Deafness Neurosensory

Sensorineural hearing loss occurs when the delicate structures of the inner ear or the nerve pathways that carry sound to the brain are damaged, affecting your ability to hear soft sounds and making even loud sounds seem muffled or unclear.

Sensorineural hearing loss, SNHL, sensorineural deafness, nerve deafness

• Inner ear (cochlea)
• Hair cells
• Vestibulocochlear nerve (auditory nerve)

Table of contents

• What Is Sensorineural Hearing Loss?
• Signs and Symptoms
• Causes and Risk Factors
• Types of Sensorineural Hearing Loss
• How Common Is This Condition?
• Diagnosis and Testing
• Treatment Options
• Prevention
• Living with Hearing Loss

What Is Sensorineural Hearing Loss?

Sensorineural hearing loss is a type of hearing loss that happens when there is damage to the inner ear or the nerve pathways that connect the inner ear to the brain^[1]. This is the most common form of hearing loss, accounting for about 90% of all reported cases^[6].

Your inner ear contains tiny structures called hair cells located in a part of the ear known as the cochlea. These hair cells are responsible for converting sound waves into electrical signals that your brain can understand as sound^[1]. When these hair cells or the vestibulocochlear nerve (the nerve that carries sound signals to your brain) become damaged or destroyed, sensorineural hearing loss occurs^[2].

The damage to these structures means that sound signals cannot reach your brain properly. You may not be able to hear soft sounds, and even louder noises may sound muffled or unclear^[1]. Unfortunately, the hair cells in your inner ear cannot repair themselves once they are damaged, which makes sensorineural hearing loss a permanent condition in most cases^[1].

Signs and Symptoms

If you have sensorineural hearing loss, you may notice several common symptoms that affect your daily life and communication with others.

Many people with this condition find it easier to hear deep voices compared to high-pitched voices, such as women’s or children’s voices^[1]. You may have particular difficulty hearing in noisy environments, such as restaurants or crowded rooms^[2]. Other people’s speech may sound mumbled or slurred, even when they are speaking clearly^[1].

Following conversations becomes challenging, especially when two or more people are talking at the same time^[1]. You might find it hard to tell the difference between certain high-pitched sounds, such as “s” or “th” sounds in words^[2].

Additional symptoms can include ringing or buzzing sounds in the ears, a condition known as tinnitus^[2]. Some people experience a feeling of being off-balance or dizzy, particularly if the hearing loss is related to conditions like Ménière’s disease^[2]. You may also notice that your hearing sounds muffled or that certain sounds seem overly loud in one ear^[1].

Causes and Risk Factors

Sensorineural hearing loss happens because of damage to the hair cells in the inner ear or to the nerve that carries sound signals to the brain^[3]. The inner part of your ear contains tiny hair cells that change sounds into electrical signals, and the nerves then carry these signals to your brain^[2].

Some people are born with sensorineural hearing loss because of problems during fetal development, such as a lack of oxygen or other complications^[1]. This congenital hearing loss can be due to genetic factors, infections that the mother passes to the baby during pregnancy (such as toxoplasmosis, rubella, or herpes), or various genetic syndromes^[2].

Others develop hearing loss later in life. The most common cause is aging, often called presbycusis, which happens as the tiny hair cells in the inner ear deteriorate over time^[1]. This age-related hearing loss is one of the most common types of hearing loss in adults, typically developing between the ages of 50 and 70^[1].

Exposure to loud noises is another major cause of sensorineural hearing loss^[3]. This can happen from a single very loud noise, such as an explosion or gunshot, or from prolonged exposure to loud environments like noisy workplaces, concerts, or regular use of noisy machines^[6]. It has been estimated that 16% of disabling hearing loss in adults worldwide is related to occupational noise^[3].

Several diseases and conditions can increase your risk of developing sensorineural hearing loss. These include acoustic neuroma (a noncancerous tumor affecting the inner ear), Ménière’s disease (a chronic ear disorder causing vertigo and tinnitus), systemic conditions like diabetes and meningitis, and traumatic brain injury^[1].

