What are conductive and sensorineural hearing loss?

Conductive hearing loss occurs when there is a problem with the outer or middle ear. One of two things is possible: sound may be unable to successfully travel through the ear canal, or, it struggles to transfer to the inner ear by the vibrations of tiny bones. Typically, conductive hearing loss happens because something is blocking the way. This could be an excess of earwax, fluid caused by an infection or abnormal bone growth.

Sensorineural hearing loss concerns the innermost part of the ear, particularly the sensitive hair cells and nerves that can be found there. Both play a crucial role in transforming sound waves into electrical impulses that can be understood and analysed by the brain, as well as beginning to filter out any unwanted background noises. If either the hair cells or nerves become damaged, this process doesn’t work as well and your hearing deteriorates.

Causes of Mixed Hearing Loss

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The causes of mixed hearing loss are essentially a combination of the causes conductive and sensorineural hearing loss. They range from inherited genetics and the natural effects of ageing to the unpredictableness of trauma or infection.

Infection

Illness and infection can affect the outer, middle and inner ear, leading to mixed hearing loss. ‘Swimmer’s-Ear’, or otitis externia as it is formally known, causes inflammation in the outer ear. As the ear canal narrows, sound becomes increasingly muffled. With middle ear infections the most common issue is fluid buildup. Too much fluid in the area behind the eardrum stops the ossicles (three tiny bones) from vibrating correctly. This means that the sound isn’t properly transferred to the inner ear. Within the inner ear, viral and bacterial infections can damage the fragile hair cells and nerves which are needed to convert sound waves into electrical impulses for the brain to understand.

Genetics

Your chances of experiencing sensorineural hearing loss do increase if there is a family history. Conductive hearing loss can also be inherited, particularly abnormal bone growth (otosclerosis). You will generally only realise you have otosclerosis when you reach your late teens or twenties when the bone growth begins to exceed what is considered normal. If any of the three ossicles expand to a disproportionate size, the lack of room within the middle ear then prevents them from vibrating correctly. Furthermore, excessive bone growth can begin to affect the sensitive nerves within the ear, causing sensorineural hearing loss.

 

Noise Exposure

Exposing yourself to consistently loud noise or a deafening one-off sound, without using ear protection, will always carry a risk of mixed hearing loss. Loud noise can damage the vital hair cells of the inner ear (sensorineural hearing loss) and rupture the eardrum (conductive hearing loss).

 

Mixed Hearing Loss Treatment

A mix of both conductive and sensorineural hearing loss requires a combination of treatments. What works for one type of hearing loss is unlikely to do so for the other. Conductive hearing loss is caused by problems in the outer ear canal whereas sensorineural hearing is concerned with the nerves and hair cells of the inner ear. As a result, mixed hearing loss treatment requires a slightly different approach.

At My Hearing, we will work closely with you to find the correct treatment to target the distinct elements of your hearing loss.

Mixed Hearing Loss Treatments: Hearing Aid or Cochlear Implant

Hearing aids are typically used to treat sensorineural hearing loss as they support the work of the delicate inner hair cells. Once damaged, these hair cells cannot repaired. This means that there aren’t enough vibrations to transform quieter, softer sounds into electrical signals that the brain can understand. A hearing aid helps by amplifying the sound, increasing the vibrations.

For a hearing aid to work as a form of mixed hearing loss treatment, you will first need to deal with the conductive hearing loss. This will likely mean a course of medication or minor surgical procedure to remove whatever is preventing sound waves from reaching the inner ear. Such blockages include earwax, a narrow ear canal and abnormal bone growth.

If your hearing loss is particularly severe, a cochlear implant may be more suitable. Instead of amplifying sound to assist the remaining hair cells, a cochlear implant simply does the entire job. A sound processor fitted to the outside of the head captures sounds, converts them into digital code and then transfers it down a wire into the inner ear. There, the surgically implanted device converts the code into electrical signals which the brain can easily understand.

Mixed Hearing Loss Treatment: Medication

Ear infections can easily spread across both the outer and inner ear. In the outer ear, the main symptom tends to be swelling and inflammation. The skin feels tender to the touch and the narrowing ear canal causes to hearing loss. Here, corticosteroids will generally be prescribed to reduce the swelling and so open up the ear canal. Normally they would be administered orally but injection can be used if necessary.

Past the eardrum and in the inner ear, the main concern is fluid build-up. Excess fluid prevents the hair cells from vibrating correctly and exerts uncomfortable pressure on the eardrum, occasionally resulting in a perforated eardrum. Painkillers and antibiotics are mostly likely to be prescribed in this instance.

When the infection is affecting both the inner and outer war, your doctor may give you a mixture of both steroids and antibiotics.

We’re Here For You

If you are searching for guidance and further information on mixed hearing loss treatment, get in touch today. We partner with highly experienced hearing aid dispensers who can provide you with expert advice on your diagnosis, ensuring that you receive the most suitable treatment.

 

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