From Silence to Sound: The Brainstem Implant that is Giving New Hope to Young Patients

Seven-year-old Nurfasha has lived in complete silence her whole life despite being surrounded by a cacophony of sounds every day. She never heard her mother call her name, be startled by thunder, or danced to music.

For Siti Nuraisyah, watching her daughter navigate life in silence was both heartbreaking and inspiring. The family adapted to her needs, creating their own special language of love expressed through signs and gestures, but Siti always hoped for more for her daughter.

Hearing aids were not effective for young Nurfasha. The cochlear implant, a more conventional intervention for the hearing impaired, was also not an option because Nurfasha was born without cochlear nerves, which transmit sound signals from the inner ear to the brain.

In 2016, during what seemed like another routine follow-up consultation with Associate Professor Henry Tan of KK Women's and Children's Hospital (KKH), a possibility was presented that changed the course of Nurfasha’s life. Then, the almost-seven-year-old had recently enrolled at The Lighthouse School for the Deaf.

Assoc Prof Tan, a Senior Consultant in Otolaryngology, had a proposal to enable Nurfasha to hear: an auditory brainstem implant (ABI), but it would require her to undergo open brain surgery, which many parents would hesitate to put their children through.

If her parents agree, Nurfasha would also be the first patient in Singapore to receive this procedure. Given the procedure’s complexity, they had their initial reservations. During pre- operative counselling by the multi-disciplinary team, Assoc Prof Tan and Assoc Prof David Low , Senior Consultant, Neurosurgery, National Neuroscience Institute (NNI) discussed the potential benefits and challenges with Nurfasha’s parents, from the surgical risks to the effectiveness of ABI. For example, while the ABI would allow Nurfasha to hear, she would need to undergo long-term therapy for her brain to learn how to interpret the meaning of different sounds and this would require a big commitment from the family.

“We wanted the best for our daughter’s future and decided to go for it after an MRI scan confirmed that she was a suitable candidate for ABI,” Siti shares.

In January 2017, a multidisciplinary team, led by Assoc Prof Low and Assoc Prof Tan, performed the surgery.

Today, 14-year-old Nurfasha attends a mainstream secondary school and communicates with her peers and teachers using sign language, speech, visual aids and other tools. The teenager enjoys listening to K-pop music.

The prevalence of hearing loss

Profound hearing loss affects a significant number of infants worldwide (about five in 10,000); in Singapore, the number stands at one in 1,000 infants.

A small subset of patients are deemed unsuitable for a cochlear implant, either because they were born without cochlear nerves, like Nurfasha, or have conditions such as brain tumours which damage the auditory nerve.

In such cases, the ABI becomes the most viable intervention to give young patients a chance at leading a more normal life. The earlier ABI can be done, the better the outcome.

“The youngest patient we have operated on was under two years old. The longer we wait, the less likely it is for the brain to be able to make sense of sound, which means the patient may hear but will find it harder to develop speech or understand language,” explains Assoc Prof Tan.

In 30% of paediatric cases, ABI has helped children achieve open-set speech recognition—this means they can understand over half of what people are saying to them without knowing the conversation prior and without needing to lip-read.

For the majority of patients, they can also identify environmental sounds like traffic, making a tangible impact on their health and safety.

The success of ABI hinges not just on the surgery itself, but also the post-surgery auditory- verbal therapy, that teaches patients how to talk and make sense of sounds. Parents are active participants in therapy as well.

“We emphasise to patients that implant surgery is only the first step in a long journey. The kids have not heard anything before so therapy is critical so their brain can interpret noise into meaningful sounds. The commitment from parents to attend these sessions with their child is important,” says Assoc Prof Low.

Leading the way in treating paediatric hearing loss

Together, KKH and NNI have performed the ABI for 12 young patients since 2017, four of whom were from overseas.

The entire process involves not just a neurosurgeon who is familiar with the nerves and blood vessels around the brain stem, but also an ear, nose and throat surgeon, audiologist, auditory-verbal therapist and paediatric anaesthetist, all working together to ensure a successful procedure.

“It feels really amazing to be able to restore one of a patient’s senses. It’s life-changing for them,” says Assoc Prof Low.

From silence to sound

The most highly anticipated moment for the medical team and patients’ parents is the “switch-on” day, which happens about four to six weeks post-operation. This is when the implanted device is turned on for the first time.

“Nurfasha’s immediate response was miraculous. She was startled and cried when the device was turned on. All of us in the room became emotional,” recalls Siti.

The transformation has been nothing short of remarkable. Where there was only silence before, now there is sound to light up her world. Where there were barriers previously, now bridges have been built. "The first time she responded to her name, I cried," Siti says, smiling through tears. “It’s so surreal. I only wish she had received the implant earlier.”

The road ahead for Nurfasha is still a long one. In addition to attending therapy, she has to continue to overcome the rigours of school and work (in future) using a mixture of speech, signing and other aids. However, Siti is optimistic that with the family’s support, things will only continue to look up. “I’m so proud of her. All her hard work has paid off.”