Sensorineural hearing loss

Aging: Presbycusis is the term for age-related hearing loss. Sensorineural hearing loss accounts for the majority of presbycusis cases. Hearing loss typically progresses slowly but persistently starting at age 60 and affects both ears. You’re at greater risk if you’ve been exposed to noise, are diabetic, or if you used tobacco over a period of time. When presbycusis is sensorineural, hearing loss typically affects high frequency sounds and speech, with background noise making the situation worse. If left untreated, hearing loss in older adults can lead to progressive social withdrawal, depression, isolation, considerable family stress, an increased risk of injury from a fall, cognitive decline, dementia and it can even negatively impact patient-doctor communication.

The World Health Organization (WHO) estimates by 2025, 1.2 billion people age 60 and older worldwide will have presbycusis, with more than 500 million individuals experiencing significant hearing impairment.

Sudden sensorineural hearing loss: This refers to severe unexplained hearing loss that occurs in less than a 72-hour period that nearly always impacts just one ear. The cause is unknown, as is the exact incidence, although it does appear to affect people ages 43 to 53 most commonly. If you or a loved one experiences sudden hearing loss, it’s considered a medical emergency and you should seek immediate medical treatment. If you wait more than three days to see a doctor, your window for treatment has been lost.

Exposure to loud noise: Noise-induced hearing loss (NIHL) is typically gradual, impacts both ears, and is accompanied by ringing in your ears (tinnitus). It’s also the most preventable cause of sensorineural hearing loss. Noise may be occupational, recreational, or accidental. Gunfire, explosions, fireworks, machinery, and loud musical instruments can cause irreversible hearing loss accompanied by high-pitched tinnitus. Although NIHL is closely associated with exposure to occupational noise, personal portable musical devices, loud toys, hair dryers, kitchen blenders, and sporting or musical events can also damage your hearing.

A 2017 report found that nearly one in four U.S. adults ages 20 to 69 showed signs of NIHL when one or both ears were tested. The same report suggested that 10–40 million adults in the U.S. younger than 70 may have NIHL-related hearing loss based on their hearing test results.

Autoimmune inner ear disease (AIED): Although it makes up just 1% of all hearing loss cases, AIED is one of the few subtypes of sensorineural hearing loss that can possibly be reversed with medication. Corticosteroid therapy, most notably oral prednisone is considered the gold standard. More than 20 autoimmune diseases have been linked to sensorineural hearing loss, including multiple sclerosis, Crohn’s disease, ulcerative colitis, and rheumatoid arthritis. What distinguishes AIED from age-related hearing loss or sudden hearing loss is that it progresses over a few weeks or months.

Most often, AIED affects people between the ages of 20 and 60. Although 50% of individuals report hearing loss in just one ear, hearing tests show that both ears are impacted 80–100% of the time. Imbalance, motion intolerance, and some degree of vertigo affect 50–80% of patients. It can be difficult for doctors to distinguish between AIED and Meniere’s disease early on since some types of Meniere’s disease that impact both ears are related to underlying autoimmune disease.

Meniere’s disease: Hearing loss associated with this disease is sudden, fluctuating, impacts one ear, and is often accompanied by tinnitus, a feeling of ear congestion or fullness, and episodes of vertigo. When your inner ear fills with excessive fluid, this can damage the delicate hair cells of the inner ear, resulting in permanent hearing loss.

Head trauma: Individuals with head trauma can suffer hearing loss as well as loud and debilitating tinnitus. If your ear incurs direct damage, this can result in hearing disturbances and dizziness. While vertigo is common even with mild head trauma, hearing loss is typically associated with major head injury. Slaps and blunt objects hitting the ear are especially common. Temporal bone fractures impacting the bony labyrinth (cochlea or vestibule) can cause sensorineural hearing loss. Most of the time when an individual suffers post-traumatic dizziness or hearing loss, signs of head injury are present, such as a skull fracture, bruises, swelling, and abrasions.

