What is Deafblindness?

In the hearing system, pathological changes in the auditory nerve and various levels of the central nervous system in the sound transmission, sensory sounds, and auditory conduction pathways cause hearing dysfunction and produce varying degrees of hearing loss, collectively referred to as deafness. It is generally considered that the average hearing threshold of speech frequency above 26dB is called hearing loss or hearing impairment. Depending on the degree of hearing loss, it is also called hard of hearing, hearing impairment, hearing loss, hearing loss, etc.

Basic Information

Also known as: Hearing impairment
English name: deafness
Visiting department: ENT
Common locations: ear
Common causes: Congenital malformations, obstruction of the external ear canal, inflammation of the middle ear, ear trauma, middle ear tumors, otosclerosis, acute infectious diseases, bacterial or viral infections, drug poisoning, atherosclerosis, bone hyperplasia, insufficient blood supply, degenerative diseases, Knock, auditory neuropathy, autoimmune disorder, Meniere's disease, central deafness

Common symptoms: Tinnitus, auditory hypersensitivity, hallucinations, hearing loss
Contagious: no

Causes of deafness

The cause of deafness is complex, with congenital and acquired factors. Among them, suppurative otitis media is the most important deafness in conductive deafness. In recent years, secretory otitis media has become a major cause of hearing loss in children. Deafness can be divided into four categories according to the location and nature of the lesion: conductive deafness, sensorineural deafness, mixed deafness, and central deafness.

Cause of conductive deafness

(1) Congenital malformations are common, including malformations of the outer ear and middle ear, such as congenital atresia of the external ear canal or tympanic membrane, auditory bone, worm window, and vestibular windows.

(2) Acquired obstruction of the external ear canal, such as palatal embolism, bone warts, foreign bodies, tumors, inflammation, etc. Suppuration or non-suppurative inflammation of the middle ear makes the sound transmission mechanism of the middle ear impaired, or the trauma of the ear damages the ossicular chain, and the middle ear is benign, malignant tumor or otosclerosis.

2. Causes of sensorineural hearing loss

(1) Congenital disease is usually caused by hypoplasia of the auditory nerve of the inner ear, or caused by viral infection during pregnancy or taking ototoxic drugs, or injuries during childbirth. Deafness due to congenital inner ear malformations is sensorineural hearing loss. According to the inner ear tomography and embryogenesis, the inner ear malformations are divided into 5 categories, that is, loss of labyrinth, common cavity malformation, cochlear development, cochlear hypoplasia and incomplete separation. In addition, large vestibular aqueduct syndrome is also a common congenital inner ear deformity that causes sensorineural hearing loss.

Congenital hearing loss in sensorineural hearing loss can also include non-hereditary and hereditary. Deafness caused by viral infection during pregnancy, caused by taking ototoxic drugs, or injured during delivery is non-hereditary deafness. Non-hereditary includes ototoxic drugs during pregnancy, viral infections during pregnancy, syphilis, bacterial infections, neonatal hypoxia, birth injury, neonatal hyperbilirubinemia; non-hereditary also includes noise exposure, head trauma during childbirth , Radiation exposure, etc. Hereditary deafness is caused by changes in genetic genes. The incidence of both non-hereditary and hereditary deafness is 50%. 70% of patients with hereditary deafness do not have other symptoms except deafness. This type of deafness is non-deaf. Syndrome deafness. Hereditary deafness includes autosomal negative, autosomal dominant, X-linked, Y-linked, mitochondrial (maternal) inheritance, etc.

