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Due to unique optical/mechanical properties and significant resistance to harsh radiation environments, corundum (α-Al2O3) is considered as a promising candidate material for windows and diagnostics in forthcoming fusion reactors. However, its properties are affected by radiation-induced (predominantly, by fast neutrons) structural defects. In this paper, we analyze thermal stability and recombination kinetics of primary Frenkel defects in anion sublattice − the F-type electronic centers and complementary oxygen interstitials in fast-neutron-irradiated corundum single crystals. Combining precisely measured thermal annealing kinetics for four types of primary radiation defects (neutral and charged Frenkel pairs) and the advanced model of chemical reactions, we have demonstrated for the first time a co-existence of the two types of interstitial defects – neutral O atoms and negatively charged O- ions (with attributed optical absorption bands peaked at energies of 6.5 eV and 5.6 eV, respectively). From detailed analysis of interrelated kinetics of four oxygen-related defects, we extracted their diffusion parameters (interstitials serve as mobile recombination partners) required for the future prediction of secondary defect-induced reactions and, eventually, material radiation tolerance. [ABSTRACT FROM AUTHOR]

The kinetics of mesoscopic pattern formation is studied for a reversible A+B<=>0 reaction between mobile oppositely charged molecules at the interface. Using formalism of the joint correlation functions, non-equilibrium charge screening and reverse Monte Carlo methods, it is shown that labyrinth-like percolation structure induced by (even moderate-rate) reaction is principally non-steady-state one and is associated with permanently growing segregation of dissimilar reactants and aggregation of similar reactants into mesoscopic size domains. A role of short-range and long-range reactant interactions in pattern formation is discussed. [ABSTRACT FROM AUTHOR]

The effects of non-equilibrium charge screening in mixtures of oppositely charged interacting molecules on surfaces are analyzed in a closed system. The dynamics of charge screening and the strong deviation from the standard Debye-Hückel theory are demonstrated via a new formalism based on computing radial distribution functions suited for analyzing both short-range and long-range spacial ordering effects. At long distances the inhomogeneous molecular distribution is limited by diffusion, whereas at short distances (of the order of several coordination spheres) by a balance of short-range (Lennard-Jones) and long-range (Coulomb) interactions. The non-equilibrium charge screening effects in transient pattern formation are further quantified. It is demonstrated that the use of screened potentials, in the spirit of the Debye-Hückel theory, leads to qualitatively incorrect results. [ABSTRACT FROM AUTHOR]

Studies the simulation of kinetic oscillations in surface reactions of reconstructing surfaces. Diffusion and surface reconstruction; Formation of mesoscopic patterns and synchronization; Surface phase propagation velocity.

The kinetics of the bimolecular A+B→0 reaction between charged reactants is studied in two dimensions, i.e., on a surface. The theory is based on the Kirkwood superposition approximation for three-particle densities and the self-consistent treatment of the electrostatic interactions defined by the non-uniform spatial distribution of similar and dissimilar reactants. Special attention is paid to pattern formation and many-particle effects arising from reaction-induced formation of loose domains containing similar reactants only. It is shown that the critical exponent α characterizing the algebraic concentration decay law, n(t)∝t-α, differs strongly between symmetric (DA=DB) and asymmetric (DA=0) reactant mobilities. This effect is abnormal from the point of view of standard chemical kinetics. It arises directly from the specific spatial distribution in the system as in ‘‘raisins A in a dough B.’’ At long reaction times the asymptotics of the interaction potentials is of non-equilibrium type at large relative distances. The accumulation kinetics in the presence of a permanent source is studied. Results of the microscopic formalism are compared with a previous mesoscopic theory. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We introduce a simplified stochastic model for the A+B2 surface reaction with diffusion of the monomer particle. We use a stochastic description which consists only of an autonomous differential equation system with four variables (the coverage of A and B and the corresponding pairs). The solution of this system is a straightforward process. We compare the values of the phase transition points with a much more complex stochastic ansatz which has been introduced earlier [Mai, Kuzovkov, and von Niessen, J. Chem. Phys. 100, 6073 (1994)]. We find good agreement in the prediction of the first-order phase transition with the complete treatment. The ansatz also gives the second-order transition, but the results are not quantitative in the neighborhood of the second-order phase transition. [ABSTRACT FROM AUTHOR]

