethodsWe developed and tested a high-resolution optical system to navigate the intricate anatomy of the cochlea during electrode insertion. The miniaturized optical system was integrated in conventional cochlear implants electrode arrays and custom-made cochlear probes. Electrode insertion were conducted in eight cadaveric human temporal bones and video recordings were acquired. Micro-computed tomography (μCT) scans were performed to evaluate the position of the modified electrode arrays.ResultsFull insertions of the modified CI electrode were successfully conducted and verified by μCT scans. Video recordings of the cochlear structures visible in scala tympani were acquired, and no scala migration was detected.DiscussionSurgeons can now follow the CI electrode's path during its insertion and reduce cochlear damage through early interventions and steering of the CI electrode. Our device will be compatible with robotic platforms that are already available to insert these electrodes.

A Sleeve-Based, Micromotion Avoiding, Retractable and Tear-Opening (SMART) Insertion Tool for Cochlear Implantation.

In conventional cochlear implantation, the insertion of the electrode array is strongly affected by the local anatomy and human kinematics. Herein, we present a concept for an insertion tool that allows to optimize the insertion trajectory beyond anatomical constraints and stabilizes the electrode array in manual implantation. A novel sleeve-based design allows the instrument to be compliant and potentially protective to intracochlear structures, while a tear-open mechanism allows it to be removed after insertion by simply retracting the tool. Conventional and tool-guided manual insertions were performed by expert cochlear implant surgeons in an analog temporal bone model that allows to simultaneously record intracochlear pressure, insertion forces and electrode array deformation. Comparison between conventional and tool-guided insertions demonstrate a substantial reduction of maximum insertion forces, force variations, transverse intracochlear electrode array movement, and pressure transients. The presented tool can be utilized in manual cochlear implantation and significantly improves key metrics associated with intracochlear trauma. The instrument may ultimately help improve hearing outcomes in cochlear implantation. The versatile design may be used in both manual cochlear implantation and motorized and robotic insertion, as well as image-guided surgery.

Application of a new computer-assisted robotic visualization system in cochlear implantation-Proof of concept.

Over the last decades conventional cochlear implant (CI) surgery has remained essentially unchanged. Nevertheless, alternative implantation techniques to further improve patient outcomes such as endaural implantation or robot-assisted surgery have been proposed in recent years. However, none of these have gained acceptance in clinical routine, thus confirming a demand for new developments. Cochlear implant surgery was performed in two mastoid bones obtained from body donors using a novel hands-free exoscope. Advantages and disadvantages of the system were evaluated. In all cases, implantation of the electrode was feasible. The system allowed for hands-free movement and adjustment of the exoscope by the head-mounted display. Network connectivity of the system leaves room for improvement. The RoboticScope is an innovative tool and can be used supportively in conventional CI surgery in the experimental setting. Although operating the device requires a certain learning curve, the usability is intuitive for every ear surgeon.

Improving the Intelligibility of Speech for Simulated Electric and Acoustic Stimulation Using Fully Convolutional Neural Networks.

Combined electric and acoustic stimulation (EAS) has demonstrated better speech recognition than conventional cochlear implant (CI) and yielded satisfactory performance under quiet conditions. However, when noise signals are involved, both the electric signal and the acoustic signal may be distorted, thereby resulting in poor recognition performance. To suppress noise effects, speech enhancement (SE) is a necessary unit in EAS devices. Recently, a time-domain speech enhancement algorithm based on the fully convolutional neural networks (FCN) with a short-time objective intelligibility (STOI)-based objective function (termed FCN(S) in short) has received increasing attention due to its simple structure and effectiveness of restoring clean speech signals from noisy counterparts. With evidence showing the benefits of FCN(S) for normal speech, this study sets out to assess its ability to improve the intelligibility of EAS simulated speech. Objective evaluations and listening tests were conducted to examine the performance of FCN(S) in improving the speech intelligibility of normal and vocoded speech in noisy environments. The experimental results show that, compared with the traditional minimum-mean square-error SE method and the deep denoising autoencoder SE method, FCN(S) can obtain better gain in the speech intelligibility for normal as well as vocoded speech. This study, being the first to evaluate deep learning SE approaches for EAS, confirms that FCN(S) is an effective SE approach that may potentially be integrated into an EAS processor to benefit users in noisy environments.