At present, many genes are known to be related to non-syndromic deafness. Mutations in one or several genes or mutations in different sites in a gene can cause deafness. However, the deafness genes and their mutation sites are different in people of different races, and even in different regions of the same race. Relevant research in China shows that GJB2, SLC26A4, and mitochondrial genes (A1555G and C1494T mutations) are the three most common genes that cause the majority of hereditary deafness in China. Genetic testing of these few genes can identify 40 % Of genetic causes, combined with family history analysis and physical examination can diagnose more than 95% of hereditary deafness. Screening and detection of deafness genes provide the possibility to prevent congenital sensorineural hearing loss and reduce its incidence. ^[1-4]

(2) Acquired deafness of infectious diseases: various acute infectious diseases, bacterial or viral infections, such as Japanese encephalitis, mumps, suppurative meningitis, measles, scarlet fever, influenza, Herpes zoster and typhoid fever can damage the inner ear and cause sensorineural hearing loss of different severity. Deafness of drug toxicity: It is more common in aminoglycoside antibiotics, such as gentamicin, kanamycin, polymyxin, dihydrostreptomycin, neomycin, and other drugs such as quinine and salicylic acid. , Cisplatin, etc. can cause sensorineural hearing loss. Ear drug poisoning is closely related to the body's susceptibility. Toxic deafness is bilateral, with tinnitus, and vestibular function can be impaired. Long-term use of such drugs in the middle ear can also penetrate the inner ear through the volute membrane, which should be noted.

(3) Senile deafness is caused by vascular sclerosis and bone hyperplasia, resulting in insufficient blood supply, degenerative lesions, and hearing loss.

(4) Traumatic deaf brain injury and temporal bone fractures damage the inner ear structure, leading to inner ear hemorrhage or inner ear damage due to strong shocks, can cause sensorineural hearing loss, sometimes accompanied by tinnitus and dizziness. The lighter can recover. Ear surgery can also cause deafness by trauma to the inner ear structure.

(5) Sudden deafness is a sensorineural hearing loss that occurs suddenly and for unknown reasons. At present, acute inner ear microcirculation disorders and viral infections are considered to be common causes of the disease.

(6) Detonation deafness is caused by acute damage to the hearing aid caused by sudden strong pressure waves and strong impulse noise. The eardrum and the cochlea are the most vulnerable parts of the hearing device. When people are exposed to more than 90dB of noise, cochlear damage can occur, and if the intensity exceeds 120dB, it can cause permanent hearing loss.

(7) Noise-induced deafness is a kind of slow-acting sensorineural hearing loss caused by long-term exposure to noise stimulation above 85dB. Mainly manifested as tinnitus and deafness, pure tone audiometry showed a 4000Hz valley notch or a high-frequency attenuation type.

(8) Auditory neuropathy. Auditory neuropathy is a disease with special clinical manifestations. The main audiological features include missing or severe abnormalities in the auditory brainstem response, normal otoacoustic emissions, disappearance of stapedius reflexes or elevated thresholds, pure tone hearing Most of the pictures are based on low-frequency hearing threshold loss. The main complaint of the patient is poor speech resolution and inability to communicate with people normally. The significant difference between auditory neuropathy and general sensorineural hearing loss is attracting more and more attention. However, the etiology, pathogenesis, and outcome of the disease remain unclear.

(9) Autoimmune Autoimmune sensorineural hearing loss is sensorineural hearing loss caused by damage to the inner ear tissue due to autoimmune disorders. This hearing loss can be progressive and fluctuating and can affect one ear or Binaural hearing loss is mostly asymmetrical. Clinically, there are many types of audiograms for patients with autoimmune sensorineural hearing loss, such as low-frequency, high-frequency, flat, and bell-shaped, but the low-frequency type is the most common. It may be related to this type of immunoreactive injury of the inner ear first before the snail tip and the middle part of the cochlea, showing typical characteristics of snail deafness, which is also a characteristic of clinical audiology.

(10) Meniere's disease Meniere's disease is an inner ear disease whose main pathological feature is membranous labyrinth. Its course is variable, with episodic vertigo, fluctuating deafness and tinnitus as its main symptoms. The cause of Meniere's disease is unknown and may be related to congenital inner ear abnormalities, autonomic dysfunction, viral infections, allergies, endocrine disorders, salt and water metabolism disorders, and so on. At present, it is generally believed that obstruction of endolymphatic reflux or malabsorption is the main cause of disease, such as narrowing or blockage of endolymphatic vessels; autonomic dysfunction can cause small blood vessels spasm in the inner ear, leading to labyrinth microcirculation disorder, tissue hypoxia, and endolymph biochemical properties. Changes, osmotic pressure increases and cause membrane stagnant water. The pathological change of this disease is hydroponic membrane labyrinth, mainly involving the volute and balloon. Compression stimulates the cochlea to produce cochlea symptoms such as tinnitus and deafness, and compression stimulates the vestibular terminal organs to produce dizziness such as dizziness. Typical symptoms are paroxysmal vertigo, fluctuating deafness, tinnitus, and a sense of tinnitus.