In this paper we introduce a stochastic model for the A+1/2B2→0 reaction on a square lattice. Reaction between an A and a B particle occurs if they are nearest neighbors on the lattice. To this system which includes adsorption and reaction steps we add the effect of A-diffusion and A-desorption. We describe the model in terms of master equations using the Markovian behavior of the system. The equations are truncated at a certain level via a modified Kirkwood approximation. The reaction is in this paper introduced between particles which are nearest neighbors on the lattice. This approach which is different from a previous article [J. Mai et al., J. Chem. Phys. 98, 10017 (1993)] requires a special treatment of the stochastic equations and the correlation functions. In particular the Kirkwood superposition approximation, which is used to truncate the hierarchy of equations, has to be modified. The resulting system of lattice equations is solved in a small region around a reference point. The solution is connected to continuous functions which describe the system behavior for larger distances. This system shows kinetic phase transitions which separate the reactive regime from two nonreactive states where the lattice is completely covered by A or B. We study the location and the character of the phase transitions in detail. With the help of correlation functions we identify the different phases of particles on the lattice. Island formation and segregation of the particles on the lattice are found to be dominant processes. It is established that finite lattices which have to be used in simulations can be seriously inadequate and miss physical processes. This problem does not appear in the ansatz presented here. [ABSTRACT FROM AUTHOR]

A surface reaction model for the A+1/2B2→0 reaction is studied by a theoretical approach. To this end, we introduce a stochastical ansatz which describes the system behavior by master equations. These equations are solved numerically in the superposition approximation. The results of the theoretical description are in good agreement with the corresponding computer simulations of the system. We focus our interest on the study of oscillations. The correlation functions and the parameter ranges in which oscillations are possible are studied in detail. This model as well as the computer simulations describe some aspects of the heterogeneously catalyzed oxidation of CO on a Pt surface. [ABSTRACT FROM AUTHOR]

The effect of an elastic (U=-λ/r3) interaction between similar particles on the kinetics of the bimolecular A+B→0 reaction is studied for the first time in terms of a novel formalism of the many-point particle densities taking into account the spatial correlations of both similar and dissimilar particles. It is shown that an elastic attraction results in the dynamic aggregation of similar particles and therefore in the reduced reaction rate unusual for the standard chemical kinetics. The distinctive time of such aggregate formation depends on the initial particle concentration and on their spatial distribution but is always considerably shorter than that for statistical aggregation of similar noninteracting particles. The latter is a distinctive feature of the self-organization in bimolecular reactions at long times and/or great particle concentrations. For the same value of the interaction parameter λ an attraction of similar particles has a greater impact on the reaction kinetics than that of dissimilar particles. [ABSTRACT FROM AUTHOR]

We study the bimolecular annihilation reaction A+B→0 with immobile reactants interacting via exchange. We extend our previous analyses to the case of unequal concentrations of A and B particles. A comparison between the direct simulation of the reaction process and an analytical approach, which is based on Kirkwood’s superposition approximation, shows reasonable agreement, although deviations are larger than in the case of equal A and B concentrations. Interestingly, the asymptotic decay forms for the particle concentrations (when formulated in terms of a suitable reaction length) parallel those encountered in diffusion-limited reactions. Here the diffusion length lD=(Dt)1/2 gets replaced by the reaction radius ξ=ln t. We discuss implications of this finding for a qualitative (but quite accurate) picture of the temporal evolution behavior. [ABSTRACT FROM AUTHOR]

