Update: December 2018
- As we hear, or mechanisms of perception of sounds
- Classification of hearing impairment
- Causes of Deafness
- Genetic deafness
- Hearing loss in children
- Acute neurosensory hearing loss
- Sensory neurosensory hearing loss
- Conductive hearing loss
Hearing impairment is a decrease in the ability to perceive and understand
sounds. It can be temporary or persistent – when a decline
sound perception lasts 3 months or more. Partial violation
hearing loss is called hearing loss if the person does not perceive sounds
volume of more than 91 dB, we are talking about deafness.
In practice, deafness means that the patient does not hear the cry
ear, whereas normally a person is able to discern whispers on
distance of 6 meters.
As we hear, or mechanisms of perception of sounds
The auricle and the ear canal “collect” sound waves,
directing them to the eardrum. Eardrum transmits
vibrations caused by sound on the chain of auditory ossicles that
communicate with the so-called snail – the structure of the inner ear,
which turns mechanical vibrations into nerve impulses.
The latter pass along the pre-vesicular nerve into the auditory area.
the cortex of the temporal lobe of the brain, where they are processed,
realized as sound. The pathology of any part of this chain can
cause hearing loss.
Classification of hearing impairment
By types of deafness:
- conductive – caused by violation of sound conduction due to
reduce mobility of the eardrum and auditory ossicles;
- sensoneural – caused by violation of formation and transfer
nerve impulse (the pathology of the cochlea, the pre-door-snail nerve) and
his perception of the temporal lobes of the cerebral cortex;
Conductive hearing disorders include, for example, deafness with
otitis when inflammatory effusion fills the cavity of the middle
ear, disrupts the normal movements of the membrane and the auditory ossicles.
Conductive deafness is a relatively favorable option, since
can be cured even in some cases required
microsurgical operation (tympanoplasty – restoration
eardrum, ossiculoplasty – prosthetic hearing
pits). Worse if hearing loss develops by
sensorineural type – to talk about the restoration of hearing in this
case is meaningless, we can talk only about
By the time of occurrence of hearing loss is:
- congenital (including genetically determined);
According to the degree of deafness:
- I – decrease in sound perception by 26 – 40 dB;
- II – by 41 – 55 dB;
- III – 56 – 70 dB;
- IV – 71 – 90 dB.
If a person does not hear sounds of 91 or more dB (shouting
ear) we are talking about total deafness.
Causes of Deafness
- Hereditary deafness. Most often passed from generation to
generation, but may occur for the first time, if inherited
goes recessive gene deafness.
- Congenital deafness. Appears due to exposure to pathogenic
factors during fetal development or in the first few minutes
- fetal hypoxia;
- birth injury;
- respiratory arrest;
- birth weight less than 2500 g.
- previous infections (rubella, cytomegalovirus,
measles, herpes, toxoplasmosis);
- ototoxic intake during pregnancy (acting on
- severe jaundice of newborns, causing toxic damage
- Acquired hearing loss:
- transferred bacterial meningitis or meningoencephalitis;
- severe measles or mumps in young children;
- chronic otitis media;
- injuries and accidents;
- use of ototoxic antibiotics, diuretics or
- exposure to professional factors (work in noisy
- excessive volume of frequently used headphones, regular
visiting bars, nightclubs and similar events with loud
- age changes (presbycusis).
Hereditary deafness may be:
- syndromic – that is, associated with a complex of genetic
violations, where deafness is only one of their factors (approximately 30%
cases); For example, in Pendred syndrome, hereditary
deafness is combined with an enlarged thyroid gland, with syndrome
Gervella-Nielsen – with cardiac arrhythmia
- isolated (70% of cases).
Genetically determined deafness occurs with a frequency of 1: 1500
newborns. Hearing impairment can occur at both
zvukoprovodnost, and at the level of sound perception. Now known
more than 300 syndromes, among the signs of which are hearing loss and more
140 genetic sites (loci) that cause isolated
In the European population, almost half the cases of non-syndromic
deafness generates the pathology of the gene GJB2, which regulates the work
ion channels of the inner ear. It is the movement of ions through
snail membrane and creates a potential difference that forms a nervous
pulse. Today, more than 300 variants of mutations of this
genes that can be inherited in different ways:
- Autosomal recessive type inheritance (75 – 80%). Modified
gene – a recessive sign of deafness – can be hidden from the
generations before generation, until it “meets” with the same
inherited from the second parent. In this case, deaf child
born in a healthy couple.
- Autosomal dominant type (15 – 20%). For the occurrence of deafness
enough one mutated gene inherited from the unheard
In Russia, the carrier of a GJB2 gene mutation is every 46
Since the changes in this gene cause hereditary deafness
not limited, possible and 3 types of inheritance – associated with
X chromosome. In this case, men are born in the family.
deaf and women remain healthy carriers of the defective
Another problem is that not always
hereditary deafness manifests itself from birth. It also happens,
that hearing impairments develop with age, as
abnormal metabolic products.