3. Causes of mixed deafness

There are lesions in both the transmission and sensory structures. Such as chronic chronic suppurative otitis media, advanced otosclerosis and so on.

4. Causes of Central Deafness

Central deafness lesions are located in the brainstem and brain, involving central cochlear nucleus and its central conduction pathway, and auditory cortex center leading to central deafness. It can be divided into the following two types:

(1) Brainstem central deafness affects the cochlear nucleus to produce unilateral deafness, and the degree is mild; if one side of the cochlear nucleus and the opposite cross fiber are involved, bilateral deafness is produced, and part of the deafness is more See, common in pontine, bulbar lesions.

(2) Cortical deafness Cortical deafness is difficult to discern the distance and nature of sound. Sometimes, although the general hearing is not damaged, the aesthetic ability of language is reduced. As one side of the cochlear nucleus fibers is projected into the bilateral auditory cortex, one or both of the auditory cortex is damaged or one side of the conduction pathway is damaged resulting in one or both hearing loss.

Deaf clinical manifestations

The common clinical symptoms of hearing impairment include tinnitus, hearing allergies, deafness, auditory hallucinations, and hearing freak.

Deafness check

Tuning fork examination is the most commonly used method to identify the nature of deafness. C tuning octave sets of five tuning forks are commonly used, whose vibration frequencies are 128, 256, 512, 1024 and 2048Hz. Note during inspection: the upper 1/3 of the tuning fork arm should be hit; the striking force should be the same, and you should not use too much force or hit a hard object on the table to avoid overtones; The plane of both arms is the same as the longitudinal axis of the external auditory meatus, and is the same height as the external auditory meatus. It is about 1 cm from the external auditory meatus. When examining the bone conduction, the bottom of the handle is placed on the cranial surface. The vibrating tuning fork cannot touch any surrounding objects. The common inspection methods are as follows:

Linner test

Also known as air-bone conduction comparison test, it is an inspection method to compare ipsilateral air-conduction and bone conduction. Take the C256 tuning fork and place it on the mastoid tympanic region after vibration to measure its bone conduction hearing. Record the time when no sound can be heard. Immediately move the tuning fork 1cm outside the outer ear canal mouth and measure its air conduction hearing. If the sound can still be heard, it means that the air conduction is longer than the bone conduction (AC> BC), and the Linner test is positive (RT "+"). Conversely, bone conduction is longer than air conduction (BC> AC), which means the Liner test is negative (RT "-").

2. Weber test

Also called the bone conduction deflection test, which compares the hearing strength of bone conduction in both ears. Take the C256 or C512 vibrating tuning fork handle at the center of the forehead or the top of the head, so that the patient compares which ear hears the sound louder. If both ears have normal hearing or both ears have the same nature and degree of hearing damage, the sound is in the middle. It is because there is no bias in bone conduction. Because air conduction has the effect of offsetting bone conduction, when the conductive deaf suffers from impaired air conduction in the ear, the bone conduction cannot be offset, so that the bone conduction of the affected ear is stronger than the healthy ear, and the sound is biased towards the affected ear. ; For sensorineural hearing loss, because the affected organs of the affected ear have lesions, the sound heard by the healthy ear is stronger, and the sound is biased towards the healthy ear. In addition to the text description, you can use " or " to indicate the side, and "=" to indicate no side.