Single Supply PWM Fully Implantable Cochlear Implant Interface Circuit With Active Charge Balancing

Low powered fully implantable cochlear implants (FICIs) untangle the aesthetic concerns and battery replacement problems of conventional cochlear implants. However, the reported FICIs lack proper charge balancing and require multiple external supplies to operate. In this work, a complete low power FICI interface circuit is designed that operates with a single supply and uses short-pulse-injection method for charge balancing. The system takes input from multi-channel piezoelectric transducers and stimulates the auditory neurons with pulse width modulated (PWM) output currents. By utilizing pulse width modulation technique with continuous interleaved sampling (CIS) sound processing strategy, a time gap is formed between two consecutive channels. Then, this gap is used for charge balancing operation. Overall power consumption of the low power FICI interface is decreased by clocked gated subthreshold amplifier and rectifier design. Furthermore, power efficient design of analog to digital converter (ADC) enhances the power reduction. The system is tested with an in-vitro test setup and it stimulates a single channel cochlear electrode with 50 dB input dynamic range while consuming $695~\mu \text{W}$ power from a single 1.8 V supply. The implemented FICI system can safely stimulate neurons for more than 18 days (with 16-hour daily operation) with an implantable 200 mWh battery without recharging. Furthermore, the short charge balance current pulses keep the electrode voltage difference after the stimulation within ±100 mV range, which ensures the residual charge is not hazardous for the auditory neurons.

Effects of different electrodes used in bone-guided extracochlear implants on electrical stimulation of auditory nerves in guinea pigs.

Objective:Conventional cochlear implants provide patients who are deaf with hearing via electrical intracochlear stimulations. Stimulation electrodes are inserted into the cochlea through a cochleostomy or round window membrane (RWM) approach. However, these methods might induce cochlear ossificans and loss of residual hearing by damaging inner ear structures. To avoid an invasive electrode insertion, we developed a novel bone-guided extracochlear implant that stimulated the auditory nerves between the cochlear bones and the RWM to prevent cochlea damage. Power consumption plays an important role in wireless implantable electronic devices. Therefore, we aimed to investigate the effects of different electrodes on the stimulating threshold currents of the auditory nerve and the power consumption of bone-guided extracochlear implants using a commercial stimulator.Materials and Methods:Inert aurum (Au) electrodes were compared with biocompatible platinum (Pt) and iridium oxide (IrOx) electrodes in practical implantable applications. IrOx electrodes were used for their high-charge storage capacity, low impedance, and biocompatibility. The electrodes were fabricated via sputtering and were experimentally characterized with cyclic voltammetry and then examined using in vivo tests.Results:Based on electrical auditory brainstem responses, IrOx electrodes yielded lower acoustic nerve-stimulating threshold currents (132 μA) compared with Au electrodes (204 μA). IrOx electrodes also had a lower acoustic nerve stimulating threshold current (132 μA) compared with Pt electrodes (168 μA).Conclusion:As expected, IrOx electrodes were beneficial in the development of multielectrode bone-guided extracochlear implants, with the lowest acoustic nerve-stimulating threshold and current consumptions compared with Au and Pt electrodes.

Asynchronous Event-driven Encoder With Simultaneous Temporal Envelope and Phase Extraction for Cochlear Implants.

Conventional cochlear implants using periodic sampling are power consuming and incapable of capturing the amplitude and phase of the input acoustic signal simultaneously. This paper presents an asynchronous event-driven encoder chip for cochlear implants capable of extracting the temporal fine structure. The chip architecture is based on asynchronous delta modulation (ADM) where the signal peak/trough crossing events are captured and digitized intrinsically, which has the advantages of significantly reduced power consumption, reduced circuit area, and the elimination of dedicated data compression circuitry. An 8-channel prototype chip was fabricated in 0.18 μm 1P6M CMOS process, occupying an area of 0.125 × 1.7 mm2 and has a power consumption of 36.2 μW from a 0.6V supply. A 16-channel stimulation encoding system was built by integrating two test chips, capable of processing the entire audible frequency range from 100 Hz to 10 kHz. Experimental characterization using the human voice is provided to corroborate functionality in the application environment.

