Types of hearing loss
Types of hearing loss
How hearing works
The human ear consists of three parts:
The external ear
It includes the pinna and the ear canal, while the process it performs is to receive sounds from the environment and transfer them to the middle ear
The middle ear
It includes the drum and the three bones behind it called the hammer, anvil and stirrup. As the sound is transmitted the eardrum pulsates and moves the three ossicles continuing its course towards the inner ear.
The inner ear
The inner ear consists of the semicircular canals, the cochlea, the auditory nerve and the vestibular nerve. It is considered one of the most complex parts of the human body and is responsible for most of hearing. The inner ear
has two main roles, converting sound waves into electrical signals so the brain can hear and understand sounds (cochlea and auditory nerve), and ensuring the balance of the human body (semicircular tubes
and vestibular nerve). The cochlea is fluid filled and contains the organ of Corti which acts as the "microphone" of the ear. It contains 4 rows of tiny hairs that receive the vibrations from the sound waves. Hair cells
at the beginning of the cochlea they carry high-pitched information and the hair cells at the end of the cochlea carry low-pitched information.
Depending on the point of the auditory pathway in which the responsible damage occurs, hearing loss is distinguished into:
Conductive hearing loss:
The damage is located in the sound conduction (transmission) system, from the environment to the auditory nerve, i.e. the ear canal, the eardrum and the space behind it. Common causes are perforation of the tympanic membrane, presence of fluid behind the tympanic membrane, otosclerosis, various anatomical abnormalities, or simply obstruction of the duct by an alveolus.
Sensorineural hearing loss:
It may be due to degeneration of the hearing organ due to age (presbycusis), exposure to intense noise of short duration (e.g. banging, gunshots) or intense prolonged noise (loudspeakers, working in a noisy environment), idiopathic sudden loss of hearing, in a hereditary predisposition or in a genetic dysfunction that occurs from birth.
Mixed hearing loss:
It is a combination of the two above and can be due to one or more lesions located throughout the auditory pathway.
Diseases that lead to hearing loss
What is auditory trauma?
Auditory trauma is the loss of hearing caused either by a sudden and loud noise or by prolonged exposure to loud noises.
What can cause auditory trauma?
As we said, auditory trauma is caused by exposure to noise. Some common causes are:
- Occupations where machines that produce loud sounds operate continuously.
- Frequent exposure to very loud music.
- Shooting (e.g. at shooting ranges) without wearing ear protection.
- General exposure to noise without the necessary protection.
- In some cases, head injuries can cause auditory trauma if the eardrum or inner ear is affected.
- Prolonged exposure to sounds above 85 dB (eg the sound of a motorcycle) is considered an increased risk for auditory trauma. In general, the factors that play the most important role are:
- The sound intensity in decibels (dB).
- The frequency of the sound, as sounds at higher frequencies are more harmful.
- The duration of exposure to noise.
Symptoms of auditory trauma
The main symptom of auditory trauma is irreversible hearing loss. However, it is very common to be accompanied by tinnitus (ringing in the ears), while more rarely these people may also suffer from vertigo (dizziness).
Treatment and prevention of auditory trauma;
Like all hearing loss, auditory trauma by current means is not reversible, but can be treated with hearing restoration by hearing aids. In some cases of acute auditory trauma, your doctor may prescribe corticosteroid medications.
The important thing in the case of auditory trauma is prevention. If you are frequently exposed to loud noise and cannot avoid it, at least protect your ears with earplugs.
What is Meniere's disease?
Meniere's disease (otherwise known as idiopathic endolymphatic hydrops) is a condition caused by excessive accumulation of the special fluid of the inner ear called endolymph, i.e. accumulation of endolymph in the semicircular canals (organ of balance) and the cochlea (organ of hearing).
What causes Meniere's disease?