Ototoxicity, which means inner ear damage from certain medications, can also cause hearing loss^[1]. Medications that can harm hearing include some antibiotics (aminoglycosides), loop diuretics, and certain chemotherapy drugs^[3].

Other causes include head injuries or trauma, infections such as mumps, measles, or scarlet fever, and autoimmune diseases^[2][3].

Types of Sensorineural Hearing Loss

There are several different types of sensorineural hearing loss based on which ear is affected and how quickly the hearing loss develops.

Unilateral sensorineural hearing loss affects only one ear, while bilateral sensorineural hearing loss affects both ears^[1]. Asymmetrical sensorineural hearing loss affects both ears, but the hearing loss is worse in one ear than the other^[1].

Sudden sensorineural hearing loss is a medical emergency that happens within 72 hours of an injury, illness, or exposure to loud noise^[1]. This rapid loss of hearing can occur instantly or develop over a few days^[13]. Sudden hearing loss typically affects one ear, although it can sometimes impact both ears^[13]. If you experience sudden hearing loss, you should see a doctor immediately, as prompt treatment can improve the chances of recovering some or all of your hearing^[13].

How Common Is This Condition?

Sensorineural hearing loss is extremely common, particularly as people age. It is the most common type of permanent hearing loss^[4].

Over 5% of the world’s population, or 430 million people, require rehabilitation to address their disabling hearing loss^[8]. By 2050, it is estimated that over 700 million people, or one in every 10 people, will have disabling hearing loss^[8].

In the United States, sudden sensorineural hearing loss affects between 1 and 6 out of 5,000 people every year, with approximately 66,000 new cases annually^[3]. The incidence of sudden hearing loss is estimated at about one in 5,000 people per year^[16].

Age-related hearing loss is particularly common, with prevalence doubling every decade of life from the second through the seventh decade, and becoming nearly universal after the eighth decade of life^[3].

Diagnosis and Testing

If you suspect you have hearing loss, it is important to see a healthcare professional for a proper diagnosis. An otolaryngologist (ear, nose, and throat specialist, also called an ENT) or an audiologist (a specialist in hearing disorders) can perform the necessary tests to diagnose sensorineural hearing loss^[2].

The diagnostic process typically begins with a review of your hearing and general health, including your family history^[19]. Your doctor will ask about when you first noticed hearing problems, whether the loss was sudden or gradual, and whether you have been exposed to loud noises or certain medications.

A physical examination of your ear will be performed using an instrument called an otoscope, which allows the doctor to look inside your ear canal for possible causes of hearing loss, such as earwax buildup, infection, or structural problems^[1].

Hearing tests are essential for diagnosing sensorineural hearing loss. The most common test is called pure tone audiometry, which is a hearing exam that plays different tones through headphones to identify hearing problems and determine the severity of hearing loss^[13]. During this test, you will listen for short tones of different volumes and pitches played into each ear separately^[19].

Tympanometry is another test that uses air pressure to determine the flexibility of the eardrum and the tiny bones in the middle ear^[19]. A speech test may also be performed, which involves listening to spoken words at different volumes and repeating them^[19].

In some cases, additional testing may be needed. This can include an MRI (magnetic resonance imaging) scan to look for tumors or other structural problems, blood tests to check for underlying conditions, or balance tests^[13].

Treatment Options

While sensorineural hearing loss cannot be cured in most cases, there are many effective treatments and devices that can help you hear better and improve your quality of life^[1].

Hearing aids are the most common treatment for sensorineural hearing loss. Modern hearing aids have advanced tremendously in recent years and function like mini-computers that can be programmed to your specific hearing needs^[19]. They work by amplifying sounds to help you hear better^[7]. Many modern hearing aids analyze the sound environment and adjust amplification automatically, offering features like feedback cancellation technology and connectivity with smartphones and other devices^[19].

For people with severe to profound hearing loss in both ears, cochlear implants may be an option^[5]. A cochlear implant is a device that is surgically placed in the inner ear. Unlike hearing aids that make sounds louder, cochlear implants bypass damaged hair cells and directly stimulate the auditory nerve^[1]. While they don’t restore normal hearing, they can help you understand speech and environmental sounds.

