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What was that? Causes of hearing loss

What was that? Causes of hearing loss

While the statistics show that hearing loss can be common in adults, many people who have lost their hearing may feel embarrassed to admit they can’t hear certain sounds.

Withdrawing from conversations when friends and family speak or feeling less confident to perform activities alone can be socially isolating and even scary for some people, especially if they don’t understand how or why.

Sounds travels through waves in the air that create vibrations in your outer and middle ear canal. These vibrations travel through your ear to reach the nerve for hearing in your inner ear (called the Cochlear nerve), which sends signals to your brain to recognise different sounds. When problems occur in your inner, middle and outer ear, your brain is unable to receive auditory nerve signals and your ability to hear sounds.

Based on the type and cause of hearing loss, advances in medical technology offer a variety of rehabilitative aids and implantable hearing devices that doctors can use for early enhancement of hearing. Although hearing cannot be completely restored, medical therapy including surgery can improve quality of life if you or a loved one has a hearing problem.

Types of hearing loss

Different types of hearing loss occur either from conditions you may be born with or that occur later in life. Types of hearing loss are categorised by the part of the hearing system that is affected.

  • Conductive hearing loss may be restored and occurs from conditions or disease in the outer or middle ear causing blockages in the ear canal, preventing sound waves travelling to the inner ear. Conductive hearing loss causes a reduction in the intensity (loudness) of sound to reach the inner ear structures.
  • Sudden deafness (also known as sensorineural hearing loss) is a permanent form of hearing loss and occurs when the nerves in the inner ear and sensory cells are damaged and can no longer transmit sound signals to your brain. Sensorineural hearing loss also reduces the intensity of sound and distorts sounds, making it difficult to hear clearly.
  • Mixed hearing loss is due to both conductive hearing loss and sensorineural hearing loss from damage in the outer or middle ear and in the inner ear.

Causes of hearing loss

Long-term exposure to loud or prolonged sound is a common cause for sensorineural hearing loss. [1] Damage to your eardrum can also cause sudden hearing loss and occurs from loud blasts of sound, sudden changes in pressure or poking your eardrum with an object.

Sensorineural hearing loss can also occur at birth from inherited or abnormal development during the pregnancy. Maternal rubella (German measles) is a common cause of sensorineural hearing loss at birth. However, many people lose their hearing as they age. Sensorineural hearing loss is the most common sense to lose between the ages of 60 and 70 years old, affecting over a third of adults in this age group. [2]

The most common cause of conductive hearing loss is from blockages in the ear canal, such as ear infections that build up fluid, earwax, tumours and abnormal bone growth (surfers ears).

A variety of medical conditions can also cause mixed hearing loss, including high blood pressure or stroke, diabetes, head injuries and viral or bacterial infections. [3] Some medications that are toxic to the sensory cells in your ears, for example some chemotherapy medication, can cause hearing loss.

Treatment for hearing loss

Hearing tests are usually performed first to reveal the extent of hearing loss and the most suitable assisted hearing system.

Dr Indu Gunawardena assesses the pattern of hearing loss and the cause of the hearing loss. She then will organise for the patient to have scans to further define the pathology. Depending on the diagnosis various surgical options are considered to treat and correct the hearing loss. Some patterns of hearing losses cannot be corrected with an operation. Then the patient is considered for hearing aids or implantable devices.

Depending on the severity of hearing loss, hearing aids may be used to amplify sounds. They are matched based on hearing and may be placed behind the ear, in the ear, in-the-canal and completely in the canal.

If hearing aids aren’t improving your hearing, depending on the type and cause of hearing loss there are a variety of surgical implanted hearing devices that can be placed even farther inside your ear to send vibrations to the inner ear.

Cochlear implants are electronic medical devices for more severe hearing loss and speech recognition. Cochlear implants are surgically placed in your inner ear, bypassing damaged portions of the ear to simulate the nerves, creating electrical impulses for the brain to hear sounds.

Middle ear implants directly vibrate the small bones in the middle ear for your inner ear to sense a sound. The sounds are sent to the implant and transmitted as electronic signals that are sent as vibrations to the auditory nerve, which are recognised as sounds by your brain.

Medical doctors who specialise in disorders of the ears, nose and throat (ENT) can discuss the risks and benefits of assisted hearing devices with you, along with your expectations and risks. To learn more, you can contact us to make an appointment with Dr Indu Gunawardena and discuss hearing treatment options.

References

 [1] Dalton DS. Cruickshanks KJ. Wiley TL. et al. Associate of leisure-time noise exposure and hearing loss Audiology 2001;40:1-9

 [2] Phan NT. McKenzie J. Juang. L. et al. Diagnosis and management of hearing loss in elderly patients Australian Family Physician 2016;45(6):366-9

 [3] Age-related hearing loss. National Institute of Deafness and Other Communication Disorders (NIH) available at https://www.nidcd.nih.gov/health/age-related-hearing-loss accessed 13 April 2017