Hearing loss

from Wikipedia, the free encyclopedia
Classification according to ICD-10
H90.- Hearing loss due to conductive or sensory sound disorder
H91.- Other hearing loss
ICD-10 online (WHO version 2019)
An elderly gentleman puts his hand to his ear as a sound amplifier

Under hearing loss ( hearing impairment, even hypoacusis ) is defined as a partial or complete loss of hearing . The severity of the disorder can range from mild hearing loss to deafness and have a variety of causes. According to a study in 2017, around 16% of the total adult population (18 years and older) in Germany are hard of hearing according to the classification of the World Health Organization . Naturally, the proportion of people who are hard of hearing increases with age.

A hearing loss can have its cause in the entire area of ​​the hearing organs. These include the outer ear with the auricle and the auditory canal , the middle ear , the cochlea , the auditory nerve and the auditory pathway up to the auditory cortex in the brain. Depending on the seat of the cause can be a conductive hearing loss (abbreviated SLS) in case of failure in the outer and middle ear, a sensorineural hearing loss (SES or IOS for I can o hr s chwerhörigkeit) in case of failure in the cochlea, a hearing loss (in disorders of the auditory nerve) and A distinction was made between central hearing loss for the area of ​​the auditory pathway in the brain. The combination of SLS and IOS is referred to as combined hearing loss .

Conductive hearing loss

Conductive hearing loss on the audio audiogram of the right ear.
<: Bone conduction
X: air conduction
The difference between the air conduction and bone conduction audiogram is typical of conductive hearing loss

The conductive hearing loss (synonym: conductive hearing loss , middle ear hearing loss ) denotes that form of deafness caused by a fault in the sound transmission in the outer ear area or in the middle ear comes about.

diagnosis

In the case of conductive hearing loss, otoscopic findings usually provide information about the cause of the hearing loss, especially in the form of pathological changes or injuries to the eardrum . In the case of unilateral conductive hearing loss, the Weber test is lateralized into the hearing impaired ear; the Rinne test is negative. In the tone audiogram , the sound conduction disorder can be recognized by the fact that the air conduction hearing threshold is at higher decibel values ​​than the bone conduction hearing threshold , i.e. the sound is heard worse via air conduction (headphones) than via bone conduction.

In the speech audiogram, there is a parallel shift of the curves for understanding numbers and words to higher decibel values, but at correspondingly higher volume levels, a 100% understanding of words is achieved.

With tympanometry , statements about the content and pressure conditions of the middle ear can be obtained.

The stapedius reflex measurement allows conclusions to be drawn about the mobility of the ossicular chain .

Imaging procedures, especially computed tomography , provide information about the contents of the middle ear and any bony changes.

causes

Possible causes are:

therapy

In principle, conductive hearing loss offers good treatment options.

Ear wax and foreign bodies that form clogs are removed mechanically, often by irrigation.

Inflammation of the ear canal is treated locally with antibiotic drops after cleaning .

Acute tubular catarrh and acute tympanic effusion usually heal spontaneously with the viral infection of the upper respiratory tract, and decongestant nasal drops are given to help. A puncture of the middle ear or paracentesis is rarely required.

Chronic middle ear catarrh ( seromucotympanum ) often requires the enlarged tonsils ("polyps", "growths") to be removed by an adenotomy . Paracentesis is usually performed at the same time. If the disease persists, the middle ear is forced to ventilate by inserting a tympanic tube into the eardrum.

Consequences of injuries, such as interruptions in the ossicular chain, can be improved or remedied by an operation ( tympanoplasty ).

In otosclerosis , the fixed stapes can be partially removed by an operation ( stapesplasty ) or the footplate can be perforated and the function of the stapes can be replaced by a prosthesis e.g. B. be replaced by titanium or platinum.

A major operational field is the treatment of chronic otitis media and cholesteatoma . The focus here is on remedying the disease, possibly also through radical surgery , but attempts are usually made to improve hearing in the sense of a tympanoplasty.

If the cause of conductive hearing loss cannot be treated (e.g. after creating a radical cavity ), wearing a hearing aid is indicated. In the case of pure conductive hearing loss (i.e. with a completely intact inner ear - see below), the success of the treatment is usually very good. Conductive hearing loss in the frequency range that is important for speech recognition rarely exceeds 40 dB (A) (see adjacent audiogram). The discomfort and pain thresholds rise or fall (loud sound events are displayed in the audiogram below) by the same value. The hearing aid acoustician only needs to select a hearing aid that amplifies as linearly as possible over a large frequency range. A filtering of the sound signals (with sensorineural hearing loss mostly compression) is not necessary here.

Damage to the inner ear by a hearing aid that is set too loud is also practically excluded in the case of pure conductive hearing loss, since the limited sound conduction of the sound conduction apparatus acts de facto as a sound protection.

However, the good prognosis for wearing a hearing aid only applies to pure speech recognition (and thus to social interaction). When listening to music, for example, there are restrictions due to the hearing aid technology, but these are mostly accepted. Aesthetic enjoyment of music is certainly better possible with headphones instead of hearing aids.

