Thomas Lenarz

Publications of Thomas Lenarz

• A device for patterned electrical stimulation of cultivated cells: preliminary tests with rat auditory neurons.

  Authors: Patrick Wefstaedt, Gerrit Paasche, John Parker, Thomas Lenarz, Timo Stöver

  European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 05/2012;

  The number of surviving spiral ganglion neurons (SGNs) is important for the function of cochlear implants. Electrical stimulation has been discussed controversially regarding its protective effectsThe number of surviving spiral ganglion neurons (SGNs) is important for the function of cochlear implants. Electrical stimulation has been discussed controversially regarding its protective effects on SGNs both in vivo and in vitro. The aim of this study was to develop a device for electrical stimulation of cultured SGNs. The developed device was first evaluated with cultivated fibroblasts at voltages from 10 to 60 V using biphasic rectangular pulses (pulse width: 10 ms, frequency: 50 Hz, stimulus burst: 1 s, interburst interval: 19 s). Possible toxic effects of 48 h patterned electrical stimulation were evaluated by propidium-iodide flow cytometry of the harvested fibroblasts. Second, the effects of 48-h electrical stimulation at voltages of 6 and 30 V on survival of cultivated SGNs were investigated as a single treatment and in the presence of brain-derived neurotrophic factor (BDNF, 100 ngml) in the culture medium. The results demonstrated constant pH and temperature behavior during electrical stimulation. Furthermore, no toxic effects on fibroblasts up to 40 V were found. The electrical stimulation of cultured neurons did not alter the survival rate compared to unstimulated control conditions. While BDNF application alone showed a significant effect on SGN survival, combination with electrical stimulation resulted in a not significantly increased cell survival. As a limitation of the study, the sensitivity of the described experimental setup appears to be low and only one stimulation pattern has been tested. Thus, experiments using different patterns of electrical stimulation and a more sensitive cultivation setup have to be carried out to fully investigate the effects of electrical stimulation on cultured SGNs. In this context, the developed device can be of help as it provides controlled and reproducible electrical stimulation conditions.

• Stable release of BDNF from the fibroblast cell line NIH3T3 grown on silicone elastomers enhances survival of spiral ganglion cells in vitro and in vivo.

  Authors: Athanasia Warnecke, Susanne Sasse, Gentiana I Wenzel, Andrea Hoffmann, Gerhard Gross, Gerrit Paasche, Verena Scheper, Uta Reich, Karl-Heinz Esser, Thomas Lenarz, Timo Stöver, Kirsten Wissel

  Hearing research. 04/2012;

  The treatment of choice for profound sensorineural hearing loss (SNHL) is direct electrical stimulation of spiral ganglion cells (SGC) via a cochlear implant (CI). The number and excitability of SGCThe treatment of choice for profound sensorineural hearing loss (SNHL) is direct electrical stimulation of spiral ganglion cells (SGC) via a cochlear implant (CI). The number and excitability of SGC seem to be critical for the success that can be achieved via CI treatment. However, SNHL is associated with degeneration of SGC. Long-term drug delivery to the inner ear for improving SGC survival may be achieved by functionalisation of CI electrodes with cells providing growth factors. Therefore, the capacity of brain-derived neurotrophic factor (BDNF)-secreting NIH3T3 cells grown on cylindrically shaped silicone elastomers (SE) to exert local and sustained neuroprotective effects was assessed in vitro and in vivo. An in vitro model to investigate adhesion and cell growth of lentivirally modified NIH3T3 cells synthesising BDNF on SE was established. The bioactivity of BDNF was characterised by co-cultivation of SGC with cell-coated SE. In addition, cell-coated SE were implanted into deafened guinea pigs. The recombinant NIH3T3 cells proliferated on silicone surfaces during 14 days of cultivation and expressed significantly increasing BDNF levels. Enhanced survival rates and neurite outgrowth of SGC demonstrated the bioactivity of BDNF in vitro. Implantation of SE with adhering BDNF-secreting NIH3T3 cells into the cochleae of systemically deafened guinea pigs induced a significant increase in SGC survival in comparison to SE without cell coating. Our data demonstrate a novel approach of cell-based long-term drug delivery to support SGC survival in vitro and in vivo. This therapeutic strategy - once transferred to cells suitable for clinical application - may improve CI performance.

• Effect of gender on the hearing performance of adult cochlear implant patients.

