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COCHLEAR IMPLANTATION IN SCHOOL-AGED CHILDREN
Abdumannop Abdumadjitovich ABDUKAYUMOV1,
Dilshod Utkurovich MUKHAMEDOV2
1Doctor of Science, Republican Specialized Scientific and Practical Medical Center for Pediatrics
2Republican Specialized Scientific and Practical Medical Center for Pediatrics
КОХЛЕАРНАЯ ИМПЛАНТАЦИЯ У ДЕТЕЙ ШКОЛЬНОГО ВОЗРАСТА
Абдуманноп Абдумаджитович АБДУКАЮМОВ1,
Дилшод Уткурович МУХАМЕДОВ2
1д.м.н., Республиканский специализированный научно-практический медицинский центр педиатрии
2Республиканский специализированный научно-практический медицинский центр педиатрии
МАКТАБ ЁШИДАГИ БОЛАЛАРДА КОХЛЕАР ИМПЛАНТАЦИЯ
Абдуманноп Абдумаджитович АБДУҚАЮМОВ1,
Дилшод Ўткурович МУХАМЕДОВ2
1т.ф.д., Республика ихтисослаштирилган педиатрия илмий-амалий тиббиёт маркази
2Республика ихтисослаштирилган педиатрия илмий-амалий тиббиёт маркази
ABSTRACT
This review presents a variety of views on cochlear implantation. The review showed that promising areas are the introduction of fully implantable cochlear implantation systems; development of new strategies for speech coding, improvement of sound processing technologies with microphones, as well as the search for new surgical approaches when installing a cochlear implant.
Key words: cochlear implantation, rehabilitation, school-age children, hearing loss.
АННОТАЦИЯ
В данном обзоре представлены данные о кохлеарной имплантации. Обзор показал, что перспективными направлениями являются внедрение полностью имплантируемых систем кохлеарной имплантации; разработка новых стратегий кодирования речи, усовершенствование технологий обработки звука микрофонами, а также поиск новых хирургических подходов при установке кохлеарного импланта.
Ключевые слова: кохлеарная имплантация, реабилитация, дети школьного возраста, тугоухость.
АННОТАЦИЯ
Ушбу шарҳда кохлеар имплантация ҳақида маълумотлар келтирилган. Шарҳ шуни кўрсатдики, тўлиқ имплантация қилинадиган кохлеар имплант тизимларини жорий этиш; нутқни кодлашнинг янги стратегияларини ишлаб чиқиш, микрофонлар билан овозни қайта ишлаш технологияларини такомиллаштириш, шунингдек, кохлеар имплантни ўрнатишда янги жарроҳлик ёндашувларни излаш истиқболли йўналишлардир.
Калит сўзлар: кохлеар имплантация, реабилитация, мактаб ёшидаги болалар, эшитиш қобилиятини йўқотиш.According to WHO (2014), there are about 540 million people in the world with some degree of hearing loss. Thus, 65-70% of the US population older than 70 suffer from clinically significant hearing loss [2, 6, 9, 14]. Severe hearing loss, which hinders social communication, affects 1-6% of the world's population [1, 7, 13]. At the same time, in the general structure of the incidence of hearing loss, the neurosensory one dominates, which makes up 60-80% and affects people of working age more often [3, 5, 10, 15].
In recent years, new technologies for nursing newborns have led to a decrease in the perinatal mortality rate, but the number of children with the consequences of ante- and intranatal injuries, with various functional and organic disorders, including those of the hearing organ, is steadily increasing. According to various authors, the number of patients with hearing impairment in childhood currently exceeds 1 million people [7, 11, 15].
The purpose of this review is to study various methods of rehabilitation of children at the stages of cochlear implantation.
The material of this review was scientific publications on this topic published over the past 10 years in the E-library and PubMed databases.
The results of this review and their discussion. Electrical stimulation of the auditory nerve has over 200 years of history. In 1794, A. Volt evoked auditory sensations by applying electrodes to his forehead. Of course, at that time, Volt did not think that in doing so he had an effect on the intact inner ear. Only in the middle of the XX century. cochlear implantation became possible when A. Dijourno and C.P. Eyries turned their scientific attention to the possibility of electrical stimulation of the inner ear during otosurgical operation in the formation of a cochleostomy. A. Dijourno and C.P. Eyries reported on the ability to distinguish sounds during direct electrical stimulation of the inner ear, and they published their observations in the journal Presse Médicale [2, 4, 8].
