Congenital hearing loss
Congenital hearing impairments are such dysfunctions of the auditory system that are associated with a decrease in hearing or loss of hearing, found at the birth of a child or soon after it was born.
The causes of congenital hearing disorders include:
- Hereditary genetic factors.
- Non-hereditary genetic features.
- Complications during pregnancy, which are caused by mothers having syphilis, rubella, mumps, and others.
- The low birth weight of the newborn is less than one and a half kilograms.
- Received asphyxiation in the process of birth, that is, a strong lack of oxygen.
- Maternal use during pregnancy of ototoxic drugs, namely, aminoglycosides, diuretics, antimalarial medicines, cytotoxic drugs.
- Postponed by an infant in the neonatal period, severe jaundice, which can cause damage to the auditory nerve in the child.
Genetic hearing impairment
Genetic hearing impairment can fall into two categories:
- non-syndromic (isolated),
Nonsyndromal disorders include hearing loss, which does not have any other accompanying symptoms that are inherited. Such hearing impairments occur in seventy percent of cases of deafness due to heredity.
Syndromic hearing impairments are caused by a decrease in hearing in combination with other factors, for example, diseases of other organs and systems. Syndromic abnormalities occur in thirty cases of deafness due to heredity. In medical practice, there are more than four hundred different syndromes, one of the manifestations of which is deafness. Such syndromes include:
- Usher syndrome - simultaneous disturbance of auditory and visual systems,
- Pendred's syndrome - in which the deafness is combined with hyperplasia of the thyroid gland,
- Gervell-Lange-Nilsson syndrome-causes a combination of deafness and cardiac arrhythmia with the appearance of a larger interval of QT,
- the syndrome of Waardenburg - describes the violation of the auditory system in combination with the appearance of pigmentation.
If we take into account the type of inheritance of hearing dysfunctions, then they can be divided into the following types:
- Autosomal recessive, which include seventy-eight percent of cases.
- Autosomal dominant, which includes twenty percent of cases.
- X-linked, which includes one percent of cases.
- Mitochondrial, which includes one percent of cases.
In modern medicine, more than a hundred genes have been identified, which, when mutated, are responsible for hearing impairment. Each population of people has its own specific mutations that are different from other populations. But it can be noted with certainty that in about a third of cases of genetic hearing impairments the cause of such negative transformations is the mutation of connexin 26 (GJB2) gene. The European race is most susceptible to the gene mutation of 35delG.
Hearing Impairment in the Elderly
Most people with acquired hearing impairments are elderly or senile. Hearing impairment in the elderly is associated with age-related changes, which result in degenerative transformations in the hearing organs. Hearing changes due to age concern all parts of the auditory system, beginning from the auricle and ending with the zone of the auditory analyzer in the cerebral cortex.
Deafness in elderly people is a complex and complex process, which is carefully studied by specialists. The elderly hearing loss is called the term "presbiakusis" and is divided into two types:
The conductive appearance of senile hearing loss is caused by changes in the degenerative nature that occur in the middle ear, as well as a decrease in the elasticity of the skull tissues.
The sensory-neural kind of senile hearing loss has four subspecies, caused by various causes:
- sensory - caused by the atrophy of the hair cells of the organ of Corti,
- neural - associated with a decrease in the number of nerve cells present in the spiral ganglion,
- metabolic - due to atrophic changes in the vasculature, weakening metabolic processes in the cochlea,
- Mechanical - associated with atrophic transformations of the main membrane of the cochlea.
Some experts adhere to a different classification of senile hearing loss. Three types of hearing disorders of an age-related nature are described:
- Presbyacusis is a deafness caused by internal factors of a genetic and physiological nature,
- sotsiokusiya - deafness, which is due to external factors that contribute to severe wear of the organs of the auditory system,
- professional noise hearing loss - hearing impairment, which occurs under the influence of strong industrial noise at the place of work of the individual.
Features of children with hearing impairment
In hard of hearing children there are significant differences in psychophysiological and communicative development. These features of children with hearing impairment prevent them from developing at the same speed as peers, and also cause problems in mastering knowledge, vital skills and skills.
Hearing impairment in children significantly reduces the quality of speech and verbal thinking. At the same time, cognitive processes and cognitive activity are also experiencing a deficit in improvement and development.
In children with hearing impairment, there may be other violations, namely:
- Problems with the functioning of the vestibular apparatus.
- Various visual defects.
