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THE recent announcement by Japanese pop princess Ayumi Hamasaki that she has gone deaf in her left ear has created much awareness in the media about hearing problems.

The media has also highlighted recent studies in the US and Hong Kong that prolonged listening to MP3 players significantly increases the risk of hearing loss later in life.

These facts are not new as Ludwig van Beethoven, the famous German composer, was known to be deaf and suffering from tinnitus (persistent ringing noise in the ear). Loud rock music has been shown to contribute to hearing loss.

Hearing is very much part of our everyday life, and most of us take it for granted. Hearing loss is the second highest registered disability in Malaysia. Statistics from the Welfare department reported 26,294 such disabilities in 2005 alone.

Sound waves travel through air to reach our eardrums. These in turn pound on the little bones called ossicles in the middle ear, to be transmitted into waves in the fluid within the cochlea of the inner ear. It is these waves that stimulate the hair cells, which in turn send electrical impulses to our brain to be perceived as sound.
Any disruption or damage to this pathway can cause hearing loss.

Hearing loss in children
About one in every 1000 school-age children in metropolitan Atlanta in the US has moderate to profound bilateral hearing loss. In the 1988 National Health Interview Survey – Child Health Supplement, parents reported that 3.5% of children (aged from birth to 17 years) in the United States had “deafness or trouble hearing” in one or both ears. These affect their speech, language, cognitive and psychological developments.

Children born with hearing loss are thus afflicted due to genetic factors (more than 50% cases), intrauterine infections (rubella, cytomegalovirus and herpes simplex virus), prematurity, maternal diabetes, toxaemia during pregnancy and lack of oxygen during birth (anoxia).

Acquired hearing loss is hearing loss that appears after birth. This can be as a result of disease, infections or injury. Some of the causes include ear infections (otitis media), ototoxic drugs (drugs that damage the auditory system), meningitis, measles, encephalitis, chicken pox, influenza, mumps, head injury and noise exposure.

Hearing loss in adults
Adults can acquire hearing loss pretty much the same way as children. Our hearing deteriorates as we grow older. In the 1994 National Health Interview Survey Core and Second Supplement on Aging, one third of adults aged 70 and older reported that they had trouble hearing. Seven percent reported that they were deaf in both ears and 8% reported that they were deaf in one ear.

Otitis media
Otitis media is an inflammation in the middle ear (the area behind the eardrum) that is usually associated with build-up of fluid. Children often present with inattentiveness, wanting the television louder than usual, misunderstanding instructions, listlessness, unexplained irritability and pulling or scatching at the ears.
Older children and adults will notice some hearing loss. Pain is a symptom when there is acute infection.
Otitis media can resolve on its own but requires treatment if it is persistent or if there is acute infection. Antibiotics are usually prescribed, but if the condition recurs or persists, grommets (little plastic ventilating tubes) can be inserted for immediate relief of symptoms.

In older children and adults, nasopharyngeal cancer must be excluded by the doctor.

Sensorineural hearing loss
This type of hearing loss is due to damage or degeneration of the inner ear, including its nerve (vestibulocochlear nerve).

Certain drugs, including high doses of antibiotics such as gentamicin (that may be required for severe infections), can cause sensorineural hearing loss. These drugs damage the hair cells in the cochlea. Infections, as mentioned earlier, can also damage these hair cells.

As we grow older, the hair cells degenerate. Constant exposure to loud noise (more than 85 decibels for eight hours or more per day) can do the same.

There is no cure for sensorineural hearing loss. Hearing aids help to amplify sound for sufferers. Cochlear implants help improve hearing in patients with profound sensorineural hearing loss.

Sudden sensorineural hearing loss is fortunately rare. If treated early, the majority do recover. Its cause is unknown but viral and sudden reduction in blood supply to the inner ear are possible causes.

Meniere’s disease (endolymphatic hydrops) is a condition that presents with repeated attacks of vertigo (dizziness), tinnitus and hearing loss. It is believed to be an auto-immune condition whereby the body produces antibodies that cause the endolymphatic sac to swell. It can be treated with medications and if severe, operations can help relieve its symptoms.

Other types of hearing loss are rare.

Otosclerosis is due to fixation of the stapes bone (the smallest bone in our body) to its footplate. It is more common in Caucasians and people from the Indian subcontinent. Sufferers find hearing aids useful. Operations can also help.

Ear tumours giving rise to hearing loss are rare. Acoustic neuroma is a benign tumour of the vestibulocochlear nerve that gives rise to sensorineural hearing loss and sometimes tinnitus and vertigo. It can be treated by external radiation therapy or surgery.

Chronic suppurative otitis media is a condition caused by chronic inflammation of the middle ear, giving rise to persistent ear discharge, pain and hearing loss. The eardrum is usually perforated. This condition requires a mastoid operation to improve symptoms.

It is important to consult a physician if one suffers from hearing loss. Treatment is directed at the cause of such hearing loss.

Even if there is no treatment, such as in the case of unilateral sensorineural hearing loss, it is important for the sufferer to understand his or her condition.