What Is Sensorineural Hearing Loss?
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:
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Unilateral - Affecting only one ear.
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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.
What Causes Sensorineural Hearing Loss?
There are many different conditions which can damage the inner ear, but they are broadly grouped into two types:
1) Congenital:
Congenital SNHL is a type of hearing loss seen at birth. Reasons include -
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Low birth weight.
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Premature birth.
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Inherited deafness.
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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 -
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Presbycusis (age-related hearing loss) - It usually affects both ears in people between the ages of 65 and 74 years.
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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.
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Viral infections - Such as measles, meningitis, and mumps.
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Other disorders - Such as Meniere’s disease, bacterial meningitis, diabetes, and inflammatory ear conditions.
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Acoustic trauma - Due to exposure to loud sounds such as firearms or explosions.
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Medicines - Ototoxic drugs such as certain antibiotics, chemotherapy drugs, and anti-inflammatory drugs.
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Tumors - Ear tumors and growths may also affect hearing health.
What Are the Signs and Symptoms of SNHL?
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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.
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Problems with hearing in a noisy environment.
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There is reduced sensitivity to soft sounds. This causes problems with communication, interpersonal skills. It also affects learning and school performance in young children.
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Balance problems.
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Perception of loud sounds is altered, causing social withdrawal and loneliness.
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Tinnitus (ringing or buzzing sound in the ear).
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Brain stroke.
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Iodine deficiency and hypothyroidism (underactive thyroid).
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Dizziness.
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.
When Is the Right Time to Test Your Child’s Hearing?
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:
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If the child does not look like they understand your language.
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If they do not attempt to form words.
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If they develop frequent ear infections.
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If they have balancing problems.
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If they do not get startled with sudden noises.
How Is Sensorineural Hearing Loss Diagnosed?
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:
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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.
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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.
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MRI - To check for any abnormalities in the ear, such as cysts or tumors.
How is Sensorineural Hearing Loss Treated?
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.
Is This Condition Permanent?
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!
