Cochlear implantation in children and adults in Switzerland

The cochlear implant (CI) is one of the most successful neural prostheses developed to date. It offers artificial hearing to individuals with profound sensorineural hearing loss and with insufficient benefit from conventional hearing aids. The first implants available some 30 years ago provided a limited sensation of sound. The benefit for users of these early systems was mostly a facilitation of lip-reading based communication rather than an understanding of speech. Considerable progress has been made since then. Modern, multichannel implant systems feature complex speech processing strategies, high stimulation rates and multiple sites of stimulation in the cochlea. Equipped with such a state-of-the-art system, the majority of recipients today can communicate orally without visual cues and can even use the telephone. The impact of CIs on deaf individuals and on the deaf community has thus been exceptional. To date, more than 300,000 patients worldwide have received CIs. In Switzerland, the first implantation was performed in 1977 and, as of 2012, over 2,000 systems have been implanted with a current rate of around 150 CIs per year. The primary purpose of this article is to provide a contemporary overview of cochlear implantation, emphasising the situation in Switzerland.

Multicenter study with a direct acoustic cochlear implant

OBJECTIVE To confirm the clinical efficacy and safety of a direct acoustic cochlear implant. STUDY DESIGN Prospective multicenter study. SETTING The study was performed at 3 university hospitals in Europe (Germany, The Netherlands, and Switzerland). PATIENTS Fifteen patients with severe-to-profound mixed hearing loss because of otosclerosis or previous failed stapes surgery. INTERVENTION Implantation with a Codacs direct acoustic cochlear implant investigational device (ID) combined with a stapedotomy with a conventional stapes prosthesis MAIN OUTCOME MEASURES Preoperative and postoperative (3 months after activation of the investigational direct acoustic cochlear implant) audiometric evaluation measuring conventional pure tone and speech audiometry, tympanometry, aided thresholds in sound field and hearing difficulty by the Abbreviated Profile of Hearing Aid Benefit questionnaire. RESULTS The preoperative and postoperative air and bone conduction thresholds did not change significantly by the implantation with the investigational Direct Acoustic Cochlear Implant. The mean sound field thresholds (0.25-8 kHz) improved significantly by 48 dB. The word recognition scores (WRS) at 50, 65, and 80 dB SPL improved significantly by 30.4%, 75%, and 78.2%, respectively, after implantation with the investigational direct acoustic cochlear implant compared with the preoperative unaided condition. The difficulty in hearing, measured by the Abbreviated Profile of Hearing Aid Benefit, decreased by 27% after implantation with the investigational direct acoustic cochlear implant. CONCLUSION Patients with moderate-to-severe mixed hearing loss because of otosclerosis can benefit substantially using the Codacs investigational device.

In vitro accuracy evaluation of image-guided robot system for direct cochlear access

HYPOTHESIS A previously developed image-guided robot system can safely drill a tunnel from the lateral mastoid surface, through the facial recess, to the middle ear, as a viable alternative to conventional mastoidectomy for cochlear electrode insertion. BACKGROUND Direct cochlear access (DCA) provides a minimally invasive tunnel from the lateral surface of the mastoid through the facial recess to the middle ear for cochlear electrode insertion. A safe and effective tunnel drilled through the narrow facial recess requires a highly accurate image-guided surgical system. Previous attempts have relied on patient-specific templates and robotic systems to guide drilling tools. In this study, we report on improvements made to an image-guided surgical robot system developed specifically for this purpose and the resulting accuracy achieved in vitro. MATERIALS AND METHODS The proposed image-guided robotic DCA procedure was carried out bilaterally on 4 whole head cadaver specimens. Specimens were implanted with titanium fiducial markers and imaged with cone-beam CT. A preoperative plan was created using a custom software package wherein relevant anatomical structures of the facial recess were segmented, and a drill trajectory targeting the round window was defined. Patient-to-image registration was performed with the custom robot system to reference the preoperative plan, and the DCA tunnel was drilled in 3 stages with progressively longer drill bits. The position of the drilled tunnel was defined as a line fitted to a point cloud of the segmented tunnel using principle component analysis (PCA function in MatLab). The accuracy of the DCA was then assessed by coregistering preoperative and postoperative image data and measuring the deviation of the drilled tunnel from the plan. The final step of electrode insertion was also performed through the DCA tunnel after manual removal of the promontory through the external auditory canal. RESULTS Drilling error was defined as the lateral deviation of the tool in the plane perpendicular to the drill axis (excluding depth error). Errors of 0.08 ± 0.05 mm and 0.15 ± 0.08 mm were measured on the lateral mastoid surface and at the target on the round window, respectively (n =8). Full electrode insertion was possible for 7 cases. In 1 case, the electrode was partially inserted with 1 contact pair external to the cochlea. CONCLUSION The purpose-built robot system was able to perform a safe and reliable DCA for cochlear implantation. The workflow implemented in this study mimics the envisioned clinical procedure showing the feasibility of future clinical implementation.