Sensorineural hearing loss

Sensorineural hearing loss in the sound audiogram
>: Bone conduction
O: Air conduction
There is practically no difference between the air conduction and bone conduction audiogram

Sensorineural hearing loss (synonym: sensorineural hearing disorder ) is the most common form of hearing loss (> 90%). Causes are defects in the inner ear (cochlea), in the auditory nerve leading to the brain , or on the auditory pathway in the brain. Since the defect is here on a sensory (see receptor (physiology) ) or neural (see neuron ) level, the term sensorineural hearing loss is also used here (in the linguistic area, sensorineural hearing loss is generally referred to as sensorineural hearing loss ).

Strictly speaking, the term inner ear hearing loss is limited to defects in the inner ear. In practice, however, the term is used for all hearing impairments beyond conductive hearing loss. In any case, it is diagnostically difficult to determine the exact cause of sensorineural hearing loss. As a rule, the most modern technology, such as the measurement of acoustic evoked potentials , is still used in suspected diagnoses .

diagnosis

The auditory canal and eardrum are optically inconspicuous ( otoscopy ) in cases of pure sensorineural hearing loss .

One-sided sensorineural hearing loss can be determined quickly and easily using tuning fork tests ( Weber test and Rinne test ).

In the hearing test ( tone audiogram ), the disturbance of sound sensation can be recognized by the fact that the normal sound conduction via the air ( air conduction ) and the sound conduction via the skull bones ( bone conduction ) only respond in the same way at significantly higher volumes ( decibel values) than with normal hearing people.

A speech intelligibility test measures the impact of hearing loss on speech understanding.

By measuring otoacoustic emissions , statements can be made about the function of the (outer) hair cells in the inner ear.

With brainstem audiometry, detailed statements can be made about this area by measuring electrical potentials from the inner ear, auditory nerve and brainstem.

Imaging procedures, especially computed tomography and magnetic resonance tomography , provide information on changes in the cochlea, the internal auditory canal with the auditory nerve and the brain stem.

causes

  • Congenital or acquired hearing loss in early childhood
(Collective term for hearing impairments that are acquired through genetic defects, infections in the womb, damage during childbirth or in early childhood - mostly through a viral infection such as mumps - and the timing of which can often not be determined)

Infections during pregnancy can lead to hearing impairment or deafness in newborns. These include rubella and cytomegaly in particular .

In the case of genetically determined hearing impairments, a distinction is made between those that occur regularly with certain other damage ( syndromes ) and those in which the hearing impairment occurs in isolation, either from birth or later in life.

Syndromes with hearing loss as part of the disorders include, in particular, Usher's syndrome (retinitis pigmentosa), Alport's syndrome , Pendred's syndrome and Waardenburg's syndrome (hereditary disease with deafness and pigment abnormalities in the skin, hair and eyes), Forney -Robinson-Pascoe Syndrome . In total, well over 100 syndromes are known that are associated with hearing disorders.

The isolated occurring hearing disorders different types of inheritance occur, namely autosomal - dominant , autosomal recessive and X-linked . There are also individual mitochondrial forms. The associated genes mostly code for cytoskeletal proteins of the inner ear , control the energy balance or influence the local distribution of ions in the inner ear.

therapy

Sensorineural hearing loss can usually neither be influenced by drugs nor surgically (for details see the individual diseases). In the case of inflammation-related inner ear damage, u. Immediate antibiotic treatment or surgery may at least prevent the damage from progressing.

The loss of function can, however, be partially compensated for with good success by fitting a hearing aid . If this cannot be used, a cochlear implant (CI, English cochlear implant ) or an active middle ear implant can restore or improve hearing performance.

Implants

  • Active middle ear implant: The partially implanted or fully implanted system picks up signals via a microphone and converts them into vibrations that are transmitted directly to the ossicles.
  • Cochlear implant: The signal picked up by the microphone is processed by a speech processor and then transmitted directly to the auditory nerve through an electrode.
  • Brain stem implant : The signal is passed on directly to brain structures.

Combined hearing loss

Combined hearing loss in the tone audiogram

If, in addition to a sound conduction disorder, there is also a sound sensation disorder, the hearing losses of the two types of hearing loss add up, one speaks of a "combined hearing loss".

diagnosis

The focus of the diagnosis is the tone audiogram. A further diagnosis of the individual components (conductive hearing loss, sensorineural hearing loss) can be carried out as with these.

causes

  • Chronic otitis media
  • Independent causes of conductive and sensorineural hearing loss
  • Otosclerosis with involvement of the inner ear

Quantitative assessment

When classifying a degree of hearing loss, a strict distinction must be made between a medical and healthcare law perspective. While the tone audiogram is usually used for medical questions , other classifications (e.g. for the degree of disability) relate more to the socially more important restriction of communication through recording the speech audiogram .

Assessment after hearing range test

Originally, the degree of hearing loss was determined according to the hearing range for numerals, the classification that is still valid today comes from Mittermaier (1952). The terms used are strictly defined and can therefore not be changed at will.

