What is Sensorineural Hearing Loss?

Sensorineural hearing loss, or SNHL, is a type of hearing problem caused by damage to the inner ear. Sensorineural hearing loss is typically caused by some form of damage to the nerve that is responsible for sending sound waves to the brain. SNHL hearing loss may also result from fluid buildup due to aging.

SNHL affects the tympanic membrane, which is also called the eardrum. The tympanic membrane helps you hear by transmitting sound waves from the outer ear to the inner ear. It also helps protect the eardrum from damage. Damage to the tympanic membrane can cause hearing loss, which may be temporary or permanent.

Types of Sensorineural Hearing Loss

There are a few different forms of sensorineural hearing loss. The types differ by whether you experience hearing loss in one or both ears, and the severity of your hearing loss.

Types of SNHL: 

• Bilateral sensorineural hearing loss — This is when you experience an equal amount of hearing loss in both ears.
• Unilateral sensorineural hearing loss — This is hearing loss in only one of your ears.
• Asymmetrical sensorineural hearing loss — This is hearing loss in both ears, but your hearing loss is worse in one of your ears.

Sudden sensorineural hearing loss, or SSHL, is deafness that occurs immediately or over the course of several days. SSHL usually only impacts one of your ears. Many people notice SSHL in the morning.

Symptoms

Your sensorineural hearing loss symptoms can be mild, moderate, or severe. 

Mild SNHL:

• Slight hearing problems
• Minor dizziness
• Sounds muffled
• Sounds seem slightly distant
• Difficulty hearing in noisy environments

Moderate SNHL:

• Increased hearing loss
• Balance issues
• Sounds seem far away
• Difficulty hearing high-frequency ranges
• Difficulty hearing low-frequency ranges

Severe SNHL:

• Dramatic hearing loss
• Ringing in your ears
• Sounds seem very far away
• Major dizziness
• Major balance issues

Sensorineural hearing loss examples:

• Mild SNHL — You might have some trouble having conversations in places with noisy backgrounds.
• Moderate SNHL — You might have trouble hearing anyone, especially young children or women, with even a little background noise. Severe SNHL—You might find it very difficult to hear anyone in any location.

Causes

Sensorineural hearing loss causes are categorized into acquired SNHL and congenital SNHL. Acquired means your hearing loss occurred after you were born. Congenital means you were born with hearing loss.

Acquired SNHL

Acquired SNHL generally develops later in life. You might develop sensorineural hearing loss for several reasons.

Acquired SNHL causes: 

• Noise — A single episode of loud noise can damage your ear. Regular episodes of loud noise can also harm your hearing.
• Age — Hearing loss is a common symptom of growing older. Age-related hearing loss occurs over time and usually affects both ears.
• Injury — Any trauma to your head or ear can lead to hearing loss. A common cause of injury is a strike to your head or falling on your ear.
• Medications — Certain drugs can damage your ears and cause hearing loss. Some drugs can result in permanent hearing loss.
• Infections — Viral infections can cause SNHL. Examples of viral infections include meningitis, mumps, and measles.
• Tumors — Abnormal growths in your inner ear can reduce hearing. Tumors usually impact only one of your ears.

Congenital SNHL

Congenital SNHL is rare and occurs before you are born.

Congenital SNHL causes:

• Maternal diabetes — Pregnant women have a higher risk of hypoglycemia. Prolonged or recurrent hypoglycemia is linked to hearing loss.
• Prematurity — Premature babies have an increased risk of hearing loss. Full development of hearing abilities occurs in the last part of pregnancy.
• Genetics — A genetic defect can also cause hearing loss. A genetic defect is a medical condition for which there is a genetic component. An abnormal gene can come from your mother or father.
• Infections — Infection during pregnancy can lead to hearing loss. If you are pregnant and suspect that you have an infection, it is important to see a doctor immediately.

Diagnosis

Your doctor will make a sensorineural hearing loss diagnosis based on a physical examination and a sensorineural hearing loss test. There are several different types of diagnostic tests available.

SNHL diagnosis tests:

• Physical exam — During a physical exam, your doctor will look for eardrum damage, fluid accumulation, earwax buildup, inflammation, swelling, foreign bodies, and structural abnormalities.
• Tuning forks — Your doctor may perform a Weber’s test or a Rinne test. During a Weber’s test, your doctor strikes a turning fork and places it on the middle of your forehead. If it sounds louder in one of your ears, you may have hearing loss. For a Rinne test, your doctor places the turning fork against a bone behind your ear and slowly moves it in front of your ear until you can no longer hear it.
• Audiogram — A medical expert called an audiologist performs a sensorineural hearing loss audiogram. For the test, you enter a soundproof booth, wear headphones, and respond to various sounds at different frequencies and volumes.

Treatment

Sensorineural hearing loss treatment might involve hearing aids or cochlear implants. There is no cure for SNHL.

Hearing Aids

Hearing aids help resolve hearing loss symptoms. Hearing aids generally make sounds louder, clearer, and focused. Hearing aids also selectively reduce background noise, so that it no longer interferes with conversations.

Cochlear Implants

A cochlear implant is an electronic device with a microphone and receiver. You wear the microphone behind your ear. Your doctor surgically implants the small receiver in your ear. The microphone collects sounds and sends them to the receiver. The receiver sends information to your auditory nerve so that your hearing can be restored.

Prognosis

Sensorineural hearing loss prognosis depends on the severity and cause of your hearing loss. Most people regain at least part of their hearing. A smaller percentage of people make a sudden full recovery within a few weeks.