HEARING IMPAIRMENT: CHARACTERISTICS, TYPES AND CAUSES - MEDICINE - 2025

The hearing impairment is any condition that causes a decrease in the ability to perceive sound, which in turn creates difficulty for verbal communication. Hearing impairment is not a disease in itself.

Rather, this type of disability is the consequence of different medical conditions that generate permanent or temporary damage to the different structures of the ear. People with hearing impairment can lead a totally normal life.

This normal life includes professional development, homework, sports, and any other type of daily life activity, even though in many cases it is necessary to have special help to achieve this goal.

Characteristics of hearing impairment

-It occurs when part or all of the ability to listen is lost. Other terms used to refer to hearing impairment are deafness or hard of hearing.

- Hearing disabilities are classified in terms of the severity and type of hearing impairment. Gravity is categorized based on the minimum sound that can be heard with the better ear. The higher the decibel (dB), the louder the sound.

-A hearing loss greater than 90 decibels is generally considered deafness. A hearing loss of less than 90 decibels is classified as hearing impairment.

-There are communication and educational obstacles related to hearing impairments that arise around communication. A student with a hearing impairment may experience difficulties in: grammar, spelling and vocabulary, taking notes, participating in discussions, watching videos or presenting oral reports.

-It is important that the parents and teachers of a child with hearing impairment do not underestimate their intelligence. Most children with this disability acquire and develop language more slowly and therefore it can be incorrectly assumed that intelligence is low.

-Although the sense of hearing has been affected, the person can lead a normal life.

Types

Classifying hearing impairment is extremely complex, since it is difficult to encompass all the edges of such a complex problem in a single classification. Thus, various types of hearing impairment can be distinguished according to their characteristics, not necessarily being mutually exclusive.

According to the moment of appearance

Congenital

The person is born with the disability, either due to malformation of the structures that make up the ear or due to abnormal functioning in the cellular and even molecular level.

At this point it is important to note that not all congenital deafness is detected early; in fact, they are divided into two large groups: hearing impairment that appears between birth and 3 years of age, and that that appears after 3 years of age.

Acquired

Disability develops throughout life due to multiple factors that can be genetic, traumatic, toxic (medications and drugs) and degenerative (aging).

In some cases of acquired hearing impairment, two different factors may be added throughout life, which are enhanced by increasing the severity of the situation.

For example, a person had an acoustic trauma during youth, causing hearing impairment, while retaining a certain degree of hearing.

Later in life, he receives long-term treatment with an ototoxic drug (such as certain antibiotics from the aminoglycoside group), which can further damage an already diseased ear; in this case both causes are added.

According to severity

Hearing impairment is understood to be any degree of hearing loss that interferes with sound perception processes to such a degree that the use of special aids is required to achieve adequate hearing (if this is possible).

In this sense, according to its severity, hearing impairment can be classified into:

Cofosis

It is also known as profound deafness. The person is unable to perceive any type of sound.

Deafness

Sounds above 75 dB are needed to achieve hearing. Technically the person is deaf, but it is not profoundly deaf (as in the case of cofosis), since with sounds amplified by devices designed for this purpose, he can achieve relatively acceptable hearing.

Hearing loss

Sounds below 75 dB can be heard but not in the full range of normal hearing.

In order to diagnose any of these conditions, an audiometry must be performed, which will yield one of the following results:

- Normal hearing, which implies that you can perceive sounds in the range of 20 dB or less.

- Mild hearing loss, in which the minimum detectable sound range is between 20 and 40 dB.

- Average hearing loss, which implies that it can detect sounds from 40-70 dB (hearing loss).

- Severe hearing loss, with which it is only capable of detecting sounds between 70 and 90 dB (deafness).

- Profound hearing loss, with which, in the best of cases, it can detect sounds above 90 dB (profound deafness) or does not detect sounds at all (cofosis).

It is important to note that the different conditions that produce decreased perception of sound can be unilateral or bilateral.

In cases where the problem is one-sided, the healthy ear can compensate for the situation and allow the person to have a relatively normal life without the need for hearing aids, although they will sometimes have trouble assessing where a sound originated.

