CONDITIONS
Deafness
Causes of Deafness- Why Hearing Loss Occurs?
What is deafness?
Deafness is complete loss of hearing ability in one or both ears.
What causes deafness?
Deafness can be present from birth, or it can develop gradually over time. Gradual hearing loss is more prevalent in individuals who:
- Work in noisy environments.
- Have experienced exposure to loud machinery and tools.
Causes of hearing loss or deafness in children
Hearing loss in children can be attributed to a variety of etiologies, and the cause is sometimes unknown. It can be present at birth (congenital) or develop later (acquired). Genetic factors can lead to hearing loss either from birth or later in life.
Some genetic syndromes including down syndrome, sickle cell disease etc. may have hearing loss as one of the symptoms.
Causes of congenital hearing loss related to complications of pregnancy or birth include:
- Low birth weight
- Inner ear malformations (e.g., Mondini malformation, large vestibular aqueduct);
- Maternal diabetes
- Maternal infections (e.g., rubella, cytomegalovirus, herpes simplex virus)
- Prematurity
- Toxemia during pregnancy
Causes of acquired hearing loss in children include:
- Buildup of ear wax
- Chronic ear infections (chronic suppurative otitis media)
- Excessive noise exposure
- Head trauma (e.g., traumatic brain injury, damage to middle or inner ear structures),
- Meningitis
- Ototoxic medications
- Presence of a foreign body
- Viral infection (e.g., measles, mumps, chicken pox).
Causes of hearing loss in adults and older adults5
Hearing loss becomes more common with age. Other factors responsible for deafness in adults include:
- Exposure to loud noise
- A ruptured ear drum due to infection or trauma
- Certain health conditions like diabetes, high blood pressure, brain tumor, brain injury
- Certain medications used to treat heart diseases, infections, or cancer
- Otosclerosis (abnormal growth of bone in middle ear)
What is a difference between hearing loss and deafness?
Hearing loss: Difficulty hearing sounds like other people do.
Deafness: When an individual cannot understand speech through hearing, even when sound is increased.
Profound deafness: Total lack of hearing. An individual with profound deafness is unable to detect sound at all.
What are the symptoms of deafness?
Particularly if hearing loss is happening gradually, noticing it can be difficult. However, following are the common signs of possible deafness:
- Asking for repetitions in conversation.
- Increasing TV volume significantly.
- Struggling to hear in noisy environments.
- Speech sounding muffled.
- Avoiding conversations.
How is deafness diagnosed?
Deafness is typically diagnosed through a combination of medical history, physical examination, and specialized tests.
Medical history: The doctor will ask about symptoms, any past medical conditions, medications, and exposure to loud noise.
Physical examination: The doctor will examine ears using an otoscope to look for any visible problems in the ear canal or eardrum.
Hearing Tests: These tests can include:
- Pure-tone audiometry: A pure-tone test is the most common screening test for hearing loss. It assesses the quietest sounds detectable at various pitches. During the test, a series of high and low tones will be played through headphones. Some will be loud, and some will be very soft. Each time a tone is heard, the person will raise their hand, push a button, or indicate hearing the sound.
- Speech audiometry: This test evaluates how well individuals can hear spoken words. It provides insight into how much a hearing aid might assist. During the test, the
- individual listens to words presented at various volume levels, often in the presence of background noise. They are then asked to repeat or respond to the words they hear.
- Tympanometry: This test measures how well eardrum moves in response to changes in air pressure. A small device is inserted into the ear. The device sends air and sound into the ear, causing eardrum to move. An individual feel changes in air pressure within the ear. Movements of eardrum are recorded by a machine on graphs known as tympanograms.
- Otoacoustic emissions (OAE) test: This measures sound waves produced by the inner ear in response to sound stimuli. A tiny tool goes into the ear. It makes and listens to sounds. The sound it makes moves the fluid in the cochlea, making hair cells move too. These moving hair cells create vibrations that make a sound called OAEs. OAEs are typically present when hearing is normal or near normal and are typically absent when there is a problem in the cochlea.
- Auditory brainstem response (ABR): ABR is a test that checks hearing sensitivity and evaluates if the neural pathways within the brainstem are transmitting sound properly. It helps in detecting auditory-neurological issues. In this test, brainwave activity in the auditory parts of the brain is recorded as a response to clicks or tones played in each ear. Electrodes are placed on the head to pick up these brain responses while an individual is resting or sleeping. The process is painless and does not cause discomfort.
Depending on the results of these tests, further evaluation by an ENT doctor (ear, nose, and throat specialist) or an audiologist may be recommended. This could include imaging tests such as CT scans or MRI scans to assess the inner ear structures.
Based on the findings from the medical history, physical examination, and test results, the doctor will diagnose the type and degree of deafness, as well as its underlying cause if possible.
How is deafness treated?
Treatment depends on the cause and severity of the deafness.
- Hearing aids: A hearing aid is a device worn either behind or inside the ear that makes sounds louder.
- Cochlear implants: These devices are surgically implanted in the ear. These are especially indicated for individuals with severe hearing loss who do not find hearing aids helpful. Cochlear implants transmit sound directly to the hearing nerve.
- Teaching lip reading or sign language.
Can deafness be prevented?
While some causes of deafness, like genetic factors or certain medical conditions, may not be preventable, there are steps individuals can take to reduce their risk of hearing loss:
- Avoid exposure to loud noise.
- Do not set the volumes of TV, music players and toys too high.
- No buds for ear cleaning.
- Protect ear from injury.
- Do not practice traditional way of pouring hot oil into the ear.
- Choose headphones or earphones that cover the ears rather than earbuds inserted directly into the ear canal when listening to music.
- When working in noisy environments like discos, nightclubs, or pubs, wear earplugs or earmuffs for protection.
References
- Hearing loss association of America. Available from: https://www.hearingloss.org/hearing-help/hearing-loss-basics/types-causes-and-treatment/ . Accessed on May 2nd 2024
- National Deaf Children’s Society. Available from: https://www.ndcs.org.uk/information-and-support/childhood-deafness/what-is-deafness/. Accessed on May 2nd 2024
- Varshney, Saurabh. Deafness in India. Indian Journal of Otology 22(2):p 73-76, Apr–Jun 2016
- Hearing tests for adults. Available from: https://medlineplus.gov/lab-tests/hearing-tests-for-adults/. Accessed on May 2nd 2024 4