This disease is idiopathic, that is, we do not know for sure the cause due to which the accumulation of endolymph in the inner ear is caused. However, various theories have been formulated such as that it can be caused by viral infections, allergic reaction or autoimmune reactions. Also, heredity seems to play an important role in this disease, since the frequency in some families is higher.
What are the symptoms of Meniere's disease?
Meniere's disease has very characteristic symptoms which are:
- • Dizziness
- • Tinnitus
- • Hard of hearing
- • Feeling of fullness in the ear
It should be noted that a characteristic of the disease is that these symptoms have flare-ups and remissions, i.e. between episodes the patient is completely fine, and there are cases where up to several years can elapse from episode to episode. Typically, an episode can last anywhere from 20 minutes to a few hours. Also characteristic of the disease is that in the majority of cases the disease affects one ear, at least in the initial stages. If the disease progresses, it tends to spread to both ears and episodes of hearing loss and tinnitus may become permanent.
Hearing aids and Meniere's disease
Hearing loss in Meniere's disease is typically of varying severity and affects one ear. Also, more commonly it is a hearing loss that begins in the low-bass frequencies. Since it is of variable gravity, it is important that the hearing aid to be used has a volume adjustment button. In cases where the induced hearing loss is particularly severe, the use of CROS or BiCROS technology headphones is recommended. Finally, regarding the tinnitus caused by the disease, headphones can also help with technologies such as TSG and Notch Therapy.
What is the treatment for Meniere's disease?
There is currently no cure for Meniere's disease, but most patients manage to control their symptoms to some extent with some of these methods:
- • Medicines aimed at reducing nausea and/or anxiety caused by vertigo.
- • Corticosteroid injections in the middle ear may help with vertigo.
- • Diuretics are often administered with the rationale that they will reduce the accumulation of endolymph.
- • Dietary changes such as reducing salt, caffeine and alcohol intake are encouraged. Also, reducing or stopping smoking can help.
- • Surgical treatment in cases where no relief method helps the patient. Surgery involves either decongesting the labyrinth from excess endolymph or, more rarely, cutting the vestibular nerve, that is, the nerve that carries balance information from the semicircular canals to the brain.
What is an Presbycusis?
Hearing loss caused by advanced age is called presbyacusia. It is the most common cause of hearing loss, affecting 1 in 2 people aged 65-75 and 2 in 3 people aged over 75, with rates increasing further with age.
What causes such hearing loss?
As we age, many factors can affect hearing such as. Most commonly, the problem is located in the inner ear, due to the weakening of the hair cells in the organ of hearing, the organ of Corti. However, the problem can be located both in the middle ear and in the neural pathways that carry the auditory stimulus from the ear to the brain to be perceived.
Research has shown that common diseases found in the elderly, such as diabetes mellitus, arterial hypertension, coronary heart disease or stroke, are related to hearing loss. The chronic deterioration of the auditory system, from factors such as chronic exposure to loud noise but also the taking of ototoxic drugs (e.g. high doses of non-steroidal anti-inflammatory drugs, specific antibiotics, some anti-cancer drugs, etc.), has a significant effect on the development of hearing loss. Finally, genetic factors are often involved in the development of presbycusis.
What are the symptoms of presbycusis?
Almost all cases of presbycusis mean hearing loss in the high frequencies.
- Almost all cases of presbyacusis are hearing loss that mainly concerns high frequencies, i.e. difficulty hearing higher "higher" sounds. Individuals will therefore experience some of the following:
- People's speech sounds muffled, as if through a closed door.
- Particular difficulty distinguishing high-frequency consonants, such as "σ", "ψ" or "θ".
- More general difficulty in clarifying speech, especially in the presence of noise. Often people with hearing loss report that "I hear but I don't understand".
- Male voices are slightly more distinct than female voices.
- Surprisingly, some sounds are too loud and annoying.
- Often, people with presbycusis also suffer from tinnitus (ringing in the ears), a common problem caused by hearing loss.
All these difficulties often lead these people to avoid social contact, especially with many people at the same time, while it creates a feeling of helplessness and often depression, especially if they also suffer from tinnitus
How is the Presbycusis treated?
