FLEX Electrode Research Articles

Integrated Electrochemical Aptamer Biosensing and Colorimetric pH Monitoring via Hydrogel Microneedle Assays for Assessing Antibiotic Treatment.

Current methods for therapeutic drug monitoring (TDM) have a long turnaround time as they involve collecting patients' blood samples followed by transferring the samples to medical laboratories where sample processing and analysis are performed. To enable real-time and minimally invasive TDM, a microneedle (MN) biosensor to monitor the levels of two important antibiotics, vancomycin (VAN) and gentamicin (GEN) is developed. The MN biosensor is composed of a hydrogel MN (HMN), and an aptamer-functionalized flexible (Flex) electrode, named HMN-Flex. The HMN extracts dermal interstitial fluid (ISF) and transfers it to the Flex electrode where sensing of the target antibiotics happens. The HMN-Flex performance is validated ex vivo using skin models as well as in vivo in live rat animal models. Data is leveraged from the HMN-Flex system to construct pharmacokinetic profiles for VAN and GEN and compare these profiles with conventional blood-based measurements. Additionally, to track pH and monitor patient's response during antibiotic treatment, an HMN is developed that employs a colorimetric method to detect changes in the pH, named HMN-pH assay, whose performance has been validated both in vitro and in vivo. Further, multiplexed antibiotic and pH detection is achieved by simultaneously employing the HMN-pH and HMN-Flex on live animals.

The Predictive Value of Preoperative Measurements of Cochlear Nerve Diameters From MRT and Postoperative Speech Perception in Adult Patients With Cochlear Implant.

The current study aims to investigate whether objective measurements of the cochlear nerve (CN), derived from preoperative MRI images, correlate with postoperative speech perception in CI patients. Retrospective cohort study. University Medical Center, tertiary academic referral center. Patients undergoing a cochlear implant surgery including MED-EL (Synchrony 2, FLEX electrode series; MED-EL, Innsbruck, Austria) Cochlear (slim straight electrodes; Cochlear Ltd., Sydney, Australia), Advanced Bionics (HiRes Ultra 3D CI, HiFocus SlimJ electrodes; Sonova, Zürich, Switzerland), and Oticon (Neuro Zti EVO; Oticon A/S, Smørum, Denmark) between 2020 and 2023. Preoperative MRI images were utilized to measure the volume of the modiolus (VM), the cross-sectional areas of the CN (ACN), and for normalization, the area of the facial nerve (AFN) and the area of the internal ear canal (AIEC). Postoperative speech perceptions were assessed through word recognition scores (WRS) at several stages following the first fitting (FF) of the CI processor: immediately after FF, 1 month, 3 months, and 6 months after FF. Sixty-eight patients were enrolled in this study. A statistically significant positive correlation between the ratio between ACN and AFN (ACN/AFN) and WRSFF was identified (R = 0.36, p < 0.003). However, this correlation disappeared in subsequent follow-up tests. Moreover, upon grouping patients based on their degree of asymmetrical hearing loss, it was observed that the correlation was primarily driven by patients with moderate to severe asymmetrical hearing loss (AHLm) on the contralateral side (R = 0.62, p = 0.0003). The present results suggest that assessing the size of the CN through MRI has limited predictive utility for postoperative speech perceptions during CI consultations. This limitation seems to be particularly relevant for AHLm patients and is confined to the initial activation period.

Wearable Microneedle Biosensor for Real-Time I-Situ Antibiotic Monitoring

Current methods for therapeutic drug monitoring (TDM) have a long turnaround time as they involve collecting patients' blood samples followed by transferring the samples to localized medical laboratories where sample processing and analysis are performed. To enable real-time and minimally invasive TDM, we have developed a microneedle (MN) biosensor to monitor the levels of two important antibiotics, vancomycin (VAN) and gentamicin (GEN). The MN biosensor is composed of a hydrogel MN (HMN), and an aptamer-functionalized flexible (Flex) electrode, named HMN-Flex. The HMN extracts dermal interstitial fluid (ISF) and transfers it to the Flex electrode where sensing of the target antibiotics happens. The HMN-Flex performance has been validated in-vitro using skin models as well as in-vivo in live rat animal models. Furthermore, we leveraged data from the HMN-Flex system to construct pharmacokinetic profiles for VAN and GEN and compared these profiles with conventional blood-based measurements.

