What Is Sensorineural Hearing Loss?
When you lose your hearing very quickly, it is called sudden sensorineural hearing loss (SSHL). It can happen instantly or over a span of several days, during which sound is gradually muffled or reduced. This type of hearing loss typically affects one ear.
Decibels measure the intensity of the sounds we hear. Frequencies measure sound waves. Losing 30 decibels in three connected frequencies is considered SSHL. There are about 4,000 cases of SSHL every year in the United States, most commonly among people aged 30 to 60.
Early treatment for SSHL can save your hearing. Most people recover, but about 15 percent have hearing loss that continues to worsen. Advances in hearing aid technology and cochlear implants are helping to improve communication for people affected by hearing loss.
SSHL is a medical emergency and requires immediate attention.
Causes of SSHL
SSHL happens when the inner ear or the nerve pathways between the ear and the brain become damaged.
Only about 10 to 15 percent of people with SSHL ever know what actually caused their hearing loss. That may be because there are more than 100 possible causes, including:
- malformation of the inner ear
- head injury or trauma
- loud-noise exposure
- neurologic conditions
- immune system diseases
- Ménière’s disease
- Lyme disease
- infectious diseases
- medications that can harm the ear
- snake bite or other toxic event
- circulatory problems
- abnormal tissue growth or tumors
- disease of the blood vessels
Infants can be born with SSHL for a variety of reasons including:
- infections that pass from the mother (such as rubella, syphilis, and herpes)
- Toxoplasma gondii (a parasite that passes through the womb)
- genetic factors
- low birth weight
Tests for Hearing Loss
Your doctor will take a medical history and conduct a physical exam. You will be asked about other medical conditions and about what over-the-counter and prescription medications you take.
You may be asked to cover one ear at a time while listening to sounds at different volumes. Tests using a tuning fork can check if there is damage to the parts of the middle ear and eardrum that vibrate.
Your hearing can be more thoroughly checked with audiometer tests. An audiologist can conduct thorough testing of your hearing ability using earphones. Different sounds and levels can be sent to each ear individually. A series of sounds at different volumes can help find the level where your hearing fades.
Additional testing for a cause of sudden sensorineural hearing loss should include an MRI (magnetic resonance imaging) scan looking for an acoustic neuroma (tumor of the nerve).
When to Test Your Child’s Hearing
Hearing loss could develop as a result of infections at birth, use of a ventilator, or certain medications known as ototoxic medications. It may not always be easy to know if your child is hearing correctly. You should have your child’s hearing tested if he or she:
- doesn’t seem to understand language
- doesn’t attempt to form words
- has had many ear infections or problems with middle-ear fluid
- doesn’t seem to startle at sudden noises or respond to sounds as you would expect
Symptoms of SSHL
Hearing loss may be noticed upon awakening in the morning. Some people become aware of it when they use earphones or hold a phone to the deaf ear. Hearing loss is sometimes preceded by a loud popping sound.
Other signs include:
- trouble following group conversations
- muffled conversation sounds
- experiencing sounds that feel too loud
- inability to hear well when there’s a lot of background noise
- more trouble hearing women’s voices than men’s
- difficulty hearing high-pitched sounds
- experiencing dizziness or balance problems
- tinnitus (hearing ringing or buzzing sounds)
Hearing loss affects only one ear for nine out of 10 people with SSHL.
Treatment for SSHL
Early treatment may help your chances for a full recovery. However, the doctor will try to identify the cause of your hearing loss before treatment can begin.
The most common treatment involves the use of steroids. Steroids can reduce inflammation and swelling. This may be especially helpful in patients who have diseases of the immune system.
Hearing aids and telephone amplifiers can help if your hearing does not improve. Sign language and lip reading can improve communication for people with severe hearing loss.
A cochlear implant can be surgically put in place. This implant doesn’t restore hearing to normal, but it can amplify sounds to a more normal level.
Outlook for SSHL
For some people, SSHL improves on its own without any medical intervention. Usually this happens in the first few days after hearing loss. This is called a spontaneous recovery. Others recover their hearing more slowly, usually within a week or two.
Fifteen percent of people who experience SSHL do not recover, but continue to lose their hearing in time.