Chronic Deafness Degrades Temporal Acuity in the Electrically Stimulated Auditory Pathway

Electrical stimulation of the auditory nerve with a penetrating intraneural (IN) electrode in acutely deafened cats produces much more restricted spread of excitation than is obtained in that preparation with a conventional cochlear implant (CI) as reported by Middlebrooks and Snyder (J Assoc Res Otolaryngol 8:258–279, 2007). That suggests that a future auditory prosthesis employing IN stimulation might offer human patients greater frequency selectivity than is available with a present-day CI. Nevertheless, it is a concern that the electrical field produced by an IN electrode might be too restricted to produce adequate stimulation of the partially depopulated auditory nerve of a deaf patient. We evaluated this by testing responses to IN and CI stimulation in adult-deafened cats. Activation of the auditory pathway was monitored by recording from the central nucleus of the inferior colliculus (ICC). Cats deaf for 153–277 days exhibited a ~ 30 % loss of auditory nerve fibers compared to cats deaf for < 18 h. Contrary to our concern, measures of thresholds and dynamic ranges showed no significant deafness-related impairment of excitation by IN or CN stimulation. Surprisingly, however, temporal acuity decreased dramatically in these adult-deafened cats, as demonstrated by a marked decrease in the maximum rate of electrical cochlear stimulation to which ICC neurons synchronized to IN or CI stimulation. For instance, half of ICC neurons synchronized to IN stimulation up to 203 pulses per second (pps) in acute deafness, whereas that number dropped to 79 pps for chronic deafness. Such a loss of temporal acuity might contribute to the poor sensitivity to temporal fine structure that has been reported in human CI users. Seemingly, the degraded temporal acuity that we observed in cats was even worse than the fine-structure sensitivity of human CI users, suggesting that most patients experience some improvement of temporal acuity resulting from restoration of patterned auditory nerve stimulation by a CI.

Cochlear volume as a predictive factor for residual-hearing preservation after conventional cochlear implantation

Objective: The preservation of residual hearing after conventional cochlear implantation (CI) is frequently observed when atraumatic soft surgery is adopted. The purpose of this study was to elucidate the predictive factors for residual hearing preservation after atraumatic CI.Patients: This study included 46 patients who underwent CI based on an atraumatic technique using a standard-length flexible electrode implant through a round window approach.Main outcome measure: Cochlear volume was measured using magnetic resonance imaging (MRI). Cochlear duct length (CDL) was taken as the length of the scala media measured using computed tomography (CT). The association between residual hearing preservation and cochlear volume/CDL was then examined.Result: Cochlear volume and CDL were significantly larger in patients with complete hearing preservation than in those with hearing loss. Multivariate logistic regression analysis revealed that cochlear volume was a significant predictive factor for residual hearing preservation.Conclusion: Residual hearing preservation after conventional CI was observed in patients with a larger cochlear volume and longer CDL. Cochlear volume could be a predictive factor for residual hearing preservation after conventional CI.

Predictive factor for residual hearing preservation after conventional cochlear implantation

Predictive factor for residual hearing preservation after conventional cochlear implantation

Young age is a positive prognostic factor for residual hearing preservation in conventional cochlear implantation.

To investigate the prognostic significance of various factors in hearing preservation after traditional cochlear implantation (CI). Retrospective case review. Academic tertiary referral center. A total of 153 implantations with mean patient age at implantation of 36 years (from 10 mo to 83 yr) and residual hearing at the frequencies 250, 500, and 1,000 Hz on the unaided preoperative pure-tone audiometry were included. CI with a conventional full-length electrode. The changes on the residual hearing 3 months after implantation were analyzed regarding patients' demographic factors, shape of the preoperative threshold curve, type of the electrode carrier, and approach of electrode insertion in the cochlea. Preservation of residual hearing was defined as measurable postoperative threshold at the frequencies 250, 500, and 1,000 Hz. Preservation of residual hearing was observed in almost half of the cases (47%). In more than half of these patients (54%), a maximal to complete hearing preservation (0-10 dB loss) was achieved. About one-third of these implantations (29%) showed a moderate preservation of residual hearing (11-20 dB loss). In the remaining 17%, the preservation of hearing was marginal (>21 dB loss). Hearing preservation and its extent were significantly better in children and adolescents compared with those in adults. The preservation of residual hearing after conventional CI is possible. Young age seems to have a positive impact on hearing preservation.