In this paper we study CO oxidation on a catalyst consisting of a Pt/Sn alloy. On this catalyst the reaction can take place at room temperature. We use for the description two basically different methods: Monte Carlo simulations and a theoretical stochastic ansatz. The stochastic ansatz introduced recently [Mai, Kuzovkov, and von Niessen, Physica A 203, 298 (1994)] is a general method for the description of surface reaction systems including mono- and bimolecular steps. Using the Markovian behavior of these systems we formulate this ansatz in terms of master equations. It turns out that the stochastic ansatz can be used as an interesting and advantageous alternative to the standard Monte Carlo simulations. The particles involved in the reaction system have different tendencies toward building structures on the surface. The coverages show a strong dependency, not only on the composition of the gas phase but also on the initial concentration of the reaction promotor OH and the concentration of Pt sites in the catalyst material. The reaction probability does not influence the qualitative trends of the coverages versus the gas phase concentration of CO. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Introduction: Rehabilitation treatment after cochlear implantation is carried out in several large centers with courses of 10 days. The time between courses ranges from several months to a year. Short courses cannot provide full rehabilitation for patients. This is not always true. In some cases, absent. Objective: To optimize the treatment method after cochlear implant surgery by introducing into clinical practice a new method of remote medical and pedagogical support for patients between inpatient treatment at cochlear implant centers, taking into account the territorial features of the Russian Federation. Objective: To evaluate the effectiveness of remote rehabilitation support for patients in remote regions, taking into account the use of telemedicine technologies, distance education of parents and patients. Material and methods: The study involved 10 children with a diagnosis of grade 4 SNT (ages 3 to 6 years). The control group consisted of 10 children with a diagnosis of grade 4 SNT (aged 3 to 6 years) who did not use remote support. Cochlear implants were installed in all inpatients (Concerto, MED-EL, Austria). At the first remote stage, after the operation and before the first connection, remote monitoring was performed by an ENT surgeon, video lectures to prepare for the first connection of the speech processor, psychological and pedagogical counseling of parents. Later, in the hospital, the first connection of the speech processor was carried out (OPUS 2, MED-EL, Austria). At the second, remote stage, continuous medical and pedagogical rehabilitation was carried out for 6 months, including weekly corrections of the appointment of the rehabilitation program as a sound educator, developing classes in the information system with an assessment of auditory developmental dynamics -- 3 times a week, questioning parents, viewing educational lectures, distance learning sessions with Speech therapist and sign teacher. Results: A survey was conducted. 3 groups of questions were used: Evaluated the quality of the Internet connection, satisfaction with remote support, improving the quality of life. Overall satisfaction in the first patients was 74.5%. In the process of further optimization of the information system, patient satisfaction increased to 92%. All patients showed an improvement in quality of life. Conclusions: In the modern world, information technology is significantly developed. But in the field of cochlear implantation are not fully used. In the first months after connecting the speech processor, the child is most in need of intensive pedagogical rehabilitation. The method of remote support for patients allows in the most important period -- after connecting to provide long-term continuous remote pedagogical and medical support and monitor the implementation of the rehabilitation program. [ABSTRACT FROM AUTHOR]

Background: Artificial Intelligence Systems (AIS) are soft- ware systems that mimic human thinking. AIS are currently used in many tasks. These are financial transactions, loan approval, assistance in making decisions on the exchange, currency detectors in ATMs, use in search engines on the Internet, use in mobile phones. Recently, artificial intelligence systems have been actively used in medicine. Actively use artificial intelligence systems in microscopy and microbiology for algorithms for the automatic recognition of certain structures. Neural networks and expert systems are also used to diagnose and monitor the patient's condition with meningitis and bacterial infections. Assistance in making a diagnosis according to examination, differential diagnosis of tuberculosis, analysis of data from CVP, ECG, Encephalogram, MRI, CT. We began to use artificial intelligence systems in rehabilitation after cochlear implantation. The success of cochlear implantation depends on many factors: on the selection of patients for cochlear implantation, successful surgery, and postoperative rehabilitation of the patient. During the rehabilitation of patients, it is very important to properly configure the auditory processor of the cochlear implant. In complex cases, subjective tuning methods cannot be used. Then objective research methods are used to configure speech processors. The most common method is to register an electrically triggered stapedial reflex. But in some cases, this study is impossible to perform. Then the telemetry method of the nerve response is used, which has less accuracy for tuning processors. At the Institute of Nasal Throat Ear and Speech, together with the Krasnoyarsk Medical University, a neural network was developed that allows the processing of telemetry data of the nerve response. Based on the results of the examination, synthesize tuning cards for the auditory processors of the cochlear implant with much greater accuracy. Results: We examined 90 patients. The examined patients were divided into two groups. The first group (85% of patients) was used to train the neural network. The second group (15% of patients) in the training sample was not taken into account and formed a comparison group to assess the effectiveness of the neural network after training. More than 80 neural networks were trained. As a result of processing, we selected the network that turned out to be optimal according to statistical indications. It turned out that for the network to work, it is enough to use only three significant parameters. The network structure consisted of three input neurons, three hidden neurons and one output neuron. The share of the correct forecast for the operation of this network was 99.2%. Conclusions: Using an expert system can significantly simplify the configuration of the speech processor in adult patients, avoid mistakes in young professionals who are just starting to set up cochlear implant systems. The use of an expert system can improve the quality of the processor fittings and reduce the rehabilitation time. [ABSTRACT FROM AUTHOR]