  Authors: Minoo Lenarz, Hasibe Sönmez, Gert Joseph, Andreas Büchner, Thomas Lenarz

  The Laryngoscope. 02/2012;

  OBJECTIVES/HYPOTHESIS: To evaluate the role of gender on the hearing performance of postlingually deafened adult patients with cochlear implants. STUDY DESIGN: Individual retrospective cohort study.OBJECTIVES/HYPOTHESIS: To evaluate the role of gender on the hearing performance of postlingually deafened adult patients with cochlear implants. STUDY DESIGN: Individual retrospective cohort study. METHODS: There were 638 postlingually deafened adults (280 men and 358 women) selected for a retrospective evaluation of their hearing performance with cochlear implants. Both genders underwent the same surgical and rehabilitative procedures and benefited from the latest technological advances available. There was no significant difference in the age, duration of deafness, and preoperative hearing performance between the genders. The test battery was composed of the Freiburger Monosyllabic Test, Speech Tracking, and the Hochmair-Schulz-Moser (HSM) sentence test in quiet and in 10-dB noise. The results of 5 years of follow-up are presented here. RESULTS: Genders showed a similar performance in Freiburger Monosyllabic Test and Speech Tracking Test. However, in the HSM test in noise, men performed slightly better than women in all of the follow-up sessions, which was statistically significant at 2 and 4 years after implantation. CONCLUSIONS: Although normal-hearing women use more predictive cognitive strategies in speech comprehension and are supposed to have a more efficient declarative memory system, this may not necessarily lead to a better adaptation to the altered auditory information delivered by a cochlear implant. Our study showed that in more complex listening situations such as speech tests in noise, men tend to perform slightly better than women. Gender may have an influence on the hearing performance of postlingually deafened adults with cochlear implants.

• Long-Term Performance of Cochlear Implants in Postlingually Deafened Adults.

  Authors: Minoo Lenarz, Hasibe Sönmez, Gert Joseph, Andreas Büchner, Thomas Lenarz

  Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery. 02/2012;

  Objective. To evaluate the stability of long-term hearing performance after cochlear implantation (CI) in postlingually deafened adults and to explore the boundaries and limitations of the presentObjective. To evaluate the stability of long-term hearing performance after cochlear implantation (CI) in postlingually deafened adults and to explore the boundaries and limitations of the present test batteries for adult CI patients.Study Design. Case series with chart review.Setting. Tertiary referral center.Subjects and Methods. A cohort of 1005 postlingually deafened adult cochlear implantees, who received their implants after age 18 years, was unilaterally implanted and had no inner ear malformations or cochlear ossification. Hearing performance with cochlear implant was evaluated with the help of 5 standard German speech tests.Results. The average performance improved significantly during the first 6 months in all tests (learning phase) and afterward entered a plateau phase in which no statistically significant improvements or deteriorations were observed for more than 20 years of follow-up. For each test, the average performance of the cohort, the ceiling effect, and the average results for high and low performers are presented.Conclusions. In this study, postlingually deafened adults required about 6 months to learn how to process the artificial signals delivered by the cochlear implant. After this learning phase, the hearing performance entered a stable plateau phase for more than 20 years. This stability reveals the long-term reliability of the technology and the biological stability of the electrode-nerve interface over years. In this study, the authors also evaluated the "ceiling effect" with 5 standard German speech tests, used for evaluation of postlingually deafened adult CI patients.

• Cochlear implant performance in geriatric patients.

  Authors: Minoo Lenarz, Hasibe Sönmez, Gert Joseph, Andreas Büchner, Thomas Lenarz

  The Laryngoscope. 02/2012;

  OBJECTIVES/HYPOTHESIS: To evaluate the hearing performance with cochlear implants (CIs) in patients who were 70 years or older at the time of implantation (geriatric patients) and compare it with theOBJECTIVES/HYPOTHESIS: To evaluate the hearing performance with cochlear implants (CIs) in patients who were 70 years or older at the time of implantation (geriatric patients) and compare it with the performance in younger adults. STUDY DESIGN: Individual, retrospective, cohort study. METHODS: A cohort of 1,005 postlingually deafened adults was selected for this study. According to their age at the time of cochlear implantation, patients were divided into four age groups: group 1, 18 to 39 years; group 2, 40 to 59 years; group 3, 60 to 69 years; and group 4, 70 years and older). The test battery was composed of four standard German speech tests: Freiburger Monosyllabic Test, Speech Tracking Test, and Hochmair-Schulz-Moser (HSM) Sentence Test in quiet and in 10 dB noise. RESULTS: Geriatric patients showed a similar learning curve as the younger adults in the first 2 years after implantation. The direct comparison of speech perception in the Freiburger Monosyllabic Test, Speech Tracking Test, and HSM Test in quiet revealed no differences between the average performance of the geriatric patients and younger adults. However, in the HSM Test in noise, the performance of the geriatric group was significantly lower than the younger adults. CONCLUSIONS: Geriatric CI patients have a similar learning curve to younger adults, and in speech tests in quiet they show a comparable performance. However, their performance is significantly lower in noisy surroundings. This may be due to the central presbycusis in patients older than 70 years and should be taken into account in postoperative fitting of these patients. Further prospective studies are required to evaluate the role of special rehabilitation methods and cognitive training to improve the speech perception in noise in geriatric CI patients.