Cochlear Implantation in Obliterated Cochlea: A Retrospective Analysis and Comparison between the IES Stiff Custom-Made Device and the Split-Array and Regular Electrodes.

Anatomical malformations, obliterations of the cochlea, or re-implantations pose particular challenges in cochlear implantation. Treatment methods rely on radiological and intraoperative findings and include incomplete insertion, the implantation of a double array, and radical cochleostomy. In addition, a stiff electrode array, e.g., the IE stiff (IES) custom-made device (CMD, MED-EL), was prescribed individually for those special cases and pre-inserted prior to facilitate cochlear implantation in challenging cases. Data on outcomes after implantation in obliterated cochleae are usually based on individual case reports since standardised procedures are lacking. A retrospective analysis was conducted to analyse our cases on obliterated cochleae treated with MED-EL devices in order to allow the different cases to be compared. Impedances and speech perception data of patients treated with the IES CMD and the double array were retrospectively compared to patients treated with a STANDARD or FLEX electrode array (the REGULAR group). Patients with a Split-Array CMD had a poor speech perception when compared to patients treated with the IES CMD device. Thus, the IES CMD can successfully be used in patients with obliterated cochleae who would otherwise be non-users, candidates for a Split-Array CMD, or candidates for partial insertion with insufficient cochlear coverage.

On the Accuracy of Clinical Insertion Angle Predictions With a Surgical Planning Platform for Cochlear Implantation.

Various studies over the last few decades have shown that the cochlea is not a uniform structure, but that its size and shape may vary quite substantially in between subjects. The surgical planning platform enables the user to quickly approximate the size of a cochlea within clinical imaging data by measuring the basal cochlear diameters A and B. It also allows for contact specific insertion angle predictions for MED-EL cochlear implant electrode arrays based on this individual anatomy approximation. The proposed, retrospective study was performed to evaluate the accuracy of these predictions. Preoperative CBCT scans of N = 91 MED-EL cochlear implant patients with different types of FLEX electrode arrays (flexible, thin, and straight arrays) were evaluated using a planning module. Both the initial version (based on an equation proposed by Escudé et al.) as well as a novel, recently proposed approach (called elliptic-circular approximation) was employed. All predictions were then compared to the actual insertion angles which were derived from postoperative CBCT images of the same patient. Most prediction deviations of the investigated cases stayed below 45deg for all electrode arrays and both prediction methods. In general, prediction deviations increased from base to apex were found to be larger for longer electrode arrays. Hardly any significant differences between the two prediction methods were observed. However, particularly large deviations were found for the Escudé method and could be substantially deceased with the updated elliptic-circular approximation approach. The new platform version with its updated prediction module allows to reliably predict insertion angles even for cochlear anatomies with slightly unusual features and shapes.

The rationale for FLEX (cochlear implant) electrode with varying array lengths.

With cochlear implantation (CI) being the standard of care for profoundly deaf cases, more and more patients with low frequency residual hearing are currently being treated with CI. In view of preserving the residual hearing, the ultimate aim of both the surgeons and the CI companies is to achieve zero-degree of electrode insertion trauma. Variations in the size and shape of cochlea, cross-sectional dimensions of ST, electrode insertion techniques with and without metal stylet rod and the experience level of the operating surgeons, all play a role in the electrode array related insertion trauma. An effective electrode design must include flexible array to accommodate the cochlear shape variation, electrode with variety of array lengths to support the concept of cochlear size specific electrode array and finally smaller cross-sectional dimensions of electrode array in matching the cross-sectional dimensions of ST. As per published reports, FLEX electrode array design offers minimal degree of electrode insertion trauma along with the possibility of patient specific electrode array length matching their cochlear size. Looking at the cross-sectional dimensions of FLEX electrode array along with its volume, it appear to be highly safe to the cochlea by not taking too much volume inside the ST. To offer additional support, otological pre-planning software tool like OTOPLAN is now clinically available in measuring the cochlear size in finding the best electrode array match along with the possibilities of anatomy based post-operative speech processor fitting.