In the description of charge screening in the electrostatic self-assembly of nanoparticles (molecules) embedded into a polar solvent, the static screening effects (a contribution associated with the rapid spatial redistribution of small and highly mobile ions of a solvent) are traditionally treated phenomenologically, using the Yukawa short-range potential for describing the interaction between these particles. However, this model has a limited range of applicability being valid only for infinitely diluted systems and high salt concentrations. During a slow self-assembling process with nanoparticle formation, very dense structural elements (aggregates) are formed, in which the distances between the nanoparticles could become comparable to the Debye radius in the Yukawa potential. For such structural elements dynamic screening effects (the contribution of nanoparticles themselves to the screening potential) become important. In this paper, using a novel integrated approach (nonlinear integro-differential kinetic equations for the correlation functions of particles), we have obtained the self-consistent solution in the 3d case and compared roles of both static (equilibrium) and dynamic (nonequilibrium) charge screening effects in different situations. This paper is a continuation of our recent study [Phys. Chem. Chem. Phys., 2014, 16, 13974], where the polar solvent effects were now taken into account. [ABSTRACT FROM AUTHOR]

A study of 3d electrostatic self-assembly (SA) in systems of charged nanoparticles (NPs) is one of the most difficult theoretical problems. In particular, the limiting case of negligible or very low polar media (e.g. salt) concentration, where the long-range NP interactions cannot be reduced to commonly used effective short-range (Yukawa) potentials, remains unstudied. Moreover, the present study has demonstrated that unlike the Debye–Hückel theory, a complete screening of the charges in SA kinetics (dynamic SA) is not always possible. Generally speaking, one has to take into account implicitly how each NP interacts with all other NPs (the true long-range interactions). Traditional theoretical methods allow us to monitor such electrostatic 3d system kinetics only for very short times, which is far from sufficient for understanding the dynamic SA. In this paper, combining an integrated analytical approach (the non-linear integro-differential kinetic equation for correlation functions) and reverse Monte Carlo in the 3d case, we have obtained a self-consistent solution of this challenging problem. We demonstrate, in particular, the existence of critical points and critical phenomena in the non-equilibrium kinetics in a 3d system of oppositely charged mobile NPs. [ABSTRACT FROM AUTHOR]

We propose a novel approach for description of dynamics of nanostructure formation for a system consisting of oppositely charged particles. The combination of numerical solution of analytical Bogolyubov-Born-Green-Kirkwood-Yvon (BBGKY) type equation set with reverse Monte Carlo (RMC) method allows us to overcome difficulties of standard approaches, such as kinetic Monte Carlo or Molecular Dynamics, to describe effects of long-range Coulomb interactions. Moreover, this allows one to study the system dynamics on realistic time and length scales. We applied this method to a simple short-range Lenard-Jones (LJ)-like three- (3D) and two-dimensional (2D) system combining the long-range Coulomb and LJ interactions. As expected, the nanoparticle growth driven by the Ostwald ripening is observed in the former case, while long-range interaction limited self-assembled nanostructures are observed in the latter case. Example of 3D structure of self-assembled nanoparticles interacting via short-range LJ and long-range Coulomb potentials obtained by improved reverse Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

Conclusion: The comprehensive Hearing Preservation classification system presented in this paper is suitable for use for all cochlear implant users with measurable pre-operative residual hearing. If adopted as a universal reporting standard, as it was designed to be, it should prove highly beneficial by enabling future studies to quickly and easily compare the results of previous studies and meta-analyze their data. Objectives: To develop a comprehensive Hearing Preservation classification system suitable for use for all cochlear implant users with measurable pre-operative residual hearing. Methods: The HEARRING group discussed and reviewed a number of different propositions of a HP classification systems and reviewed critical appraisals to develop a qualitative system in accordance with the prerequisites. Results: The Hearing Preservation Classification System proposed herein fulfills the following necessary criteria: 1) classification is independent from users' initial hearing, 2) it is appropriate for all cochlear implant users with measurable pre-operative residual hearing, 3) it covers the whole range of pure tone average from 0 to 120 dB; 4) it is easy to use and easy to understand. [ABSTRACT FROM AUTHOR]