Feasibility of Using EMG for Early Detection of the Facial Nerve During Robotic Direct Cochlear Access

HYPOTHESIS Facial nerve monitoring can be used synchronous with a high-precision robotic tool as a functional warning to prevent of a collision of the drill bit with the facial nerve during direct cochlear access (DCA). BACKGROUND Minimally invasive direct cochlear access (DCA) aims to eliminate the need for a mastoidectomy by drilling a small tunnel through the facial recess to the cochlea with the aid of stereotactic tool guidance. Because the procedure is performed in a blind manner, structures such as the facial nerve are at risk. Neuromonitoring is a commonly used tool to help surgeons identify the facial nerve (FN) during routine surgical procedures in the mastoid. Recently, neuromonitoring technology was integrated into a commercially available drill system enabling real-time monitoring of the FN. The objective of this study was to determine if this drilling system could be used to warn of an impending collision with the FN during robot-assisted DCA. MATERIALS AND METHODS The sheep was chosen as a suitable model for this study because of its similarity to the human ear anatomy. The same surgical workflow applicable to human patients was performed in the animal model. Bone screws, serving as reference fiducials, were placed in the skull near the ear canal. The sheep head was imaged using a computed tomographic scanner and segmentation of FN, mastoid, and other relevant structures as well as planning of drilling trajectories was carried out using a dedicated software tool. During the actual procedure, a surgical drill system was connected to a nerve monitor and guided by a custom built robot system. As the planned trajectories were drilled, stimulation and EMG response signals were recorded. A postoperative analysis was achieved after each surgery to determine the actual drilled positions. RESULTS Using the calibrated pose synchronized with the EMG signals, the precise relationship between distance to FN and EMG with 3 different stimulation intensities could be determined for 11 different tunnels drilled in 3 different subjects. CONCLUSION From the results, it was determined that the current implementation of the neuromonitoring system lacks sensitivity and repeatability necessary to be used as a warning device in robotic DCA. We hypothesize that this is primarily because of the stimulation pattern achieved using a noninsulated drill as a stimulating probe. Further work is necessary to determine whether specific changes to the design can improve the sensitivity and specificity.

Bimanual anterior segment revision surgery for anterior capsule contraction syndrome associated with anterior flexion of intraocular lens haptics

PURPOSE To report the incidence of anterior capsule contraction syndrome (ACCS) and to present a novel minimally invasive bimanual technique for anterior segment revision surgery associated with ACCS with anterior flexion of the intraocular lens haptics. METHODS A consecutive cohort of 268 eyes of 161 patients undergoing phacoemulsification and implantation of the same type of hydrophilic acrylic aspheric intraocular lens cohort were analysed and a novel technique of minimally invasive bimanual technique for anterior segment revision surgery is described. RESULTS We identified four eyes (1.5%) of three patients with advanced ACCS. Successful restoration of a clear visual axis with minimal induction of astigmatism and rapid visual rehabilitation was achieved in all four cases. CONCLUSION This technique is a safe and minimally invasive alternative to laser or vitrector-cut capsulotomy to restore a clear visual axis. In cases of advanced ACCS, it offers the option for haptic reposition or amputation.