Randomized placebo-controlled clinical trial investigating the effect of antioxidants and a vasodilator on overall safety and residual hearing preservation in cochlear implant patients

BackgroundThe standard therapy for patients suffering from sensorineural hearing loss is cochlear implantation. The insertion of the electrode array into the cochlea, with potential mechanical trauma and the presence of this foreign body inside the cochlea, may lead to free radical formation and reduced blood perfusion of the cochlea which can result in a loss of residual hearing. Studies have suggested that a particular combination of the antioxidants vitamins A, C and E as well as the vasodilator magnesium (together: ACEMg) may protect the residual hearing.MethodsThe potential protective effect of ACEMg on residual hearing preservation in cochlear implant (CI) patients was investigated in a single-centre, randomized, placebo-controlled, double-blind phase II clinical trial. CI candidates with some residual hearing in low frequencies receiving MED-EL implants of different FLEX electrode array lengths were treated with ACEMg tablets or placebo respectively 2 days preoperatively and up to 3 months postoperatively. The study objective was to demonstrate that ACEMg is more efficacious than placebo in preserving residual hearing during cochlear implantation by comparing the hearing loss (change in hearing thresholds at 500 Hz from baseline) 3 months after the first fitting between the two treatment groups and to investigate the treatments’ safety.ResultsFifty-one patients were included in the study, which had to be terminated before the recruitment goal was reached because of IMP-resupply mismanagement of one partner. In the intention-to-treat population, 25 patients were treated with ACEMg and 24 patients with placebo. The mean hearing loss at 500 Hz was (± 15.84) 30.21 dB (placebo) or (± 17.56) 26.00 dB (ACEMg) 3 months after the initial fitting. Adjusting the postoperative hearing loss for the baseline residual hearing, planned electrode length and surgeon results in 8.01 dB reduced hearing loss in ACEMg-treated patients compared to placebo-treated ones. The safety analysis revealed that ACEMg was generally well-tolerated with adverse event frequencies below the placebo level.ConclusionThis is the first clinical trial investigating a drug effect on residual hearing in CI patients. These first-in-man data may suggest that a perioperative oral administration of ACEMg is safe and may provide protection of residual hearing in CI patients.Trial registrationEU Clinical Trial Register No. 2012-005002-22. Registered on 6 December 2013. Funding: European Commission FP7-HEALTH-2012-INNOVATION-2.

Interaction Between Electric and Acoustic Stimulation Influences Speech Perception in Ipsilateral EAS Users.