3. Schwabach test

Also known as bone conduction comparison test, in order to compare the time of bone conduction between normal and patients, the vibrating C256 tuning fork handle is alternately placed in the tympanic sinus area of the mastoid part of the patient and the examiner for comparison. Bone conduction time is longer than normal ears, which is prolonged by the Schwabati test (ST "+"), which is conductive deafness; if it is shorter than normal, it is shortened by the bone conduction contrast test (ST "-"), which is the sensory sound Neurological hearing loss.

4. Subjective hearing detection technology

It mainly includes pure tone hearing threshold test and speech test for adults, pediatric behavior test and child speech test for children. The subjective response of the patient can be used to test the auditory sensitivity and the evaluation of the ability to communicate in daily life. Objective detection techniques include acoustic impedance testing, auditory brainstem response (ABR) and otoacoustic emission (OAE) testing, and 40Hz event-related potentials. Auditory Steady State Evoked Potential (ASSR) has the characteristics of fast, non-invasive, good frequency specificity, good correlation with behavioral hearing threshold, objective test methods, and objective judgment of results. When the modulation frequency is> 60Hz, it is not affected by wakefulness, and it is an ideal quantitative diagnosis method for hearing loss in children, especially infants.

5. Imaging examination

It mainly includes functional magnetic resonance imaging and positron emission tomography. Functional magnetic resonance imaging (fMRI) technology can observe human brain activity in the awake state, can directly reflect event-related changes in brain function, has high spatial resolution, and has no radiation damage, and can be used for sensorineural hearing loss in adults and children patient. In recent years, SilentfMRI technology has become the first choice and main method to study the function of auditory conduction pathways, and it is expected to provide new ideas for clinical diagnosis, treatment and assessment of prognosis. Positron emission tomography (PET) can detect human functions and diagnose diseases from genes, molecules, and overall levels earlier, accurately, quantitatively, and objectively. ^[5-6]

Deafness diagnosis

The medical history should be carefully examined; the external auditory canal and tympanic membrane should be checked; a tuning fork examination and pure tone audiometry should be performed to find out the nature and extent of deafness. For children and uncooperative adults, subjective behavioral audiometry and guest observation audiometry can also be performed, such as acoustic impedance audiometry, auditory brainstem response audiometry, and cochlear electrograms. Combined with clinical manifestations can be diagnosed.

Deafness treatment

1. Treatment of conductive and mixed deafness

Early active treatment of acute and chronic suppurative otitis media and secretory otitis media are important measures to prevent and treat conductive deafness. Tympanoplasty has a certain effect on improving the hearing of conductive deafness. The application of full artificial ossicles and partial artificial ossicles has significantly improved the hearing effect of conductive deaf tympanoplasty. With the development of artificial hearing implantation technology, the application of bone-anchored hearing aids and vibration sound bridges of implantable hearing devices in recent years has opened up new treatment options for the treatment of conductive deafness and mixed deafness.

Bone anchor hearing aids are implantable bone conduction hearing systems for conductive or mixed hearing impairments, and unilateral hearing loss. Bone anchor hearing aids take a form called direct bone conduction. This method is different from traditional air conduction and bone conduction hearing aids in many aspects. A tiny titanium implant is fixed in the bone behind the ear, and it will have a bone fusion with the human bone. Bone fusion takes about three months in adults and six months in children. Once the bone fusion is formed, a bridge base can be fixed to the titanium implant and the speech processor can be clamped on it. When the speech processor detects sound, it transmits the sound directly through the bones to the inner ear. This process bypasses the outer and middle ears.

Vibration acoustic bridge is a middle ear implantation device, which has a wider range of applications than other hearing aids. It is mainly suitable for adults and children with moderate to severe sensorineural deafness, conductive deafness and mixed deafness. A vibratory acoustic bridge is different from a hearing aid. Hearing aids simply amplify the sound, and a vibroacoustic bridge converts sound into mechanical vibration. A vibratory acoustic bridge is also different from a cochlear implant. The cochlear implant sends electrical signals to stimulate nerve fibers. The mechanical vibration is transmitted to the middle ear structure or directly to the inner ear.