The Pneumococcal Polysaccharide Capsule and Pneumolysin Differentially Affect CXCL8 and IL-6 Release from Cells of the Upper and Lower Respiratory Tract

The polysaccharide capsule and pneumolysin toxin are major virulence factors of the human bacterial pathogen Streptococcus pneumoniae. Colonization of the nasopharynx is asymptomatic but invasion of the lungs can result in invasive pneumonia. Here we show that the capsule suppresses the release of the pro-inflammatory cytokines CXCL8 (IL-8) and IL-6 from the human pharyngeal epithelial cell line Detroit 562. Release of both cytokines was much less from human bronchial epithelial cells (iHBEC) but levels were also affected by capsule. Pneumolysin stimulates CXCL8 release from both cell lines. Suppression of CXCL8 homologue (CXCL2/MIP-2) release by the capsule was also observed in vivo during intranasal colonization of mice but was only discernable in the absence of pneumolysin. When pneumococci were administered intranasally to mice in a model of long term, stable nasopharyngeal carriage, encapsulated S. pneumoniae remained in the nasopharynx whereas the nonencapsulated pneumococci disseminated into the lungs. Pneumococcal capsule plays a role not only in protection from phagocytosis but also in modulation of the pro-inflammatory immune response in the respiratory tract.

The importance of pneumococcal capsule in inate immunity and biofilm formation

Chapter 1 gives an overview about Streptococcus pneumoniae, its role as a human pathogen and its virulence factors. Additionally, biofilm development and its relevance in clinics are introduced, and the innate immune response to pneumococcus as well as bacterial-viral interactions in the upper respiratory tract are also discussed. Chapter 2 emphasizes the three main topics of this thesis: the role of capsule and pneumolysin in the immune response in the respiratory tract, biofilm formation of S. pneumoniae serotypes and commensal streptococci in vitro, and host innate immune responses to RSV and S. pneumoniae during in vitro co-infections. Aims and hypotheses are provided here. Chapter 3 is divided into two parts: First, the release of the pro-inflammatory cytokines CXCL8 and IL-6 from the human pharyngeal epithelial cell line Detroit 562 and from human bronchial epithelial cells (iHBEC) is described in response to S. pneumoniae. Capsule was shown to suppress the release of both cytokines in both cell lines tested, but release was much less from iHBEC cells. During intranasal colonization of mice, suppression of CXCL8 release by the capsule was also observed in vivo, but the effect was only measured in the absence of pneumolysin. Long term, stable nasopharyngeal carriage in a mouse model resulted in the dissemination of nonencapsulated pneumococci into the lungs, whereas encapsulated strains remained in the nasopharynx. The S. pneumoniae capsule thus plays a role in modulation of the pro-inflammatory immune response in the respiratory tract. Second, results on immunological cells and immune regulation in a long term, stable nasopharyngeal carriage mouse model are presented. Mice were infected with encapsulated or nonencapsulated pneumococcal strains, and after 1, 3, 8 and 15 days, were sacrificed to evaluate the numbers of CD45+ cells, neutrophils, macrophages, FoxP3+ regulatory T-cells and CD3+ T-cells in the nasal mucosa as well as the amount of secreted IL-10 in the nasopharynx. Nasopharyngeal colonization which is effectively silent resulted in the stimulation of FoxP3+ regulatory T-cells and IL-10 release associated with immune homeostasis, whereas lung infiltration was required to increase the number of neutrophils and macrophages resulting in a stronger innate immune response in the nasal mucosa. Chapter 4 contains results of mono- and co-stimulation using RSV and pneumococci or pneumococcal virulence factors on the human bronchial epithelial cell line BEAS-2B. An increase in CXCL8 and IL-6 levels was measured for mixed stimulations of RSV and pneumococcus when encapsulated bacteria were used. Increasing pneumolysin concentrations resulted in enhanced CXCL8 levels. Priming of bronchial epithelial cells with RSV opens the door for more severe pneumococcal infections. Chapter 5 is composed of two parts: The first part describes initial biofilm formation of serotypes 6B and 7F in a static model in vitro. Biofilms of both serotypes contained SCVs, but only serotype 6B increased in SCV formation between 16 and 65h of incubation. SCV stability was tested by passaging clones in complex medium, where SCV production is not associated with advantages in growth. Serotype 6B lost the SCV phenotype indicating a fast adaptation to a changing nutritional environment. Limitations of our in vitro model are discussed. The second part is about initial biofilm formation of mixed culture growth of S. pneumoniae with commensal streptococci. Competition dominates this process. S. oralis and pneumococcus compete for nutrients, whereas mixed species growth of S. mitis or S. pseudopneumoniae with S. pneumoniae is mainly influenced by other factors. In Chapter 6 the findings of chapters 3, 4 and 5 are discussed and an outlook for further studies is provided. Chapters 7, 8, 9, 10 and 11 contain the references, the acknowledgements, the curriculum vitae, the appendix and the declaration of originality.