Objectives:The aim of this study was to determine electric-acoustic masking in cochlear implant users with ipsilateral residual hearing and different electrode insertion depths and to investigate the influence on speech reception. The effects of different fitting strategies—meet, overlap, and a newly developed masking adjusted fitting (UNMASKfit)—on speech reception are compared. If electric-acoustic masking has a detrimental effect on speech reception, the individualized UNMASKfit map might be able to reduce masking and thereby enhance speech reception.Design:Fifteen experienced MED-EL Flex electrode recipients with ipsilateral residual hearing participated in a crosssover design study using three fitting strategies for 4 weeks each. The following strategies were compared: (1) a meet fitting, dividing the frequency range between electric and acoustic stimulation, (2) an overlap fitting, delivering part of the frequency range both acoustically and electrically, and (3) the UNMASKfit, reducing the electric stimulation according to the individual electric-on-acoustic masking strength. A psychoacoustic masking procedure was used to measure the changes in acoustic thresholds due to the presence of electric maskers. Speech reception was measured in noise with the Oldenburg Matrix Sentence test.Results:Behavioral thresholds of acoustic probe tones were significantly elevated in the presence of electric maskers. A maximum of masking was observed when the difference in location between the electric and acoustic stimulation was around one octave in place frequency. Speech reception scores and strength of masking showed a dependency on residual hearing, and speech reception was significantly reduced in the overlap fitting strategy. Electric- acoustic stimulation significantly improved speech reception over electric stimulation alone, with a tendency toward a larger benefit with the UNMASKfit map. In addition, masking was significantly inversely correlated to the speech reception performance difference between the overlap and the meet fitting.Conclusions:(1) This study confirmed the interaction between ipsilateral electric and acoustic stimulation in a psychoacoustic masking experiment. (2) The overlap fitting yielded poorer speech reception performance in stationary noise especially in subjects with strong masking. (3) The newly developed UNMASKfit strategy yielded similar speech reception thresholds with an enhanced acoustic benefit, while at the same time reducing the electric stimulation. This could be beneficial in the long-term if applied as a standard fitting, as hair cells are exposed to less possibly adverse electric stimulation. In this study, the UNMASKfit allowed the participants a better use of their natural hearing even after 1 month of adaptation. It might be feasible to transfer these results to the clinic, by fitting patients with the UNMASKfit upon their first fitting appointment, so that longer adaptation times can further improve speech reception.

Psychoacoustic and electrophysiological electric-acoustic interaction effects in cochlear implant users with ipsilateral residual hearing

Cochlear implant users with ipsilateral residual hearing combine acoustic and electric hearing in one ear, this is called electric-acoustic stimulation (EAS). In EAS users, masking can be shown for electric probes in the presence of acoustic maskers and vice versa. Masking effects in acoustic hearing are generally attributed to nonlinearities of the basilar membrane and hair cell adaptation effects. However, similar masking patterns are observed more centrally in electric hearing. Consequently, there is no consensus so far on the level of interaction between the two modalities. Animal studies have shown that electric-acoustic interaction effects can result in reduced physiological responses in the cochlear nerve and the inferior colliculus. In CI users with residual hearing, it has recently become feasible to record intracochlear potentials with a high spatial resolution via the implanted electrode array. An investigation of the electrophysiological effects during combined electric-acoustic stimulation in humans might be used to assess peripheral mechanisms of masking.Seventeen MED-EL Flex electrode users with ipsilateral residual hearing participated in both a behavioral and a physiological electric-acoustic masking experiment. Psychoacoustic methods were used to measure the changes in behavioral thresholds due to the presence of a masker of the opposing modality. Subjects were stimulated electrically with unmodulated pulse trains using a research interface and acoustically with pure tones delivered via headphones. Auditory response telemetry was used to obtain objective electrophysiological changes of electrically evoked compound action potential and electrocochleography for electric, acoustic and combined electric-acoustic presentation in the same subjects.Behavioral thresholds of probe tones, either electric or acoustic, were significantly elevated in the presence of acoustic or electric maskers, respectively. 15 subjects showed significant electric threshold elevation with acoustic masking that did not depend on the electric-acoustic frequency difference (EAFD), a measure for the proximity of stimulation sites in the cochlea. Electric masking showed significant threshold elevation in eleven subjects, which depended significantly on EAFD. In the electrophysiological masking experiment, reduced responses to electric and acoustic stimulation with additional stimulation of the opposing modality were observed. Results showed a similar asymmetry as the psychoacoustic masking experiment. Response reduction was smaller than threshold elevation, especially for electric masking. Some subjects showed reduced responses to acoustic stimulation with electric masking, especially for small EAFD. The reduction of electrically evoked responses was significant in some subjects. No correlation was observed between psychoacoustic and electrophysiological masking results.From present study, it can be concluded that both electric and acoustic stimulation mask each other when presented simultaneously. Electrophysiological measurements indicate that masking effects are already to some extent present in the periphery.