Hearing loss in children
If in adults, hearing loss leads to impaired
disability and problems with communication, deafness in children causes
impaired mental development: the developing brain lacks
According to WHO, 40% of hearing loss and deafness in children have
60% of cases of hearing loss in children could be prevented:
- 31% are infectious diseases: measles, meningitis,
rubella, cytomegalovirus. This group includes patients with
chronic otitis media.
- 17% are caused by impaired normal pregnancy and
childbirth: these are very premature babies, patients who have suffered asphyxia
birth and jaundice of newborns;
- 4% affected by drug use, toxic
affecting the hearing aid;
- 8% – other causes of deafness.
In order to reduce hearing does not prevent the normal development
child, you need as early as possible to start treatment for deafness. And for that
it is important to understand that the baby does not hear. As practice shows,
parents usually notice such things too late – and violations
hearing is first detected in a child during an examination before
enrollment in kindergarten.
How to determine deafness in a child:
- the baby does not respond to harsh sounds: rattles out of the field
sight, claps, knock falling objects, etc.
- the child does not respond to his own name by the age of 1.5;
- if you call the baby from behind, he will not turn around (many
parents interpret this as “stubbornness” or
- schoolchildren have problems with studies, answers in the lessons –
the child does not hear the teacher sufficiently for mastering
New knowledge (which is also often interpreted as “absent-mindedness”
According to doctors, 30% of under-performing students have one-sided
hearing loss Among repeaters, it is found 10 times more often than
among the rest of the children.
Since parents often turn on the mechanisms of psychological
protection that allows you to ignore the deafness of the child is very important
time to go through all the research. Now working in Russia
screening program (early detection) of hearing loss in
Previously, an infant was screened for hearing changes.
called “pea sample”: it was necessary to shake a jar,
наполненной сухим горохом, вне поля зрения baby With this sound
It turned out pretty loud: 80 – 90 dB. Normal child over 2
weeks (namely, at this age, the response to the sound is formed) with
sharp noise shudders, blinks, opens his eyes wide, tries
turn to the sound source or, on the contrary, freezes,
by listening. Accordingly, a sign of deafness in infants
it became the absence of such a reaction.
Now for a quick survey using special devices
which serves sounds (clicks) of different volume and fix
acoustic response – extremely weak sound vibrations,
generated by the cochlea. This method is called registration.
delayed otoacoustic emission. He is absolutely
safe and does not require a long procedure. If the baby is sleeping, everything
The examination can be completed in 2 minutes.
According to current clinical guidelines, such a survey
must pass all children still in the hospital – up to 3 days after birth.
If results show abnormal, up to 3 months
the child should be re-examined, and in case
if problems with hearing are confirmed, then by 6 months of life you need
The treatment consists either in the selection of a hearing aid (and
hearing aid must be bilateral), or in the cochlear
implantation – an operation in which electrodes are implanted
directly into the cochlea, amplifying the beep.
And after hearing aids, and after cochlear implantation,
the child will need lessons with the deaf-and-dumb and speech therapist in order
to learn to perceive and distinguish sounds and master
Acute neurosensory hearing loss
Although a sharp decrease in hearing can be caused
foreign body contact, most often hearing impairment, developed
in a few hours, it turns out to be a consequence hearing impairment
analyzer, that is, a special case of sensorineural hearing loss.
Patients usually describe their condition as “muting”,
�”Broken telephone wire”. Causes that may cause
- exposure to infectious agents: viruses (measles, mumps,
herpes, flu, encephalitis) or bacteria (diphtheria, meningitis,
- circulatory disorders: hypertension, ischemic heart disease, cerebral
- trauma (craniocerebral, barotrauma);
- ototoxic effect of drugs.
But it is possible to determine the exact cause only in 10 – 15% of cases, in
all other patients hearing loss is called idiopathic
(most often implying the vascular nature of the pathology).
Often, hearing loss is associated with tinnitus,
30–65% of these patients have deafness within a week
on their own.
However, it’s not worth waiting for the problem to resolve itself.
by myself. Hospitalization in a specialized hospital and
- glucocorticoids, optimally – the introduction into the cavity of the middle ear,
if there is no such possibility, intravenously;
- preparations that improve rheological properties, “fluidity”
blood, and microcirculation (pentoxifylline, vinpocetine);
- antioxidants and hypoxia resistance enhancers:
lack of oxygen in the tissues in violation of blood flow
(ethyl methyl hydroxypyridine succinate, vitamins A, E).
- hyperbaric oxygenation.
