Sensorineural hearing loss refers to a condition where there is a hearing loss due to the hair cells of the inner ear being damaged. This article deals with the causes, types, symptoms, and treatment of SNHL.
Our ears have three portions, namely outer, middle, and inner ear. When the inner ear is damaged, sensorineural hearing loss (SNHL) occurs. It is referred to as sensorineural because the inner ear and hearing nerve need to work together for proper hearing. SNHL accounts for around 90 % of hearing loss cases. It might be permanent and can be mild, moderate, severe, and total.
Sensory hearing loss is usually a consequence of damaged cochlear hair cells. These hair cells can be abnormally formed at birth or damaged after birth. Some of the causes include infections, certain drugs, and genetic mutations. And neural hearing loss is a consequence of damaged cochlear nerve. This nerve is responsible for the transmission of impulses to the brain. SNHL usually results in a gradual deterioration of a person’s hearing over many years and can be accompanied by symptoms, such as tinnitus (ringing in the ears) and vertigo. SNHL can be either:
Unilateral - Affecting only one ear.
Bilateral - Affecting both ears.
The common kinds of sensorineural hearing loss are presbycusis (age-related) and noise-induced hearing loss. The frequent symptoms of SNHL include the inability to distinguish voices in a noisy environment, difficulty following a conversation over the phone, a few sounds feel very loud, feel that people are mumbling, and difficulty following and understanding speech. The symptoms are common to all types of hearing loss, so it is important to consult a doctor and run necessary tests to rule out other causes and conditions.
Diagnosis is generally made by an audiologist with the help of an audiogram, tympanometry, and speech audiometry. As of now, there is no cure for SNHL, and treatment is done with the help of hearing aids. In severe cases, a cochlear implant is indicated.
There are many different conditions which can damage the inner ear, but they are broadly grouped into two types:
Congenital SNHL is a type of hearing loss seen at birth. Reasons include -
Low birth weight.
Maternal infections such as rubella and German measles during pregnancy.
2) Acquired hearing loss:
Acquired SNLH is developed at a later stage in life, unlike the congenital type. Reasons include -
Presbycusis (age-related hearing loss) - It usually affects both ears in people between the ages of 65 and 74 years.
Noise-induced hearing loss (NIHL) - Prolonged exposure to loud noise higher than 85 decibels or exposure to a single loud noise like gunfire or explosion.
Viral infections - Such as measles, meningitis, and mumps.
Other disorders - Such as Meniere’s disease, bacterial meningitis, diabetes, and inflammatory ear conditions.
Acoustic trauma - Due to exposure to loud sounds such as firearms or explosions.
Medicines - Ototoxic drugs such as certain antibiotics, chemotherapy drugs, and anti-inflammatory drugs.
Tumors - Ear tumors and growths may also affect hearing health.
Those with sensorineural hearing noise can hear muffled sounds but not understand the context of what is being spoken, and this leads to gradual isolation.
Problems with hearing in a noisy environment.
There is reduced sensitivity to soft sounds. This causes problems with communication, interpersonal skills. It also affects learning and school performance in young children.
Perception of loud sounds is altered, causing social withdrawal and loneliness.
Tinnitus (ringing or buzzing sound in the ear).
Iodine deficiency and hypothyroidism (underactive thyroid).
Pathophysiology of Sensorineural Hearing Loss:
The abnormal formation or function of the hair cells present in the inner ear results in sensory hearing loss. And any damage to the vestibulocochlear nerve or the eighth cranial nerve results in neural hearing loss.
It is not easy to know if a child has hearing problems or not. Children can develop hearing loss due to infections at birth. In the following situations, it is best to get your children tested for hearing loss:
If the child does not look like they understand your language.
If they do not attempt to form words.
If they develop frequent ear infections.
If they have balancing problems.
If they do not get startled with sudden noises.