The Effect of Cochlear Size on Cochlear Implantation Outcomes.

Objectives To determine if cochlear duct length and cochlear basal diameter, measured using routinely available radiology software, affect hearing outcomes after cochlear implantation with two different length electrodes. Methods55 patients who received a Med-El Flex electrode were retrospectively reviewed. 34 patients received the Flex 31 electrode (31mm) and 21 patients received the Flex 28 electrode (28mm). Preoperative high-resolution CT scans of the temporal bone were reformatted in the axial and coronal plane. The basal diameter of the cochlear (A-value) and the outer-wall lengths of the cochlear duct were measured using readily available imaging software. Postoperative plane X-rays were used to determine the degree of electrode insertion and the number of electrodes within the cochlea and speech discrimination scores at 6 months were evaluated. Results The cochlear metrics obtained were comparable with those previously published in the literature. There was no significant difference in the degree of insertion or speech outcomes between the two electrode lengths. However, when the group who had received the shorter electrode were analysed, there was an association seen between both cochlear duct length and cochlear diameter and speech outcomes. ConclusionsCochlear size may be a factor in determining speech outcomes that cannot be explained solely by insertion depth or degrees of insertion. Further studies are required to determine if cochlear duct length is an independent predictor of speech outcomes.

Hearing preservation cochlear implantation in children: The HEARRING Group consensus and practice guide

Objectives: To provide multidisciplinary cochlear implant teams with a current consensus statement to support hearing preservation cochlear implantation (HPCI) in children, including those children with symptomatic partial deafness (PD) where the intention is to use electric-acoustic stimulation (EAS). The main objectives are to provide guidelines on who is a candidate, how to assess these children and when to implant if Med-El Flex electrode arrays are chosen for implantation.Methods: The HEARRING group reviewed the current evidence and practice regarding the management of children to be considered for HPCI surgery emphasizing the assessment needed prior to implantation in order to demonstrate the benefits in these children over time. The consensus statement addresses following three key questions: (1) Should these children be treated? (2) How to identify these children? (3) How to manage these children?Summary: The HEARRING group concludes that irrespective of the degree of residual hearing present, the concepts of hearing and structure preservation should be applied in every child undergoing cochlear implantation and that HPCI is a safe and reliable treatment option. Early detection and multidisciplinary assessment are key to the identification of children with symptomatic PD, these children should undergo HPCI as early as possible.

Residual Hearing Outcomes After Cochlear Implant Surgery Using Ultra-flexible 28-mm Electrodes.

To evaluate the preservation of low frequency residual hearing after cochlear implant surgery using an electrode for atraumatic implantation and complete cochlear stimulation. Retrospective clinical record study. Tertiary referral center. Fifty-six patients with functional deafness who had undergone cochlear implant surgery and received a Flex electrode (MED-EL GmbH, Innsbruck, Austria) between 2011 and 2014. Audiometric testing was performed before surgery and at the time of initial fitting. Change in low frequency residual hearing measured by pure tone audiometry. Preoperative hearing was relatively poor. After surgery low frequency residual hearing was partially preserved in most cases, however there was a significant hearing loss at all frequencies compared with the preoperative state. In only 23% of all cases complete hearing preservation was observed. Despite the use of a flexible electrode, complete preservation of low frequency residual hearing can only be achieved in a minority of patients. The use of a full insertion electrode of 28 mm in patients with poor preoperative thresholds does not allow for usable additional hearing at present.

Insertion Depth in Cochlear Implantation and Outcome in Residual Hearing and Vestibular Function.