• Directing neuronal cell growth on implant material surfaces by microstructuring.

  Authors: Uta Reich, Elena Fadeeva, Athanasia Warnecke, Gerrit Paasche, Peter Müller, Boris Chichkov, Timo Stöver, Thomas Lenarz, Günter Reuter

  Journal of biomedical materials research. Part B, Applied biomaterials. 01/2012;

  For best hearing sensation, electrodes of auditory prosthesis must have an optimal electrical contact to the respective neuronal cells. To improve the electrode-nerve interface, microstructuring ofFor best hearing sensation, electrodes of auditory prosthesis must have an optimal electrical contact to the respective neuronal cells. To improve the electrode-nerve interface, microstructuring of implant surfaces could guide neuronal cells toward the electrode contact. To this end, femtosecond laser ablation was used to generate linear microgrooves on the two currently relevant cochlear implant materials, silicone elastomer and platinum. Silicone surfaces were structured by two different methods, either directly, by laser ablation or indirectly, by imprinting using laser-microstructured molds. The influence of surface structuring on neurite outgrowth was investigated utilizing a neuronal-like cell line and primary auditory neurons. The pheochromocytoma cell line PC-12 and primary spiral ganglion cells were cultured on microstructured auditory implant materials. The orientation of neurite outgrowth relative to the microgrooves was determined. Both cell types showed a preferred orientation in parallel to the microstructures on both, platinum and on molded silicone elastomer. Interestingly, microstructures generated by direct laser ablation of silicone did not influence the orientation of either cell type. This shows that differences in the manufacturing procedures can affect the ability of microstructured implant surfaces to guide the growth of neurites. This is of particular importance for clinical applications, since the molding technique represents a reproducible, economic, and commercially feasible manufacturing procedure for the microstructured silicone surfaces of medical implants. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater , 2012.

• Effect of technological advances on cochlear implant performance in adults.

  Authors: Minoo Lenarz, Gert Joseph, Hasibe Sönmez, Andreas Büchner, Thomas Lenarz

  The Laryngoscope. 12/2011; 121(12):2634-40.

  To evaluate the effect of technological advances in the past 20 years on the hearing performance of a large cohort of adult cochlear implant (CI) patients. Individual, retrospective, cohortTo evaluate the effect of technological advances in the past 20 years on the hearing performance of a large cohort of adult cochlear implant (CI) patients. Individual, retrospective, cohort study. According to technological developments in electrode design and speech-processing strategies, we defined five virtual intervals on the time scale between 1984 and 2008. A cohort of 1,005 postlingually deafened adults was selected for this study, and their hearing performance with a CI was evaluated retrospectively according to these five technological intervals. The test battery was composed of four standard German speech tests: Freiburger monosyllabic test, speech tracking test, Hochmair-Schulz-Moser (HSM) sentence test in quiet, and HSM sentence test in 10 dB noise. The direct comparison of the speech perception in postlingually deafened adults, who were implanted during different technological periods, reveals an obvious improvement in the speech perception in patients who benefited from the recent electrode designs and speech-processing strategies. The major influence of technological advances on CI performance seems to be on speech perception in noise. Better speech perception in noisy surroundings is strong proof for demonstrating the success rate of new electrode designs and speech-processing strategies. Standard (internationally comparable) speech tests in noise should become an obligatory part of the postoperative test battery for adult CI patients.

• Benefits of the HiRes 120 coding strategy combined with the Harmony processor in an adult European multicentre study.