Semiautomatic Cochleostomy Target and Insertion Trajectory Planning for Minimally Invasive Cochlear Implantation

A major component of minimally invasive cochlear implantation is atraumatic scala tympani (ST) placement of the electrode array. This work reports on a semiautomatic planning paradigm that uses anatomical landmarks and cochlear surface models for cochleostomy target and insertion trajectory computation. The method was validated in a human whole head cadaver model (n = 10 ears). Cochleostomy targets were generated from an automated script and used for consecutive planning of a direct cochlear access (DCA) drill trajectory from the mastoid surface to the inner ear. An image-guided robotic system was used to perform both, DCA and cochleostomy drilling. Nine of 10 implanted specimens showed complete ST placement. One case of scala vestibuli insertion occurred due to a registration/drilling error of 0.79 mm. The presented approach indicates that a safe cochleostomy target and insertion trajectory can be planned using conventional clinical imaging modalities, which lack sufficient resolution to identify the basilar membrane.

Benefit of a Contralateral Routing of Signal Device for Unilateral Cochlear Implant Users.

Objective: To investigate objective and subjective effects of an adjunctive contralateral routing of signal (CROS) device at the untreated ear in patients with a unilateral cochlear implant (CI). Design: Prospective study of 10 adult experienced unilateral CI users with bilateral severe-to-profound hearing loss. Speech in noise reception (SNR) and sound localization were measured with and without the additional CROS device. SNR was measured by applying speech signals at the untreated/CROS side while noise signals came from the front (S90N0). For S0N90, signal sources were switched. Sound localization was measured in a 12-loudspeaker full circle setup. To evaluate the subjective benefit, patients tried the device for 2 weeks at home, then filled out the abbreviated Speech, Spatial and Qualities of Hearing Scale as well as the Bern benefit in single-sided deafness questionnaires. Results: In the setting S90N0, all patients showed a highly significant SNR improvement when wearing the additional CROS device (mean 6.4 dB, p < 0.001). In the unfavorable setting S0N90, only a minor deterioration of speech understanding was noted (mean -0.66 dB, p = 0.54). Sound localization did not improve substantially with CROS. In the two questionnaires, 12 of 14 items showed an improvement in mean values, but none of them was statistically significant. Conclusion: Patients with unilateral CI benefit from a contralateral CROS device, particularly in a noisy environment, when speech comes from the CROS ear side. © 2014 S. Karger AG, Basel.

Cochlear implant candidates with psychogenic hearing loss.

Abstract Conclusions: Specific requests for cochlear implantations by persons with psychogenic hearing loss are a relatively new phenomenon. A number of features seems to be over-represented in this group of patients. The existence of these requests stresses the importance of auditory brainstem response (ABR) measurements before cochlear implantation. Objective: To describe the phenomenon of patients with psychogenic hearing losses specifically requesting cochlear implantation, and to gain first insights into the characteristics of this group. Methods: Analysis of all cases seen between 2004 and 2013 at the University Hospital of Bern, Switzerland. Results: Four cochlear implant candidates with psychogenic hearing loss were identified. All were female, aged 23-51 years. Hearing thresholds ranged from 86 dB to 112 dB HL (pure-tone average 500-4000 Hz). ABRs and otoacoustic emissions (OAEs) showed bilaterally normal hearing in two subjects, and hearing thresholds between 30 and 50 dB in the other two subjects. Three subjects suffered from depression and one from a pathologic fear of cancer. Three had a history of five or more previous surgeries. Three were smokers and three reported other close family members with hearing losses. All four were hearing aid users at the time of presentation.

An image-guided robot system for direct cochlear access

The aim of direct cochlear access (DCA) is to replace the standard mastoidectomy with a small diameter tunnel from the lateral bone surface to the cochlea for electrode array insertion. In contrast to previous attempts, the approach described in this work not only achieves an unprecedented high accuracy, but also contains several safety sub-systems. This paper provides a brief description of the system components, and summarizes accuracy results using the system in a cadaver model over the past two years.

Designer aminoglycosides prevent cochlear hair cell loss and hearing loss.

