Medical breakthroughs in the treatment of hearing loss

May 5, 2014

The ability to hear sounds can be partially or completely impaired, resulting in hearing loss. It is one of the most common conditions affecting the elderly. There are three different types of hearing loss, depending on which part of the ear is affected. Conductive hearing loss results from a problem in the outer and/or middle ear, and sensori-neural hearing loss arises from damage in the inner ear. A combination of the two results in mixed hearing loss. The severity of hearing loss can be ranked as mild, moderate, severe or profound.

Hearing Loss is Common

Hearing loss is very common, affecting about 8% of the population overall. Hearing loss can happen at any age. About four in 1,000 babies in Singapore are born with hearing loss. More frequent excessive exposure to noises from leisure-related activities has contributed to an increasing number of children and young adults having noise-induced deafness. A study among National Service conscripts in Singapore revealed a hearing loss prevalence of almost 40 in 1,000, especially those with frequent exposure to loud noise. In the elderly, approximately one in three people between the ages of 65 and 74 has hearing loss. About 50% is expected to have significant hearing loss by 80 years of age.

Effects of Hearing Loss

Hearing-impaired people suffer certain social, psychological and physical problems as a result of their hearing loss.

Psychological Consequences

Embarrassment
Frustration
Depression
Insecurity
Low self-esteem
Lack of self-confidence

Social Consequences

Communication difficulties
Inattentiveness
Lack of concentration

Breakthrough Treatments for Hearing Loss

A person with hearing loss should consult a doctor who will look for any serious and/or treatable causes. Hearing tests can be arranged where hearing loss can be confirmed and the degree of hearing loss determined. Medications and/or surgery may be required for some causes of hearing loss. There are many forms of hearing loss, e.g., ear wax and chronic middle ear infections, for which effective treatments exist.

Although permanent loss of inner ear hair cells results in hearing loss which cannot be reversed, advancement in technology has helped to minimise the resulting disability.

Hearing Aids

Modern hearing aids are likely to benefit most patients with hearing loss. Yet, in Singapore, almost 70% of the elderly who need hearing aids are not keen on having them. This is despite the fact that 40% experience negative psycho-social effects as a result of the handicap.

One reason for this is the misguided belief that hearing aids are ineffective. While this may be true for hearing aids of the past, modern digital hearing aids have added features and processing schemes that were previously not possible, making hearing amplification better and more comfortable. With increased advancement in technology, sophisticated features are incorporated in most devices today. These include providing users with enhanced listening in noise and better appreciation of music. Besides better functioning, there is a trend towards increasing miniaturisation, which has progressed from body-worn aids, to aids worn behind the ear and in the ear canal. FM systems can be used to enhance the effectiveness of hearing aids, by improving signal-to-noise ratio.

Newer hearing aid technologies include those which can be implanted into the middle ear by surgery. The potential advantages of implantable hearing aids are the elimination of feedback and the occlusion effect, as well as improved fidelity and cosmesis. There are also bone-anchored hearing aids, where the hearing aid is fitted onto a titanium screw, which bio-integrates with the mastoid bone. This type of hearing aid is useful for patients who are not able to wear a hearing aid in the ear canal, such as those with chronic ear infections or atretic ear canals.

Cochlear Implants

For those who find hearing aids of limited benefit due to the severity of damaged hair cells, cochlear implant may be a viable option. Using electrical signals, the cochlear implant stimulates the hearing nerve directly, without the need to rely on viable cochlear-hair cells to work. The implant consists of an internal portion which is surgically placed under the skin, and an external speech processor that sits behind the ear. Following surgery, the cochlear implant is activated about a week later. In a process called MAPping, the audiologist uses customised software to set appropriate levels of electrical stimulation to allow audibility of soft sounds and at the same time, ensure uncomfortable loudness sensations are not produced. Subsequent periodic adjustments are made to optimise the sound quality.

In general, with a personal experience of more than 500 cochlear implant surgeries performed, I find this technology very effective in suitable patients. The ages of patients whom I had implanted ranged from nine months to 82 years. Increasingly, patients are opting for cochlear implants in both ears. Hearing in both ears offers better hearing in noisy environments as well as more effective localisation of the direction of sounds.

Future Directions

In cell and molecular biology, the regeneration, repair and protection of hearing cells and nerves are exciting rapidly evolving fields. Gene therapy has been shown to be an effective method of providing long-term support to hearing cells in animals. Over the last few years, much progress has been made in the molecular basis of age-related hearing loss, with the aim of preventing hearing loss in the elderly. However, the progress made so far is still largely experimental and has not been applied in routine clinically use. .

Embracing Medical Advancements

The quality of life in persons suffering from hearing loss is often negatively affected. In adults, untreated hearing loss can lead to anxiety, embarrassment and withdrawal from social contact. The good news is that in the vast majority of patients, modern technology and medical advancement can potentially alleviate the disability resulting from hearing loss.

Source: EZ Health

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