  Authors: Andreas Büchner, Thomas Lenarz, Peter-Paul Boermans, Johan H M Frijns, Patrizia Mancini, Roberto Filipo, Claire Fielden, Huw Cooper, Martin Eklöf, Anders Freijd [......] Olivier Sterkers, Joachim Müller-Deile, Petra Ambrosch, Silke Helbig, Bruno Frachet, Stéphane Gallego, Eric Truy, Ellen Jeffs, Antonio Morant, Jaime Marco

  Acta oto-laryngologica. 11/2011; 132(2):179-87.

  The Harmony processor was found to be reliable, comfortable and offered a substantially increased battery life compared with the previous generation processor. No significant improvement in speechThe Harmony processor was found to be reliable, comfortable and offered a substantially increased battery life compared with the previous generation processor. No significant improvement in speech understanding with HiRes was demonstrated from objective measures, but the majority of subjects showed a clear subjective preference for the combination HiRes 120/Harmony processor. To evaluate experience with the Harmony™ sound processor, together with the HiRes 120 strategy. Postlingually deafened adults implanted with a CII or HiRes 90K were included and divided into three groups: (1) experienced users using the Platinum body-worn processor; (2) experienced users who had been using other processors; (3) new users with the Harmony processor from first fitting. The latter group entered a randomized crossover protocol where half were initially fitted with HiRes and half with HiRes 120. The initial strategy was used for 3 months and the alternative for a further 3 months. Speech perception tests and questionnaires were performed. The study included 65 subjects. Implementing HiRes 120 was straightforward. The speech test group results did not show significant differences between HiRes and HiRes 120. However, the questionnaires showed significantly higher ratings for HiRes 120 in some instances. Subjects were highly satisfied with the Harmony processor.

• Electron microscopy changes of cochlear implant electrodes with permanently high impedances.

  Authors: Martin Durisin, Christian Krause, Christoph Arnoldner, Georgios Kontorinis, Andreas Buechner, Thomas Lenarz, Anke Lesinki-Schiedat, Oliver Profant, Juergen Neuburger

  Cochlear implants international. 11/2011; 12(4):228-33.

  Impedance measurements by means of telemetry have provided us with an objective test of cochlear implant function. Unmeasurable impedance suggests a possible defect on the corresponding channel ofImpedance measurements by means of telemetry have provided us with an objective test of cochlear implant function. Unmeasurable impedance suggests a possible defect on the corresponding channel of the electrode. However, increasing impedances could suggest inflammatory and/or proliferating processes along the electrode. In this report we examined correlations between high impedance, measured in vivo and in vitro findings on the electrode surfaces. We describe recurrent increases in cochlear implant electrode impedance in the same channels, which could initially be reversed by reprogramming the implant, and with anti-inflammatory treatment using cortisone and antibiotics. Subsequently, however, the impedances remained consistently high, indicating a cochlear implant defect. After the removal of the cochlear implant, the electrodes were examined using light and scanning electron microscopy. Examination of the electrodes with normal impedance values revealed, in the great majority of the electrodes, silver shining surfaces. On the other hand, electrodes with high impedances were found coated with tissue. Further analysis of these electrodes using scanning electron microscopy also demonstrated surface changes. Persistently high impedances were related to changes on the electrodes' surface and to coating with tissue in this case. These changes can result in adhesive processes and technical malfunction, leading to explantation and difficult re-implantation. Therefore, close and professional supervision of cochlear implant patients is needed.

• Radiological diagnosis of incomplete partition type I versus type II: significance for cochlear implantation.

  Authors: Georgios Kontorinis, Friedrich Goetz, Alexandros Giourgas, Thomas Lenarz, Heinrich Lanfermann, Anja M Giesemann

  European radiology. 10/2011; 22(3):525-32.

  To investigate an extended cohort of patients with incomplete partition (IP) and examine the adequacy of the existing classifications based on radiological criteria and on their implications forTo investigate an extended cohort of patients with incomplete partition (IP) and examine the adequacy of the existing classifications based on radiological criteria and on their implications for cochlear implantation. Patients with IP admitted to a tertiary referral centre during the period 2000-2010 were retrospectively examined. The subjects were initially classified into IP-I, IP-II and atypical cases. For cochlear implant recipients relevant aspects were analysed. Eighty-three ears (49 patients) with IP were found, 19 with IP-I, 54 with IP-II and 10 atypical. Thirty-three patients received a cochlear implant (11 with IP-I, 19 with IP-II and three atypical) achieving heterogeneous though mostly promising results. Cerebrospinal fluid gushing was the commonest surgical complication, particularly in cases of IP-I. In general, patients with IP-II performed better than those with IP-I. Cochlear implantation promises adequate hearing rehabilitation for most patients with IP. As we move from IP-I to IP-II better results and lower risk for gushing shall be expected. Based on radiological findings we suggest a modified classification into IP-I, atypical IP-I (with large vestibular aqueduct (LVA) and better partition), IP-II (Mondini deformity) and atypical IP-IIa (without LVA) and b (without LVA but with semicircular canal dysplasia). • Radiological (CT and MR) features are of crucial importance for cochlear implantation • Imaging can identify two types of incomplete cochlear partition and atypical cases • Detailed pre-operative radiological assessment can help predict complications and outcome • A more comprehensive radiological classification of these anomalies is proposed.

