ConditionEar, nose & throat
Sensorineural Hearing Loss (SNHL)
Sensorineural hearing loss (SNHL) is hearing loss caused by damage to the inner ear (cochlea) or the hearing nerve, rather than a blockage in the ear canal or middle ear. It is the most common type of permanent hearing loss. The main causes are aging (presbycusis) and noise exposure, followed by genetics, infections, medicines and Ménière's disease. It usually cannot be reversed, but hearing aids and cochlear implants work well. Sudden hearing loss in one ear is an emergency that needs treatment within days.
Also called: SNHL, nerve deafness, perceptive hearing loss, inner ear hearing loss
At a glance
- What it is
- Hearing loss from damage to the inner ear hair cells or hearing nerve.
- Common causes
- Aging, noise exposure, genetics, infections, ototoxic medicines, Ménière's disease, acoustic neuroma.
- Symptoms
- Muffled speech, trouble in noisy places, tinnitus, high-pitched sounds lost first.
- Diagnosis
- Audiogram showing nerve-type loss. MRI if one-sided or asymmetric.
- Treatment
- Hearing aids, cochlear implants, steroids for sudden loss, hearing protection to prevent progression.
When to get help
Call 911 or go to the ER
- Sudden hearing loss with facial weakness, double vision, slurred speech, severe dizziness or inability to walk (possible stroke)
See a doctor within a day or two
- Sudden hearing loss or muffling in one ear over hours to 3 days, even without pain: see a doctor within days, ideally within 72 hours, for a hearing test and steroid treatment
- Hearing loss after a head injury, an explosion or barotrauma from diving
Book a routine appointment
- Gradual hearing loss, difficulty following conversations or needing the TV louder
- Hearing loss or tinnitus in one ear only
- A child who does not respond to sounds, or has speech delay
- Taking a medicine known to affect hearing, such as cisplatin or aminoglycosides
Usually safe to manage at home
- Using hearing protection in noisy environments and keeping personal audio volume moderate
How sensorineural hearing loss happens
Sound waves travel through the ear canal and middle ear to the cochlea, where thousands of tiny hair cells convert vibrations into nerve signals. These hair cells do not regenerate in humans. When they or the hearing nerve are damaged, sounds become quieter and less clear, especially speech in background noise.
Sensorineural vs conductive hearing loss
| Feature | Sensorineural | Conductive |
|---|---|---|
| Location | Inner ear or hearing nerve | Ear canal, eardrum or middle ear |
| Common causes | Aging, noise, genetics, infections, medicines | Earwax, ear infection, fluid, perforated eardrum, otosclerosis |
| Sound quality | Quieter and distorted | Quieter but clear |
| Reversible? | Usually permanent (except some sudden losses) | Often treatable |
| Treatment | Hearing aids, implants | Remove the cause, surgery, aids |
When both types occur together, it is mixed hearing loss.
Causes
Acquired
- presbycusis: age-related hearing loss, affecting about a third of people aged 65 to 74 and about half of those over 75
- noise: loud work environments, firearms, concerts and personal audio. Explosions cause acoustic trauma
- ototoxic medicines: cisplatin, aminoglycoside antibiotics, high-dose loop diuretics
- infections: meningitis, mumps, measles, cytomegalovirus
- Ménière's disease
- acoustic neuroma
- autoimmune inner ear disease
- head injury
- sudden sensorineural hearing loss: often unexplained, possibly viral or vascular
Congenital
- genetic causes account for about half of hearing loss in babies, including connexin 26 (GJB2) mutations
- congenital cytomegalovirus infection
- prematurity, severe jaundice and low oxygen at birth
Symptoms
- muffled speech and sounds
- difficulty understanding speech in noise or on the phone
- asking people to repeat themselves
- turning up the TV or radio
- trouble hearing high-pitched voices and consonants (s, f, th)
- tinnitus (ringing, buzzing or hissing)
- dizziness or imbalance with some causes
- withdrawal from conversations and social situations
Sudden sensorineural hearing loss
A loss of at least 30 decibels over 3 consecutive frequencies within 72 hours, usually in one ear. Many people wake up with it or mistake it for a blocked ear. AAO-HNS guidelines recommend:
- an audiogram promptly
- oral or injected corticosteroids, ideally within 2 weeks, best within the first days
- MRI to rule out acoustic neuroma
About a third to two-thirds of people recover some hearing, more often with early treatment. See sudden sensorineural hearing loss.
Diagnosis
- otoscopy to check the ear canal and eardrum
- tuning fork tests (Weber and Rinne)
- pure-tone audiometry and speech testing
- tympanometry to check middle ear function
- MRI of the internal auditory canals for one-sided or asymmetric loss or tinnitus
- newborn hearing screening and genetic testing in children
Treatment
Hearing aids
The main treatment for most SNHL. Modern digital aids are small and programmable. Over-the-counter hearing aids are available in the US for adults with perceived mild to moderate loss.
Cochlear implants
For severe to profound loss when hearing aids do not help enough. An electrode in the cochlea stimulates the hearing nerve directly. Children born deaf benefit most when implanted early.
Other options
- bone-anchored hearing devices and CROS aids for single-sided deafness
- assistive listening devices, captioning and hearing loops
- auditory rehabilitation and communication strategies
- treating the cause where possible
Prevention
- wear earplugs or earmuffs in noise above 85 dB
- keep personal audio below 60% volume and take listening breaks
- monitor hearing during ototoxic treatment
- vaccinate against measles, mumps and meningitis
- get regular hearing checks after 50, or sooner with symptoms
Untreated hearing loss is linked with social isolation, depression and a higher risk of dementia, and treating it may help reduce these risks.
Frequently asked questions
What is sensorineural hearing loss?
It is hearing loss caused by damage to the inner ear's hair cells or the hearing nerve. It is the most common type of permanent hearing loss and is usually caused by aging or noise exposure.
Can sensorineural hearing loss be cured?
Usually not, because damaged hair cells do not regrow. However, sudden sensorineural hearing loss can partly or fully recover, especially with early steroid treatment. Hearing aids and cochlear implants restore much function.
What causes sudden sensorineural hearing loss?
Often no cause is found. Suspected causes include viral infections, reduced blood flow to the inner ear and immune reactions. Rarely, an acoustic neuroma or stroke is responsible. It needs prompt assessment and treatment.
How is sensorineural hearing loss different from conductive hearing loss?
Sensorineural loss comes from inner ear or nerve damage and is usually permanent. Conductive loss comes from problems in the ear canal or middle ear, such as wax or fluid, and is often treatable.
Do hearing aids help sensorineural hearing loss?
Yes. Hearing aids are the main treatment and help most people hear and understand speech better. For severe to profound loss, cochlear implants are often more effective.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS): Clinical practice guideline: Sudden hearing loss (update)
- National Institute on Deafness and Other Communication Disorders (NIDCD): Hearing loss and older adults; Noise-induced hearing loss
- American Speech-Language-Hearing Association (ASHA): Sensorineural hearing loss
- World Health Organization: World report on hearing
- CDC: Hearing loss in children