14 September 2010
By Risha Chitlangia
New Delhi, India
Soon, four-yearold Fatima will be able to hear when her mother shouts her name. An Iraqi national, the child suffered from profound deafness since birth. Her parents had lost all hope when doctors told them Fatima was not eligible for a cochlear implant surgery, as she suffered from bilateral sensorineural hearing loss with underdeveloped cochlea – the auditory portion of the inner ear – and auditory nerve. But the family is now jubilant after doctors at Indraprastha Apollo Hospital in a rare surgery carried out an auditory brain stem implant.
On August 25, doctors made an opening at the back of her skull and entered the brain stem to place the implant. First, a receiver stimulator was subcutaneously placed behind her right ear. "The stimulator is connected with an electrode array – which has 21 platinum contact points – through a wire. We made a hole in the skull to reach the brain stem. We located the cochlear nucleus and implanted the electrode array," said Dr Kishore.
The biggest challenge was to place the electrode in the brain stem. Even a minor mistake can prove to be fatal or cause paralysis. "It is a difficult surgery. In a normal hearing process sound waves are transmitted to the ear. They travel from the eardrum through the middle ear to the cochlea, where sound waves get converted to electrical impulses. These electrical impulses travel through the brain stem to the hearing centre of the brain. In this case, however, the middle link was missing and we had to make a passage to deliver electrical impulse directly to the brain centre," said Dr Pranav Kumar, neurosurgeon, who was in the team that performed the 8-hour surgery.
The implant was successfully placed and doctors tested it while Fatima was still in the operation theatre. "It is important to check whether the implant works or not while operating. We can’t take the risk of opening the skull again. We electrically invoke the auditory brain stem and study its response. We can also then finetune the implant," said Dr Kishore.
Four-year-old Fatima, an Iraqi national, was born deaf. In a rare surgical procedure, an auditory implant was placed inside her brain stem. Four weeks from now, Fatima will be able to hear
Doctors say, 3-4% of people suffering from severe to profound deafness are ideal candidates for this surgery
In such patients, the cochlea is either damaged or absent. And the cochlear nerve or the auditory nerve – which carries electrical signals to the brain – is also missing
Duration of surgery |
- A receiver stimulator is subcutaneously placed behind the ear
- A hole is drilled in the skull to reach the brain stem
- The stimulator is connected through a wire to an electrode array which has 21 platinum contact-points
- Electrode array is placed in cochlear nucleus in brain stem
- Surgeons test the implant by stimulating auditory brain stem