• The vestibulocochlear nerve: aplasia and hypoplasia in combination with inner ear malformations.

  Authors: Anja M Giesemann, Georgios Kontorinis, Zajaczek Jan, Thomas Lenarz, Heinrich Lanfermann, Friedrich Goetz

  European radiology. 09/2011; 22(3):519-24.

  To determine features of hypoplasia and aplasia of the vestibulocochlear nerve (VCN) in combination with inner ear malformations (IEMs). Index cases were retrospectively selected from all IEMsTo determine features of hypoplasia and aplasia of the vestibulocochlear nerve (VCN) in combination with inner ear malformations (IEMs). Index cases were retrospectively selected from all IEMs collected since 1995. CT and MRI data were reviewed by two neuroradiologists. The number and thickness of visible nerves in the cerebellopontine angle cistern and inside the internal auditory canal (IAC) were analysed. MR images for 176 patients with IEMs were analysed. Labyrinthine aplasia and otocyst deformity showed 100% correlation, and IAC malformations exhibited 92% correlation with VCN aplasia. Cochlear aplasia, complete aplasia of the semicircular canals, severe cochlear hypoplasia, common cavity, incomplete partition type 1 and mild cochlear hypoplasia showed decreasing degrees of correlation with hypoplasia of the VCN. The remaining types of IEM did not demonstrate VCN hypoplasia. Certain forms of IEM show 100% correlation with hypoplasia or aplasia of the VCN, while others correlate less strongly and some do not usually exhibit VCN hypoplasia. MRI should always be carried out for those forms often correlated with VCN hypoplasia. KEY POINTS : • Vestibulocochlear nerve deficiency can be strongly suspected in certain inner ear malformations • Bony cochlear aplasia and cochlear nerve aplasia are strongly correlated • In semicircular canal aplasia, hypoplasia of the vestibular nerve can be found • Before cochlear implantation, the type of any IEM should be fully understood.

• Development and evaluation of the modiolar research array--multi-centre collaborative study in human temporal bones.

  Authors: Robert J S Briggs, Michael Tykocinski, Roland Lazsig, Antje Aschendorff, Thomas Lenarz, Timo Stöver, Bernard Fraysse, Mathieu Marx, J Thomas Roland, Peter S Roland, Charles G Wright, Bruce J Gantz, James F Patrick, Frank Risi

  Cochlear implants international. 08/2011; 12(3):129-39.

  Multi-centre collaborative study to develop and refine the design of a prototype thin perimodiolar cochlear implant electrode array and to assess feasibility for use in human subjects. Multi-centreMulti-centre collaborative study to develop and refine the design of a prototype thin perimodiolar cochlear implant electrode array and to assess feasibility for use in human subjects. Multi-centre temporal bone insertion studies. The modiolar research array (MRA) is a thin pre-curved electrode that is held straight for initial insertion with an external sheath rather than an internal stylet. Between November 2006 and February 2009, six iterations of electrode design were studied in 21 separate insertion studies in which 140 electrode insertions were performed in 85 human temporal bones by 12 surgeons. These studies aimed at addressing four fundamental questions related to the electrode concept, being: (1) Could a sheath result in additional intra-cochlear trauma? (2) Could a sheath accommodate variations in cochlea size and anatomies? (3) Could a sheath be inserted via the round window? and (4) Could a sheath be safely removed once the electrode had been inserted? These questions were investigated within these studies using a number of evaluation techniques, including X-ray and microfluoroscopy, acrylic fixation and temporal bone histologic sectioning, temporal bone microdissection of cochlear structures with electrode visualization, rotational tomography, and insertion force analysis. Frequent examples of electrode rotation and tip fold-over were demonstrated with the initial designs. This was typically caused by excessive curvature of the electrode tip, and also difficulty in handling of the electrode and sheath. The degree of tip curvature was progressively relaxed in subsequent versions with a corresponding reduction in the frequency of tip fold-over. Modifications to the sheath facilitated electrode insertion and sheath removal. Insertion studies with the final MRA design demonstrated minimal trauma, excellent perimodiolar placement, and very small electrode dimensions within scala tympani. Force measurements in temporal bones demonstrated negligible force on cochlear structures with angular insertion depths of between 390 and 450°. The MRA is a novel, very thin perimodiolar prototype electrode array that has been developed using a systematic collaborative approach. The different evaluation techniques employed by the investigators contributed to the early identification of issues and generation of solutions. Regarding the four fundamental questions related to the electrode concept, the studies demonstrated that (1) the sheath did not result in additional intra-cochlear trauma; (2) the sheath could accommodate variations in cochlea size and anatomies; (3) the sheath was more successfully inserted via a cochleostomy than via the round window; and (4) the sheath could be safely removed once the electrode had been inserted.