On the other hand, when the problem is bilateral, it is already considered a disability that requires special aids and techniques to allow the person to function normally in their social environment.

According to the forecast

Hearing impairment can be permanent or temporary. In the first case, hearing does not recover and can even worsen over the years until it reaches cofosis.

In the second case, the hearing impairment is transitory and eventually the affected person can regain normal hearing, or reach the range of mild-moderate hearing loss without this implying a disability.

According to the site of the injury

They are divided into two large groups:

Driving deafness

When the problem is in the outer ear or the middle ear. They are usually the ones with the best prognosis.

Sensorineural deafness

In these cases, the lesion is in the inner ear, in the nerves that carry the auditory impulse and even in the auditory cortex itself, where the brain interprets the sounds.

Causes of hearing impairment

Hearing impairment has many causes, some more common than others. Next, mention will be made of the most common in both children and adults.

Causes in children

Although rare, there are congenital causes of deafness in children. In general, hearing deficit is associated with other features of a particular syndromic complex, and more than 400 syndromes in which hearing loss is present have been identified to date.

Among these, we can mention Waardenburg syndrome, characterized by partial albinism and deafness; Usher syndrome, where hearing loss and visual defects are associated; and Alport syndrome, characterized by deafness and kidney dysfunction.

In these, as in all cases of congenital deafness of genetic origin, a particular gene has been identified, which can be inherited to the next generation.

In most cases of congenital deafness the problem is at the level of the cochlea; that is, in the receptors located in the inner ear. However, there are certain congenital conditions - such as hypoplasia of the external auditory canal or malformations of the pinna - that are related to this type of disability.

In these cases, the surgical reconstruction of the structures with problems can lead to the recovery of hearing potential.

Perinatal causes

More frequent than deafness of genetic origin is deafness due to perinatal factors, among which are prematurity, low birth weight, infections of the mother such as rubella or toxoplasmosis, as well as treatment of the mother during pregnancy with ototoxic medications.

All of these predispositions can cause hearing problems in the newborn. These problems can manifest from the moment of birth or later in life, even beyond the age of 3.

During early childhood the baby is very vulnerable to external elements that can damage the ear. Infections such as viral meningitis, mumps, and even measles can result in some degree of hearing impairment.

On the other hand, recurrent otitis, trauma and the use of ototoxic drugs during the first years of life can cause deafness.

A common cause of decreased hearing ability (but not disability unless the cause is not corrected) is the introduction of foreign bodies into the external auditory canal, as well as the formation of earwax plugs. In these cases the hearing loss is easily corrected by eliminating the cause.

Causes in adults

In young adults, the most frequent causes of hearing impairment are the use of ototoxic drugs or medications, and acoustic trauma from exposure to sounds above 100 dB, such as: explosions, detonation of firearms, noise from equipment industrial, loud music, among others.

In these cases, the hearing loss can be temporary or permanent, depending on the intensity of the sound, the exposure time and the severity of the damage.

On the other hand, certain tumors such as acoustic nerve neurilloma can lead to deafness.

In older adults, conditions such as earwax plug may occur, which conditions reversible conduction deafness since, when the plug is removed, hearing recovers.

Aging

On the other hand, as you age, a condition known as otosclerosis may occur, in which the joints of the small bones of the middle ear become stiffer, which generates poorer conduction of sound. Ultimately, this leads to progressive and irreversible conduction deafness.

Something similar happens with the receptors of the middle ear, which degenerate and become less effective, conditioning the natural hearing loss of the elderly.

Treatment of hearing impairments

The treatment of hearing impairment must be individualized according to each case. The priority is to correct the cause; if this is not possible, they will be used from microamplifiers to cochlear implants to ensure that the patient can regain their hearing.

In the case of childhood deafness, early diagnosis is very important, since the earlier the problem is identified, the better the prognosis.

In the most severe and irreversible cases, treatment focuses on providing the person with tools that allow them to act in their daily life, such as sign language and other strategies that will allow them to have a happy and functional life.

References

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