- Dysfunction of the brain is minimal, which leads to inhibition of the overall development of the psyche.
- Extensive brain damage that causes oligophrenia.
- Defects in the brain systems that lead to the appearance of infantile cerebral palsy and other movement disorders.
- Disturbances in the functioning of auditory and speech zones in the brain.
- Diseases of the central nervous system and the body as a whole, which cause severe mental illness - schizophrenia, manic-depressive psychosis and so on.
- Diseases of internal organs of a serious degree (heart, kidneys, lungs, digestive tract, etc.), which generally weaken the child's body.
- Serious social and pedagogical neglect.
There are two types of hearing impairment and children, which depend on the degree of loss of the ability to perceive and process sounds:
- hearing loss, which affects children who are hard of hearing,
With hearing loss, the perception of speech, but only said loudly, articulate and close to the ear, is preserved. Although, of course, the capabilities of this child to full-fledged speech communication with others are limited. Deafness is different in that it perceives certain tones of speech without the ability to perceive and distinguish the speech itself.
Various auditory disorders in childhood lead to inhibition and distortion of the development of speech functions. But, at the same time, researchers noted the following fact that if a severe hearing loss occurs at a time when the child has already mastered the skills of reading and writing to a good degree, then the disease does not lead to defects in the development of speech. Although in this case there are various violations associated with pronunciation.
The most important factors that affect the development of speech of children with hearing impairment are:
- Degree of hearing loss - children with auditory impairment speak worse as poorly as they hear.
- The age period of the onset of a pathological hearing disorder - the earlier the hearing defects arose, the harder it is to disturb speech, until the appearance of deafness.
- Conditions for the development of the child and the presence of correct psychocorrectional measures - the earlier special measures are used to develop and preserve the correct speech, the higher the effectiveness.
- Physical development of general character and mental development of the child - a more complete speech is noted in children with good physical development, good health and normal mental development. In children with weakened health (passive, flaccid children) and mental disorders, there will be significant defects in speech.
Classification of hearing disorders
Hearing impairment can be divided into several types:
- Conductive - arising from the blockage of any quality that appears in the outer or middle ear. In this case, sound can not normally penetrate into the inner ear.
- Neural - are due to a complete loss of brain ability to perceive and process electrical impulses. In some cases, the brain can not correctly decipher the received signals. These disorders include "auditory dissynchronization" or "neuropathy."
- Sensory - appear if there are dysfunctions of the hair cells of the inner ear. As a result, the snail can not normally pick up sounds.
- Sensoneural - combined disorders in which there are dysfunctions of hair cells, as well as large inaccuracies in the perception and processing of brain signals of sound nature. Such types of violations are persistent, because it is almost impossible to establish how a snail and brain participate in hearing loss. The greatest difficulty in the correct diagnosis is noted when examining small children.
- Mixed - these include the synthesis of sensorineural and conductive disorders. With such a hearing loss, the sound signals can not normally be transmitted from the outer and middle ear to the inner ear, and there are disturbances in the functioning of the inner ear, brain zones and neural parts of the hearing system.
Classification of Preobrazhensky hearing impairment
In modern practice, there are several classifications of auditory disorders. One of the most popular is the classification of hearing disorders by Professor BS Preobrazhensky. It is based on the level of perception of oral loud speech and speech, whispered. The study of the perception of loud speech is necessary due to the fact that it contains elements of whisper speech, namely, voiceless consonants and unstressed parts of the word.
According to this classification, there are four degrees of hearing impairment: mild, moderate, significant and severe. An easy degree is characterized by the perception of spoken speech at a distance of six to eight meters, and whispered from three to six meters. Moderate degree of hearing loss is diagnosed when spoken language is perceived at a distance of four to six meters, a whisper is from one to three meters. A significant degree of auditory disorders is determined by understanding spoken language at a distance of two to four meters, and a whisper speech - from the auricle to one meter. Severe degree of auditory disorders is allocated in the case of understanding spoken language at a distance from the auricle to two meters, and whispering - from complete misunderstanding to discrimination at a distance of half a meter.
Conductive and sensorineural hearing impairment
Conductive hearing impairments are characterized by a worsening of the conduction of sounds due to defects in the outer or middle ear. Normal conductivity of sound signals is provided only by properly functioning auditory meatus, tympanic membrane and earbone. In case of any violations of the above mentioned organs, there is a partial decrease in hearing, called deafness. With partial hearing loss, there is a certain deterioration in the ability to perceive sound signals. Conductive hearing loss allows you to recognize speech if an individual is able to hear it.