• Cochlear implantation in Pendred syndrome.

  Authors: Georgios Kontorinis, Thomas Lenarz, Anke Lesinski-Schiedat, Juergen Neuburger

  Cochlear implants international. 08/2011; 12(3):157-63.

  The objective of this study was to examine the anatomical, audiological, and surgical factors that can affect the hearing outcome in Pendred syndrome cochlear implant recipients. Patients withThe objective of this study was to examine the anatomical, audiological, and surgical factors that can affect the hearing outcome in Pendred syndrome cochlear implant recipients. Patients with Pendred syndrome represent challenging cochlear implant candidates, combining goiter, severe-to-profound hearing loss, and inner-ear dysplasias. The hearing outcome and further relevant parameters in such patients have not been adequately evaluated yet. Retrospective study in a tertiary referral cochlear implant centre. Data of patients with Pendred syndrome, who had undergone cochlear implantation in the 10-year period 1999-2008, were evaluated. Five cochlear implant recipients with Pendred syndrome were identified, four unilateral and one bilateral. The average postoperative follow-up duration for these patients was 4.8 years. Enlarged vestibular aqueduct and Mondini dysplasia were the most common anatomical findings. Although these anatomical variances did not affect the electrode insertion, they prolonged the duration of the surgery. Cerebrospinal fluid gusher was the most common intraoperative complication. All patients enjoyed satisfactory hearing rehabilitation. Cochlear implantation is the proper method for optimal hearing rehabilitation in patients with Pendred syndrome. Although the precise pathogenetic mechanism and the genetic background of deafness in Pendred syndrome have not been completely understood, the preexisting hearing experience represents a positive factor for satisfying hearing outcome. The inner-ear malformations can cause mild surgical difficulties and extended surgery duration. The cochlear implant surgeon should be aware of these difficulties to avoid complications.

• Binaural unmasking of multi-channel stimuli in bilateral cochlear implant users.

  Authors: Lieselot Van Deun, Astrid van Wieringen, Tom Francart, Andreas Büchner, Thomas Lenarz, Jan Wouters

  Journal of the Association for Research in Otolaryngology : JARO. 06/2011; 12(5):659-70.

  Previous work suggests that bilateral cochlear implant users are sensitive to interaural cues if experimental speech processors are used to preserve accurate interaural information in the electricalPrevious work suggests that bilateral cochlear implant users are sensitive to interaural cues if experimental speech processors are used to preserve accurate interaural information in the electrical stimulation pattern. Binaural unmasking occurs in adults and children when an interaural delay is applied to the envelope of a high-rate pulse train. Nevertheless, for speech perception, binaural unmasking benefits have not been demonstrated consistently, even with coordinated stimulation at both ears. The present study aimed at bridging the gap between basic psychophysical performance on binaural signal detection tasks on the one hand and binaural perception of speech in noise on the other hand. Therefore, binaural signal detection was expanded to multi-channel stimulation and biologically relevant interaural delays. A harmonic complex, consisting of three sinusoids (125, 250, and 375 Hz), was added to three 125-Hz-wide noise bands centered on the sinusoids. When an interaural delay of 700 μs was introduced, an average BMLD of 3 dB was established. Outcomes are promising in view of real-life benefits. Future research should investigate the generalization of the observed benefits for signal detection to speech perception in everyday listening situations and determine the importance of coordination of bilateral speech processors and accentuation of envelope cues.

• Options for hearing rehabilitation in children with cochleovestibular nerve dysplasia.