Conclusion: The comprehensive Hearing Preservation classification system presented in this paper is suitable for use for all cochlear implant users with measurable pre-operative residual hearing. If adopted as a universal reporting standard, as it was designed to be, it should prove highly beneficial by enabling future studies to quickly and easily compare the results of previous studies and meta-analyze their data. Objectives: To develop a comprehensive Hearing Preservation classification system suitable for use for all cochlear implant users with measurable pre-operative residual hearing. Methods: The HEARRING group discussed and reviewed a number of different propositions of a HP classification systems and reviewed critical appraisals to develop a qualitative system in accordance with the prerequisites. Results: The Hearing Preservation Classification System proposed herein fulfills the following necessary criteria: 1) classification is independent from users' initial hearing, 2) it is appropriate for all cochlear implant users with measurable pre-operative residual hearing, 3) it covers the whole range of pure tone average from 0 to 120 dB; 4) it is easy to use and easy to understand. [ABSTRACT FROM AUTHOR]

An approach to analysis of time series of edge localized modes (ELMs) is proposed. It is based on the use of the autoregressive moving average model, which decomposes time series into deterministic and noise components. Despite the inclusion of nonlinearity in the model, the resulting deterministic equations for the ELM time series measured on Axially Symmetric Divertor Experiment Upgrade tokamak turn out to be linear. This contrasts with the findings on JAERI tokamak (JT-60U) and tokamak à configuration variable that ELMs exhibit features of chaotic dynamics, namely, the presence of unstable periodic orbits. This methodology for distinguishing chaotic behavior is examined, and found to be susceptible to misinterpretation. [ABSTRACT FROM AUTHOR]

Objectives: Today, cochlear implantation is the only treatment for the fourth degree of hearing loss and deafness. The result of cochlear implantation depends on a careful selection of patients, a high-quality operation and the right rehabilitation tactics. An extremely important stage of the operation is intraoperative monitoring, which includes telemetry of the implant state, telemetry of the nervous response and registration of the electrically induced stapedial reflex. The first two stages are performed through special modules that are integrated into the software, the third stage is performed using a surgeon who visually determines the thresholds of the stapedial reflex. The aim of our work is to determine the relationship between the thresholds of the electrically induced stapedial reflex, the thresholds of the response of the auditory nerve, recorded in automatic mode and subjective levels of the most comfortable volume. Material and methods: We examined 25 patients aged 10 months to 42 years who underwent cochlear implantation using the Concerto cochlear implant (MedEl, Austria) at St. Petersburg Research Institute of ENT SPECIALIST. The threshold of the stapedial reflex and the threshold of response of the auditory nerve at 2, 5, 8, and 11 electrodes were recorded for each patient. It is worth noting that auditory nerve response thresholds were recorded in all patients, and the stapedial reflex was recorded only in 20. We also examined 30 late-deaf patients from 18 to 54 years old with experience of wearing a speech processor from 3 to 5 years, who performed cochlear implantation using the Concerto cochlear implant (MedEl, Austria) in St. Petersburg Research Institute of ENT. Each patient was configured with two training cards. The first map was created using subjective patient ratings, and the second using automatic recording of auditory nerve responses. Stimulation was performed on all electrodes. Results and conclusions: As our study showed, the thresholds of the stapedial reflex and the thresholds of response of the auditory nerve differ very slightly. On the 2nd electrode, the difference is 2%, on the 5th electrode -- 5%, on the 8th electrode -- 10%, on the 11th electrode -- 7%. Maps created using different data were very similar in appearance to the tuning curve, however, they differed in volume. More often than not, maps created using automatic recording of auditory nerve responses were quieter than maps constructed from subjective assessments of patients. The best correlation between the maps was observed on electrodes 7 through 12. [ABSTRACT FROM AUTHOR]

Cochlear implantation uses data on the tonotopic organization of the cochlea in the distribution of signals through the channels of the electrode of the cochlear implant. The more accurate and natural the stimulation of the auditory nerve fibers, the better the perception of speech, sounds and speech intelligibility. Traditionally, when tuning processors, the principle of frequency distribution of electrodes is used, which is close to the tonotopic organization of the cochlea, taking into account the used coding strategy. These average values do not take into account the individual characteristics of the patient's cochlear anatomy. In the FSBI "SPb NII ENT" software was used to process the data of postoperative computed tomography in 3D to determine the geometric dimensions and anatomical features of the cochlea. According to the formulas obtained using the synchrotron, data were obtained on the individual frequency distribution of the studied cochlea, depending on the angular position of the electrode. Based on this data, the processor settings were corrected. Seven patients aged 8 to 36 years were examined using the Med-El cochlear implantation system, Concerto implant with various types of electrodes. Computed tomography of the temporal bones was performed in the standard mode on various devices with a slice thickness of 0.6 mm or less. After the anatomical adjustment, all patients noted a more natural sounding; in 3 patients, the peculiarities of the position of the electrodes were revealed, requiring additional adjustment of the adjustment. Deaf teachers noted an improvement in speech intelligibility. A new tool has appeared that allows you to significantly improve the quality and provide an individual approach to tuning processors after cochlear implantation. Thanks to the sound coding of the lowest frequencies, the electrode reaching the tonotopic location of the dendrites of the auditory nerve at low frequencies, the individual distribution of frequencies on each electrode, maximum speech intelligibility and natural sounding are achieved. [ABSTRACT FROM AUTHOR]