Conductive hearing impairments result from:
- impassability of the auditory canal,
- anomalies in the structure and functioning of the middle ear, namely the tympanic membrane and / or ear pits.
Sensorineural hearing impairments are caused by defects in the functioning of the inner ear (cochlea), or by a malfunction in the proper functioning of the auditory nerve, or by the lack of the ability of certain brain zones to perceive and process sounds. In the first case, a pathological deformation of the hair cells is observed, which are located in the corti's organ of the cochlea. In the second and third cases, sensorineural hearing impairments are caused by the pathology of the VIII cranial-cerebral nerve or the brain regions that are responsible for the auditory system. In this case, a fairly rare phenomenon is the disruption of the functioning of exclusively auditory zones of the brain, which is called the central hearing disorder. In this case, the patient can hear normally, but at such a low quality of sound that he can not understand the words of other people at all.
Sensingural disorders of the auditory system can lead to deafness of various degrees - from low to high, as well as to hearing loss in full. Experts believe that sensorineural hearing loss is most often caused by pathological changes in the functioning of the cochlear hair cells. Such degenerative changes can be both congenital and acquired. With the acquired transformations, they can be caused by infectious diseases of the ears, or noise injuries, or a genetic predisposition to the appearance of anomalies in the auditory system.
Violation of phonemic hearing
Phonemic hearing is the ability to distinguish between language phonemes, namely, to analyze and synthesize them, which is expressed in understanding the meaning of speech spoken in a certain language. Phonemes are the smallest units of which any language consists; of them are the structural components of speech - morphemes, words, sentences.
When perceiving speech and non-speech signals, there are differences in the functioning of the hearing system. Non-verbal hearing is a person's ability to perceive and process nonverbal sounds, namely musical tones and various noises. Speech hearing is a person's ability to perceive and process the sounds of human speech native or other languages. In the speech hearing, a phonemic hearing is distinguished, with which the phonemes and sounds responsible for the semantic load of the language are distinguished, that a person can analyze individual sounds of speech, syllables and words.
Violations of phonemic hearing are found in children and adults. The causes of the violation of phonemic hearing in children are as follows:
- Absence of the formation of acoustic images of individual sounds, in which phonemes can not differ in sound, which causes, when speaking, the replacement of some sounds by others. Articulation is not fully adequate, because not all sounds a child can pronounce.
- In some cases, the child can articulate all sounds, but at the same time, he does not know how to distinguish what sounds he needs to pronounce. In this case, the same word can be pronounced by the child in different ways, because the phonemes are mixed, which is called mixing phonemes or interchange of sounds.
In case of hearing impairment, the child has a sensory dyslasia, which means that it is impossible to pronounce sounds correctly. There are three forms of dyslalia:
Acoustico-phonemic dyslasia is characterized by the presence of defects in the design of speech with the help of sounds, which is caused by the inability to fully process the phonemes of the language due to anomalies in the sensory link of the speech perception system. At the same time, it should be noted that the child does not have any disorders of the auditory system, that is, there is no hearing loss or deafness.
Violation of the phonemic hearing in adults is due to local brain lesions, namely:
- sensory temporal aphasia,
- sensory aphasia of the nuclear zone of the sound analyzer.
Light cases of sensory temporal aphasia are characterized by the understanding of individual words or short phrases, especially those that are used daily and refer to the constant routine of the patient's day. In this case, a disorder of phonemic hearing is observed.
Severe cases of sensory aphasia are characterized by complete incomprehension of speech by a sick person, words cease to have a meaning for him and turn into a combination of incomprehensible noises.
Sensory aphasia, expressed in the defeat of the nuclear zone of the sound analyzer, not only leads to a violation of the phonemic hearing, but also to a serious speech disorder. As a result, it becomes impossible to distinguish the sounds of oral speech, that is, to understand speech by ear, as well as other speech forms. Such patients do not have active spontaneous speech, it is difficult to repeat the words they heard, the letter under dictation and reading is broken. We can conclude that due to the violation of the phonemic hearing, the whole system of speech is pathologically transformed. In these patients, the ear for music is preserved, as is the articulation.
Conductive hearing impairment
Conductive hearing impairments are caused by the impossibility of its conduction in normal form through the auditory passage due to disorders in the outer and middle ear. The features of conductive hearing loss were described in the previous sections.