  Authors: Georgios Kontorinis, Friedrich Goetz, Stephanie Ruehl, Andreas Buechner, Thomas Lenarz, Anke Lesinski-Schiedat

  Cochlear implants international. 05/2011; 12 Suppl 1:S109-13.

• Determination of the curling behavior of a preformed cochlear implant electrode array.

  Authors: Thomas S Rau, Omid Majdani, Andreas Hussong, Thomas Lenarz, Martin Leinung

  International journal of computer assisted radiology and surgery. 05/2011; 6(3):421-33.

  Accurate insertion of a cochlear implant electrode array into the cochlea's helical shape is a crucial step for residual hearing preservation. In image-guided surgery, especially using an automatedAccurate insertion of a cochlear implant electrode array into the cochlea's helical shape is a crucial step for residual hearing preservation. In image-guided surgery, especially using an automated insertion tool, the overall accuracy of the operative procedure can be improved by adapting the electrode array's intracochlear movement to the individual cochlear shape. The curling characteristic of a commercially available state-of-the-art preformed electrode array (Cochlear Ltd. Contour Advance(TM) Electrode Array) was determined using an image-processing algorithm to detect its shape in series of images. An automatic image-processing procedure was developed using Matlab and the Image Processing Toolbox (MathWorks, Natick, Massachusetts, USA) to determine the complete curvature of the electrode array by identifying the 22 platinum contacts of the electrode. A logarithmic spiral was used for a comprehensive mathematical description of the shape of the electrode array. A fitting algorithm for nonlinear least-squares problems was used to provide a complete mathematical description of the electrode array. The system was tested for curling behavior as a function of stylet extraction using nine Contour Advance Research Electrodes (RE) and additionally for nine Contour Advance Practice Electrodes (PE). All arrays show a typical pattern of curling with adequate predictability after the first 2 or 3 millimeters of stylet extraction. Although non-negligible variations in the overall curling behavior were detected, the electrode arrays show a characteristic movement due to the stylet extraction and only vary minimally after this initial phase. These results indicate that the risk of intracochlear trauma can be reduced if the specific curling behavior of the electrode carrier is incorporated into the insertion algorithm. Furthermore, the determination of the curling behavior is an essential step in computer-aided cochlear implant electrode development. Experimental data are required for accurate evaluation of the simulation model.

• Preoperative prediction of vestibular schwannoma's nerve of origin with posturography and electronystagmography.

  Authors: Hendrik Borgmann, Thomas Lenarz, Minoo Lenarz

  Acta oto-laryngologica. 05/2011; 131(5):498-503.

  Chances of hearing preservation are better in patients with vestibular schwannoma (VS) from the superior vestibular nerve (SVN) than from the inferior vestibular nerve (IVN). Pathologic posturographyChances of hearing preservation are better in patients with vestibular schwannoma (VS) from the superior vestibular nerve (SVN) than from the inferior vestibular nerve (IVN). Pathologic posturography and electronystagmography (ENG) findings are more common in schwannomas from the SVN compared with tumors from the IVN. In this way, computerized dynamic platform posturography (CDPP) and ENG contribute to predict the nerve of origin of VS and can be used indirectly as a prognostic factor for hearing preservation. To test whether preoperative CDPP or ENG results contribute to predict the nerve of origin in VS and also to evaluate the influence of the nerve of origin on hearing preservation. Eighty-nine patients with VS originating from the IVN and 22 patients with VS from the SVN were included. Hearing loss due to surgery was calculated on postoperative and preoperative audiograms. Caloric response was measured by ENG and condition 5 and 6 score were recorded by CDPP before surgery. Hearing loss due to surgery was significantly lower in patients with tumors from the SVN than from the IVN (p = 0.011). Pathologic results in preoperative ENG (p < 0.0001) and CDPP (p = 0.025) were significantly more frequent in subjects with SVN than with IVN schwannomas.

• The effect of different lubricants on cochlear implant electrode insertion forces.

  Authors: Georgios Kontorinis, Gerrit Paasche, Thomas Lenarz, Timo Stöver

  Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 04/2011; 32(7):1050-6.

