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Causes of Permanent Hearing Loss

Causes of Permanent Hearing Loss

Permanent hearing loss can be caused due to certain biological and environmental factors. The degree of permanency pertaining to auditory loss may vary from one case to another, wherein hearing may diminish drastically, or the loss of auditory functions may affect one or both the ears.
Ningthoujam Sandhyarani
Hearing aids different kinds
As we all know, the ear is an important sensory organ, responsible for receiving sound waves. The three major parts of the ear are the outer, middle, and inner ear. Each of these, play crucial roles in the optimal functioning of the ear. The mildest of damage in any part of the ear can lead to injury, infections, and loss of hearing.
Loss of hearing is the partial or total inability to perceive sound waves, which can be temporary or permanent in nature. It can also vary in degrees, wherein the loss of hearing could be minimal or severe, and may affect only one ear or both. The extent of defect or damage often determines whether the condition is treatable or not. Temporary hearing problems are usually treated with antibiotics or surgery, whereas permanent loss of hearing may be irreversible after all treatment options have been exhausted. However, in cases of partial loss of audition, hearing aids, and cochlear implants help amplify sound. There are mainly three types of hearing loss:
Conductive hearing loss occurs when certain faults in the outer or middle ear hinder the flow of sound waves. Therefore, causing sound to be inadequately transmitted through the ear.
Sensorineural hearing loss may occur as a result of damage caused to the inner ear or the auditory nerves that lead to the brain. In such cases, the distorted signals received by the brain greatly hamper the hearing ability of the individual. Sensorineural hearing loss includes Cortical or Central hearing loss.
In mixed hearing loss, factors that cause conductive and sensorineural loss of hearing are responsible for the lapses in auditory functions.
Risk Factors of Hearing Impairment
Noise-Induced Hearing Loss
Any noise which exceeds 85 db (decibels) is considered to be harmful because it damages the hair cells within the ear. These sensory cells, convert sound into electric signals that are received by the brain. Extremely loud sounds can either cause instantaneous damage or gradually degenerate the sensory cells. Occupational noise-induced hearing loss (ONIHL) is also a type of NIHL, which results from prolonged exposure to high intensity sounds. People working in mechanical, constructional, and industrial workshops often succumb to this type of auditory loss. However, these external factors can be controlled and minimized by using appropriate earmuffs and other protective auditory devices.

Genetic factors
Deafness in some cases is triggered by gene mutation, which may either result in Syndromic or Nonsyndromic deafness. Syndromic deafness is comparatively less common, however its diagnosis entails the simultaneous existence of other conditions and syndromes. On the other hand, Nonsyndromic deafness only affects specific genes and does not cause collateral damage. In autosomal dominant auditory cases, loss of hearing occurs when the mutated gene is passed on from one generation to the other. In autosomal recessive deafness, both the parents must carry the recessive gene in order for it to be passed to the children. In such cases, while some children may be merely carriers with no evident symptoms, some may be unaffected and non-carriers, and some may be affected by hearing loss.

Physical Trauma
Accidents can also lead to inaudibility. An injury to the head, fracture, damage to the eardrum from Q-tips, pressure fluctuations, and acute infections can also lead to loss of hearing or partial deafness.

Ménière's Disease
Ménière's disease affects the inner ear and its fluid-filled tubes, which help in maintaining the posture and balance of the body. The exact cause of this disease is still unknown, but it occurs when these tubes burst and cause endolymph fluids to leak. This fluid interferes with the balance functions and sound signals between the inner ear and brain, thus leading to significant hearing loss. The person suffering from this disease also experience spells of dizziness, vertigo, tinnitus (a ringing or hissing sound in ear), auditory fluctuations, and pressure in the ear.

Autoimmune Inner Ear Disease (AIED)
AIED is an inflammatory ear disease, which occurs when body's immune system mistakenly attacks itself and focuses upon the cells of the inner ear. This internal imbalance causes tinnitus, inflammation, vertigo, and stuffiness in the ear. The symptoms become more pronounced with time, and the initial loss of hearing in one ear spreads to the other as well.

Acoustic Neuroma
Acoustic neuroma is a benign tumor which grows on the vestibulocochlear nerve. The pressure applied by the tumor causes the nerve to get compressed and lose control over its auditory functions. The ability to balance is also hampered and results in vertigo, and nausea.

The use of certain medicines, results in the accumulation of toxins within the ear which drastically hamper its functioning. The degree of auditory lapse and the scope of recovery depends upon the amount of toxins lodged by the medication. In most cases, the damage caused by ototoxicity is irreversible and leads to substantial or permanent loss of hearing.

Presbycusis is an age-related hearing loss, which occurs when the ear stops receiving adequate supply of blood. Conditions such as heart diseases, blood pressure, diabetes, and other circulatory ailments can drastically hamper the circulation of oxygenated blood to the ear. This condition affects both the ears simultaneously. While high-pitched sounds become unclear and are misinterpreted by the listener, low-pitched sounds may remain audible. Often, the symptoms of this condition progress gradually thereby making it difficult to gauge its onset.

Other Causes of Hearing Loss
  • Infections within the womb including German measles, cytomegalovirus, and herpes simplex virus.
  • Complications related to the Rh factor in blood.
  • Premature birth.
  • Birth asphyxia or lack of oxygen at birth.
The diagnosis of hearing impairment is done based on physical examination and hearing tests such as whispered speech tests, tuning fork test, and pure tone audiometry. After confirming that the impairment is permanent, the doctor may prescribe hearing aids, cochlear implants, assistive listening devices, or other communication aids.
If you happen to stay in a noisy environment, it is advisable to use earplugs or other protective auditory devices. A sudden loss of hearing can be temporary, but if ignored it can cause further damage.
Disclaimer: This article is for informative purposes only, and should not be used as a replacement for expert medical advice.