The specialist will ask you questions to understand your symptoms and medical history. Then the specialist will perform a physical examination and ask you about any previous medical conditions and the medications that you are currently taking. The tests include:
Physical examination - You will have to cover one ear at a time, while the doctor plays sounds at different volumes. He or she will also conduct tests using a tuning fork, which measures the vibrations in your ear.
Audiometry - This test can detect hearing loss more accurately. Here, a number of different sounds at different volume levels are sent individually to each ear.
MRI - To check for any abnormalities in the ear, such as cysts or tumors.
A thorough evaluation of the extent of the hearing loss is necessary to be conducted by a hearing health professional who would diagnose the actual type of hearing loss and suggest appropriate treatment.
In the case of bilateral hearing loss, which is mild to moderate, hearing aids may help. But, in case of severe hearing loss, even using hearing aids will not help as it would just amplify the distorted sounds and in the presence of background noise, it would lead to more confusion and frustration.
In that case, cochlear implants may be the solution. A cochlear implant is an electronic device that is placed in the ear surgically and stimulates the hearing nerve by converting sound waves directly to electrical impulses.
Sensorineural hearing loss is unfortunately permanent because it is not possible to repair or replace the hair cells in the inner ear. Hearing does not recover overtime on its own. The percentage of hearing that as already been lost will remain permanent. Some types of sudden sensorineural hearing loss (SSHL) can be cured with immediate medical help.
For more information on SNHL, consult an audiologist online!
Some people cannot hear at all the frequencies. So they are advised to use hearing aids. Using a hearing aid is not a disability. It is an adaptation to a different hearing frequency. A good hearing aid will help in the proper hearing. When a hearing aid does not have the potential to provide proper functioning, then it can lead to disability. Only total deafness is considered as a disability.
Hearing loss can be mild, moderate, and severe. Severe cases result in total deafness. This might be due to the damage of the auditory nerve. Genetics might be the reason for it. You should consult your doctor to identify which level you are in to know the prognosis rate.
Early treatment has a good prognosis. Medical or surgical procedures can treat sensorineural hearing loss. Sensorineural hearing loss leads to reduced quality of life and isolation. You should contact your doctor and ask for the treatment options.
If sensorineural hearing loss is mild or severe in one ear, then using a conventional hearing aid is the usual treatment method. However, hearing aids need some degree of useable hearing. Therefore it is not useful in complete hearing loss cases.
Sensorineural hearing loss not only reduces the ability to hear mild sounds but also the ability to listen clearly. The function of understanding the speech is also lost. Sensorineural hearing loss is caused by a birth injury, diseases, genetic syndromes, and drugs that are toxic to the auditory system.
Four different levels of deafness are mild, moderate, severe, and profound. It is necessary to identify the cause for that particular degree of deafness. With proper treatment plans and aids, it is possible to cope up with a hearing loss. With modern medicine, hearing loss is not a very big complication.
Severe hearing loss can be categorized based on the severity level, as follows:
- Mild hearing loss - Hearing loss ranging from 20 to 40 decibels.
- Moderate hearing loss - Hearing loss ranging from 41 to 60 decibels.
- Severe hearing loss - Hearing loss ranging from 61 to 80 decibels.
Typically, hearing aids have an estimated lifespan of around two to seven years. Depending on the style and quality, some may have a longer life. The lifespan also depends on the type. In-the-ear hearing aids last for four to five years, while behind-the-ear hearing aids have a five to six years lifespan.
If hearing loss is because of exposure to loud noise, then supplementation with vitamins A, C, and E with magnesium is a remedial treatment. Folic acid helps to keep your ears sharp if your hearing loss is due to aging. To minimize noise-induced hearing loss, vitamins A, C, and E, coupled with magnesium, is the best treatment option.
When you try to attend a hearing test with tinnitus, it might be difficult to understand certain words, pitches, and sounds. There are certain other protocols to be followed for tinnitus patients. Please inform the health care provider about your condition before beginning the test.
Last reviewed at:
17 Apr 2020 - 4 min read
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