  Application of different lubricants during the cochlear implant electrode insertion can affect the insertion forces. Parameters related to cochlear trauma, such as insertion forces, gained more andApplication of different lubricants during the cochlear implant electrode insertion can affect the insertion forces. Parameters related to cochlear trauma, such as insertion forces, gained more and more importance, especially in regard to preservation of residual hearing. The impact of lubricants on the insertion forces has not been systematically examined yet. Nucleus 24 Contour Advance electrodes were inserted into an artificial model of the human scala tympani filled with glycerin, sodium hyaluronate (Healon), and water or soap solution of 10% Bathox and 90% distilled water. A specially designed insertion protocol was applied so as any remains of the lubricants in the scala tympani model or on the electrodes' surface could be completely removed. Force measurements were performed by a force measurement system equipped with a 10 N load cell. Average (AF) and maximum (MF) insertion forces were recorded for every lubricant. The highest values were documented with water (AF = 0.139 N, MF = 0.367 N) and the lowest with the soap solution (AF = 0.065 N, MF = 0.148 N). Application of Healon and glycerin resulted in low, comparable values between each other. The application of lubricants affects significantly the electrode insertion forces. As soap solution is not usable, for the time being, in human cochlear implantation, low insertion forces combined with the antiadhesive features of Healon make it a proper lubricant for intracochlear application. Because of the low recorded forces, soap solution represents an ideal experimental model for in vitro electrode-mechanics studies.

• Outcomes and special considerations of cochlear implantation in waardenburg syndrome.

  Authors: Georgios Kontorinis, Thomas Lenarz, Alexandros Giourgas, Martin Durisin, Anke Lesinski-Schiedat

  Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 04/2011; 32(6):951-5.

  The objective of this study was a state-of-the-art analysis of cochlear implantation in patients with Waardenburg syndrome (WS). Twenty-five patients with WS treated with cochlear implants in ourThe objective of this study was a state-of-the-art analysis of cochlear implantation in patients with Waardenburg syndrome (WS). Twenty-five patients with WS treated with cochlear implants in our department from 1990 to 2010. The 25 patients with WS underwent 35 cochlear implantations. Hearing outcome was evaluated using HSM sentence test in 65 dB in quiet, Freiburg Monosyllabic Test, and categories of auditory performance for children and compared with that of a control group. Anatomic abnormalities of the inner ear were examined using magnetic resonance imaging and computed tomography of the temporal bones. The mean follow-up time was 8.3 years (range, 0.3-18.3 yr). The majority achieved favorable postimplantation performance with mean HSM scores of 75.3% (range, 22.6%-99%) and Freiburg Monosyllabic Test scores of 67.8% (range, 14%-95%). However, in 4 cases, the results were less satisfactory. The comparison with the control group did not reveal any statistical significance (p = 0.56). In 6 patients (24%), behavioral disorders caused temporary difficulties during the rehabilitation procedure. Except of isolated large vestibule in 1 patient, the radiological assessment of the 50 temporal bones did not reveal any temporal bone abnormalities. Most patients with WS performed well with cochlear implants. However, WS is related to behavioral disorders that may cause temporary rehabilitation difficulties. Finally, temporal bone malformations that could affect cochlear implantation are notcharacteristic of WS.

• Impact of the insertion speed of cochlear implant electrodes on the insertion forces.

  Authors: Georgios Kontorinis, Thomas Lenarz, Timo Stöver, Gerrit Paasche

  Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 04/2011; 32(4):565-70.

  Objective of the present experimental research study was to examine the hypothesis that cochlear implant insertion speed can significantly affect the insertion forces. Cochlear implant electrodeObjective of the present experimental research study was to examine the hypothesis that cochlear implant insertion speed can significantly affect the insertion forces. Cochlear implant electrode insertion forces can influence the insertion trauma and the preservation of residual hearing. The effect of the electrode insertion speed on the insertion forces still remains unknown. Force measurements were performed while inserting human electrodes in an artificial scala tympani model at different speeds. For these measurements, an Instron 5542 Force Measurement System with a 10 N load cell and Nucleus 24 Contour Advance electrodes were used. Additionally, the insertion speed was measured through videos of 116 human implantations; these videos were recorded in our theaters and involved different surgeons and electrode types. Progressive increase in insertion speed from 10 to 200 mm/min resulted in significant, proportional increase in the average insertion forces from 0.09 to 0.185 N and in the maximum forces from 0.18 to 0.42 N, respectively. The average insertion speed used in the theaters during human cochlear implantations was 96.5 mm/min (range, 42-165.2 mm/min) and depended on the electrode type and the surgeon. High insertion speeds cause significant increase of the forces. Cochlear implant surgeons should use low and stable speeds during the insertion. Insertion speed close to the average value used in the theaters should be applied on experimental models, to approximate human implantation conditions.