Introduction: At the St. Petersburg Institute of Ear, Throat, Nose and Speech, more than 5,000 patients with a cochlear implant (CI) are observed. Great experience has been gained not only in surgical interventions, but also in the rehabilitation measures of implanted patients. Special groups of patients deserve special attention -- elderly patients, patients with various abnormalities of the middle and inner ear, patients who have undergone meningitis, patients with auditory neuropathy. Auditory neuropathy (ANSD) is a syndrome characterized by impaired speech intelligibility. Thresholds of hearing, while this can vary from 1 to 4 degrees. Diagnostic criteria for ANSD are the absence of registration of thresholds of VSR, the presence of the microphone potential of the cochlea, and in some cases the registration of otoacoustic emission. Objective: The purpose of the study was to identify the features of rehabilitation measures in patients with auditory neuropathy. Material and methods: The study involved 15 patients with heart failure from 3 to 9 years. All of them underwent CI. Within 2 years, the dynamics of the tuning cards of the speech processor, auditory testing were carried out. Results. All patients regularly used CI. All showed stable responses to tonal signals of 30--35 dB. When evaluating training cards, 27% of patients had high MSL thresholds, used the CIS strategy, and a low stimulation frequency. 73% of patients showed progress in speech intelligibility, and 27% showed little progress. 60% of patients reached level 5 of speech intelligibility (intelligibility of simple sentences) in 24 months, 7% -- level 6 (understanding of speech of family members) in 24 months. Conclusions: In all patients with ANSD, steady responses to tonal signals of 30--35 dB were observed. The group of patients with heart failure is heterogeneous, which may be related to the topography of the disorder (pre-/postsynaptic disorders), the rehabilitation periods for this group of patients should be increased. In the development of auditory reactions, an integrated approach is important -- regular settings of the KI processor, classes with a sign teacher, speech therapist and independently in the family. [ABSTRACT FROM AUTHOR]

The round window niche area is dramatically important in terms of cochlear implantation as its individual variations influences approach to the scala tympani of the cochlea. Methods. The syntopy of round window niche area and adjacent regions was examined on 20 cadaveric temporal bones. Results and discussion. Three types of free edge of the round window niche tegmen were distinguished. In 11 specimens out of 20 well-formed free edge of the tegmen was revealed and round window membrane was fully visualized. In 6 cases a well-formed free edge of the tegmen was detected but due to the angle of this anatomic structure the membrane was only partly observed. In 3 specimens free edge of the tegmen was hypertrophic and protruded medially obscuring the membrane and the chamber of the round window niche. In 16 cases in hypotympanum area we observed a tunnel between the finiculus and fustis. This tunnel connected tympanic cavity and petrous bone cells below the cochlea. Three degrees of expression of this structure were discerned: I - 11/20 bones presented wide tunnel; II -- in 5/20 specimens only a small foramen was revealed under the finiculus; III -- in 4/20 cases this tunnel was not visualized. Learning outcome. A wide tunnel, which can be observed under the cochlea after the posterior tympanotomy, may mimic the round window niche. This can lead to the false electrode insertion. The potential risk of jugular bulb and carotid artery damage should be kept in mind as infracochlear pneumatization may serve as a pathway leading to these vessels. [ABSTRACT FROM AUTHOR]