Assessment according to the speech audiogram

After the development of Freiburg speech audiometry ( Hahlbrock , 1957), this method soon became the basis for determining hearing loss (HG Boenninghaus and D. Röser, 1958 and 1973), which could now be expressed as a percentage. The Boenninghaus-Röser tables are also the basis for calculating the percentage of hearing loss according to the so-called weighted total word comprehension (Feldmann). Determining the percentage of hearing loss is therefore a very complex assessment. Equating the hearing loss in decibels from the audio audiogram with the percentage hearing loss is not permitted.

The following subdivision is common according to the degree of severity; the percentage hearing loss relates to the individual ear:

Degree of hearing loss according to the speech audiogram Hearing loss
mild hearing loss 20-40%
moderate hearing loss 40-60%
severe hearing loss 60-80%
Residual hearing 80-95%
deafness 100%

The percentage of hearing loss in both ears is used to assess the degree of disability (GdB) or the reduced ability to work (MdE).

Assessment according to the tone audiogram

Although the tone audiogram is primarily used for diagnostic purposes, it can also be used to assess the degree of hearing loss. Unfortunately, there are different classifications around the world, some of which are country-specific. For the classification of the degrees of hearing loss, reference is now made to the WHO definition, which is also binding for hearing aid care for patients with statutory health insurance in accordance with the Aids Directive of the Federal Joint Committee:

Degree of hearing loss according to the tone audiogram mean hearing loss 0.5, 1, 2 and 4 kHz
mild hearing loss 25-40 dB
moderate hearing loss 40-60 dB
severe hearing loss 60-80 dB
Deafness > 80 dB

Spoken language skills

As a rule, people who are hard of hearing have complete spoken language skills and can read and understand all written and printed texts like people who are not hard of hearing. However, there are also those with hearing impairments who have a poorer understanding of spoken and written language because the person affected was hard of hearing before or during the language acquisition. This can be compensated for by appropriate supervision and support.

See also

literature

Web links

Individual evidence

  1. ↑ P. von Gablenz, E. Hoffmann, I. Holube: Prevalence of hearing loss in northern and southern Germany. ENT (2017), online first. doi: 10.1007 / s00106-016-0314-8 . PMID 28271167
  2. ↑ From Gablenz P, Holube I: Prevalence of hearing loss in northwest Germany. ENT (2015), 63 (3), 195-214. doi: 10.1007 / s00106-014-2949-7 . PMID 25720301
  3. ^ MG Crowson, R. Hertzano, DL Tucci: Emerging Therapies for Sensorineural Hearing Loss. In: Otology & neurotology: official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. Volume 38, number 6, 07 2017, pp. 792-803, doi: 10.1097 / MAO.0000000000001427 , PMID 28383465 , PMC 5465007 (free full text) (review).
  4. Jump up ↑ KJ Cruickshanks, TS Tweed, TL Wiley, BE Klein, R. Klein, R. Chappell, DM Nondahl, DS Dalton: The 5-year incidence and progression of hearing loss: the epidemiology of hearing loss study. In: Archives of Otolaryngology - Head & Neck Surgery. Volume 129, number 10, October 2003, pp. 1041-1046, doi: 10.1001 / archotol.129.10.1041 , PMID 14568784 , ( free full text ).
  5. ↑ Dieter Mrowinski: Audiometry: a guide for the practical hearing test , Georg Thieme Verlag, Stuttgart 2006, ISBN 978-3-13-118003-2 , pp. 51-61.
  6. ↑ R. Mittermaier: auditory examination with special consideration of reduced earning capacity. In: Arch. Ohr.-, Nas.- u. Kehlk.-Heilk. 161 (1952), pp. 94, 314.
  7. ↑ K.-H. Hahlbrock: Speech audiometry . Georg Thieme Verlag, Stuttgart 1957 (2nd edition 1970)
  8. ↑ H.-G. Boenninghaus, D. Röser: Percentage hearing loss determination of speech hearing and determination of the reduction in earning capacity. In: Z. Laryng. Rhinol. 37 (1958) 719
  9. ↑ H.-G. Boenninghaus, D. Röser: New tables for determining the percentage hearing loss for speech hearing. In: Z. Laryng. Rhinol. 1973 Mar; 52 (3), pp. 153-161.
  10. ↑ H. Feldmann: The problem of the quantitative assessment of hearing impairments in the assessment. A new suggestion to calculate the percentage of hearing loss. In: Z. Laryng. Rhinol. Otol. 1988 Jul; 67 (7), pp. 319-325.
  11. ↑ Michael Reiss: Specialist knowledge of ENT medicine: Differentiated diagnostics and therapy. Springer, 2009, ISBN 978-3-540-89440-7 , p. 1065, Chapter 26.2.1 Assessment of hearing loss
  12. ↑ Harald Feldman: The opinion of the ear, nose and throat doctor. 6th edition. Thieme Verlag, ISBN 978-3-13-542306-7 .