It has long been known that cochlear implantation may cause loss of residual hearing and vestibular function. Different insertion depths may cause varying degrees of intracochlear trauma in the apical region of the cochlea. The present study investigated the correlation between the insertion depth and postoperative loss of residual hearing and vestibular function. Thirty-nine adults underwent unilateral cochlear implantation. One group received a Med-El +Flex electrode array (24 mm; n = 4), 1 group received a Med-El +Flex electrode array (28 mm; n = 18), and 1 group received a Med-El +Flex electrode array (31.5 mm; n = 17). Residual hearing, cervical vestibular-evoked myogenic potentials, videonystagmography, and subjective visual vertical/horizontal were explored before and after surgery. The electrode insertion depth and scalar position were examined with high-resolution rotational tomography after implantation in 29 subjects. There was no observed relationship between the angular insertion depth (405° to 708°) and loss of low-frequency pure-tone average. Frequency-specific analysis revealed a weak relationship between the angular insertion depth and loss of hearing at 250 Hz (R= 0.20; p = 0.02). There was no statistically significant difference in the residual hearing and vestibular function between the +Flex and the +Flex electrode array. Eight percent of the cases had vertigo after surgery. The electrode arrays were positioned inside the scala tympani and not scala vestibuli in all subjects. In 18% of the cases, the +Flex electrode array was not fully inserted. The final outcome in residual hearing correlates very weakly with the angular insertion depth for depths above 405°. Postoperative loss of vestibular function did not correlate with the angular insertion depth or age at implantation. The surgical protocol used in this study seems to minimize the risk of postoperative vertigo symptoms.

Cochlear Implantation for Profound Hearing Loss After Multimodal Treatment for Neuroblastoma in Children

ObjectivesNeuroblastoma (NBL) predominantly affects children under 5 years of age. Through multimodal therapy, including chemotherapy, radiotherapy, surgery, and peripheral blood stem cell transplantation, the survival rate in patients with NBL have improved while treatment-related complications have also increased. Treatment-related ototoxicity, mainly from cisplatin, can result in profound hearing loss requiring cochlear implantation (CI). We analyzed the effectiveness and hearing preservation of CI recipients who had treated with multimodal therapy due to NBL.MethodsPatients who received multimodal therapy for NBL and subsequent CIs were enrolled. A detailed review of the perioperative hearing test, speech evaluation, and posttreatment complications was conducted. Speech performance was analyzed using the category of auditory performance (CAP) score and the postoperative hearing preservation of low frequencies was also compared. Patients who were candidates for electro-acoustic stimulation (EAS) used an EAS electrode for low frequency hearing preservation.ResultsThree patients were identified and all patients showed improvement of speech performance after CI. The average of CAP score improved from 4.3 preoperatively to 5.8 at 1 year postoperatively. Two patients who were fitted with the Flex electrode showed complete hearing preservation and the preserved hearing was maintained over 1 year. The one remaining patient was given the standard CI-512 electrode and showed partial hearing preservation.ConclusionPatients with profound hearing loss resulting from NBL multimodal therapy can be good candidates for CI, especially for EAS. A soft surgical technique as well as a specifically designed electrode should be applied to this specific population during the CI operation in order to preserve residual hearing and achieve better outcomes.