The language and other sound signals heard through the vibrating sound bridge are clear and have good sound quality. In a complex listening environment, if there is a large background noise, communication can be carried out without obstacles. You can also hear lighter, higher-frequency sounds, such as children's voices and violin playing. At the same time, the external auditory canal of the patient is completely open after implantation of the vibroacoustic bridge, thereby eliminating the feeling of blockage and other discomfort caused by the closure of the ear canal; it is also comfortable and beautiful when worn. ^[7]

2.Treatment of sensorineural hearing loss and central hearing loss

For sensorineural hearing loss, the focus is on prevention and early detection and treatment. The current genetic diagnosis of deafness and screening of newborns in China have greatly improved the incidence of sensorineural hearing loss.

(1) Actively prevent and treat deafness caused by acute infectious diseases, do a good job in the prevention, isolation and treatment of infectious diseases, and strengthen the body (especially children) 's resistance.

(2) For the use of ototoxic drugs, the indications must be strictly controlled. If there is poisoning, the drug should be stopped immediately, and vitamins and vasodilator drugs should be used.

(3) According to different reasons and different stages of pathological changes, comprehensive treatment with different drugs can be taken, such as drugs that promote neurotrophic and cochlear microcirculation, various vasodilators, and biological products that promote metabolism.

(4) With the development of electronic technology, computer technology, biomaterial science and biomedical engineering technology, starting from the end of the last century, cochlear implants, vibrating acoustic bridges and bone anchored hearing aids have entered clinical applications abroad. Cochlear implantation is suitable for patients with severe to very severe sensorineural hearing loss; cochlear implantation is currently the only medical device that can restore hearing in patients with total deafness. Vibration acoustic bridge and bone anchored hearing aids are suitable for patients with moderate to severe sensorineural hearing loss, conductive hearing loss, and mixed hearing loss. The above three types of implantable hearing devices cover almost all types of hearing restoration treatments for patients with hearing loss at different levels, so that patients with different levels of deafness or even deafness can be restored to near-normal hearing, so that patients with full deafness can enter normal Schools even use telephone to communicate.

Cochlear implantation requires the patient to have a sufficient number of auditory nerve residues. The stimulation electrodes will be inserted into the cochlea. If the patient's auditory nerve does not exist, for example, patients after acoustic neuroma resection cannot accept cochlear implantation. Auditory brainstem implantation can place stimulation electrodes on the patient's brainstem (cochlear nucleus), and patients can still regain hearing. This technology is relatively mature abroad, and no successful cases have been reported in China. Indications include bilateral acoustic neuroma, cochlear ossification, internal auditory stenosis and auditory nerve hypoplasia. This type of patient can regain hearing after receiving an auditory brainstem implant, and it is reported that the implanted patient's speech perception ability is worse than that of the cochlear implanted patient. ^[8]

references

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2. Dai Pu, Yu Fei, Kang Dongyang, etc. Diagnosis and clinical application of mitochondrial DNA 1555 site, GJB2 gene and SLC26A4 gene. Chinese Journal of Otorhinolaryngology Head and Neck Surgery, 2005: 40, 769 ~ 773.

3. Sun Baochun, Dai Pu. Classification of inner ear malformations in sensorineural hearing loss and its relationship with SLC26A4 and GJB2 genes. Chinese People's Liberation Army Military Medical Training College (PhD thesis), 2011: 05.

4. JacklerRK, LuxforWM, HouseWF. Congenital Malformations of the Inner Ear: AClassification Basedonembryogenesis: Laryngoscope, 1987: 97 (Suppl 40): 2-14.

5. Han Demin. Clinical Audiology: Journal of Audiology and Speech Diseases, 2007: 15, 1-3.

6. Zhai Suoqiang. Analysis of clinical audiological characteristics of deafness: Chinese Journal of Otology, 2011: 236 240.

7. Zhao Shouqin. Vibroacoustic bridge implantation: Journal of Audiology and Speech Diseases, 2011: 19, 394 ~ 395.

8. Wang Liang, Zhang Daoxing, Dong Mingmin. Clinical application of auditory brainstem implantation: Chinese Medical Abstracts Otorhinolaryngology, 2004: 145 ~ 148.