In 1959, William House, an otosurgeon from California, already familiar with the technique of working on the cerebellopontine angle using the first microscopes, standardized the surgical approach to the cochlea through a round window [1, 13]. The invention of the single channel cochlear implant at W. House took almost 10 years. The first single-channel implant was a rigid structure and stimulated all fibers of the auditory nerve simultaneously; the user of such a device was able to distinguish only the rhythm of speech. W. House collaborated mainly with J. Urban, the production of single-channel cochlear implants continued until 1995, the main purpose of this device was the direct study of the mechanism of its functioning for scientific purposes [14].
In 1966 F.B. Simmons was the first to perform cochlear implantation with the introduction of a multichannel cochlear implant in a deaf patient [13]. This experimental study showed that when a certain section of the auditory nerve fibers is stimulated by means of an electrode array, auditory sensations of different frequencies occur. Later, M. Merzenich confirmed the obtained data by studying the features of electrical stimulation of the auditory nerve in macaques [11].
Since 1967, intensive development of the cochlear implantation system and surgical approaches to the cochlea of the inner ear began. The first step in the development of a high-tech method of providing medical care to patients with severe hearing loss and deafness was the invention by the G. Clark team in 1978 of a multichannel cochlear implant [14]. That same year, despite skepticism from much of the medical community, including otorhinolaryngologists, the first successful cochlear implant was performed in Australia. Four years later (1982), Cochlear launched the commercial production of CI systems under the brand name Nucleus. The first user of a multichannel cochlear implant produced by Cochlear was 37-year-old Australian Gray Carrick. In 1985, the US Food and Drug Administration (FDA) approved the use of the Nucleus implant systems in the US in postlingual patients over 18 years of age with total deafness. In 1990, the same organization approved the Nucleus implant for use in children aged 2 to 17 in the United States. In 1990, Ingeborg and Hochmair founded MED-EL, headquartered in Innsbruck, Austria. In 1991, MXM-Neurelec (France) launched its first multichannel implant: it was fully digital and adapted for insertion into the ossified cochlea [10].
The number of patients undergoing CI increases annually [8]. According to cochlear implant manufacturers, in 2007 (Cochlear Corporation, Med El and Advanced Bionics) 120,000 people were operated on in the world. According to statistics provided by Cochlear Corporation (Australia), in 2007, the number of patients operated on with the systems of this manufacturer was 91,000 people, of which 42,000 were children, the rest were adults. According to statistics provided by Advanced Bionics (USA), in 2007, the number of patients operated on by their own CI system was 24,000 people, 55% of them were adults, 45% were children. Approximately 1,200 people were operated on with the Advanced Bionics cochlear implantation system (USA) binaurally, of which 45% are adult patients, 55% are children. The literature lacks sufficient coverage of data on patients implanted with the Med El (Austria) and MXM (Neurelec) (France) cochlear implant systems. By the end of 2007, the approximate number of binaurally implanted patients using CI systems from Cochlear, Advanced Bionics and Med El ranged from 6000 to 7000 people worldwide [12].
According to the National Institute on Deafness and Other Communication Disorders (NIDCD) in 2010, approximately 188,000 people worldwide became users of cochlear implant systems, of which the proportion of users living in USA, there are 41,500 adults and 25,500 children [14].
According to the data, the shares of the world market of manufacturers for 2009 are distributed as follows: Cochlear - 67%, Advanced Bionics - 17%, Med EL - 14%, MXM - 2% [15].
Previously, CI surgery was performed mainly in adults and children who lost their hearing after mastering speech (postlingual and perilingual patients), at present, a significant number are children with congenital deafness (prelingual patients). Normally, the formation of speech begins already in the first year of a child's life, which is a fundamental moment in the development of the psyche and intellect [14]. It is believed that the earlier the cochlear implantation operation is performed, the faster the child will be able to learn to speak and, accordingly, adapt socially. It should be emphasized that CI is not a one-time surgical operation, but a system of long-term and expensive measures, including the selection of patients, their comprehensive diagnostic examination, surgical treatment, and postoperative rehabilitation [5, 11].