Today there is no way to completely cure or reverse presbyacusis, as with most types of ear infections. The way it is treated is with hearing aids.
What is otosclerosis?
Otosclerosis is a condition in which we have abnormal bone production in the middle ear. It can affect one or both ears.
What are the causes of otosclerosis?
Normally, the 3 auditory ossicles in the middle ear (hammer, anvil, and stirrup) transmit the drum's vibrations from the sound waves to the cochlea, in order to convert them from vibrations to nerve signals. In otosclerosis, the presence of extra bone in the middle ear restricts the mobility of the ossicles (usually pinning the stapes), resulting in sound no longer being able to reach the cochlea effectively, causing conductive hearing loss.
While there is no absolute cause for otosclerosis, there are several risk factors for developing it:
- Genetic Factors, it develops more often in people who have a family history of otosclerosis.
- Pregnancy, probably due to hormonal causes.
- Viral infections, such as the measles virus.
- Gender, more common in women.
- Race, it is more common in whites.
- Age, usually occurs between the ages of 30 and 50.
What are the symptoms of otosclerosis?
As we said, the main symptom of otosclerosis is hearing loss, which worsens as the disease progresses. Typically, bass and mid frequencies are lost first, with high frequencies being affected in fairly advanced stages of the disease. In addition, people with otosclerosis may experience:
- Tinnitus, the "ringing in the ears"
- Feeling dizzy
- Balance problems
How is otosclerosis treated?
The choice of how to treat otosclerosis depends on the exact location of the abnormal bone in the middle ear and the severity of the disease. In its mildest forms, treatment can be done with a hearing aid, effectively restoring the lost frequencies and avoiding surgery.
In case the disease is more extensive, the treatment is anabolectomy surgery, during which the immobilized agitator and excess bone are surgically removed and a special prosthesis is inserted in the agitator's place, replacing its function of oscillating the liquid inside the cochlea. In case there is otosclerosis in both ears, it is worth noting that the surgery will be done first in one ear and after a sufficient period of time (usually at least 6 months) in the other.
What is cholesteatoma?
Cholesteatoma is the abnormal growth of skin tissue or a skin cyst in the middle ear and/or the bone behind the ear, the mastoid process. Although it is a benign disease, it can cause significant complications if left untreated.
What are the causes of cholesteatoma?
There are several reasons that can lead to the development of a cholesteatoma. The most common is Eustachian tube dysfunction. The special "tube" that ventilates the middle ear and balances the air pressures on either side of the eardrum, when it malfunctions it stops performing the above roles leading to an abnormal pressure difference on the two sides of the tympanic membrane, causing the eardrum to recede inwards . When this happens, the area tends to collect wax and skin, leading to the development of cholesteatoma. Also, infections of the middle ear can lead to cholesteatoma, while in rare cases it can be congenital, i.e. present at birth.
What are the symptoms of cholesteatoma?
A cholesteatoma when it starts to develop can be completely asymptomatic. Then, as this gets older the symptoms typically get worse. The main symptoms and/or complications of cholesteatoma are:
- • Ear infections, often with purulent, foul-smelling discharge
- • Hearing loss, potentially permanent
- • Dizziness, feeling that the world is spinning around the patient or that the patient is spinning around himself
- • Tinnitus
- • Feeling of fullness and/or pain in the affected ear
If cholesteatoma is neglected and spreads further it may rarely cause:
- • Facial nerve palsy
- • Corrosion of the auditory ossicles
- • Brain Abscess
- • Meningitis
What is the treatment of cholesteatoma?
The treatment of cholesteatoma is to remove it surgically under general anesthesia. The primary purpose of the operation is to completely clear the ear of the cholesteatoma, and secondarily to preserve the integrity of the auditory ossicles where possible. In case the disease has eroded the bones, surgery can be performed to repair the damage, and thus restore hearing.