Hearing loss impacts millions of people around the world every year. While this debilitating condition is common, it is not created equal.
Regardless of the cause, hearing loss fits into two categories: Sensorineural and conductive hearing loss. Each form of hearing loss can vary in severity and degree.
In this article, we examine some key differences between conductive and sensorineural hearing loss and explore some of the most effective treatments for each.
How Common Is Hearing Loss?
Hearing loss is thought to be a condition that only affects older adults.
While it is true that age remains the strongest predictor of hearing loss, this condition doesn’t only affect the elderly. Hearing loss can affect anyone at any age.
According to hearing health statistics issued by the Hearing Loss Association of America, roughly 48 million people in the United States are living with some degree of hearing loss.
Hearing loss is also one of the foremost debilitating conditions worldwide, affecting five percent of the world’s population, or around 430 million people.
Hearing impairments, regardless of cause, fit into two distinct categories: Conductive and sensorineural hearing loss. Mixed hearing loss is a combination of the two. Let’s take some time to explore each in more detail.
What Is Conductive Hearing Loss?
Conductive hearing loss occurs when sound cannot pass through the outer ear, ear canal, and middle ear.
Sound is hindered in some way from reaching the inner ear. This hearing loss can be unilateral, occurring in only one ear, or bilateral.
The outer ear (pinna) helps gather sound waves, directing them through the ear canal to the middle ear. The middle ear houses the eardrum and three small bones known as the ossicles (malleus, incus, and stapes).
What Causes Conductive Hearing Loss?
In many cases, the culprit behind conductive hearing loss is trauma or obstruction by a foreign body.
Here are some of the most common causes of conductive hearing loss.
Obstruction by a foreign body
It’s not uncommon for small foreign objects to get lodged in the ear canal.
This obstruction can cause conductive hearing loss as sound waves cannot reach the inner ear. Hearing loss due to ear canal obstruction is most prevalent in small children.
Trauma to the ossicles in the middle ear
Since the ossicles are required to send sound vibrations to the inner, any trauma that fractures these tiny bones can disrupt the auditory process.
Unfortunately, serious trauma to these bones can render permanent hearing loss.
Earwax impaction
Earwax buildup (cerumen) is a very common cause of conductive hearing loss.
Over time, earwax can build up and clog the ear canal up to the eardrum, not allowing sound to pass through to the middle ear.
Infections in the ear
Otitis media (middle ear infection) and otitis externa (infection in the ear canal) can cause conductive hearing loss.
As infections worsen, inflammation and fluid buildup can hinder sounds from reaching the inner ear.
Some other causes of conductive hearing loss include:
- Tumors in the middle ear
- Eustachian tube dysfunction/blockage
- Stenosis (narrowing of the ear canal)
- Microtia and atresia (abnormalities to outer ear and ear canals)
- Otosclerosis (bones in the middle ear become stuck in place)
- Cholesteatoma (abnormal collection of skin cells inside the ear)
- Ruptured eardrum (tympanic membrane perforation)
- Mastoiditis (infection of the mastoid bone behind the ears)
What Is Sensorineural Hearing Loss?
While conductive hearing loss involves issues to the outer and middle ear, sensorineural hearing loss involves issues to the inner ear and auditory nerve.
These auditory components are essential in delivering sound and electrical impulses to the brain.
The inner ear, composed of a network of interconnected semicircular canals, houses important auditory components like the cochlea and inner and outer hair cells.
These hair cells act as sensory receptors for auditory (hearing) and vestibular (balance) systems.
What Causes Sensorineural Hearing Loss?
Age and long-term exposure to loud noise are the two most common causes of sensorineural hearing loss.
Age-related hearing loss (presbycusis)
Age remains the most common cause of sensorineural hearing loss. According to the National Institute on Deafness and Other Communication Disorders (NIDCD), age-related hearing loss affects roughly one in three people in the United States between the ages of 65 and 74.
Noise-induced hearing loss
Degenerative hearing loss occurs gradually over time, but sensorineural hearing loss can also result from exposure to loud sounds. Noise-induced hearing loss can happen suddenly (sudden sensorineural hearing loss) or through long-term exposure to loud noise.
The NIDCD states that around 40 million people live with noise-induced hearing loss in the United States.
Often, this type of hearing loss is permanent.
Some other causes of sensorineural hearing loss:
- Ototoxic medications
- Ménière’s disease
- Autoimmune inner ear disease
- Cochlear otosclerosis
Conductive vs. Sensorineural Hearing Loss: Symptoms
Many of the symptoms of both conductive and sensorineural hearing loss overlap.
Each present with symptoms that are common to hearing loss in general. For example, both types of hearing loss share symptoms like:
- Difficulties hearing speech in noisy environments with a lot of background noise.
- Difficulties hearing speech over the phone.
- Difficulties determining the direction where sounds are coming from.
- Having to increase volume on the TV and other devices constantly.
- Tinnitus (ringing in the ear).
Additional Symptoms of Conductive Hearing Loss
Per the American Academy of Otolaryngology-Head and Neck Surgery, additional conductive hearing loss symptoms can include:
- Ear discomfort, pain, or tenderness
- Fluid drainage from the ears
- Dizziness or vertigo
- Aural fullness (feeling of stuffiness or fullness in the ears)
Conductive vs. Sensorineural Hearing Loss: Diagnosing
Diagnosing conductive and sensorineural hearing loss should be done by trained healthcare providers who work in the audiology field, such as an ENT or an audiologist.
These hearing care specialists can perform a hearing test to screen for hearing loss and interpret data from audiograms.
These, along with high-frequency tests, can help determine your level of hearing loss and help guide treatment.
Additional Diagnostic Testing for Conductive Hearing Loss
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A physical examination will be required to check for blockages, infections, or abnormalities.
- Fork tests, like the Rinne test and Weber test, use tuning forks to help determine if sounds are being transmitted through bone conduction or air conduction. This helps determine the presence and degree of conductive hearing loss.
- A tympanometry test evaluates middle ear function, checking the condition and movement of the tympanic membrane as it responds to pressure changes.
Do Treatment Options Differ for Conductive and Sensorineural Hearing Loss?
Treatment options for hearing loss depend on the cause of the hearing loss. Generally, sensorineural hearing loss is treated through hearing aids or cochlear implants.
While conductive hearing loss may use these treatments, there may be additional treatments. For example, simple removal of earwax could improve hearing.
Also, antibiotics or steroid injections for ear infections may be required. In some cases, more intensive interventions may be needed, like surgery to repair an eardrum.
Conclusion
Hearing loss can be a debilitating condition classified in two ways: sensorineural and conductive hearing loss.
While these two certainly overlap in prognosis, they differ greatly in the cause, diagnostic procedures, and treatment.
If you’re experiencing hearing loss but are unsure of the cause, it’s best to consult an audiology professional who can help diagnose the hearing impairment and select the right treatment plan. Check out the USA Rx blog for more information about hearing loss, treatment options, and more.
References, Studies and Sources:
Quick Statistics About Hearing | NIDCD
Hearing Loss Facts and Statistics | HearingLoss.org
Deafness and hearing loss | WHO