The implantation operation lasts from one to three hours under general anesthesia. Then comes the most important stage of cochlear implantation - postoperative rehabilitation. For implanted patients, the interaction between the audiologist, the teacher of the deaf and the parents, as well as the emotional contact of each of them with the child, is of particular importance. However, the main process of learning, automating the necessary skills should be provided by parents at home. Usually, 3-4 weeks after CI surgery, the speech processor of the cochlear implant is first turned on and adjusted according to the thresholds for the occurrence of auditory sensations and thresholds for comfortable loudness. Rehabilitation of patients after cochlear implantation takes from several months to 5 years [8, 12].
An interesting fact is that recommendations regarding the selection of candidates for cochlear implantation in various literature sources have certain discrepancies [9]. When selecting adult patients for surgery, speech intelligibility in various conditions (in silence, against a background of noise), intelligibility of monosyllabic words using specially prepared test batteries, provided binaural use of optimally tuned hearing aids [11].
With regard to the criteria for selecting children for cochlear implantation, there are many discrepancies. Thus, children aged 12-24 months are candidates for CT only if they are diagnosed with a high degree of hearing loss (more than 110 dB nHL). Cochlear implantation in children older than 2 years is performed only in the case of diagnosing a high degree of hearing loss and deafness with the ineffectiveness of binaural use of optimally tuned hearing aids for 3 months. The effectiveness of the use of hearing aids, the level of development of speech skills is specified by questioning with the help of specially designed batteries of tests intended for parents, guardians, etc. [19]. In addition, the development of speech skills is controlled by a teacher of the deaf, a defectologist, who must have experience in communicating with such patients. When selecting preschool children for CI, one- and polysyllabic word recognition tests are often used. Correct recognition of less than 30% of the presented words under the condition of binaural use of optimally tuned hearing aids is an indication for CI [10].
In addition to the generally accepted criteria for selecting patients for CI, foreign literature contains data on the use of this method in the treatment of tinnitus [4].
Successful use of cochlear implantation in the case of unilateral hearing loss with preserved hearing function in the opposite ear has also been reported [7]. In order to determine the effect of unilateral CI on speech intelligibility in a noisy environment before and after surgery, the examined patients were offered a number of tests performed in various acoustic situations. The results of the studies showed that absolutely all patients improved speech intelligibility, especially in noisy environments. Many scientists propose to expand the indications for cochlear implantation by including patients with unilateral hearing loss in the selection criteria [11].
Normally, bilateral hearing is formed under conditions of constant acoustic stimulation. The bilateral structure of the auditory analyzer enables a normally hearing person to confidently determine the sound source and its direction in space. The ability of the auditory analyzer to understand spoken language in complex acoustic situations is also provided by the structures and mechanisms of binaural interactions in the cerebral cortex. The process of speech recognition involves such complex acoustic phenomena as the phenomenon of the acoustic shadow of the head, interaural (interaural) differences in the perceived signals in time, intensity and spectral composition, including the mechanisms of unmasking and summation of sounds [10].
Currently, in the practice of modern hearing aids, there are three types of binaural stimulation [12]:
1) bilateral stimulation is carried out by acoustic signals from hearing aids converted in a certain way;
2) bilateral stimulation is carried out by electrical impulses from two cochlear implants.
3) bimodal stimulation is performed by a combination of acoustic stimulation from a hearing aid in one ear and electrical stimulation from a cochlear implant in the other ear.
Timely bimodal and bilateral stimulation can provide a patient with bilateral hearing loss with the necessary conditions for the adequate development of binaural auditory skills, which is almost impossible with monoural stimulation. Therefore, today experts consider binaural stimulation as a standard technology for effective hearing aids for both children and adults. With regard to bimodal stimulation, in some cases, after unilateral cochlear implantation, patients refuse to use a hearing aid in the ear opposite to the implanted one. In the foreign literature, the reasons for refusing to wear a hearing aid during bimodal stimulation are named, namely: the actual auditory sensations of patients in the period before the CI, patients' beliefs about the advantage of using a cochlear implant speech processor for unilateral cochlear implantation over the use of hearing aids, as well as poor-quality, desynchronized, according to patients, the sound of a jointly used hearing aid and cochlear implant speech processor [5]. However, data obtained during the study of bimodal and bilateral electrical stimulation by European specialists indicate that speech intelligibility with bimodal stimulation was significantly higher compared with bilateral stimulation from cochlear implants [2]. Although the intelligibility of monosyllabic words in the group of binaurally implanted patients was somewhat higher, the group of patients with bimodal stimulation showed a better result in terms of speech intelligibility in noise conditions and in various acoustic situations presented experimentally in FFP. This fact is explained by the fact that in the process of bimodal stimulation, the perception of sounds in the region of speech frequencies responsible for the formation of the auditory image is enhanced [13].
