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Updated 11 February 2013

Hearing loss

Hearing loss is an invisible problem which can go unnoticed for years. The sooner a hearing deficiency is diagnosed, the better.

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Definition


Hearing loss is an invisible problem which can go unnoticed for years. The sooner a hearing deficiency is diagnosed, the better.

Children should undergo hearing screening before the age of nine months. The average age children with a hearing loss are identified, is two years and four months, which is often too late: the first few years of a child's life is when they acquire speech and language and learn to communicate.

Testing must be performed by a qualified person, such as an audiologist, using a audiometer. Tests determine whether there is hearing loss, its severity, where the damage is, and what aid would be suitable.
Hearing loss is graphed on an audiogram.

Alternative names


Decreased hearing; deafness; loss of hearing.

Possible causes


Hearing impairment has two main causes: the dominant one, genetic (inherited); and acquired causes.

Inherited causes


Of all types of inherited deafness, one third is present at birth, another third starts during childhood, and the rest manifest in adulthood.

Acquired causes


There are many ways in which people acquire hearing loss:
Pre-birth:
  • German measles and other infections:

If the mother gets German measles during the first eight weeks of pregnancy there is an 86% chance her baby will be hearing impaired. The disease appears to be dangerous throughout pregnancy. During the first 28 days of pregnancy, exposure to cytomegalovirus is also dangerous.
  • Rhesus incompatibility and other factors:

  • Metabolic illnesses such as diabetes and thyroid problems also pose a risk. During and just after birth:

    Birth injuries, jaundice and a lack of oxygen can all damage hearing. After birth:

    • Viral and bacterial infections such as meningitis

    • Drug toxicity

    • Excessive noise exposure

    • Middle ear infection (the most common type caused by a build-up of fluid in the middle ear)

    • Head trauma
      Another cause of hearing loss is a condition known as presbycusis, which occurs slowly as people age. It is believed to be hereditary.

    Types of hearing loss


    Hearing loss is normally divided into two categories: conductive hearing loss, and sensorineural hearing loss, depending on where the hearing loss originates in the ear. One can also have a mixed hearing loss, which is a combination of the two. This distinction is key in providing proper treatment.

    Conductive hearing loss
    This may be caused by:

    • Middle-ear infection (otitis media): Infection of the middle ear is a common disorder, especially in young children. An acute infection is very painful and should be treated immediately. If not, a rupture of the eardrum may follow. A healthy eardrum will typically heal itself by closing the rupture with scar tissue. However, an accumulation of scar tissue following many episodes of infection can cause a conductive hearing loss which may be difficult to reverse.

    • Cerumen (earwax) or other debris. If this is removed by a professional without complication, the hearing is typically fully restored.

    • Fractured chain of bones.

    • Perforated eardrum.

    • Outer ear deformity.

    • Otosclerosis.

    Sensorineural hearing loss
    Into this category fall:

    • Congenital conditions, which implies that your child was born with hearing loss, stemming from a known or unknown history. It may be a consequence of genetic syndromes, like Down’s syndrome; or factors during pregnancy, such as use of alcohol, drugs or medications; or illnesses contracted by the mother before or during pregnancy; or complications during labour.

    • Acoustic trauma: regular exposure to excessively loud sounds or a brief exposure to sudden impact sounds can cause sensorineural hearing loss. Fireworks and cap guns are often cited.

    • Illness and infections: severe cases of certain infections such as measles, mumps, meningitis or whooping cough can lead to various degrees of sensorineural hearing loss.

    • Ageing.

    Homecare/ self treatment


    Should the hearing loss be the result of wax build-up, the ear could be gently and regularly flushed out with ear syringes or wax softeners.

    When to see a doctor


    The symptoms of hearing deficiency are varied, so it is better to seek medical attention if you experience any of the following symptoms:
    • frequent earaches

    • frequent colds with ear discharge

    • lack of attention to casual conversation

    • if the child is late to start talking

    • verbal directions are often ignored

    • a lack of social involvement and social withdrawal

    • difficulty in speech, or hearing mumbling when people talk

    • frequent confusion and misunderstanding conversations, often leading to inappropriate responses or asking people to repeat themselves

    • regular visual scanning of someone's face when they're talking or turning the head to one side when paying attention

    • reading disability and/or spelling errors

    • needing to turn up the volume on the TV or radio

    What to expect at the doctor


    The doctor will require your medical history and perform a physical examination. Some of the information the doctor will need includes:
    • if the hearing loss is in both ears or one ear;

    • the severity of the hearing loss (mild, severe or complete inability to hear any sound);

    • if words sound garbled;
    • how long the loss of hearing problem has been present and if it occurred before the age of 30; and

    • if there is ringing or other sounds (tinnitus) or ear pain.

    At the physical examination diagnostic tests will be performed. These include:

    • an audiometry test (an electronic hearing test);

    • an auditory response test;

    • a CT scan of the head (if a tumour or fracture is suspected);

    • a head X-ray;

    • a tympanometry test (for detection of disorders of the middle ear);

    • a caloric test (test using differences in temperature to diagnose ear nerve damage); and/or

    • an MRI of the ear.

    Treatment


    There are as many treatments as there are types and degrees of hearing loss:
    • Hearing aid: This is a small system which amplifies sound. It consists of a microphone, an amplifier and a receiver. Hearing aids differ in size – from the behind-the-ear type to very small, almost unnoticeable hearing aids which fit in the ear canal.

    • Cochlear implants: An electrical apparatus is surgically implanted into the bone behind the ear. It consists of a microphone (which receives sounds), a speech processor (which selects usable sounds), and a coil (which decodes and sends electric impulses to the electrodes). These components are worn externally.

     
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