Pitch Matching Psychometrics in Electric Acoustic Stimulation

Combined electric-acoustic stimulation (EAS) is a therapeutic option for patients with severe to profound mid- and high-frequency hearing loss while low-frequency hearing is mostly unaffected. The present study investigates bimodal pitch matching in EAS users as a function of the angular placement of electrodes. Results are compared with data obtained from previous pitch matching studies. Knowledge of electric and acoustic pitch mapping may be important for effective fitting to control the frequency range of acoustic and electric processing. Pitch adjustment experiments were conducted in eight subjects with residual hearing in the opposite ear as well as in the implanted ear. Four subjects received a standard 31.5-mm electrode array and four subjects received the shorter, more flexible 24-mm FLEX electrode array (PULSARCI100 or SONATATI100 stimulator, MED-EL, Innsbruck, Austria). The subjects' task was to listen to single-electrode stimuli presented at a fixed rate (800 pulses per second) via the cochlear implant and to adjust the frequency of the acoustic stimulus until the perceived pitch matched the perception of the electrically conveyed stimulus. Two to four of the most apical electrodes were tested depending on the range of the individual's residual hearing. Postoperative x rays (modified Stenver's view) were analyzed to compare individual pitch matching data in terms of the electrode arrays' insertion angle. The average mean frequency match for the most apical electrode 1 in EAS subjects implanted with the FLEX array was 583 Hz, while for the two subjects with a deep insertion of the 31.5-mm standard electrode array, the matches were 128 and 223 Hz. Because the residual hearing in the EAS subgroup was rather limited in the high-frequency range, a limited number of basal electrodes were assessed to determine the slope of the electric place/pitch function. A considerable variation in terms of the individual pitch function was observed. The slope of the pitch function varied to a large extent among subjects. The differences between contra- and ipsilateral adjustments were very small (mean average 14 Hz) and within the range of the variance (average SD 124 Hz). The application of a pitch matching procedure to assess the electric/acoustic crossover frequency is feasible. In the present study, ipsi- and contralateral pitch matches made by EAS patients were nearly equal; therefore, a severe alteration in the excitation pattern of the basilar membrane in the implanted ear can be ruled out.

Hearing Preservation After Complete Cochlear Coverage in Cochlear Implantation With the Free-Fitting FLEXSOFT Electrode Carrier

To demonstrate the possibility of atraumatic insertion with the free-fitting FLEX electrode by evaluating the degree of hearing preservation postoperatively. Retrospective study. Academic tertiary care center. Twenty-two severely to profoundly hearing impaired subjects with measurable residual hearing preoperatively. Atraumatic implantation with the 31.5-mm-long, free-fitting, and highly flexible FLEX electrode using either the round window approach or a cochleostomy technique. Subjects were tested preoperatively in unaided condition and at varying intervals postoperatively. Preoperative and postoperative low-frequency pure-tone average (PTA) and PTA shifts were calculated. Speech perception was measured preoperatively and postoperatively using the Freiburger monosyllabic word test in quiet. Preoperative low-frequency hearing could be preserved to a certain degree in 77.3% of subjects (17/22) after insertion of the FLEX electrode up to the point of first resistance. Complete loss of residual hearing was observed in 22.7% of subjects (5/22). In 18.2% of the subjects (4/22), the preoperative PTA was preserved within 10 dB. Pure-tone average results between preoperative and most recent testing showed statistically significant differences (p < 0.001 to p = 0.031) for almost all loudness levels ranging from 125 Hz to 1.5 kHz. The maximum threshold shift was 40 dB at 250 Hz for the lower frequencies up to 1 kHz. Monosyllable testing in quiet demonstrated significant improvement over time (p < 0.001). This study showed that preservation of residual hearing is possible in a high number of subjects when a flexible electrode and atraumatic surgical techniques are used.

Small-fenestra cochleostomy for MED-EL electrode

Although the physical characteristics of cochlear implant electrode arrays vary substantially among manufacturers, many otolaryngologists have adopted a surgical cochleostomy technique that is similar for all of them. The objective of this study was to compare the insertion dynamics of the MED-EL Flex electrode using two different sized cochleostomies. Six temporal bones were prepared with either a small fenestra (∼1.0 mm) or a large fenestra (∼1.8 mm) cochleostomy and the electrodes inserted under video fluoroscopy. The resulting video images were analysed for depth of insertion as well as dynamic flexion of the electrode during insertion. The study demonstrated that smallfenestra cochleostomies have a 'pool cue' or 'billiard cue' effect, stabilizing the electrode cable and resulting in easier and deeper insertions. This is achieved by limiting the buckling of the electrode just inside the cochleostomy site.