For sudden sensorineural hearing loss, immediate treatment is crucial. Your doctor may recommend corticosteroid medications, either in pill form or injected through the eardrum, to reduce inflammation and swelling in the inner ear^[17]. Treatment with steroids should begin as soon as possible after the onset of sudden hearing loss for the best chance of recovery^[13].

Other assistive devices and technologies can help improve communication. These include telephone amplifiers, vibrating alarms, closed captioning for television, and apps that convert speech to text in real time^[2][20].

Speech therapy and auditory rehabilitation programs can help you learn strategies to communicate more effectively with hearing loss^[2]. These programs teach you how to use visual cues, such as lip reading, and provide techniques for improving communication in challenging listening situations.

In some cases, treating an underlying condition may help. If your hearing loss is caused by an autoimmune disease, treating that condition may prevent further hearing loss^[10]. If a tumor such as an acoustic neuroma is causing hearing loss, surgical removal of the tumor may be necessary^[12].

Prevention

While not all cases of sensorineural hearing loss can be prevented, there are steps you can take to protect your hearing and reduce your risk.

Protecting your ears from loud noises is one of the most important preventive measures. Wear ear protection, such as earplugs or earmuffs, when you are exposed to loud environments, including noisy workplaces, concerts, or when using loud machinery^[23]. Keep the volume on electronic devices, especially when using headphones, at a safe level^[8].

If you work in a noisy environment, follow workplace safety guidelines and use appropriate hearing protection. Taking breaks from noise exposure can also help protect your hearing^[23].

Regular hearing tests can help identify hearing loss early, allowing for prompt intervention^[19]. Getting a baseline hearing test provides a reference point for measuring any future changes in your hearing.

Be aware of medications that can damage hearing. If you need to take medications known to be ototoxic, such as certain antibiotics or chemotherapy drugs, discuss the risks with your doctor and have your hearing monitored regularly^[3].

Managing underlying health conditions can also help prevent hearing loss. Conditions like diabetes and cardiovascular disease have been linked to hearing loss, so maintaining good overall health may help protect your hearing^[1].

For pregnant women, getting vaccinated against infections like rubella and avoiding exposure to infections during pregnancy can help prevent congenital hearing loss in babies^[8].

Living with Hearing Loss

Living with sensorineural hearing loss requires adaptation and the use of practical strategies to improve daily communication and quality of life.

Communication strategies can make a significant difference in your daily interactions. Face people directly when they are speaking to you, as this allows you to pick up visual cues and see their lip movements^[20]. Choose quieter, well-lit settings for conversations whenever possible^[20]. Reduce background noise by closing windows or moving to a quieter location, which makes it easier to focus on conversations^[20].

Don’t hesitate to tell others about your hearing loss and what they can do to help you understand them better^[20]. Ask people to repeat themselves when needed, and request that they face you when speaking. Many people are willing to help once they understand your needs.

Adapting your home environment can also help. Arrange furniture to create optimal viewing angles for conversations, install visual alert systems (such as flashing lights for doorbells or smoke alarms), and use amplified or captioned telephones^[20].

It’s important to address the emotional aspects of hearing loss. Many people experience feelings of frustration, isolation, or depression when dealing with hearing loss^[22]. Support groups, whether in-person or online, can provide comfort and practical advice from others who have faced similar challenges^[22]. Professional counseling can offer strategies for coping with the emotional and mental aspects of living with hearing loss^[20].

Using your hearing aids or other assistive devices consistently is crucial for getting the most benefit from them. Work closely with your audiologist to ensure your devices are properly fitted and programmed for your specific needs^[19].

Practicing mindfulness and relaxation techniques can help reduce the stress and mental fatigue that can come from straining to hear^[20]. These practices can improve your overall sense of well-being.

Remember that addressing hearing loss has been shown to improve quality of life^[19]. With the right support, treatment, and coping strategies, you can continue to lead a fulfilling and active life.