If the issue of binaural hearing aids using traditional hearing aids has long been resolved, then there are conflicting opinions regarding CI [2].
Existing technologies in the binaural CI system make it possible to determine the sound source, increase the level of speech intelligibility, a separate point is the improvement in speech intelligibility in a noisy environment in comparison with the results obtained after unilateral cochlear implantation [15]. In addition, patients who underwent binaural CI noted an improvement in speech intelligibility in the course of filling out the questionnaire, both in a noisy environment and in silence, a conversation with other people acquired a natural tone and proceeded freely [10].
At the same time, binaural cochlear implantation also has negative characteristics: additional or prolonged surgical intervention, unproven effectiveness in relation to the spent material resources, as well as other therapeutic measures on the side of the operated ear [5].
According to some scientists, for adult patients, the time interval between unilateral CI and CI in the other ear can be 5-10 years. Unlike an adult patient, a deaf child needs binaural cochlear implantation no later than the age of 4-5 years for the timely development of binaural hearing. Bilateral CT is recommended to be performed simultaneously or after a short time interval (1-3 years) [6].
The success of cochlear implantation depends on the preservation and plasticity of the function of the auditory cortex, which is able to provide central processing of information supplied by the cochlear implant/auditory nerve complex [9]. This should take into account the ability of the brain to process information and learning, as well as the time factor. The time factor suggests a decrease in the plasticity of the central parts of the auditory system with age and is the main one in CI in children with congenital deafness. This is determined by the presence of a so-called critical time window, before the completion of which the achievement of normal verbal communication through the development of language must be resumed through the restored auditory function (the so-called auditory input). In addition, there is also a critical time window for the development of binaural signal processing capabilities (which is important for binaural hearing aids and binaural CI) [3].
At the International Congress of Audiologists, held in Innsbruck, it was decided to prepare documents on the unification (standardization) of approaches to the rehabilitation of patients using CI in various countries of the world. And if in the international community the issue of developing a unified approach to the rehabilitation of patients with deafness at the decision-making stage and after implantation is one of the main priorities, then it is undoubtedly relevant for our country as well [4, 12].
Hearing loss is one of the most common congenital anomalies [9]. According to the Second International Conference on Newborn Hearing Screening Diagnosis and Intervention (2nd International Conference on Newborn Hearing Screening Diagnosis and Intervention), hearing impairment occurs in 2-3 out of 1000 newborns, which is twice as high as the incidence of nonunion of the lip (palate).), ten times - than the frequency of phenylketonuria. In the treatment of hearing loss, a large arsenal of surgical, medical and physiotherapeutic means is used. Insufficient efficiency and high cost of drug therapy for various forms of hearing loss predetermine the search for modern methods of treatment, the development of new approaches to the social adaptation of people with hearing loss. The first plan is the rehabilitation of such patients. In the case of bilateral sensorineural hearing loss of the IV degree and deafness, even multiply amplified sound does not create auditory sensations in a person, therefore, it is undeniable that cochlear implantation at the present stage is the method of choice in the rehabilitation of patients with a high degree of hearing loss and deafness. Hearing is an integral part of the adequate functioning of the individual: it is he who forms speech, and therefore participates in the development of intellectual abilities, social and emotional functioning in the world of hearing people [7]. In addition to the ability to perceive acoustic information through the CI system for deaf patients, it also achieves a sufficient level of communication skills, which positively affects the quality of life of patients.
Thus, it follows that among the global trends in the field of improving cochlear implantation systems, the use of electroacoustic stimulation in patients with residual perception of low-frequency sounds, a new approach that uses sparing surgery in order to minimize trauma to the apex of the cochlea, while maintaining hearing, comes to the fore. patient at low frequencies. In addition, the following areas in audiology, otosurgery and hearing and speech rehabilitation are promising: the introduction of fully implantable cochlear implantation systems; development of new strategies for speech coding, improvement of sound processing technologies with microphones, as well as the search for new surgical approaches when installing a cochlear implant.