Cochlear Implants and Auditory Neuropathy Spectrum Disorder

Objective: The results of cochlear implantation in patients that present with auditory neuropathy spectrum disorder (ANSD) patients have been variably reported. The effectiveness of the treatment modality varies in such patients. Hearing rehabilitation in this group of patients has been very challenging. Considerable controversy exists whether to provide conventional amplification (hearing aids or personal FM systems) or cochlear implants (CI) to children with ANSD. With this background, we present our experience with select subset of ANSD cases that derived benefit from cochlear implant. Methodology: We studied and evaluated all the paediatric cases (i.e. less than 12 years of age) using audiological test battery. The cases with other co-morbidities, abnormality of auditory nerve and cochlea were excluded. Diagnosed cases of ANSD were given bilateral, behind the ear, digital hearing aids as per their behavioural responses for 6 months and enrolled for communication development in the auditory verbal habilitation program. They were evaluated for auditory perception using Category of Auditory Performance scoring system. The ANSD cases that derived “intermediate benefit” as per our criteria at 6 months post hearing aids were taken up for unilateral cochlear implant. All the implanted ANSD cases continued in auditory verbal habilitation program of our hospital and their progress on auditory perception post cochlear implant was monitored using CAP scoring system. Results: A total of 1313 cases were evaluated for hearing loss. Out of these 65 cases were detected to have ANSD (42 bilateral and 23 unilateral ANSD).Unilateral ANSD cases were excluded from the study. Hearing aids were fitted in all the bilateral ANSD cases. After 6 months of hearing aid fitting thirteen ANSD cases showed “intermediate benefit” and were taken up for cochlear implant. After 6 months of implant usage all ANSD cases showed “good” progress on CAP. Conclusion: Hearing aid trial should be given to all the cases diagnosed with ANSD and those who derive “intermediate benefit” from hearing aids and AVT should be considered for cochlear implant.

Optical cochlear implant: evaluation of insertion forces of optical fibres in a cochlear model and of traumata in human temporal bones

Optical stimulation for hearing restoration is developing as an alternative therapy to electrical stimulation. For a more frequency-specific activation of the auditory system, light-guiding fibres need to be inserted into the coiled cochlea. To enable insertion with minimal trauma, glass fibres embedded in silicone were used as models. Thus, glass fibres of varying core/cladding diameter with and without silicon coating (single as well as in bundles) were inserted into a human scala tympani (ST) model. Insertion cochlear model force measurements were performed, and the thinner glass fibres that showed low insertion forces in the model were inserted into cadaveric human temporal bones. Silicone-coated glass fibres with different core/cladding diameters and bundle sizes could be inserted up to a maximum depth of 20 mm. Fibres with a core/cladding diameter of 50/55 μm break during insertion deeper than 7-15 mm into the ST model, whereas thinner fibres (20/25 μm) could be inserted in the model without breakage and in human temporal bones without causing trauma to the inner ear structures. The insertion forces of silicone-coated glass fibres are comparable to those measured with conventional cochlear implant (CI) electrodes. As demonstrated in human temporal bones, a minimal traumatic implantation of an optical CI may be considered feasible.

Improved Perception of Music With a Harmonic Based Algorithm for Cochlear Implants

The lack of fine structure information in conventional cochlear implant (CI) encoding strategies presumably contributes to the generally poor music perception with CIs. To improve CI users' music perception, a harmonic-single-sideband-encoder (HSSE) strategy was developed , which explicitly tracks the harmonics of a single musical source and transforms them into modulators conveying both amplitude and temporal fine structure cues to electrodes. To investigate its effectiveness, vocoder simulations of HSSE and the conventional continuous-interleaved-sampling (CIS) strategy were implemented. Using these vocoders, five normal-hearing subjects' melody and timbre recognition performance were evaluated: a significant benefit of HSSE to both melody (p < 0.002) and timbre (p < 0.026) recognition was found. Additionally, HSSE was acutely tested in eight CI subjects. On timbre recognition, a significant advantage of HSSE over the subjects' clinical strategy was demonstrated: the largest improvement was 35% and the mean 17% (p < 0.013). On melody recognition, two subjects showed 20% improvement with HSSE; however, the mean improvement of 7% across subjects was not significant (p > 0.090). To quantify the temporal cues delivered to the auditory nerve, the neural spike patterns evoked by HSSE and CIS for one melody stimulus were simulated using an auditory nerve model. Quantitative analysis demonstrated that HSSE can convey temporal pitch cues better than CIS. The results suggest that HSSE is a promising strategy to enhance music perception with CIs.

