Cochlear implants can improve quality of life for the elderly, not just children with congenital hearing loss.
Hearing loss in the elderly is a growing concern in Singapore, affecting about a third of those over 65 years old. However, the condition can be improved with a number of options, including a cochlear implant.
Usually associated with children with congenital hearing loss, a cochlear implant is recommended when hearing aids are not enough to correct poor hearing.
“A hearing aid amplifies sound and passes the amplified sound through the external to the middle and inner ear. The cochlear implant, however, bypasses this usual route and directly stimulates the hearing nerve in the inner ear or cochlea,” said Dr Vanessa Tan, Consultant, Department of Otorhinolaryngology-Head and Neck Surgery, Singapore General Hospital (SGH).
Cochlear implants have been used for more than half a century; at SGH, it has been used since 1997 for both adults and children. With improved technology, today’s implants are smaller and slimmer than the early devices, and compatible with magnetic resonance imaging (MRI). Initially, cochlear implants were used for patients with severe-to-profound hearing loss in both ears.
“Now they can be used in patients with ski-slope pattern of hearing loss, where there is severe-to-profound hearing loss only over certain frequencies, typically the mid to high frequencies,” said Dr Tan, who is also Director, SGH Centre for Hearing and Ear Implants.
Cochlear implants can also help restore hearing in patients with single-sided deafness. Hearing with both ears is important, allowing one to identify where sounds are coming from and to hear better in noisy situations.
Patients with hearing loss first undergo a variety of tests, including with the most powerful hearing aids. If they are unable to hear adequately even with the best hearing aids, they may be candidates for an implant.
The cochlear implant team — comprising the ear, nose and throat (ENT) surgeon, auditory verbal therapist and audiologist — then takes the patient through the journey of cochlear implantation.
The procedure is done under general anaesthesia, and takes about two to three hours, with the patient usually discharged the day after surgery. The audiologist will activate the implant about three weeks after the surgery. Programming of the implant, known as mapping, is done to maximise speech sounds heard by the patient. Mapping sessions are performed regularly to get the best outcome from the implant.
Hearing well is important for both young and old alike, said Dr Ng Jia Hui, Consultant, Department of Otorhinolaryngology-Head and Neck Surgery, SGH. Hearing is crucial to a child’s speech and language development, while studies have shown that hearing loss is linked to cognitive decline and dementia in older people. “One study demonstrated that every 10dB (decibel) drop in hearing can lead to a 20 per cent increased risk of developing dementia. This is not surprising, as many activities in the daily living of elderly people require them to hear well,” she added.
Other aspects of healthy ageing may be impacted too when hearing is impaired. These include social engagements, physical mobility and activity, as well as falls and vitality.
SGH has conducted about 600 cochlear implants to date. Its youngest cochlear patient was 10 months old, while the oldest was 86 years old.
How implants work Cochlear implants directly stimulate the hearing nerve and send strong sound signals to the inner ear. During surgery, one component is placed under the skin behind the ear and another outside the ear to collect, process and transmit sound to the internal component.
The sounds received via an implant are different from a hearing aid, with some patients describing what they hear as “cartoonish” or “robotic”. The sound quality improves over time as the brain
re-trains itself to hear and interpret the sounds received.
The internal component lasts the patient’s lifetime; in extremely rare circumstances, a replacement via a second surgery may be needed. The external component is fitted with rechargeable
batteries, and can be upgraded every five to seven years if needed.
Wearers should not participate in contact or vigorous sports to avoid damaging the electronic external component, while a waterproof casing lets them hear while swimming.
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