Bacterial infections represent a rapidly growing challenge to human health. Aminoglycosides are widely used broad-spectrum antibiotics, but they inflict permanent hearing loss in up to ~50% of patients by causing selective sensory hair cell loss. Here, we hypothesized that reducing aminoglycoside entry into hair cells via mechanotransducer channels would reduce ototoxicity, and therefore we synthesized 9 aminoglycosides with modifications based on biophysical properties of the hair cell mechanotransducer channel and interactions between aminoglycosides and the bacterial ribosome. Compared with the parent aminoglycoside sisomicin, all 9 derivatives displayed no or reduced ototoxicity, with the lead compound N1MS 17 times less ototoxic and with reduced penetration of hair cell mechanotransducer channels in rat cochlear cultures. Both N1MS and sisomicin suppressed growth of E. coli and K. pneumoniae, with N1MS exhibiting superior activity against extended spectrum β lactamase producers, despite diminished activity against P. aeruginosa and S. aureus. Moreover, systemic sisomicin treatment of mice resulted in 75% to 85% hair cell loss and profound hearing loss, whereas N1MS treatment preserved both hair cells and hearing. Finally, in mice with E. coli-infected bladders, systemic N1MS treatment eliminated bacteria from urinary tract tissues and serially collected urine samples, without compromising auditory and kidney functions. Together, our findings establish N1MS as a nonototoxic aminoglycoside and support targeted modification as a promising approach to generating nonototoxic antibiotics.

The pre- and post-somatic segments of the human type I spiral ganglion neurons--structural and functional considerations related to cochlear implantation.

Human auditory nerve afferents consist of two separate systems; one is represented by the large type I cells innervating the inner hair cells and the other one by the small type II cells innervating the outer hair cells. Type I spiral ganglion neurons (SGNs) constitute 96% of the afferent nerve population and, in contrast to other mammals, their soma and pre- and post-somatic segments are unmyelinated. Type II nerve soma and fibers are unmyelinated. Histopathology and clinical experience imply that human SGNs can persist electrically excitable without dendrites, thus lacking connection to the organ of Corti. The biological background to this phenomenon remains elusive. We analyzed the pre- and post-somatic segments of the type I human SGNs using immunohistochemistry and transmission electron microscopy (TEM) in normal and pathological conditions. These segments were found surrounded by non-myelinated Schwann cells (NMSCs) showing strong intracellular expression of laminin-β2/collagen IV. These cells also bordered the perikaryal entry zone and disclosed surface rugosities outlined by a folded basement membrane (BM) expressing laminin-β2 and collagen IV. It is presumed that human large SGNs are demarcated by three cell categories: (a) myelinated Schwann cells, (b) NMSCs and (c) satellite glial cells (SGCs). Their BMs express laminin-β2/collagen IV and reaches the BM of the sensory epithelium at the habenula perforata. We speculate that the NMSCs protect SGNs from further degeneration following dendrite loss. It may give further explanation why SGNs can persist as electrically excitable monopolar cells even after long-time deafness, a blessing for the deaf treated with cochlear implantation.

Speech Intelligibility in Noise With a Single-Unit Cochlear Implant Audio Processor.

INTRODUCTION The Rondo is a single-unit cochlear implant (CI) audio processor comprising the identical components as its behind-the-ear predecessor, the Opus 2. An interchange of the Opus 2 with the Rondo leads to a shift of the microphone position toward the back of the head. This study aimed to investigate the influence of the Rondo wearing position on speech intelligibility in noise. METHODS Speech intelligibility in noise was measured in 4 spatial configurations with 12 experienced CI users using the German adaptive Oldenburg sentence test. A physical model and a numerical model were used to enable a comparison of the observations. RESULTS No statistically significant differences of the speech intelligibility were found in the situations in which the signal came from the front and the noise came from the frontal, ipsilateral, or contralateral side. The signal-to-noise ratio (SNR) was significantly better with the Opus 2 in the case with the noise presented from the back (4.4 dB, p < 0.001). The differences in the SNR were significantly worse with the Rondo processors placed further behind the ear than closer to the ear. CONCLUSION The study indicates that CI users with the receiver/stimulator implanted in positions further behind the ear are expected to have higher difficulties in noisy situations when wearing the single-unit audio processor.