Nanosecond laser pulse stimulation of the inner ear-a wavelength study.

Optical stimulation of the inner ear, the cochlea, is discussed as a possible alternative to conventional cochlear implants with the hypothetical improvement of dynamic range and frequency resolution. In this study nanosecond-pulsed optical stimulation of the hearing and non-hearing inner ear is investigated in vivo over a wide range of optical wavelengths and at different beam delivery locations. Seven anaesthetized guinea pigs were optically stimulated before and after neomycin induced destruction of hair cells. An optical parametric oscillator was tuned to different wavelengths (420 nm–2150 nm, ultraviolet to near-infrared) and delivered 3–5 ns long pulses with 6 µJ pulse energy via a multimode optical fiber located either extracochlearly in front of the intact round window membrane or intracochlearly within the scala tympani. Cochlear responses were measured using registration of compound action potentials (CAPs). With intact hair cells CAP similar to acoustic stimulation were measured at both locations, while the neomycin treated cochleae did not show any response in any case. The CAP amplitudes of the functional cochleae showed a positive correlation to the absorption coefficient of hemoglobin and also to moderate water absorption. A negative correlation of CAP amplitude with a water absorption coefficient greater than 5.5 cm−1 indicates additional phenomena. We conclude that in our stimulation paradigm with ns-pulses the most dominant stimulation effect is of optoacoustic nature and relates to functional hair cells.

Effect of Surgical Technique on Electrode Impedance after Cochlear Implantation

We compare the evolution of electrode impedance values (IVs) following either conventional cochlear implantation or implantation by the soft surgery (SS) technique. We performed a retrospective chart review of 20 consecutive adult patients who underwent implantation with the Nucleus CA 24 device between 2004 and 2007. Five patients with preoperative residual hearing at the frequencies 256, 512, and 1,024 Hz underwent implantation by an SS cochlear implantation technique (SS group), and the 15 other patients underwent a conventional implantation technique (conventional cochleostomy [CC] group). The active electrodes were classified as distal (17 to 22), middle (10 to 16), or proximal (3 to 9) according to their position in relation to the tip of the electrode array. Their IVs were collected at 1, 3, 12, 24, and 36 months after implantation. Changes in auditory thresholds at 3 and 24 months were reported for patients in the SS group. The postoperative IVs of both the CC and SS groups decreased significantly between 1 and 3 months after implantation (p < 0.05) and then remained stable. The IVs after 12 months were significantly lower (p < 0.05) in the SS group than in the CC group. Patients who underwent the SS technique displayed lower long-term electrode IVs than did their counterparts in the CC group. If electrode IVs are indeed an indirect representation of cochlear fibrosis, the use of the SS technique in lieu of the CC technique could reduce fibrotic development.

Implications of Minimizing Trauma During Conventional Cochlear Implantation

To describe the relationship between implantation-associated trauma and postoperative speech perception scores among adult and pediatric patients undergoing cochlear implantation using conventional length electrodes and minimally traumatic surgical techniques. Retrospective chart review (2002-2010). Tertiary academic referral center. All subjects with significant preoperative low-frequency hearing (≤70 dB HL at 250 Hz) who underwent cochlear implantation with a newer generation implant electrode (Nucleus Contour Advance, Advanced Bionics HR90K [1J and Helix], and Med El Sonata standard H array) were reviewed. Preimplant and postimplant audiometric thresholds and speech recognition scores were recorded using the electronic medical record. Postimplantation pure tone threshold shifts were used as a surrogate measure for extent of intracochlear injury and correlated with postoperative speech perception scores. : Between 2002 and 2010, 703 cochlear implant (CI) operations were performed. Data from 126 implants were included in the analysis. The mean preoperative low-frequency pure-tone average was 55.4 dB HL. Hearing preservation was observed in 55% of patients. Patients with hearing preservation were found to have significantly higher postoperative speech perception performance in the CI-only condition than those who lost all residual hearing. Conservation of acoustic hearing after conventional length cochlear implantation is unpredictable but remains a realistic goal. The combination of improved technology and refined surgical technique may allow for conservation of some residual hearing in more than 50% of patients. Germane to the conventional length CI recipient with substantial hearing loss, minimizing trauma allows for improved speech perception in the electric condition. These findings support the use of minimally traumatic techniques in all CI recipients, even those destined for electric-only stimulation.