Objectives: Cochlear implantation (CI) has become the standard treatment for severe-to-profound sensorineural deafness in the last 30 ears. It is well known that some patients are denied from the surgery due to surgical reasons (ossification, severe malformations) and anesthesiology related reasons (severe comorbidities). Material and Method: Twelve adult (aged 21 -- 64 years) subjects underwent unilateral CI under LA in our institution between October 2014 and August 2017. All subjects had an American Society of Anesthesiologists (ASA) Physical Status classification of 4, corresponding with significant comorbidity. In comparison with some other studies no conscious sedation was used at our institution due to the potential risk of adverse side effects. Result and Conclusion: Total operating time was calculated as time from incision to dressing placement, the mean time was 27 ± 5.2 min. The time included electrode impedances testing and our new developed electrically evoked pure tone audiometry (ePTA). Subjects' pain was assessed intraoperatively, in 6 and 24 h after surgery with the Numeric Pain Rating Scale (NRS- 11). The NRS-11 is 11-point scale in which a score of 0 means ''no pain'' and 10 means ''worst pain imaginable.'' Ten subjects did not experience any pain during surgery and reported the NRS score was 0. One subject reported some pain during the drilling of the antrotomy and his intraoperative NRS score was 2. And one subject experienced pain during round window overhang removal (NRS score 3). NRS scores varied from 0 to 3 in the postoperative period (6 and 24 h) and analgesics were administered when the LA had worn off. CI surgery under local anesthesia was found to be safe in patients with significant comorbidities where general anesthesia is contraindicated. [ABSTRACT FROM AUTHOR]

Objective: To use videonystagmography (VNG) to reveal vestibulometric signs of vestibular dysfunction before cochlear implantation (CI) and investigate the possible influence of unilateral CI on vestibular function. Material: 30 consecutive patients (19 women and 11 men) with bilateral chronic deafness received unilateral CI. All patients were examined preoperatively and postoperatively (in 1 week and 1 month after CI). Patients were aged 18-55 years. Methods: The nystagmometric signs of possible peripheral / central / mixed vestibular dysfunction were assessed using computerised registration and automatic analysis of spontaneous, optokinetic and caloric nystagmus by means VNG. Results: Preoperatively, 8/30 patients with bilateral chronic deafness suffered from bilateral chronic vestibulopathy with complaints of unsteadiness / oscillopsia / vertigo. The salient videonystagmographic signs were spontaneous nystagmus, abnormalities of optokinetic and caloric nystagmus, in particular their nontrivial asymmetry. The videonystagmographic symptoms of peripheral vestibular dysfunction were revealed in 1 week after CI in 4/30 patients. The number with postoperative vestibular unsteadiness decreased to 2/30 at 1 month after CI. 2/30 patients experienced vestibular complaints with spontaneous nystagmus after the implant activation during program switch. 10/30 patients underwent medical therapy (glucocorticosteroids, benzodiazepines, non-loop diuretics, betahistines) after CI with positive effect; in so doing, possible unsteadiness in the early postoperative period was diminished and postoperative audiological performance did not deteriorate. Conclusions: Deaf adult patients (75% of the cases) with central spontaneous nystagmus absence, regularity of symmetric optokinetic nystagmus presence and caloric responsiveness preservation had good prognosis for cochlear implantation in terms of vestibular function. The presence of spontaneous nystagmus (33% of patients) was the proof of decompensation stage of vestibular dysfunction both before and after cochlear implantation. Videonystagmographic evidence of vestibular dysfunction was rarely elicited after cochlear implantation: 13% of patients in the early postoperative period, 6% in the later postoperative period, and 6% during implant fitting. [ABSTRACT FROM AUTHOR]

The subject is a 33-year-old female with bilateral sensorineural deafness due to fractures of the skull base, temporal bones, and facial bones when she was 19 years old (in 2003). In 2004 she was unilateral implanted with a MEDEL C40 cochlear implant. In 2013 she was reimplanted with a MED-EL CONCERTO cochlear implant. The HDCIS strategy with standard biphasic pulses and pulse duration extended up to 100-120 ms, and Maplow compression = 2000 were initially used. Three channels (10, 11, and 12) were disabled due to high impedance. Two channels (3 and 9) were disabled due to the absence of auditory perception. She reported the complaints about the low volume of the external sound, her own voice, and poor speech intelligibility. Increasing the MCL in the enabled channels was not possible due to facial nerve stimulation. The application of triphasic pulse stimulation allowed for a significant increase in the pulse amplitude without stimulating the facial nerve, and as such, it was possible to reach loud subjective levels, activate channel 3, and achieve a satisfactory auditory sensation. Increasing the interphase gap for triphasic pulses from the standard 2.1 ms to 10 or 20 ms led to a further increase in volume, but dramatically reduced the rate of stimulation. At a 30 ms interphase gap, she assessed the sound as indistinct and unclear. Volume categorization, phoneme intelligibility, and disyllabic word intelligibility measurements were made across the following conditions: (i) biphasic stimulation: VC = very quiet, PI = 25%, DWI = 23%; (ii) triphasic stimulation with a 2.1 ms interphase gap: VC = medium-loud, PI = 27%, DWI = 30%; (iii) triphasic stimulation with a 10 ms interphase gap: VC = comfortably loud, PI = 30%, DWI = 33%; and (iv) triphasic stimulation with a 20 ms gap: VC = comfortably loud, PI = 30%, DWI = 28%. During follow-up the patient chose the fitting with triphasic stimulation and a 10 ms interphase gap. Speech intelligibility increased slightly. Triphasic pulse stimulation is an effective fitting method for increasing volume perception and improving speech intelligibility without stimulating the facial nerve. [ABSTRACT FROM AUTHOR]