Acoustic neuroma: Also called vestibular schwannoma, this noncancerous tumor causes gradual, one-sided hearing loss in 90% of individuals that most commonly impacts high frequencies. Although hearing loss is progressive in most individuals, in about 12% of cases, it occurs suddenly. Other symptoms include vertigo, tinnitus and facial nerve weakness.

Medications: Hearing disturbances have been linked to more than 200 different medications. Ototoxic medications cause damage to the sensory cells in your inner ear. The most common ones include aspirin in very high doses, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen, antibiotics, certain chemotherapy drugs, and loop diuretics. Tinnitus is often the first symptom, followed by hearing loss and dizziness. While some cases clear up after you stop taking the medication, it’s possible to suffer permanent hearing loss.

Inherited: As with many other conditions and diseases, genes and family heritage can play a role in your hearing loss. Hearing genes can mutate or become more susceptible to ear damage and deterioration as you age.  Genetic sensorineural hearing loss appears to be twice as common in developed countries as underdeveloped countries. While this type of hearing loss is most frequently diagnosed in children, genetic predisposition can increase the risk of hearing loss associated with ototoxic medications and noise in older adults.

If you suffer permanent damage to the sensory cells of your inner ear, sounds are diminished and speech can sound distorted. If you’re an older adult, the chance is greater that you’ll lose the ability to detect high-frequency sounds, which will make it difficult for you to tell the difference between certain consonant sounds. Speech will likely sound garbled or muddy and, in some cases, will be completely incomprehensible.

Damage to the delicate hair cells in your inner ear and the nerves connected to them can also make it challenging to distinguish between different sound frequencies. Hearing and speech researcher Arthur Boothroyd provided this analogy in an NPR interview: “The frequencies in sound are like the colors in the spectrum. Imagine that the red bleeds over into the yellow and the yellow bleeds over into the green, and so on. That's the sort of thing that we believe happens in the cochlea.”

Noise trauma is the most common preventable cause of sensorineural hearing loss. According to the American Speech-Language-Hearing Association (ASHA), protecting your ears from loud noise is one of the best ways to preserve your hearing regardless of your age. ASHA offers the following tips:

• Avoid situations where you need to shout to be heard
• Limit exposure to noisy machinery
• Wear protective earmuffs if your job warrants it
• Avoid sitting near the speakers at loud events
• Keep the volume down when listening to recorded music, videos, and games, especially when using earbuds or earphones

A good rule of thumb when it comes to headphones and volume is to never raise the volume on your device above 50% of its capability. 

Your doctor will conduct a thorough ear examination, note your medical history, ask about your specific symptoms, and inquire about hearing problems affecting other members of your family. These are the questions you can expect to be asked during your appointment:

• When did your hearing loss begin?
• Was it sudden or has your hearing gradually been getting worse?
• Does your hearing loss involve one or both ears?
• Are you experiencing ringing in your ear, a feeling of fullness, dizziness, ear drainage, or ear pain?
• Is there a history of hearing loss in your family?
• Have you been exposed to loud noise in the workplace?
• Do you have a history of ear infections, ear injury, or straining to hear?
• Do you have a history of stroke, diabetes, or heart disease?
• What medications are you currently taking?
• Were you prescribed intravenous antibiotics, diuretics, salicylates, or chemotherapy?

During the exam, a device called an otoscope will be used to examine your external ear canal for a build-up of ear wax, foreign bodies, or skin abnormalities. Your doctor will refer you to an audiologist, who will perform an audiogram to determine the type, degree, and configuration of your hearing loss. This test reveals how loud sounds need to be at different frequencies for you to hear them. In some cases, the doctor may order a CT (computed tomography) scan or MRI (magnetic resonance imaging) of the head and an ABR test (automated brainstem response) for hearing.

Treatment depends on the underlying cause and degree of hearing loss. Options include:

• Continued observation with repeated hearing tests
• Corticosteroids (oral or injection through the eardrum) to reduce inner ear hair cell swelling and inflammation
• Evaluation and fitting of a hearing aid(s) or other assistive listening devices
• Surgery to correct the underlying cause of the hearing loss
• Surgery to implant a cochlear hearing device, an electronic device implanted behind the ear that stimulates auditory fibers in your acoustic nerve