All these tools are designed to reduce inflammation (including
caused by tissue damage during ischemia) and restore normal
blood flow in the inner ear.
Paradoxically, although such a scheme is indicated in the clinical
recommendations for the treatment of sensorineural hearing loss (including
foreign guidelines), the same recommendations stipulate that
schemes are developed empirically (based on the experience of observations and
treatment) and there is still not enough conclusive evidence of their
clinical efficacy. Research relevant
requirements of modern evidence-based medicine are still underway and
results not yet published.
Sensory neurosensory hearing loss
With this pathology, deafness is caused by a lesion.
the sound perception department of the auditory analyzer, ranging from
receptors of the inner ear and ending with the cortex of the temporal part
brain. Simply put – by various factors.
nerve cells die, the sensing and analyzing sounds that
leads to deafness.
Pathology may be congenital (it was discussed in detail
above) and acquired.
The factors provoking the acquired sensorineural
- prolonged increased noise level (prof. harm);
- age-related changes (presbycusis);
- chronic vascular pathology;
- chronic purulent otitis, labyrinthitis, intracranial
complications of ENT diseases (meningitis, abscesses);
- chronic intoxication, including at work;
- blood clotting disorders (microthrombus formation and how
consequence of impaired microcirculation of the inner ear).
When sensorineural hearing loss is primarily reduced perception
high-pitched sounds and the ability to distinguish between whispers, whereas
low frequencies, hearing can remain normal for quite some time.
Bone and air conduction are equally reduced by
audiogram clearly visible descending curve showing violations
hearing primarily at high frequencies.
The mechanisms of development of neurosensory deafness are not fully understood,
but in general, circulatory disturbance is considered the main factor.
Accordingly, the treatment is primarily aimed at restoring
- correction of background diseases (normalization of blood pressure, level
cholesterol, treatment of infection, etc.);
- Nootropics (Piracetam, Cerebrolysin, Cavinton),
- blood clotting agents (acetylsalicylic
- B vitamins, antioxidants.
Treatment is carried out by supporting courses twice a year. Like
in a situation with acute sensorineural hearing loss, the doctor decides how
treat deafness based on personal experience and recommendations
experts. Relevant evidence
the effectiveness of a particular scheme does not exist.
Over time, patients most often require hearing aids –
selection of hearing aids.
Conductive hearing loss
For violations at this level, complete deafness is rare, but
hearing loss can be quite significant. This violates
sound conduction through the eardrum system – auditory
bones – the inner ear.
- blockage of the external auditory canal (sulfur plug, external
otitis, foreign body);
- impaired mobility and function of the eardrum:
perforation (due to inflammation or injury), timpanosclerosis (deafness
after chronic inflammation), membrane retraction in acute
tubootitis when due to impaired hearing function decreases
pressure in the middle ear.
- impaired mobility of the auditory ossicles: serous or purulent
effusion in the tympanic cavity during otitis, cholesteatoma (pathological
squamous epithelial formation caused by chronic
inflammation) caries of the auditory ossicles (again, the result
chronic otitis media), otosclerosis.
Most often conductive deafness – in one ear (one-sided).
A characteristic sign of conductive hearing loss is your own
the voice is given in the sick ear “like in a barrel”. This is due to the fact that
bone conduction remains normal whereas airborne
decreases, that is, the affected ear really hears the voice only
�”From the inside.” The same confirms the tuning fork tests – when
put to the mastoid process (behind the ear) tuning fork heard
better than being brought to your ear. Audiogram if it is done
(most often the diagnosis is made earlier, on the basis of the anamnesis and data
direct examination) also shows a decrease in air
sound conduction at normal bone.
Treatment will depend on the reason for hearing loss:
- in the presence of a foreign body or sulfuric plug – removal for
restoration of the patency of the ear canal;
- external otitis media – topically anti-inflammatory drops (as
typically combining antibiotics, antifungal agents and
glucocorticoids: Anauran, Candibiotik, Otofa, Polydex, etc.) or
ointment; when inflammation decreases, swelling and hearing decrease
- tubootitis (eustachitis) and serous otitis media – recovery
patency of the auditory tube: vasoconstrictor nose drops for
removal of edema from the mouth of the auditory tube, physiotherapy (blowing),
children – removal of adenoids; as hearing function recovers
pipe pressure on both sides of the eardrum level,
restoring its mobility.
- purulent inflammation requires the use of antibiotics as a local,
and systemically (in tablets), if there is a perforation of the membrane,
it is desirable to conduct a course of washing the tympanic cavity (does
- chronic purulent process may require surgery;
- otosclerosis can only be treated promptly: affected hearing
bones are replaced with prostheses.
In general, with conductive hearing loss, the prognosis is favorable if
treatment started on time, hearing is restored in full.