In patients with residual hearing it is crucially important not to alter the fine structures of the cochlea. In this study we analyzed the anatomic variations of the "hook" region on 35 cadaveric temporal bones and tried to find out the optimal electrode insertion rout. Basing on the distance between the edges of oval and round windows all 35 cadaveric temporal bones were divided into two groups: "small" and "big" ones (on the ground of classification proposed by F. Atturo, M. Barbara, H. Rask-Andersen). It was revealed that this distance correlates with the position of the "hook" region structures: osseous spiral lamina, spiral ligament, basilar membrane, cochlear aqueduct and accessory aqueduct housing inferior cochlear vein. In the experimental study we compared 4 types of electrode insertion: via round window, with the use of anterior cochleostomy, anterior-inferior cochleostomy and enlarged round window. It was proved that the most nontraumatic approach in both "small" and "big" cochleae is the electrode delivery via round window membrane. This approach in all cases enabled electrode insertion without altering "hook" region structures. When anterior cochleostomy was performed in both "small" and "big" cochlea spiral ligament and lateral portion of the osseous spiral lamina were inevitably damaged in all the specimens. In 33% "big" cochlea cases basilar membrane was also altered. Whereas in temporal bones with anterior-inferior cochleostomy spiral ligament and osseous spiral lamina remained intact in 66% of "big" cochlea and in 50% of "small" cochlea and there was a significant risk especially in "small" bones (83 %) of damaging the cochlea aqueduct and accessory aqueduct. As for the enlarged round window approach we revealed alteration of cochlea aqueduct and its accessory canal in 75% cases ("small" cochlea) and 50% cases ("big" cochlea). [ABSTRACT FROM AUTHOR]

Background: Binaural hearing is the fundamental property of the properly functioning hearing system. The advantages of binaural hearing have been repeatedly demonstrated in research on healthy human subjects. The benefits of binaural perception are sound localization ability, better speech intelligibility in both silence and noise, simplicity of oralaural development and education processes, and improvement of the quality of life. Methods The group consisted of 32 adults (n=32) with asymmetric hearing loss of different etiology. Each patient had been using hearing aids for some time before cochlear implantation. Hearing ability was analyzed in 32 postlingual adults who received a cochlear implant (MED-EL; Innsbruck, Austria). The standard test procedure included pure tone audiometry in free field (using modulated tones) and speech audiometry in free field in both silence and noise (monosyllabic and polysyllabic Russian word lists). Results: The thresholds of modulated tones were 60-80 dB with hearing aids but increased to 40-45 dB when patients used unilateral cochlear implant. The combination of a unilateral cochlear implant and an opposite non-implanted hearing aid recovered sound localization capacity. The comparison of monosyllabic and polysyllabic words intelligibility before surgery and in 12 month post-surgery showed different degrees of increase in hearing ability. Before surgery the results were 4,8±1,72% % on the monosyllabic and 11,39±3,13% on the polysyllabic test, and 12 months post-surgery the results were 39,51±3,5% on the monosyllabic and 69,14±5,1% on the polysyllabic test. The combination of a cochlear implant and a hearing aid, however, revealed better results of speech intelligibility both (59,34 ± 4%) on the monosyllabic (59,34 ± 4%) and on the polysyllabic tests (85,7±7,4%), accordingly. Conclusion: Cochlear implantation is the best choice for postlingual patients with asymmetric hearing loss without any hearing-aid effect. Unilateral cochlear implantation in combination with a traditional hearing aid on the opposite non-implanted ear or bilateral cochlear implantation (binaural hearing) improves speech intelligibility, recovers sound localization ability and other binaural effects, and, as a result, increases efficiency of patients' rehabilitation after cochlear implantation. [ABSTRACT FROM AUTHOR]