Nerve deafness; Hearing loss - sensorineural; Acquired hearing loss; SNHL; Noise-induced hearing loss; NIHL; Presbycusis
Sensorineural deafness is a type of hearing loss. It occurs from damage to the inner ear, the place of origin of the nerve that runs from the ear to the brain (auditory nerve), or the brain.
We often take for granted all of the sounds around us, the bark of a dog, the buzz of a bee, or the melody of our favorite symphony. Yet for many people, the world is a very quiet place. They've lost the ability to hear sounds in one or both ears. Let's talk about hearing loss. To understand how you lose hearing, you first need to know what normally happens inside your ear when you hear. Say that a fire engine roars past. First, the sound of the siren reaches your eardrum in your outer ear. Your eardrum vibrates, which moves three tiny bones in your middle ear. These bones push the sound along to the cochlea, a fluid-filled chamber in your inner ear. The cochlea is lined with tiny hairs that vibrate when the sound waves hit them. These hairs convert the sound waves into an electrical signal. That's when your brain realizes that a fire engine is headed toward you. Hearing loss can have many different causes. Loud noises, pressure changes while you're scuba diving, or a head injury can all damage the delicate structures in your ear that allow you to hear. Infections like measles, mumps, and meningitis can also damage the ear. Sometimes earwax can build up in your ear and block your hearing like a plug. As you get older, you may gradually lose your hearing, even if you don't have an illness or injury. When the damage or other problem is to your outer or middle ear, it's called conductive hearing loss. For example, your eardrum may not vibrate when you hear sound. Or, the tiny bones in your middle ear may not move sound to the inner ear. Sensorineural hearing loss is caused by a problem in the inner ear. Often it's because the tiny hair cells that move sound through the ear don't work right because of damage or disease, and stem cells in the ear can't keep up with the repair. If you have problems with both your inner and outer ear, then you have mixed hearing loss. So, how do you treat hearing loss? If you're noticing that voices sound fuzzy and you can't make out what people are saying, see your doctor for a hearing test. The doctor will examine your ears, and give you a test called audiometry to check the type and amount of hearing you've lost. You may also have imaging tests such as a CT or MRI scan if you've had a head injury. A hearing aid can amplify sounds to help you hear more clearly. Today's hearing aids are so small they're barely noticeable. If you have a buildup of earwax in your ear, an ear syringe filled with warm water can help flush it out. Sometimes surgery can be done to fix damage in your ear and improve your hearing. Don't accept hearing loss as an inevitable part of growing older. See your doctor for a hearing evaluation. Often, hearing loss that's due to a problem in your outer or middle ear can be reversed. Protect the hearing that you do have by avoiding loud noises, and wearing earplugs when you have to be exposed to loud sounds.
Symptoms may include:
- Some sounds seem overly loud in one ear.
- You have problems following conversations when two or more people are talking.
- You have problems hearing in noisy areas.
- It is easier to hear men's voices than women's voices.
- It is hard to tell high-pitched sounds (such as "s" or "th") from one another.
- Other people's voices sound mumbled or slurred.
- You have problems hearing when there is background noise.
Associated symptoms may include:
- Feeling of being off-balance or dizzy (more common with Meniere disease and acoustic neuromas)
- Ringing or buzzing sound in the ears (tinnitus)
The inner part of the ear contains tiny hair cells (nerve endings), that change sounds into electric signals. The nerves then carry these signals to the brain.
Sensorineural hearing loss (SNHL) is caused by damage to these special cells, or to the nerve fibers in the inner ear. Sometimes, the hearing loss is caused by damage to the nerve that carries the signals to the brain.
Sensorineural deafness that is present at birth (congenital) is most often due to:
- Genetic syndromes
- Infections that the mother passes to her baby in the womb (toxoplasmosis, rubella, herpes)
SNHL may develop in children or adults later in life (acquired) as a result of:
- Age-related hearing loss
- Disease of the blood vessels
- Immune disease
- Infections, such as meningitis, mumps, scarlet fever, and measles
- Injury of the ear or head
- Loud noises or sounds, or loud sounds that last for a long time
- Meniere disease
- Tumor, such as acoustic neuroma
- Use of certain medicines
- Working around loud noises every day
In some cases, the cause is unknown.
What to Expect at Your Office Visit
The goal of treatment is to improve your hearing. The following may be helpful:
- Hearing aids
- Telephone amplifiers and other assistive devices
- Safety and alert systems for your home
- Sign language (for those with severe hearing loss)
- Speech reading (such as lip reading and using visual cues to aid communication)
A cochlear implant may be recommended for certain people with severe hearing loss. Surgery is done to place the implant. The implant makes sounds seem louder, but does not restore normal hearing.
You will also learn strategies for living with hearing loss and advice to share with those around you for talking to someone with hearing loss.
Arts HA, Adams ME. Sensorineural hearing loss in adults. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 152.
Eggermont JJ. Types of hearing loss. In: Eggermont JJ, ed. Hearing Loss. Cambridge, MA: Elsevier Academic Press; 2017:chap 5.
Le Prell CG. Noise-induced hearing loss. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 154.
National Institute on Deafness and Other Communication Disorders website. Noise-induced hearing loss. NIH Pub. No. 14-4233.
Shearer AE, Shibata SB, Smith RJH. Genetic sensorineural hearing loss. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 150.
Last reviewed on: 5/30/2022
Reviewed by: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.