Restoring the gift of hearing

According to the World Health Organization’s 2015 estimate, there are 360 million people in the world with disabling hearing loss – or 5.3 percent of the world’s population. 91 percent of these are adults and the rest are children. Luckily, there are treatment options available to restore hearing, even in cases of severe deafness, explains Dr Shailendra Sivalingam, an ear, nose and throat (ENT) specialist at Sunway Medical Centre.

What causes hearing loss?

Contrary to popular belief, hearing loss is not the sole domain of the aged. It can be brought on by a variety of factors, ranging from birth or congenital abnormalities in children to other acquired causes that affect any age group. According to Dr Sivalingam, in cases where children are born normal, developing jaundice, measles or rubella can damage their hearing permanently. “Diseases like meningitis can also cause complete hearing loss,” he says.

Acquired causes include exposure to excessive noise, viral or bacterial infections, or the use of certain antibiotics, anti-malarial medications, chemotherapy drugs, or even pain medications such as aspirin.

Hearing loss ranges from mild to severe. “If you have a mild hearing loss you can’t really understand conversation but you can hear a dog barking,” explains Dr Sivalingam. “If you have profound hearing loss you cannot pick up the sound of an airplane engine.”

Types of treatment devices available

The main types of treatment devices currently available are cochlear implants; bone anchored hearing aids (BAHA), auditory brain stem implants and standard hearing aids. The best treatment device is highly dependent on the individual’s condition.

A standard hearing aid is the only treatment that does not require surgery. A BAHA, on the other hand, is a more sophisticated hearing aid that is fixed onto the bone. While the cochlear implant is designed to completely take over the function of the cochlear – the portion of the inner ear that picks up sounds and converts them into electrical signals for the brain – a BAHA requires a functioning cochlear to work.

A BAHA differs from a standard hearing aid by being surgically fixed to the bone behind the ear, making it much more effective. “BAHAs require less power to amplify sound and the clarity is better because by anchoring it onto the bone, sounds are transmitted more effectively,” says Dr Sivalingam.

Cochlear implants, though requiring a more complex surgery than a BAHA, are suitable for those who have severe hearing loss or who are completely deaf. “The cochlear implant is one of the main treatments for people who are deaf from birth. It’s actually the only way to treat their hearing loss,” says Dr Sivalingam.

When a patient only has mild hearing loss, they still have function in the cochlea. In such cases, “something that can assist the cochlea”, such as a normal hearing aid will do the job, explains Dr Sivalingam.

In rare cases when the patient does not have a functioning auditory nerve, the cochlear implant will not work and the alternative is to use an auditory brain stem implant, which is embedded into the brain itself – a more complex surgery that is riskier and which offers lower sound quality.

Complexities of implant surgeries

Cochlear implant surgeries are more complex than BAHA surgeries. With a BAHA, a small opening is made behind the ear, under general anesthesia. “We find a suitable spot for the implant, drill in a special screw, and fix the implant onto it, that's all,” says. Dr Sivalingam. “We don't have to drill open the bone and find the cochlear like we do the cochlear implant.”

Cochlear implant surgery, however, is major. The bone is opened to insert an electrode into the cochlear, which will take over the job of receiving sound wave signals and converting them into electric signals for the brain.

Patients who were not born deaf are likely to see better and quicker results from cochlear implant surgery than those who have never been able to hear before. “Someone who was born deaf doesn’t know what sounds are like because he has never heard sounds or people speaking,” says Dr Sivalingam. “So you have to train them to understand it.”

“People who became deaf after birth should be able to achieve 80 percent of the hearing quality a normal person hears in six months,” he says. “If they continue rehabilitation, in about two to five years they can hear as well as a person with normal hearing.”

“For those who were born deaf, the percentage ranges from 60 to 70 percent in the first six months, and in two to five years they can reach 85 to 90 percent,” concludes Dr Sivalingam.

Dr Shailendra Sivalingam is an ear, nose and throat (ENT) surgeon at Sunway Medical Center. He specialises in cochlear and BAHA implants, neuro-otologic tumours, otologic diseases and surgery, tympanoplasty (eardrum repair) and balloon sinuplasty. Previously, he was a clinical fellow in otology, neurotology and base of skull surgery at Gruppo Otologico in Piacenza, Italy. He is qualified as a fellow of the European Board of Otorhinolaryngology.

Sunway Medical Centre
5, Jalan Lagoon Selatan, Bandar Sunway
46150 Petaling Jaya, Selangor, Malaysia
Tel: +603 7491 9191
www.sunwaymedical.com